Dụng Cụ Chỉnh Hình Và Chân Tay Giả Trong Phục Hồi Chức Năng (Ấn Bản Thứ 3)

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Section II  Orthoses in Rehabilitation
drop test, talar bulge) provide an elementary method to
identify an MTJ unable to lock.
An ineffective locking mechanism at the MTJ is often
more clinically significant than the absolute degree of fore­
foot deformity. For example, a forefoot varus deformity of
3 degrees with a poor MTJ locking mechanism may be symp­
tomatic, whereas an 8-degree forefoot varus deformity with a
normal MTJ locking mechanism may not be.
Identifying Forefoot Deformities
Although the prevalence of forefoot deformity, with or with­
out symptoms, is well documented, less agreement exists
regarding which types of deformity are most common.47,61
If an individual has bilateral forefoot deformity, the deformi­
ties may not be of the same severity or type. MTJ deformi­
ties change the location of the lock of the forefoot against the
rearfoot.4 Although these osseous frontal plane deformities
alter the direction of motion, they do not limit the total ROM
of the MTJ.4 In forefoot varus, locking of the forefoot occurs
in an inverted position relative to the rearfoot.4 Forefoot
varus results from ontogenetic failure of the normal valgus
rotation of the head and neck of the talus in relation to its
body during early childhood development.4,45,55
Compensations for foot deformities are viewed in a relaxed
weight-bearing position referred to as relaxed calcaneal stance
(RCS). When excessive pronation of the STJ compensates for
the deformity on weight bearing, the condition is called a
compensated forefoot varus (Figure 8-12A). When the STJ
cannot adequately pronate to accommodate an inverted fore­
foot, an uncompensated forefoot varus is present. The medial
forefoot does not make contact with the ground, and the lat­
eral forefoot is subjected to excessive pressure. Thick callus
develops beneath the head of the fifth metatarsal, and the risk
of stress fracture is increased. Plantarflex of the first ray and
pronation at the MTJ are common compensations that allow
the medial forefoot to make contact with the ground (see
Figure 8-12B). Persistent MTJ stress may lead to joint damage
and excessive forefoot abduction and eversion.
Forefoot valgus occurs in the frontal plane deformity,
locking the forefoot in eversion relative to the rearfoot.4 Root
suggests that this deformity results from ontogenetic overro­
tation of the talar head and neck in relation to its body dur­
ing early childhood development.4,45,55 Forefoot valgus can
be a rigid or flexible deformity. In rigid forefoot valgus, the
compensatory weight-bearing mechanism occurs at the STJ
as excessive supination or calcaneal inversion. It is a result of
excessive premature GRFs at the first metatarsal head, caus­
ing rapid STJ inversion and increasing loading forces beneath
the fifth metatarsal head. Thick callosities are often present
beneath the first and fifth metatarsal heads. In contrast, flex­
ible forefoot valgus is usually an acquired soft tissue condi­
tion. It most often occurs as a consequence of uncompensated
rearfoot varus as an attempt to increase weight bearing along
the medial foot. Because this deformity is flexible, no com­
pensatory mechanism is necessary. Contact force beneath the
first metatarsal head simply pushes it up out of the way, and
the foot functions as if this condition were not present.
1
2
3
4
5
Calcaneus
everted
A
B
1
2
3
4
5
Forefoot
inverted
First ray
plantar flexed
FIGURE 8-12  A, In relaxed calcaneal stance, compensation for a
forefoot varus deformity is normally subtalar joint pronation, result­
ing in an everted calcaneus. B, In an uncompensated forefoot varus,
the subtalar joint is unable to compensate. Instead, the first ray plan­
tarflexes to achieve weight bearing medially on the foot. (Courtesy
Stride, Inc., Middlebury, Conn.)

Chapter 8  Foot Orthoses
193
The First Ray
Assessment of first ray position is also carried out in STN
position. Ideally, the first ray lies within the common trans­
verse plane of the lesser metatarsal heads. To examine mobil­
ity of the first ray, the examiner holds the first metatarsal head
between the thumb and index finger and performs a dorsal
and plantar glide while stabilizing the lesser metatarsal heads
with the other hand. Normally, first ray movement is at least
one thumb width above and below the plane of the other
metatarsal heads.4
As stance phase is completed, activity of the peroneus lon­
gus creates a pronatory twist of the forefoot, stabilizing the
medial column of the foot on the ground, locking the MTJ
about its longitudinal axis, and converting the foot to a rigid
lever for propulsion. Adequate plantarflex of the first ray must
be present for conversion from flexible forefoot to a rigid
lever. Three factors determine how much first ray plantarflex
must occur: amount of inversion of the foot at propulsion,
width of the foot, and length of the second metatarsal.4 The
more the foot inverts during propulsion, the further the first
ray must plantarflex to make ground contact. Elevation of
the medial forefoot is related to foot width; wide feet require
more first ray plantarflex. An excessively long second meta­
tarsal also increases the distance that the first ray must plan­
tarflex to make ground contact.
In some instances, the first ray is inappropriately dorsi­
flexed above the plane of the other metatarsals, resulting in
restriction of plantarflex and impeding normal propulsion.
The first ray may also be plantar flexed below the plane of
the other metatarsals. In uncompensated rearfoot varus, for
example, the eversion motion of the calcaneus is insufficient,
the medial condyle fails to make contact with the ground,
and excessive weight bearing is present on the lateral border
of the foot. The peroneus longus contracts to pull the first
metatarsal head toward the ground in an attempt to load the
medial side of the foot. This action is possible because of the
cuboid pulley system (Figure 8-13).4 When the STJ remains
abnormally pronated in late stance phase, orientation of the
cuboid tunnel is altered and the mechanical advantage of the
peroneus longus is lost. The MTJ cannot lock, and the foot is
unstable throughout propulsion.
The presence of a rigid plantar flexed first ray some­
times results in a functional forefoot valgus (Figure 8-14).
A
D
B
C
A
D
B
C
A
B
FIGURE 8-13  A, Cuboid pulley mechanism in a normal foot. B, In an abnormally pronated foot, the
mechanical advantage of the peroneals is impaired. A, Talus; B, calcaneus; C, cuboid; D, the cunei­
forms. (Courtesy Stride, Inc., Middlebury, Conn.)
1
2
3
4
5
Compensatory
STJ
supination
FIGURE 8-14  Plantarflexed first ray deformity in relaxed calcaneal
stance. Compensation occurs at the subtalar joint, with lateral gapping
and medial compression. (Courtesy Stride, Inc., Middlebury, Conn.)

194
Section II  Orthoses in Rehabilitation
The compensatory mechanism for this condition is similar
to that for rigid forefoot valgus: STJ supination or calcaneal
inversion on weight bearing to lower the lateral aspect of the
foot to the ground.
The Hallux
In normal gait, dorsiflexion of the hallux occurs during the
late propulsive phase as the body moves forward over the
foot. Sagittal plane motion of the hallux is assessed as passive
ROM. The stationary arm of the goniometer is positioned
along the medial first metatarsal and the mobile arm along
the medial proximal phalanx of the hallux. The axis is medial
to the first MTP joint.54 Sufficient force is applied to bring the
hallux to its end ROM. Normal range of hallux dorsiflexion is
between 70 and 90 degrees.4,54
In hallux limitus deformity, pathomechanical function­
ing of the first MTP joint prevents the hallux from mov­
ing through its full range of dorsiflexion during propulsion.
Repetitive trauma to the first MTP joint can lead to ankylosis,
or hallux rigidus. Functional hallux limitus is a condition in
which full first MTP ROM is present when non–weight bear­
ing, but a functional restriction of hallux dorsiflexion occurs
during gait. Functional hallux limitus disrupts the normal
windlass mechanism previously described.62,63
Limitation of hallux dorsiflexion prohibits the normal pro­
gression of the foot and interferes with propulsion of the body
over the hallux. Several gait compensations can overcome this
limitation.62,63 An abducted or toe-out gait pattern shifts pro­
pulsion to the medial border of the hallux. A pinched callus
then develops from friction between the hallux and shoe dur­
ing propulsion. Alternatively, the IP joint of the hallux may
hyperextend, causing a callus in the sulcus of the IP joint.
Hallux abductovalgus (HAV) is a progressive, acquired
deformity of the first MTP joint that eventually results in a val­
gus subluxation of the hallux.4,45 This deformity is caused by
abnormal STJ pronation with hypermobility of the first ray.4
A common misconception is that HAV is hereditary.
Although the congenital osseous abnormalities that lead to
aberrant STJ pronation are hereditary, HAV occurs to com­
pensate for these other deformities. Another misconcep­
tion is that HAV is caused by restrictive footwear. Although
inappropriate or restrictive footwear can accentuate or
speed the progression of HAV deformity when present, the
deformity is frequently observed in populations that do not
typically wear shoes.4,45
Additional Observations
Several other important observations are made as the non–
weight-bearing examination is completed. Non–weight-
bearing arch height is observed for later comparison to
weight-bearing arch height as a composite estimate of
foot pronation. Toes are inspected for positional deformi­
ties such as hammertoe, claw toe, crossover deformity, and
the presence of bunions or bunionettes. The plantar foot is
checked for callus, plantar warts, or other signs of excessive
pressure. The shoes are inspected for excessive or uneven
wear patterns.
STATIC WEIGHT-BEARING CLOSED KINETIC
CHAIN EXAMINATION
The open chain kinetic motion evaluated in the non–weight-
bearing examination is dramatically different from the
functional sequence of events in the closed kinetic chain of
standing and walking. Open kinetic chain pronation (calca­
neal dorsiflexion, eversion, and abduction) and supination
(calcaneal plantarflex, inversion, and adduction) are tripla­
nar motions around the STJ.4,13,29 During closed kinetic chain
pronation, internal rotation of the leg is coupled with talar
adduction and calcaneal plantarflex and eversion. Closed
kinetic chain supination couples external rotation of the leg
with talar abduction and calcaneal dorsiflexion and inversion.
In the open kinetic chain, movement is initiated in the distal
segment (the foot). In the closed kinetic chain, motion is ini­
tiated proximally (at the tibia and talus). A thorough closed
kinetic chain examination includes static postural observa­
tions, dynamic motion testing, and gait assessment.
Compensatory mechanisms that result from intrinsic
deformities are assessed as the foot is subjected to GRFs dur­
ing the static weight-bearing examination. This provides
valuable insight regarding how the body compensates for
the intrinsic foot deformities or impairments of normal foot
joint function identified in the non–weight-bearing examina­
tion. Improper foot functioning can lead to a complex series
of compensations that influence the mobility patterns of the
foot and lower leg, as well as the knee, hip, pelvis, and spine.
The patient stands in a relaxed, weight-bearing posture
(RCS). The examiner observes the patient's preferred stance,
noting postural alignment and foot placement angle. The
patient then adjusts the stance position, if necessary, to assume
equal weight-bearing double-limb support, with feet 5 to 10 cm
apart and oriented in neutral toe-in and toe-out foot placement
angle. This adjusted posture, with neutral foot placement angle,
offers a better frame of reference for assessing planar alignment
and enhances the reliability and consistency of the measure­
ment.41 Postural alignment or body symmetry of the patient is
evaluated in the frontal, sagittal, and transverse planes.
Frontal Plane
Static weight-bearing examination in the frontal plane
focuses on the angular relation of the calcaneus and the tibia
and fibula with respect to the floor and the relation between
the pelvis and the lower leg.
Calcaneal Alignment to the Floor
With the patient in double-limb stance posture, a line bisect­
ing the posterior surface of the calcaneus is visualized and the
angular relation between the line and the floor taken. Because
the infracalcaneal fat pad often migrates (related to prolonged
weight bearing), care must be taken to avoid errors in visual
assessment (Figure  8-15). Palpation of the osseous medial,
lateral, and inferior borders of the calcaneus helps factor
out fat pad migration and improve measurement accuracy.
Calcaneal alignment can also be quantified with a protrac­
tor to measure the degree of calcaneal tilt relative to vertical.64

Chapter 8  Foot Orthoses
195
The key question to answer is whether the calcaneus is
inverted, vertical, or everted relative to the floor during stance;
the actual angular degree is not as important as the relative
orientation of the calcaneus. This component of the exami­
nation assesses the ability of the STJ to provide enough pro­
nation to compensate for its neutral position. In the normal
closed chain STN position, the calcaneus is in 1 to 4 degrees
of varus (inversion). The STJ must have an equal amount of
compensatory pronation to lower the medial condyle to the
ground for a vertical calcaneus. If a patient has uncompen­
sated rearfoot varus of 10 degrees in STN as well as restricted
calcaneal motion (−4 degrees) eversion, the STJ would not be
able to achieve sufficient pronation or eversion in stance for
normal calcaneal alignment. Instead, the calcaneus would be
in an inverted alignment relative to the floor. Inverted calca­
neal position also occurs when a rigid forefoot valgus or rigid
plantarflexed first ray deformity is present. STJ supination is a
compensatory mechanism for both deformities.
In contrast, forefoot varus deformity requires excessive com­
pensatory STJ pronation; calcaneal eversion occurs in weight
bearing. The position of the calcaneus with respect to the floor
provides insight into the type of STJ compensation present and
can be correlated with the biomechanical findings of the non–
weight-bearing examination. If the STJ is unable to pronate
enough to compensate completely for a deformity, additional
pronatory motion occurs at the MTJ or by eversion tilting of
the talus within the ankle mortise.4,41,48 The functional rearfoot
unit (calcaneus and talus) may assume a valgus (everted) posi­
tion relative to the floor, even if calcaneal eversion is restricted.
Tibiofibular Alignment
Proximal structural malalignments, such as tibial varum or
valgum, contribute to abnormal foot pronation and overuse
injuries. In osseous congenital tibial varum, the distal third of
the tibia is angled medially in the frontal plane, whereas in
tibial valgum, the distal tibia inclines away from the midline.41
Tibial alignment can be measured with either a standard
goniometer (Figure 8-16) or a bubble inclinometer; both assess
the angular relation between the bisection of the distal third of
the lower leg relative to the supporting surface.41,65 Radiographic
measurement of lower leg position is better correlated with clin­
ically assessed tibiofibular position values than with isolated
tibial position. Radiographic measurement may be the most
accurate method to isolate true tibial varum.66
A
B
FIGURE 8-15  A, Calcaneal alignment to floor. B, Lateral migration of the infracalcaneal fat pad can
give the illusion of an everted calcaneal to floor alignment. (Courtesy Stride, Inc., Middlebury, Conn.)
FIGURE 8-16  Goniometric assessment of tibiofibular varum. The
proximal arm of the goniometer is aligned with the bisection of the
distal third of the tibiofibular complex, and the distal arm is level
with the floor. The axis of measurement shifts with the degree of
varum or valgum deformity and may not always fall directly behind
the calcaneus.

196
Section II  Orthoses in Rehabilitation
Test position is critical because variation in STJ alignment
greatly influences tibiofibular varum measurement values.
Tibiofibular varum values are larger in RCS than in the STN
position because of the combined effects of osseous malalign­
ment and varus leg alignment associated with compensatory
STJ pronation in stance.65–67 The incidence of tibiofibular
varum appears to be high, although no clear normative val­
ues have been established.
The alignment of the distal third of the leg relative to the
floor more accurately represents tibiofibular position than
tibial position. Values assessed in STN reflect neutral tibio­
fibular alignment, whereas values assessed in RCS represent
compensatory tibiofibular repositioning in response to STJ
and MTJ pronation. High tibiofibular varum values mea­
sured in STN elevate the medial foot from the supporting sur­
face, requiring excessive compensatory foot pronation during
gait. High tibiofibular varum values in RCS suggest excessive
foot pronation, although the source of that pronation cannot
be isolated.
Alignment of the Pelvis and Lower Leg
The final component of the frontal plane assessment evalu­
ates symmetry of the anterosuperior iliac spines, iliac crests,
greater trochanters, gluteal folds, popliteal creases, genu
varum or valgum deformities, fibular heads, patellae, and
malleolar levels. Asymmetry often indicates sacroiliac joint
dysfunction or leg length discrepancy, influencing foot posi­
tion and function in the closed kinetic chain.
Sagittal Plane
The second component of the weight-bearing examina­
tion considers function in the sagittal plane. The examiner
looks for evidence of genu recurvatum or excessive knee flex­
ion, navicular drop, talar bulge, and inadequate or excessive
height of the longitudinal arch.
Knee Position
Viewing the patient's stance from the side, the examiner
observes the verticality of the tibia. In genu recurvatum, the
proximal tibia is aligned behind the axis of the TCJ, resulting
in hyperextension of the knee and plantarflex of the TCJ with
relative shortening of the limb. Genu recurvatum also occurs
as a compensation for equinus deformity at the ankle. When
true leg-length discrepancy is present, two types of compen­
sation are possible. If limb length difference is small, genu
recurvatum may adequately shorten the longer limb. For
larger limb length differences, knee flexion of the longer limb
is often used to minimize asymmetry.
Navicular Drop
The position of the navicular is examined by using the navic­
ular drop test, a composite measure of foot pronation focus­
ing on displacement of the navicular tuberosity as a patient
moves from closed kinetic chain STN to RCS position.68
Excessive navicular displacement is associated with col­
lapse of the MLA and may be correlated with midfoot pain
or other symptoms of excessive foot pronation.41 Subotnick69
established an interdependency between MTJ and STJ func­
tion based on articulation of the navicular and cuboid with
the talus and calcaneus. Brody68 suggested that the navicular
drop test is a valid assessment of STJ function in the closed
kinetic chain. Although navicular drop occurs with STJ pro­
nation that stems from intrinsic foot deformity, it can also be
the result of muscle insufficiency or ligamentous laxity.41
To measure navicular drop, an index card is held perpen­
dicular to the medial foot, the level of the navicular tuberosity
is marked in STN position and RCS, and the distance between
the marks is calculated.38 Normative studies report a mean
navicular drop of between 7.3 and 9 mm.39,70 A navicular drop
of more than 10 mm is considered abnormal.70
Talar Bulge and Arch Height
When excessive STJ pronation is present in stance, the talus
moves into adduction and plantarflex. Displacement of the
talar head causes an observable medial bulge in the region
of the talonavicular joint.71 The height of the MLA normally
decreases moderately in weight bearing as a result of normal
STJ pronation. Pes planus deformity (flatfootedness) is char­
acterized by excessive collapse of the MLA. In hereditary rigid
flatfoot, the MLA is low or absent in non–weight-bearing and
weight-bearing positions. In flexible flatfoot, the height of the
MLA is normal in non–weight bearing but drops excessively
in weight bearing because of abnormal STJ pronation. In nor­
mal foot alignment, the medial malleolus, navicular tuberosity,
and first metatarsal head fall along the Feiss line.71 In a severely
pronated foot, the navicular tuberosity lies below the Feiss line.
In extreme cases the tuberosity may even rest on the floor.71,72
Transverse Plane
The final component of the static weight-bearing exami­
nation considers foot function in the transverse plane. The
examiner looks for signs of excessive pronation or forefoot
adduction and torsional deformities of the lower extremities.
Toe Sign
A positive toe sign indicates excessive pronation or abduction
of the foot in the transverse plane (Figure 8-17). The sign is
determined by the number of toes that can be seen, in a pos­
terior view, when the patient is standing in RCS with a neu­
tral foot placement angle.63 Normally no more than 1.5 toes are
visible beyond the lateral border of the foot. If more toes can
be seen, abnormal pronation may be present, causing exces­
sive transverse plane motion or abduction of the foot. A false-
positive toe sign can occur in the presence of a relative toe-out
foot placement angle associated with lateral rotational deformi­
ties (e.g., femoral retroversion) or muscle imbalances that limit
internal rotation of the hip (e.g., tight piriformis). Ensuring that
the patient's patellae are oriented in the frontal plane before
assessing toe sign reduces the risk of false-positive findings.
Torsional Deformities
Transverse plane abnormalities of the femur and tibia also
adversely affect normal foot functioning. The femoral shaft
normally has 12 degrees of medial rotation relative to the

Chapter 8  Foot Orthoses
197
femoral head and neck (Figure  8-18). In femoral antever­
sion more than 12 degrees of rotation are present, whereas
in retroversion, fewer than the expected 12 degrees of medial
rotation are present.71 In normal transverse plane tibial align­
ment, the fibular malleolus is situated posterior to the tibial
malleolus, for 20 to 30 degrees of lateral rotation.71 Internal
tibial torsion or femoral anteversion increase medial rota­
tional forces, leading to abnormal foot pronation. Excessive
external tibial rotation or femoral retroversion increases lat­
eral rotational forces, leading to abnormal foot supination.
To assess femoral torsion, the patient lies in the prone
position with the knee in 90 degrees of flexion.41 The exam­
iner palpates the greater trochanter as the lower limb is pas­
sively moved laterally (representing hip internal rotation)
and medially (representing hip external rotation). Femoral
torsion is measured at the point where the greater trochan­
ter is most prominent (Figure 8-19). When there is “normal”
anteversion of 12 degrees, tibial position will indicate slight
internal rotation of the hip. A vertical tibia indicates femoral
retroversion.
Tibial torsion is assessed with the patient in the supine
position, with 90 degrees of ankle dorsiflexion and the leg
placed neutrally in the frontal plane (Figure 8-20). The exam­
iner holds the stationary arm of the goniometer parallel to
the table surface while the mobile arm is aligned with the TCJ
axis as it passes through the medial and lateral malleoli. This
angular displacement represents tibial torsion. Normally, 20
degrees of external tibial torsion are present.
DYNAMIC GAIT ASSESSMENT
The final component of the clinical evaluation is observation
of foot function during walking. During the dynamic gait
assessment, extrinsic factors that affect foot function (e.g.,
muscle imbalances or weaknesses, proximal structural defor­
mities, kinesthetic or proprioceptive losses) are observed.
Videotaping the individual while he or she is walking on a
runway or treadmill may enhance the accuracy of the assess­
ment. The function of the rearfoot, midfoot, and forefoot
is examined at each of the subphases of the gait cycle, with
­special attention to compensatory gait mechanisms.
FUNCTIONAL FOOT ORTHOSES
Although 4 to 6 degrees of triplanar STJ pronation are nec­
essary to provide adequate shock absorption and accom­
modation to uneven ground terrain, persistent or recurrent
abnormal pronation disrupts normal temporal sequencing
of the gait cycle. This disruption creates an unstable osseous
and arthrokinematic situation that contributes to pathologi­
cal musculoskeletal conditions.4,44
Compensatory motion occurs in the primary plane of a given
deformity. In frontal plane deformities (e.g., rearfoot varus or
FIGURE 8-17  Toe sign, demonstrating excessive transverse plane
motion as evidenced by the abducted position of the forefoot.
Anteverted hip
“Toeing in”
due to
anteverted hip
“Toeing out”
due to
retroverted hip
Retroverted hip
A
B
FIGURE 8-18  A, With excessive femoral anteversion, the limb appears to be internally rotated when
the head of the femur is well seated in the acetabulum. B, With femoral retroversion, the limb appears
to be externally rotated when the femur is well seated in the acetabulum. (From Magee DJ. Orthopedic
Physical Assessment, 3rd ed. Philadelphia: Saunders, 1997. p. 475.)

198
Section II  Orthoses in Rehabilitation
forefoot varus), the typical compensatory motion is eversion at
the STJ. In transverse plane deformities (e.g., torsional deformi­
ties of the hip, femur, or tibia), the typical compensatory motion
is adduction at the STJ. In sagittal plane deformities (e.g., ankle
equinus), the typical compensatory motion is dorsiflexion at
the STJ. Root's model suggests that single-plane compensatory
motion is beneficial, allowing adequate accommodation for a
deformity.4 Because the STJ is a triplanar structure, however,
movement in one plane leads to movement in the others as well.
The associated motion of the other planes has the potential to
become dysfunctional and destructive.4
A functional foot orthosis is an orthopedic device designed
to promote structural integrity of the joints of the foot and lower
limb by resisting the GRFs that cause abnormal skeletal motion
during the stance phase of gait.45 A functional foot orthosis
attempts to control abnormal foot functioning during stance by
controlling excessive STJ and MTJ motion, decelerating prona­
tion, and allowing the STJ to function closer to its neutral posi­
tion at MSt.73–76 In contrast, an accommodative foot orthosis is
used to distribute pressures over the plantar surface for individ­
uals with fixed deformity or vulnerable neuropathic feet.
Criteria for Abnormal Pronation
Five criteria are used to determine whether pronation is
abnormal. Pronation is considered an abnormal mechanical
condition when the following conditions are present:
1. STJ pronation is more than the normal 4 to 6 degrees.4,27,36,75
2. The foot pronates at the wrong time, disrupting the normal
sequencing of events during closed kinetic chain motion.
3. Pronation is recurrent, with each step contributing to
repetitive microtrauma to musculoskeletal structures.
4. Pronation happens at a location other than the STJ (e.g.,
when MTJ pronation compensates for limited STJ motion).
5. Unnecessary destructive compensatory motion occurs in
the other planes of motion of the STJ.4
Causes of Abnormal Foot Mechanics
Three pathological situations contribute to abnormal foot
mechanics: structural malalignment, muscle weakness or
imbalance, and loss of structural integrity.
Structural Malalignment
Structural malalignment can be intrinsic or extrinsic to the
foot or caused by abnormal mechanical forces.4 Rearfoot and
forefoot varus and valgus, ankle equinus, and deformities of
the rays are examples of intrinsic deformities. Congenital and
developmental conditions, such as tibial varum or valgum,
FIGURE  8-19  Assessment of femoral torsion in prone position
with a standard goniometer. The examiner palpates the greater tro­
chanter and rotates the lower leg. Femoral torsion is measured at the
point of greatest prominence of the greater trochanter.
FIGURE 8-20  Tibial torsion is measured as the angle between hori­
zontal and the plane of the axis of the talocrural joint.

Chapter 8  Foot Orthoses
199
torsional deformities of the tibia or femur, and other condi­
tions that occur above the foot and ankle are extrinsic defor­
mities. The types of abnormal mechanical forces that might
contribute to pathomechanical foot function include obesity,
leg length discrepancies, and genu valgum or varum. Orthotic
management for structural malalignment is preventive; con­
trol of aberrant or excessive STJ and MTJ motion forestalls
the sequence of mechanical events associated with abnormal
pronation or supination, minimizing the consequences of
painful foot conditions.
Muscle Weakness or Imbalance
A variety of upper and lower motor neuron diseases result in
muscular weakness, abnormal muscle tone, or paralysis of the
foot, with resultant instability of foot structure and reduced
mechanical efficiency during gait.42 In Charcot-Marie-Tooth
disease (hereditary sensory motor neuropathy), for example,
weakness of intrinsic, peroneal, and anterior tibial muscles
contributes to development of a “cavus” foot, with claw toes,
metatarsus adductus, or other deformities of the rays.42 When
muscle weakness or imbalance is present, the examiner must
identify its origin and extent, the specific soft tissue struc­
tures involved, the resultant mechanical foot deformities, and
the potential to reduce them. An effective foot orthosis for
a patient with muscular weakness deters the pathomechan­
ical sequelae that result from such induced structural foot
deformities.
Compromised Joint Integrity
Compromised joint integrity and mechanical instability
can also be caused by pathological musculoskeletal condi­
tions of the foot or ankle, including arthritis, acute trauma,
or chronic repetitive injury. In rheumatoid arthritis, for
example, joint deformity results from synovitis and pan­
nus formation. Autodestruction of connective tissue weak­
ens tendons, contributes to muscle spasm and shortening,
and erodes cartilaginous surfaces. Eventually, joint dislo­
cations occur.77
The loss of protective sensation associated with periph­
eral neuropathy also contributes to compromised joint
integrity. Patients with diabetes mellitus, chronic alcohol­
ism, or Hansen's disease (leprosy) are particularly vulner­
able. Inability to perceive microtrauma because of sensory
compromise, weakness of intrinsic muscles of the foot, com­
promised autonomic control of the distal blood flow, and
the poor nutritional and metabolic state of soft tissues com­
bine to increase the risk of plantar foot ulceration. If neu­
ropathic osteoarthropathy (Charcot-Marie-Tooth disease)
occurs, significant bone and joint destruction, collapse
of the midfoot, and a fixed rocker bottom deformity can
result.78 Plantar ulceration at the apex of the collapsed cune­
iforms or cuboid is common.79 Whenever mechanical insta­
bility is present, normal joint orientation is altered, and gait
compensation shifts weight-bearing forces. A foot orthosis
can be used to reduce pain, reduce weight-bearing stresses,
control abnormal or excessive joint motion, or compensate
for restricted motion.
GOALS OF ORTHOTIC INTERVENTION
A functional foot orthosis attempts to improve foot mechan­
ics during walking, regardless of the cause of foot dysfunc­
tion, by the following actions:
• Controlling velocity of pronation
• Redistributing plantar pressures
• Supporting abnormal structural forefoot positions that
lead to abnormal rearfoot function in stance
• Supporting abnormal rearfoot deformities that lead to
excessive STJ pronation
• Resisting extrinsic forces of the leg that lead to aberrant
pronation and supination of the foot
• Improving calcaneal positioning at IC
• Repositioning the STJ in neutral position just before heel rise
• Fully pronating the MTJ, when the STJ is in the neutral
position, to lock and stabilize the foot, converting it into a
rigid lever for propulsion
• Allowing normal plantarflex of the first ray and stabilizing
the forefoot in response to the retrograde GRFs sustained
during propulsion
• Providing a normal degree of shock absorption during LR
A functional foot orthosis does not support the MLA of
the foot; STJ pronation is controlled by the pressure of the
rearfoot post on the calcaneus at the sustentaculum tali. The
ultimate goal is to stop, reduce, or slow abnormal compensa­
tory motion of the joints of the foot as the foot and leg inter­
act with the GRFs.
MEASUREMENT AND FABRICATION
The information gathered in the non–weight-bearing and static
weight-bearing examinations and in gait analysis provides
direction for orthotic prescription. A simple plaster cast is used
to make an accurate negative impression of the patient's foot
in the STN position. A positive model based on this impres­
sion is then prepared. Thermoplastic materials are heat molded
over the model to form an orthotic shell. Accommodative pad­
ding, soft tissue supplements, and covering materials are added
to address the patient's functional foot problem. The orthosis
is fitted to the patient, and its effect on foot function during
gait is evaluated. An early wearing schedule is devised, and an
appointment for a recheck visit is scheduled.
Negative Impression
If a foot orthosis is to control abnormal pronation and supi­
nation effectively and minimize painful symptoms in gait, the
negative foot impression must precisely duplicate the existing
foot structure, including any intrinsic deformities. The goal
of the foot impression is to capture the patient's STN position
during the MSt phase of the gait cycle.
Comparison of Negative Casting Techniques Used
for Fabrication of Foot Orthotics
Multiple strategies can be used to take negative impressions,
including suspension techniques, modified suspension tech­
niques, direct pressure techniques, foam impression systems,

200
Section II  Orthoses in Rehabilitation
digital casting, and in-shoe vacuum casts. The negative impres­
sion techniques may be applied with the patient in semi–weight-
bearing, weight-bearing, or non–weight-bearing positions. Foot
measurements are greatly influenced by the technique used to
obtain the impression.80
The foam box technique (Figure 8-21) captures a nega­
tive impression of the foot with the patient in semi–weight-
bearing. Typically, the patient is seated on a firm surface
and the practitioner directs the foot to the foam box. After
the foot makes contact with the foam and the desired posi­
tion is established, the practitioner applies a downward
pressure along the tibial axis moving the heel into the foam
followed by the forefoot. The foot is then removed from the
box leaving a negative impression in the foam. The foam
box technique requires less technical skills and is more
time efficient than plaster negative casting. It might be used
when the goal is to fabricate an accommodative (soft) foot
orthosis.81,82
Digital casting technique produces a digital foot impres­
sion and allows for a variety of positions depending on
the scanning device, which might include an optic laser,
digitizer, pressure mat system, or digital photography.83,84
Computerized images of the foot can be viewed by the prac­
titioner from multiple angles and some software allows the
practitioner to modify the images (Figure 8-22). The CAD/
CAM system uses a milling apparatus to create the actual
orthosis.
Plaster casting has traditionally been the gold standard for
obtaining negative cast impressions.85 Because maintenance
of the STN position and correct loading of the forefoot are
difficult to control in weight-bearing impression techniques,
suspension and direct pressure non–weight-bearing tech­
niques appear to be the most reliable methods for making
accurate negative impressions. The direct pressure technique,
one of the easiest procedures to learn, captures the STN posi­
tion by loading the fourth and fifth metatarsal heads to mimic
GRFs during MSt (Figure 8-23). Alternative casting proce­
dures are also available.86,87
Direct Pressure Impression Technique
The patient is placed in the prone position, in the figure-of-four
position used for goniometric measurement. Two double-layer
thickness wraps of 5-inch plaster bandage are used to make the
negative cast. The first wrap is cut to surround the foot from
just distal to the fifth metatarsal head, around the posterior heel,
to just beyond the first metatarsal head. The second wrap is cut
so that, when draped over the plantar surface of the forefoot, it
overlaps the first wrap at the metatarsals.
The first wrap is thoroughly moistened with tepid water
and any wrinkles in the mesh are smoothed. The top edge of
the plaster splint is folded 0.5 inch, providing reinforcement
to prevent distortion when the cast is later removed. The first
wrap is draped over the heel, just below the malleoli, and along
the borders of the foot to just beyond the first and fifth meta­
tarsal heads. Because total contact with the sole of the foot
is essential, the plaster is carefully smoothed along the sides
of the foot, across its plantar surface, and around the curves
of the malleoli. The second wrap is moistened and draped
FIGURE  8-21  Negative cast impression using the foam box technique. (Courtesy of Amfit, Inc.,
Vancouver, Wash.)

Chapter 8  Foot Orthoses
201
around the forefoot, overlapping the distal edges of the first
layer. Any excess bandage is folded into the sulcus of the toes.
This layer should also have a wrinkle-free total contact with
the foot and toes.
Once both wraps are in place, the foot is positioned in the
STN position by maintaining appropriate forefoot loading
pressure at the fourth and fifth metatarsal heads. The plaster
splint is sufficiently hardened when an audible click is pro­
duced when it is tapped. The negative cast is then carefully
removed. The skin is gently pulled around the reinforced top
edge to loosen contact from the cast. A downward force over
the superior border of the heel cup is exerted to free the heel
from the cast. A gentle forward force is then provided to free
the forefoot and remove the cast from the foot.
Errors in Negative Casting
Accuracy in the negative impression is the key to an effec­
tive orthotic. Although the casting procedure is simple, three
types of errors during the process can compromise the effi­
cacy of orthotic design.
First, the foot may be inadvertently supinated at the longi­
tudinal MTJ axis as a result of contraction of the anterior tibi­
alis while the patient “helps” hold the foot still. Alternatively,
the loading force may be applied too far medially at the fore­
foot, creating a false forefoot varus. An orthosis manufac­
tured from such a cast can cause excessive pressure plantar to
the distal aspect of the first metatarsal shaft. It can also lead
to lateral ankle instability or the development of a functional
hallux limitus or HAV deformities.88
The second common casting error occurs when the foot
is excessively supinated at the oblique MTJ axis. Improper
FIGURE 8-22  Example of a negative cast impression using the digital casting technique. (Courtesy
of Amfit, Inc., Vancouver, Wash.)
FIGURE 8-23  Negative cast impression by the direct pressure tech­
nique. The foot is maintained in STN position while the plaster
hardens.

202
Section II  Orthoses in Rehabilitation
loading at the fourth and fifth metatarsal heads results in
insufficient dorsiflexion of the forefoot. When this happens,
transverse skin folds can be seen inside the negative cast at
the MTJ. An orthosis manufactured from this cast creates an
excessive sagittal plane angulation plantar to the calcaneocu­
boid joint (lateral longitudinal arch), with pain and irritation
on weight bearing.88
The third error occurs when the STJ is excessively pro­
nated during casting, placing the foot in a false forefoot val­
gus position. An orthosis manufactured from this cast does
not capture the STN position and is ineffective in controlling
the symptoms of abnormal pronation.88
Positive Cast Modifications
Once a satisfactory negative impression of the patient's foot
has been obtained, a positive cast is made and then modified.
The hardened negative impression is filled with liquid plaster
and allowed to dry. The negative cast is peeled away, leaving a
positive mold of the foot (Figure 8-24). Modifications to the
positive cast ensure an effective correction in foot alignment
and function by redirecting forces through the foot. Those
made to enhance comfort include plaster additions to relieve
pressure-sensitive regions of the forefoot and MLA. Because
the negative cast is taken in a non–weight-bearing position,
it is also modified to allow for the elongation of the foot and
expansion of the soft tissues in weight bearing. The cast is
also modified to allow for normal plantarflex of the first
metatarsal during propulsion.45,89 Intrinsic or extrinsic posts
can be added for further correction of forefoot or rearfoot
deformities.
Forefoot Posting
Two techniques can be used to provide orthotic correction
for forefoot deformity. Both are based on modification of the
positive cast impression. The first, a traditional Root func­
tional orthosis, uses an intrinsic correction. A plaster plat­
form is applied to the positive cast at the level of the MTP
joints to balance the abnormal forefoot to rearfoot relation
(Figure 8-25). A lateral platform corrects forefoot valgus, and
a medial platform corrects forefoot varus.45 When the shell is
pressed over the modified positive mold, it creates a convexity
at the distal anterior border of the orthosis. This posting tech­
nique achieves correction by effectively realigning the skeletal
structure of the foot.89 The intrinsic posting technique is often
selected when shoe volume is limited, as in some women's
footwear.
5
1
5
1
5
1
A
B
C
FIGURE 8-25  Cross section at the level of the metatarsophalangeal joints, with first and fifth metatar­
sals labeled, demonstrating intrinsic modifications to the positive mold. A, A lateral platform corrects
forefoot valgus. B, A medial platform corrects forefoot varus. C, A neutral balancing platform maintains
forefoot alignment and serves as a base for extrinsic posts. (Courtesy Stride, Inc., Middlebury, Conn.)
FIGURE 8-24  The modification process of forefront position on a
positive cast.

Chapter 8  Foot Orthoses
203
A second forefoot posting technique involves a variation of
Root's original design, referred to as a standard biomechani­
cal orthosis. In this technique, a neutral platform is formed
on the positive mold, but the existing valgus or varus posi­
tion of the forefoot is maintained. An extrinsic forefoot post or
wedge is attached to the bottom of the orthotic shell to ­support
the forefoot in its position of deformity. Unwanted compensa­
tory motion is prevented by stabilizing the distal border of the
orthosis (Figure 8-26). Although an orthosis with an extrinsic
correction takes up more space inside the shoe than an intrin­
sically corrected orthosis, it can more easily be modified if
the individual has difficulty tolerating the original posting
prescription.
Rearfoot Posting
As the foot makes contact with the ground and moves
through stance during gait, GRFs act on the joints of the foot.
An orthosis acts as an interface between the ground and the
foot, creating its own orthosis reactive force. In a foot that
pronates excessively, the foot orthosis is designed to decrease
STJ pronation during weight bearing by creating a supination
moment acting medial to the STJ axis.2 This can be accom­
plished by adding an extrinsic rearfoot post or wedge to the
inferior surface of the heel cup or by modifying the plaster
mold to incorporate an intrinsic rearfoot post to the heel cup
of the orthosis. A rearfoot post effectively reduces rearfoot
pronation (eversion) during the contact phase of gait as well
as the angular velocity of eversion.2,90,91
Extrinsic rearfoot posts are attached to the bottom of the
orthosis shell beneath the heel (see Figure 8-26B). A medial
wedge or rearfoot post increases orthosis reactive forces at the
sustentaculum tali (medial to the STJ axis) to reduce abnormal
STJ pronation. It also promotes stability of the heel by increas­
ing the contact surface of the orthosis beneath the heel.89,90 An
intrinsic rearfoot post can be made with a medial heel skive
technique. A plaster modification is performed on the medial
aspect of the heel of the positive mold to increase the amount
of varus (medial) sloping within the heel cup of the orthosis
in an effort to control pronation.2 An intrinsic rearfoot post
reduces overall bulk of the orthosis for optimal fit within a
shoe. A combination of intrinsic and extrinsic rearfoot post­
ing permits more correction than possible with either method
independently.
The Orthotic Shell
To be effective, a functional orthosis must be made on
the basis of a neutral position model of the patient's foot.
Prefabricated foot supports do not offer adequate control of
foot motion or resistance to GRFs and cannot fulfill all cri­
teria of functional foot orthoses. A custom orthosis, made
of rigid or semirigid materials, can offer maximal resis­
tance to weight-bearing forces and optimal realignment of
foot structure. Accommodative orthoses, made of softer
materials, support the arches of the foot and provide relief
to pressure-­sensitive areas while offering minimal control
of STJ motion.92,93 A semifunctional orthosis is a hybrid of
functional and accommodative orthoses that combines the
motion effectiveness of a semirigid shell with soft posting
and accommodative material to cushion the foot.
Many studies have evaluated the effectiveness of the differ­
ent types of orthotic materials in controlling rearfoot mechan­
ics and clinical symptoms.92–96 Some suggest that orthotic
materials be classified by degree of rigidity (soft, semirigid,
rigid), but standards for the classification of materials are not
well established.1
A rigid orthosis achieves maximal motion control and bio­
mechanical correction of a foot deformity, is lightweight, and
takes up the least space within the shoe. Some clinicians are
concerned that orthoses made of rigid materials are uncom­
fortable to the wearer. Anthony45 suggested, however, that
those “who propose rigid devices to be patient intolerant are
generally less acquainted with the theory of podiatric biome­
chanics and the correct diagnostics and prescription formu­
laries that are critical for the provision of a truly functional
foot orthosis.”
Semirigid materials, such as polypropylene and TL-2100
(Performance Materials Corp., Camarillo, Calif.), are attrac­
tive alternatives to rigid orthotic shells. Polypropylene is
a flexible olefin polymer that resists breakage. TL-2100 is a
thermoplastic composite of resin and fiber that is harder and
more rigid than polypropylene.1
Soft orthoses are often made of closed-cell foams man­
ufactured from heat-expanded polyethylene. Examples of
such foams include Aliplast and Nickleplast (Alimed, Inc.,
Dedham, Mass.) and Plastazote (Bakelite Xylonite Ltd,
Croydon, United Kingdom), cross-linked polyethylene
expanded foams available in many densities. Pelite (Fillauer,
Inc., Chattanooga, Tenn.) is a cross-linked, closed-cell foam
that can be heat molded in the fabrication of semiflexible foot
orthoses. Various rubberized or thermoplastic cork materials
are also used.1 Lightweight and available in different densities,
these materials are effective in orthotics for which accom­
modation and shock absorption are desirable. These same
features limit the durability and the useful life of the ortho­
sis, however, because these materials are prone to rapid and
­permanent shape deformation.1
A
B
FIGURE 8-26  Standard biomechanical orthosis with an extrinsic
forefoot post (A) and an extrinsic rearfoot post (B).

204
Section II  Orthoses in Rehabilitation
For some individuals, extrinsic accommodative modifica­
tions are necessary to address a particular deformity. Examples
of accommodative supplements are listed in Table 8-1.
Covering Materials
Once appropriate posts and supportive materials are attached
to the shell of the orthosis, a covering material is applied
to provide an interface with the skin of the foot. Vinyl is a
commonly used orthosis-covering material. Spenco (Spenco
Medical Corporation, Waco, Texas) and various other
­fabric-covered neoprene materials are resistant to shearing
and enhance shock absorption. They are often chosen as cov­
ering materials for certain sport orthoses when shear forces
are expected to be high or for occupational situations that
demand prolonged standing on hard surfaces.
MANAGING REARFOOT DEFORMITY
In a well-aligned foot, 4 to 6 degrees of STJ pronation occur
during the stance phase of gait. In rearfoot varus, more than
6 degrees of STJ pronation are present. A fully compensated
rearfoot varus deformity of 10 degrees pronates at the STJ 10
degrees during gait to lower the medial condyle of the calca­
neus to the ground, but only 6 degrees of this pronation are
considered excessive.
The appropriate orthotic design for rearfoot varus is a
medial post or medial wedge. Complete orthotic correction
is difficult to achieve and quite uncomfortable for the indi­
vidual wearing the orthosis. Because of this, the initial goal
is often to create an orthosis that provides 50% correction
of a rearfoot deformity. To correct the excessive 6 degrees of
pronation, for example, a medial rearfoot post or wedge of
3 degrees would be applied to the orthosis.
If an individual with a rearfoot varus deformity of 10
degrees is uncompensated to −5 degrees of calcaneal ever­
sion, a medial or varus wedge of 3 degrees is not effective
because the STJ would reach its end-range eversion motion
(−5 degrees) before the orthosis provided support. To man­
age uncompensated rearfoot deformity effectively, the varus
wedge must be large enough to prevent the STJ from reach­
ing its end ROM. In this example, a larger medial rearfoot
varus post or wedge of at least 5 degrees is necessary. When
the rearfoot is aggressively posted (more than 3 or 4 degrees
of varus posting), the distal medial aspect of the orthosis shell
loses contact with the ground, as if a forefoot varus deformity
were present. In these circumstances, a medial forefoot post is
used to counteract the induced apparent forefoot varus.
MANAGING FOREFOOT DEFORMITY
For forefoot varus deformities, a medial (varus) wedge or post
is indicated. For forefoot valgus deformities, lateral (valgus)
posts or wedges are used. Forefoot deformities can be cor­
rected through intrinsic plaster modifications or extrinsic
posting. For an orthosis to be accurately balanced so that it
does not wobble, a forefoot deformity must be corrected to
its fullest extent (e.g., an 8-degree forefoot varus deformity
requires an 8-degree medial wedge or post).
The addition of a large extrinsic post to the distal end of
the orthotic shell often creates problems with shoe fit. One
possible solution is to correct large forefoot deformities with
a combination of intrinsic and extrinsic techniques. In this
example, a 4-degree medial intrinsic plaster platform and a
4-degree extrinsic medial forefoot post or wedge would pro­
vide the desired correction without bulkiness. For individu­
als with a forefoot varus deformity of 10 degrees or more,
TABLE 8-1  Accommodative Padding and Soft Tissue Supplements for Functional Foot Orthotics
Supplement
Description
Metatarsal mound
A dome-shaped addition in the form of a teardrop positioned with the apex just proximal to the metatarsal
heads to support a collapsed transverse metatarsal arch. Often used to control symptoms of neuroma by
reducing shearing of the metatarsals during contact phase. Reduction of the shearing eliminates irritation
to the interdigital nerves of the forefoot.
2-5 bar
A pad of uniform thickness placed beneath the second through fifth metatarsal heads relieves pressure beneath
the first metatarsal head during propulsion. Used when a rigid plantar flexed first ray is present.
Metatarsal head cutout
A U-shaped pad positioned beneath a rigid plantar flexed metatarsal head to relieve pressure from a painful
callosity. Often used for hammertoe deformity.
Morton's extension
An extension of the plastic shell, or the addition of an inlay made of dense material, beneath the shaft of the first
metatarsal to the sulcus of the hallux. Often used for a dorsiflexed first ray or Morton's toe.
Heel cushion
Placed in the heel cup of the orthosis to enhance heel cushioning and shock absorption. Often made of the soft
tissue–supplementing material Poron (Rodgers Co., Rogers, Conn.) or a viscoelastic polymer. Used when
irritation or atrophy of the infracalcaneal fat pad is present or for calcaneal stress fracture.
Forefoot extension
A soft tissue–supplementing material such as Poron is added to the distal end of the orthotic shell to cushion the
metatarsal heads or as a base for other forefoot inlays.
Scaphoid pad
A material of soft to medium density placed beneath the medial longitudinal arch to decelerate pronatory forces.

Chapter 8  Foot Orthoses
205
a semipronated or pronated negative cast can reduce the
forefoot deformity to a more manageable degree.86
Plantarflex of the first ray is managed according to the level
of flexibility of the deformity. A fully flexible plantar flexed
first ray deformity does not require orthotic intervention.
A semirigid or rigid plantar flexed first ray deformity requires
the addition of a metatarsal (second through fifth) bar inlay.
The thickness of the inlay is determined by how far below the
first metatarsal head lies relative to the plane of the remaining
metatarsal heads. The orthotic intervention for patients with a
rigid plantar flexed first ray and forefoot varus is an extended
medial forefoot wedge. The forefoot post is modified with
a cutout to accommodate the dropped first metatarsal head
position. In some cases, a small forefoot varus deformity com­
bined with a large, rigidly plantar flexed first ray deformity
results in a functional forefoot valgus (see Figure 8-14).
ORTHOTIC CHECKOUT AND
TROUBLESHOOTING
Delivery of an orthosis includes evaluation of its fit, comfort,
and mechanical alignment. The orthotic shell should end just
proximal to the metatarsal heads. The width is evaluated to
ensure that normal first ray plantarflex and propulsion are
not compromised. The position of the orthosis within the
shoe is also evaluated; its volume, impact on heel height,
points of excessive pressure, and tendency to cause pistoning
during gait are considered. On initial fitting, many individu­
als report that the orthosis feels slightly strange or unusual.
The orthosis should not, however, cause undue discomfort.
Fit and mechanical functioning of the orthosis are evaluated
in standing and walking.
Patient education in appropriate break-in protocols and
wearing schedules is an important component of orthotic
delivery. A new orthosis is usually worn for 2 hours on day
1, 4 hours on day 2, 6 hours on day 3, and so forth, until the
individual is able to wear the orthosis comfortably all day.
A follow-up visit is scheduled after the orthosis has been
worn for at least 2 weeks. By this time, the patient should feel
comfortable with the orthosis for normal activities of daily
living. Thereafter, progressively increased use of the orthosis
for all activities, including sport and occupational use, should
be well tolerated. Adjustments are occasionally necessary to
optimize patient comfort and mechanical alignment.
CONTROVERSY WITH ROOT'S PARADIGM
Much discussion on the basic components of Root's the­
ory has occurred in the past decade.50,97–104 Root's theory is
founded on “normal” foot structure and the concept of the
STN position: the point of maximal congruence in the artic­
ulation of the talus and navicular.4,13,29,60 STN position sup­
posedly (1) minimizes stress to the surrounding joints and
ligaments, (2) is the most efficient position regarding muscle
function and attenuation of the impact forces at IC, and (3)
represents the point at which the foot converts from a mobile
adapter to a rigid lever.4,41,60 According to Root's traditional
theory, normal foot alignment occurs just before TSt during
gait, when the STJ is in the neutral position and the MTJ is
fully locked.4
The major criticisms of Root's paradigm raise concerns
about reliability of measurement of the STN position, the
position of STN position during the gait cycle, and criteria for
“normal” foot alignment.38,61,99,103
Reliability of Measurement
When considering available evidence about reliability of foot
measurements and the STN position, although acceptable lev­
els of intrarater reliability exist,39,40,46,48,105,106 interrater reliabil­
ity of foot measurements and the STN position is low.38,97,99,103
Diamond and colleagues107 and Cook and colleagues106 found
that interrater reliability can be improved with training.
McPoil and Hunt38 noted that considerable confusion exists
regarding the definition and measurement of STN position.
They suggested that Root's STN position may misinterpret the
of work by Wright and colleagues,108 who referenced relaxed
standing position, not STN neutral, as the basis of their work.
To further add to the confusion, the definition of STN posi­
tion used in some reliability studies was not identical to Root's
methods.103 Based on the review of reliability studies, McPoil
and Hunt38 suggested that physical therapists are not able to
agree on position and motion of the STJ.
Subtalar Position in Stance
According to Root, ideal foot alignment occurs just before
TSt during gait, when the STJ is in the neutral position and
the MTJ is fully locked.4,109 In a study of rearfoot motion of
51 healthy adults, McPoil and Cornwall110 marked patients’
lower leg and calcaneus with bisection lines and then filmed
relative calcaneal and lower leg position while walking, while
standing in a double-support relaxed standing, and while in
STN position. Their findings did not support Root's para­
digm. They found that (1) the rearfoot is slightly inverted
before IC, (2) maximal rearfoot pronation was reached at the
37.9% point of stance phase, and (3) the neutral position of
the rearfoot for the typical pattern of rearfoot motion should
be the resting standing foot posture rather than STN posi­
tion.108 As a result, they suggested that the relaxed standing
foot position rather than the STN position should be used
during casting.108
Pierrynowski and Smith111 used three-dimensional analy­
sis and six experienced raters to study the pattern of rearfoot
motion throughout the gait cycle relative to the STN posi­
tion. The right lower extremities of nine patients were evalu­
ated by each rater six to seven times, and the STN position
was recorded. Patients then walked on a treadmill and were
recorded for 30 seconds to allow the capture of approximately
25 walking cycles. For most patients, the rearfoot was everted
throughout stance, with maximal eversion occurring at 44%
of the gait cycle.111 They found that STN position occurs at
64% and 74% of the gait cycle, with the rearfoot inverted
between these points. The rearfoot was everting from 0%
to 44%, inverting from 44% to 70%, everting from 70% to
90%, and inverting from 90% to 100% of the gait cycle.109

206
Section II  Orthoses in Rehabilitation
The authors concluded that the manufacture of foot orthoses
should not be associated with the STN position.111
Criteria for Normal Alignment
Root described deviations from normal foot alignment as
intrinsic foot deformities, which can lead to aberrant lower
extremity function and musculoskeletal pathological condi­
tions.4,60 Root and colleagues109 defined three criteria for nor­
mal foot and ankle alignment in the loaded STN position: (1)
a bisection of the lower leg being in parallel to the bisection of
the calcaneus, (2) the plane of the metatarsal heads being per­
pendicular to the bisection of the calcaneus, and (3) the distal
third of the lower leg being perpendicular to the floor. McPoil
and colleagues38,97 examined 116 feet in 58 asymptomatic indi­
viduals, finding 8.6% with forefoot varus, 44.8% with forefoot
valgus, 14.7% with a plantar flexed first ray, 83.6% with subta­
lar varus, and 98.3% with tibiofibular varum. Only 17% (116
feet) of the 58 individuals evaluated demonstrated normal cri­
teria.38 In an examination of forefoot to rearfoot relations of 120
healthy asymptomatic individuals, Garbalosa and colleagues47
found that only 4.58% of the 234 feet studied exhibited nor­
mal criteria, 86.67% had forefoot varus, and 7.75% had forefoot
valgus. Astrom and Arvidson112 performed standardized clini­
cal assessments on 121 healthy individuals, finding that none
demonstrated an ideal foot position; most had a valgus posi­
tion in the STN position (mean, 2 degrees), forefoot in varus
(mean, 6 degrees), calcaneal valgus in stance valgus (mean, 7
degrees), and 6 degrees of tibial varus with respect to vertical.
The evidence from these studies suggests that an “ideal” foot
may be based on a questionable theoretical concept.
FOOT TYPE AND LOWER EXTREMITY
BIOMECHANICS
A question that has been the focus of recent research focuses
on the relation between various foot types and the amount of
pronation during gait. Recent reviews of the literature sug­
gest this question might not have a simple answer. Dicharry
and colleagues113 compared static and dynamic measures of
navicular drop in 72 healthy adults. Although the partici­
pants had significantly different static measures of various
foot types, they only displayed small or no differences dur­
ing running and walking. The findings suggest that features
other than foot type affect dynamic joint function. According
to Razeghi and Batt,114 foot type alone cannot explain ankle
and foot kinematics because of the interrelated function of
the subtalar, talocrural, and knee joints. Ball and Afheldt103
suggested that attempts to justify static classification of foot
type schemes as a means of predicting dynamic joint function
have had mixed results.
FOOT TYPE AND LOWER EXTREMITY
OVERUSE INJURIES
Many researchers have reported an association between abnor­
mal alignment of the foot and lower extremity and occurrence
of lower extremity injuries. Dahle and colleagues115 studied
the relation between foot type (classified in standing as supi­
nated, pronated, or neutral) and occurrence of ankle sprain and
knee pain in 55 athletes during the football and cross country
seasons. Although the relation between foot type and subse­
quent ankle sprain was not supported, foot type was strongly
related to knee pain; 48% of those with pronated feet and 50%
of those with supinated feet had significant knee pain com­
pared with 21% of those classified with neutral alignment.
Gross and colleagues116 examined the relationship between
forefoot and rearfoot varus alignment to hip conditions in 385
older adults. Older adults with more forefoot varus were 1.8
times more likely to have ipsilateral hip pain, 1.9 times more
likely to have hip pain or tenderness, and 5.1 times more likely
to have undergone total hip replacement when compared to
older adults with less forefoot varus. There was not a signifi­
cant relationship between older adults with rearfoot varus and
hip conditions. Powers and colleagues117 compared prone STN
rearfoot position of 15 patients diagnosed with patellofemoral
pain with 15 control subjects, reporting a statistically significant
difference in rearfoot varus found in the patellofemoral group
(8.9%) compared with control subjects (6.8%). In a retrospec­
tive study of the relation between foot posture and incidence of
medial tibial stress syndrome, Sommer and Vallentyne118 mea­
sured foot angle in 14 standing limbs with medial tibial stress
syndrome (MTSS) and 36 control limbs. They reported mean
foot angle of 137 degrees in symptomatic limbs compared with
145 degrees in asymptomatic limbs. They also reported that a
standing foot angle of less than 140 degrees and a varus align­
ment of the rearfoot or forefoot, measured qualitatively in STN
position, were predictive of a previous history of MTSS.
Some reports do not support the relation between foot
type and lower extremity injury. Donatelli and colleagues119
reported no statistically significant relations among static or
dynamic foot posture and injury status in professional base­
ball players. Razeghi and Batt114 suggested that arch height
may not influence injury occurrence. Similarly, Cowan and
colleagues120,121 found that individuals in the U.S. Army with
low arches might be less likely to have lower extremity injury.
Considering the variety of reports in the literature, Razeghi
and Batt114 surmised that “the effect of foot type on the occur­
rence of lower extremity injuries has not been the subject of
well-controlled studies and few, if any, causal correlations
have been demonstrated.”
ORTHOSES AND LOWER EXTREMITY
FUNCTION
Overpronation has been implicated as a cause of many over­
use injuries. Traditionally a foot orthosis is used to help con­
trol abnormal foot functioning during the stance phase by
controlling excessive STJ motion, decelerating pronation, and
allowing the STJ to function closer to its neutral position dur­
ing stance.74–76 Literature about efficacy of foot orthoses in
controlling lower extremity and foot biomechanics is grow­
ing.7,122 A systematic review and metaanalysis conducted by
Richter and colleagues120 reported there is evidence for the
use of foot orthoses to prevent lower limb overuse conditions.

Chapter 8  Foot Orthoses
207
Effect on Rearfoot Biomechanics
The use of foot orthoses is based on the premise that control
of frontal plane rearfoot motion in stance provides a means of
controlling pronation of the foot. Novick and Kelley123 investi­
gated the effects of medially posted rigid orthoses in 20 asymp­
tomatic individuals during the LR phase of the gait cycle. They
report a significant decrease in calcaneal angle (angle between
the sagittal plane and bisected posterior tubercle of the calca­
neus), calcaneal eversion angle (mathematical sum of the tibia
vara angle plus the calcaneal angle), angular velocities and
angular accelerations, as well as a shift medially in the center
of pressure relative to the ankle joint. These findings that an
orthosis is able to reposition the rearfoot concur with earlier
studies examining the effects of orthoses on rearfoot mechan­
ics.93,96,124,125 McClean and colleagues126 examined the impact
of custom foot orthoses on lower extremity mechanics of
15 female runners. The runners performed five running trials
with and without the orthoses. The runners displayed signifi­
cant reduction in maximum rearfoot eversion angle (2 degrees)
and rearfoot eversion velocity while wearing the orthoses.
Johanson and colleagues127 examined the effects of three dif­
ferent orthotic posting methods on subtalar pronation during
ambulation in 22 individuals with a forefoot varus deformity of
at least 8 degrees. Individuals ambulated in running shoes with
(1) unposted prefabricated shells with a polyurethane arch sup­
port and (2) individualized shells posted at the rearfoot, (3) at
the forefoot, and (4) at both the rearfoot and forefoot. Forefoot
posts were approximately 50% of the measured forefoot varus
deformity, and the rearfoot posts were 80% of the forefoot
post. Running shoes without shells were used as the control.
Measurements of calf to calcaneus and calcaneus to vertical
were recorded for each situation. Shells with and without post­
ing decreased calcaneal angles compared with running shoes
alone. Concurrent posts of rearfoot and forefoot decreased cal­
caneal angles similar to rearfoot posting alone; both decreased
the angle more than forefoot posting alone. Similarly, Genova
and Gross128 found significant reduction in calcaneal eversion
during static stance with shoes alone and shoes with ortho­
ses, compared with the barefoot condition, in 13 individuals
with barefoot standing calcaneal eversion angles of at least 10
degrees. The condition of the shoes and the orthoses was not
statistically different in controlling eversion in static standing.
Individuals demonstrated lower angles for maximal calcaneal
eversion during stance and for calcaneal eversion at heel rise for
the shoe with an orthosis compared with the shoe alone during
fast walking on a treadmill. Branthwaite and colleagues129 inves­
tigated the biomechanical effects of simple orthotic designs at
rearfoot in 9 individuals with varus deformities of the feet by
using biplanar orthoses (medial wedging at the heel) or cobra
pads (medial wedging and an arch support). A decrease in cal­
caneal eversion occurred with the biplanar orthosis compared
with no insole, but no difference occurred with cobra insoles.
Neither condition produced significant changes in the maxi­
mal eversion velocity.
The difficulty in predicting the biomechanical effects of
orthoses on the rearfoot was demonstrated by Brown and col­
leagues,130 who compared shoes only, over-the-counter arch
supports, and custom-made semirigid orthoses to control
rearfoot pronation in 24 patients with a forefoot varus defor­
mity. Custom-made orthoses were posted at both the rear­
foot and forefoot, with forefoot posts at 60% of the forefoot
deformity and rearfoot posts at 50% of the forefoot defor­
mity. Although a difference was found in the total prona­
tion among the three groups, the authors suggest additional
research is warranted to identify orthotic factors responsible
for the biomechanical effects associated with the clinical suc­
cesses of foot orthotics. Butler and colleagues131 found that
rigid or soft orthoses posted 6 degrees at rearfoot were unable
to control calcaneal eversion excursion, peak eversion, and
eversion velocity during running in individuals with normal
foot alignment.
Miller and colleagues132 suggested that mechanisms by
which orthoses control rearfoot motions are not as clear as
might be expected. The examination of GRFs during ambula­
tion of 25 individuals with pes planus with or without a rear­
foot device found no significant change in the mediolateral
GRFs during the stance phase of gait. Significant differences
were found, however, in the vertical and anterior posterior
GRFs during various percentages of the stance phase.
Several variables that must considered in interpreting these
disparate findings, including the materials used, whether
individuals are running or walking, foot alignment and bio­
mechanics, and posting methods. Although rearfoot mechan­
ics appear to be altered by foot orthoses, further investigation
into the mechanisms responsible for these effects is needed.
Effect on Lower Limb Biomechanics
Foot orthoses influence lower extremity kinematics and
kinetics as well as rearfoot mechanics. Eng and Pierrynowski95
examined the three-dimensional effects of soft foot orthoses
during the contact, MSt, and propulsion phases of walking
and running on the talocrural and subtalar joints and knee
joints in 10 women with a history of patellofemoral joint
pain and forefoot varus or calcaneal valgus greater than ­
6 degrees. Soft orthoses produced a modest decrease in fron­
tal and transverse plane motion in the talocrural and subtalar
joints and knee joint during walking and running. Knee joint
motion in the frontal plane decreased during the early and
MSt phases of walking but increased during the contact and
MSt phases of running. This work demonstrates the complex
coupling of lower extremity kinematics with motions of the
STJ; reductions in subtalar motion in the frontal plane have
an impact on knee function in both the frontal and transverse
planes during walking.
McPoil and Cornwall133 also studied the effects of soft
and rigid orthoses on tibial rotation. Ten individuals with
documented rearfoot or forefoot deformity ambulated with
unposted, premolded, soft orthoses and rigid polyethylene
orthoses posted according to the individual's deformity. Both
orthoses decreased the rate and amount of tibial internal rota­
tion during walking. Stacoff and colleagues134 observed the
effects of medially posted cork orthoses on calcaneal and tib­
ial motions in five runners. Three-dimensional tibiocalcaneal
rotations were assessed after inserting intracortical bone pins

208
Section II  Orthoses in Rehabilitation
into the calcaneus and tibia. Although the effects on eversion
and tibial rotation were small and variable, a statistically sig­
nificant orthotic effect was present for total tibial rotation.
The authors, noting that the differences were unsystematic
across conditions and were specific to each individual, specu­
lated that the effects of orthoses might be proprioceptive as
well as mechanical.
Joseph and colleagues135 studied the relationship between
ankle pronation/eversion with excessive knee valgus and risk
of anterior cruciate ligament injury in female athletes during
drop jumps. Ten female athletes performed drop jump land­
ings with and without a medially posted orthosis. A three-
dimensional kinematics of the knee and ankle were measured
during the jump. The authors reported a significant decrease
in ankle pronation/eversion and knee valgus at initial contact
when the athletes had a medial post in their shoes. Their find­
ings support medial orthotic posts for potentially decreas­
ing the risk of anterior cruciate ligament injury. Tillman and
­colleagues136 evaluated the impact of orthotic posting on the
tibial rotation induced by jumping from a 43-cm-high plat­
form in seven women without foot malalignments by using
three conditions (shoes only, shoes with orthoses posted 8
degrees medially, and shoes with orthoses posted 8 degrees
laterally). Tibial internal rotation increased by 2.6 degrees
with laterally posted inserts and decreased by 3.1 degrees
with medially posted inserts. Nester and colleagues137 exam­
ined the effects of medially and laterally wedged orthoses on
the kinematics of the rearfoot, knee, hip, and pelvis during
walking, reporting main effects on the rearfoot, with mini­
mal effects at knee, hip, or pelvis. Laterally wedged orthoses
increased pronation and decreased laterally directed ground
forces, whereas medially wedged orthoses decreased prona­
tion and increased the laterally directed ground forces.
Williams and colleagues138 examined the effects of graphite
“inverted” orthoses (orthoses used to provide more aggressive
control of pronation by using an inverted position as opposed
to a more vertical orientation), standard graphite orthoses
posted with a 4-degree medial wedge, or shoes alone in 11
runners who had been initially fitted with the standard ortho­
ses for various lower extremity injuries. Surprisingly, the three
conditions produced no significant differences in the peak
rearfoot eversion or rearfoot eversion excursion.
A significant decrease in the rearfoot inversion moment
and work with the inverted orthosis suggests this orthotic
design might decrease demand on the structures control­
ling eversion. However, increased internal tibial rotation as
well as an adduction moment at the knee occurred with the
inverted orthosis, raising concern that potential for lateral
stress increases with this aggressive orthotic approach.
Kuhn and colleagues139 examined quadriceps femoris
Q-angle in 40 men with bilateral pes planus or hyperprona­
tion syndrome before and after the insertion of foot orthot­
ics. Thirty-nine of the 40 men had significant decrease in
bilateral Q-angle in the direction of correction after inser­
tion of full-length flexible orthotics. Men with asymmet­
rical Q-angle measurements showed significantly greater
symmetry of Q-angle measures after orthotic placement.
Kuhn and colleagues134 noted that hyperpronation can cause
the tibia to internally rotate, leading to femur internal rota­
tion and resulting in lateral tracking of the patella. They
concluded that insertion of full-length flexible orthotics in
men with hyperpronation significantly improves quadriceps
femoris Q-angle.
Stackhouse and colleagues140 studied biomechanics during
running in 15 individuals with normal alignment. Individuals
ran with both rearfoot and forefoot strike patterns and with
and without semirigid orthoses with 6 degrees of rear­
foot posting. The orthoses did not change rearfoot motion
in either strike pattern but did reduce internal rotation and
genu valgum by approximately 2 degrees through most of the
stance phase. Although no statistically significant reduction
occurred in the inversion moment and inversion work, the
authors believed that the reductions they found were clini­
cally relevant and might explain the reduction of injuries seen
when orthoses are used.
Although evidence supports the fact that foot orthoses
can and do influence lower extremity kinematics and kinet­
ics, the variability of individual responses makes it difficult
to determine exactly which biomechanical effects will occur.
This variability also makes it difficult to forecast who is likely
to benefit from orthotic intervention. Efficacy of foot ortho­
ses is not solely the result of altered rearfoot kinematics, as
proposed by Root. The contribution of the neuromuscu­
lar system to the effect of orthotic intervention is now being
considered.
Effect of the Neuromuscular System
Nigg and colleagues,141 citing problems in previous studies
(e.g., small skeletal changes produced by orthotic use, minimal
decrease in impact forces, and nonsystematic effects caused
by individual variability), proposed that mechanisms involv­
ing the neuromuscular system contribute to the way that foot
orthoses alter lower extremity function. They were especially
interested in sensitivity of the foot and pressure distribution
on the foot surface, noting that (1) the foot has many sensory
receptors to detect forces and deformations acting on it, (2)
the sensors detected input signals into the foot with patient-
specific thresholds, and (3) individuals with similar sensitiv­
ity thresholds seem to respond to their movement patterns in
a similar way. They suggested that force signals from the floor
were filtered by the shoe, the orthosis, and finally by the plantar
surface of the foot, which then transferred the filtered informa­
tion to the central nervous system. The central nervous system,
in turn, prompted dynamic responses in the lower extremity on
the basis of patient-specific conditions. Comfort of the orthosis
is an important consideration; a comfortable orthosis is likely
to minimize muscular work during walking. According to
Nigg and colleagues,136 an optimal orthosis would reduce mus­
cle activity, feel comfortable, and improve musculoskeletal and
neuromuscular performance in walking.
Based on his analysis of the role of impact forces on foot func­
tion in gait, Nigg142 proposed a new paradigm focusing on loco­
motor systems and strategies for impact and movement control.
The dynamical systems model of motor control suggests that

Chapter 8  Foot Orthoses
209
locomotor systems keep general kinematic and kinetic situa­
tions similar for any given task. Nigg suggests that a muscle tun­
ing reaction occurs to cause forces that affect muscle activation
before ground contact, and that muscle adaptation (to ensure
constant joint movement pattern) affects muscle activation dur­
ing ground contact. The interplay of realignment of the skeleton
and locomotor system muscle tuning affects joint and tendon
loading and, in turn, fatigue, comfort, work, and performance.
Electromyographic and Imaging Evidence
Mundermann and colleagues143 studied 21 recreational run­
ners who used a flat shoe insert, posting alone, custom-
molded orthoses, and custom-molded orthoses and posting.
They analyzed the effects of each condition on lower extrem­
ity kinematics, kinetics, and electromyographic data as well
as comfort during use. Thirty-five percent of differences in
comfort were explained by changes in 15 kinematic, kinetic,
and electromyographic variables, and these 15 variables cor­
rectly classified the corresponding orthotic condition in 75%
of cases. Mundermann and colleagues144 suggested that com­
fort not only reflected subjective perceptions but was also
related to biomechanical variables. In an extension of their
work, Mundermann and colleagues144 observed that the
effects of molding were more important than posting on
change in kinematic and kinetic variables.
Hertel and colleagues145 examined electromyographic activ­
ity of the vastus medialis, vastus lateralis, and gluteus medius
during functional activities in 30 individuals with different
foot types, comparing electromyographic activity in four con­
ditions: no orthotic, 7 degrees medial rearfoot post, 4 degrees
lateral rearfoot post, and neutral rearfoot post. Surface electro­
myographic activity data of the muscles was collected while the
individuals performed single-leg squatting, lateral stepdown,
and maximum vertical jump. During single-leg squat and lat­
eral stepdown, higher vastus medialis and gluteus medius activ­
ity was noted with all orthotic conditions. During the vertical
jump, less vastus lateralis was noted with all orthotic conditions.
Foot type did not influence the outcome in any of the activities.
Kulig and colleagues146 studied the influence of foot
orthoses on tibialis posterior activation in six adults with
pes planus. Exercises consisting of resisted foot adduction
and plantarflex were performed barefoot and then with foot
orthoses and shoes a week later. Magnetic resonance images
of tibialis posterior, tibialis anterior, peroneus longus, medial
gastrocnemius, and soleus were obtained pre- and postexer­
cise. When wearing foot orthoses and shoes, only the tibialis
posterior was activated. When barefoot, the magnetic reso­
nance image signal intensity of the tibialis posterior was lower
and five of the six participants activated the tibialis posterior
and additional muscles. The researchers concluded that selec­
tive activation of the tibialis posterior can be improved in
people with pes planus by wearing foot orthoses with shoes.142
Bird and colleagues147 considered electromyographic
activity of lumbar erector spinae and gluteus medius muscles
with prefabricated foot wedges (a 5-degree lateral wedge, a
5-degree medial wedge, or a 2-cm heel wedge). Although no
change in amplitude of electromyographic signal occurred,
wedging at the heel and lateral forefoot led to earlier elec­
tromyographic activity of the erector spinae. Gluteus muscle
activity was delayed with bilateral heel wedges, as was ipsilat­
eral gluteus activity when a unilateral heel wedge was used.
Although changes of onset for the erector spinae and gluteus
medius averaged only 4% and 2% of the gait cycle, respec­
tively, the researchers suggested that these changes are likely
to be clinically significant over the course of a day.
Vanicek and colleagues148 considered how foot orthoses
affected the ability of six healthy alpine skiers to hold a ski­
er's squat position and on the duration of fatigue of the vastus
lateralis. Individuals were examined under three conditions:
no orthoses, high-volume orthoses, and low-volume orthoses
(based on the amount of foam incorporated into the orthosis).
A decrease in median firing frequencies toward the end of
contraction suggested that high-volume orthoses reduced
myoelectric fatigue. However, no significant differences in the
ability to sustain a squat occurred under the three conditions.
Postural Control
If neuromuscular systems play a role in the effectiveness of
orthoses, changes in balance and posture control would be
anticipated with their use. Guskiewicz and Perrin149 examined
the effects of custom orthoses in 13 patients with acute ankle
inversion sprains and in 12 noninjured patients. As antici­
pated, orthoses reduced postural sway in the medial and lat­
eral and inversion and eversion directions, with a larger effect
in patients who had the injury. The researchers propose that,
by restricting undesirable motions, the orthoses enhanced
the ability of joint mechanoreceptors to detect movement.
In contrast, Hertel and colleagues150 found that six different
orthotic interventions (shoe only; molded Aquaplast orthoses
[Aquaplast Thermoplastics, Wyckoff, NJ]; orthoses in the neu­
tral, medially posted, and laterally posted positions; and a pre­
fabricated, rigid, laterally posted heel wedge) did not influence
postural sway in 15 patients with unilateral ankle sprains while
they performed unilateral standing. None of the orthotic con­
ditions decreased frontal or sagittal postural sway compared
with shoes alone. Hertel and colleagues151 also studied 15
healthy patients with normally aligned feet under the same six
conditions, focusing on center of pressure length and velocity
in both the frontal and sagittal planes during unilateral stance.
In this study, sagittal plane motion was not different among
the various conditions; however, medially posted orthoses
reduced frontal plane motion more than the other condi­
tions. Frontal plane center of pressure excursion increased
with a prefabricated, rigid, laterally posted heel wedge com­
pared with medially and neutrally posted conditions. Frontal
plane velocity was lower with medial posting compared with
a prefabricated, rigid, laterally posted heel wedge and neutral
orthoses. The prefabricated, rigid, laterally posted heel wedge,
however, produced significantly greater frontal plane veloci­
ties than the medially or laterally posted conditions.
Percy and Menz152 found that orthoses did not affect pos­
tural stability in 30 professional soccer players in bipedal, dom­
inant leg, and tandem stance. Sway was assessed under four
conditions: barefoot, soccer shoes only, soccer shoes with soft

210
Section II  Orthoses in Rehabilitation
insoles, and soccer shoes with rigid orthoses. The research­
ers concluded that orthoses had no beneficial or detrimental
effects in the elite athletes studied. In contrast, Olmsted and
Hertel153 found that foot orthoses differentially benefit those
with various foot types. They assessed static and dynamic pos­
tural control in 30 patients grouped by rectus, planus, or cavus
foot type. Patients wore custom-molded, semirigid foot ortho­
ses for 2 weeks between baseline and posttest measurement.
Improvement in reach occurred in three of eight directions on
the Star Excursion Balance Test in those with cavus foot type.
Patients with cavus foot type also demonstrated a decreased
center of pressure velocity in static stance.
Rome and Brown154 examined postural sway in 50 patients
identified as pronators (per the Foot Posture Index) in a ran­
domized clinical trial. Patients were assigned either to a con­
trol or orthotic group. The orthotic group wore prefabricated,
high-density ethyl vinyl acetate orthoses with low-density
ethyl vinyl acetate rearfoot wedging for 4 weeks. At 4 weeks,
medial-lateral sway decreased in the orthotic group; however,
no differences in anterior-posterior sway or mean balance
occurred between the groups.
Collectively, these studies suggest that orthoses do affect elec­
tromyographic activity, balance, and postural control. Health
professionals may be better able to identify those most likely to
benefit from orthotic intervention if measures of postural con­
trol and neuromuscular function are incorporated along with
the assessment of lower extremity and foot skeletal alignment.
MANAGEMENT OF OVERUSE INJURIES
Although the specific biomechanical and neurological
effects of foot orthoses on walking and running are not com­
pletely understood, orthoses can and do reduce symptoms
and improve function. Although current evidence does not
include many randomized, controlled clinical trials, the avail­
able evidence does support efficacy of orthotic intervention
in the management of lower extremity injuries.
Pain Associated with Foot Deformity
Burns and colleagues155 examined the effect of custom foot
orthoses on foot pain (and other factors) in individuals with
cavus foot type. The study consisted of 154 individuals with
75 randomly selected to the custom foot orthoses group and
79 to the control group. At 3 months’ follow-up,153 individu­
als reported data with mean foot pain improvement of 31.2
points with custom foot orthosis and 20.3 points with the con­
trol. Individuals with the custom foot orthoses improved pain
scores by 74% compared with 43% with the control group.
D'Ambrosia156 reported on 200 individuals who had used
orthoses to manage a variety of running injuries, including
posterior tibial syndrome, pes plano valgum, metatarsalgia,
plantar fasciitis, and iliotibial band tendonitis. Almost all had
severe pronation with forefoot varus before prescription of an
orthosis. Rates of reported improvement were quite high: 73%
in posterior tibial syndrome, 90% in pes plano valgum, 86%
in metatarsalgia, 82% in plantar fasciitis, and 66% in iliotib­
ial band syndrome. Of those with cavus foot type, only 25%
showed improvement with orthotic use.
Donatelli and colleagues157 received follow-up surveys from
53 (65%) of 81 individuals who had previously been fitted
with custom-molded, semirigid orthoses for pes planus and
chondromalacia, with 95% having a forefoot varus deformity.
All respondents had a 6 to 8 week trial of temporary ortho­
ses modified according to alterations in pain before receiving
custom-molded, semirigid orthoses. Respondents were asked
to describe or rate pain relief with orthoses, orthotic satis­
faction, continued use of orthoses, and ability to return to
previous level of activity. Ninety-six percent of respondents
reported pain relief, 91% were satisfied with their orthoses,
94% were still wearing their orthoses (length of time with
orthoses varied from 3 months to 2 years from time surveyed),
and 70% were able to return to their previous level of activity.
Moraros and Hodge158 surveyed 525 individuals who used
custom-fitted orthoses provided by podiatric physicians to
determine effectiveness and patient satisfaction. Of the 453
records completed in useable form (89% response rate), the
chief symptom was fully resolved in 62.5%, partially resolved in
32.8%, and unresolved in 4.7%. Overall satisfaction for fit and
quality was 83.1%. Although limitations are inherent in survey
research, the relatively high response rate and sample support
the usefulness of orthoses in relieving painful foot symptoms.
Patellofemoral Pain Syndrome
The role of foot orthoses on patellofemoral pain has been the
subject of several studies that have provided research data
for a systematic review on the efficacy of foot orthoses in
the treatment of patellofemoral pain.6 Barton and colleagues
found evidence to support the use of foot orthoses for treat­
ment of patellofemoral pain.6 Johnston and Gross159 assessed
the effect of foot orthoses on pain, stiffness, and function in
sixteen individuals with patellofemoral pain and excessive
foot pronation. Following baseline assessments, the individu­
als were fitted with custom foot orthoses. Statistically signifi­
cant improvements in pain and stiffness were found 2 weeks
following the foot orthotic intervention and improvements in
physical function were noted at the 3-month follow-up.
Barton and colleagues160 used a variety of weight-bearing
measurements to compare foot and ankle characteristics of indi­
viduals with patellofemoral pain syndrome to those without the
syndrome. In relaxed stance, individuals with patellofemoral
pain syndrome had signifcantly greater pronated foot posture
than the control group when determined by longitudinal arch
angle and posture index measurements. The patellofemoral pain
syndrome group also demonstrated greater ranges of motion
when subtalor joint neutral was used as a reference posture.
In a single subject design, Way161 investigated the use of
a custom-molded thermoplastic foot orthosis on PFPS in
a 19-year-old collegiate softball player with a mild forefoot
varus bilaterally and increased midfoot pronation during
MSt and TSt. Intervention included pain-free stretching and
strengthening exercises, modalities, and nonsteroidal antiin­
flammatory medication. The study design involved a 13-day
baseline phase, a 17-day intervention phase (after which the
patient removed orthoses for an 11-day withdrawal phase),
and a second intervention phase in which orthoses were rein­
troduced for the last 32 days of the study. Pain was rated by

Chapter 8  Foot Orthoses
211
a visual analog scale, and function was evaluated with the
Functional Index Questionnaire. Pain decreased in each con­
secutive phase; function improved between phases for seven
of the nine functional activities assessed in the Functional
Index Questionnaire. On the basis of these findings, Way161
suggested that orthotic intervention is appropriate for PFPS.
Saxena and Haddad162 retrospectively reviewed 102 out­
comes of interventions in individuals with chondromalacia
patella, retropatellar dysplasia, or PFPS. Multiple interven­
tions were noted, including semiflexible orthotics. Overall,
76.5% of patients demonstrated a reduction in pain and
improved function, and 2% were asymptomatic after a 2- to
4-week intervention period.
Sutlive and colleagues163 sought to identify characteristics
of patients with PFPS likely to improve with a combination
of orthoses and modified activity. They examined 50 patients
in active military duty who had symptoms of PFPS during
a partial squat or when ascending stairs. Measures included
(1) rearfoot alignment in STN, (2) forefoot to rearfoot align­
ment, (3) navicular drop, (4) RCS, (5) Q angle, (6) tibial varum
or valgum, (7) tibial torsion, (8) leg length, and (9) standard
goniometric and postural test positions to determine ROM
and tissue tightness. Patients wore unposted, premolded, full-
length insoles with full arch support and heel cushioning for
21 days while concurrently limiting various activities. All com­
pleted a visual analog scale and a Global Rating of Change
Questionnaire at baseline and at the end of the interven­
tion period. Thirty-three of 50 patients completed the study,
with a total of 78 knees with PFPS (many had bilateral symp­
toms). Data from 27 patients who demonstrated 50% or more
improvement in visual analog scale scores were examined to
determine which patient characteristics could predict orthotic
success. Likelihood ratios identified several predictors of suc­
cessful outcome: forefoot valgus of 2 degrees or more, great toe
extension of 78 degrees or less, and navicular drop of 3 mm or
less. Of those with PFPS, the patients with these three charac­
teristics were more likely to respond to orthotic intervention.
Plantar Fasciitis
The use of foot orthoses in the management of plantar fasci­
itis has also been examined. A 12-month study by Landorf and
colleagues164 compared the effectiveness of sham, prefabricated
and custom orthoses on pain and function in 136 individuals
with plantar fasciitis. Participants were allocated to one of the
three groups (sham, prefabricated, or custom) by a computer-
generated random assignment and no other treatments were
allowed during the 12-month trial. The prefabricated and cus­
tomized groups experienced greater improvements in function
and pain as compared to the sham group at 3 months but only
the orthotic effects on function were statistically significant.
Compared to the sham, the mean pain score for the prefabri­
cated and custom orthosis was 8.7 and 7.4 points better and the
mean function score was 8.4 and 7.5 points better respectively.
All three groups improved with function and pain compared
with baseline status at 3 months and 12 months, and there were
only slight differences between the groups at 12 months.
Gross and colleagues165 studied 15 individuals with plan­
tar fasciitis for at least 1 month. Eight patients had excessively
pronated feet, and seven had a cavus foot type. Eleven of 15
had unsuccessfully used noncustom arch supports before
enrollment in the study. At baseline, patients completed the
pain and disability index of the Foot Function Index, were
timed during a 100-m walk, and rated pain experienced
during the walk with the visual analog scale. They received
custom-fabricated, posted, multilayer orthoses with a ther­
moplastic core and were reevaluated after 12 to 17 days of
orthotic use. Although no differences in preintervention and
postintervention walk times occurred, visual analog scale
pain ratings after the walk were lower than baseline, with only
one patient demonstrating increased pain after the walk test.
The scores on the subsections of the Foot Function Index also
improved after orthotic use, with improvement of 66% in the
pain subscale and 75% in the disability subscale. All patients
continued to wear their orthoses at a follow-up phone call
made 2 to 6 months after testing.
Seligman and Dawson166 retrospectively evaluated 10 older
individuals (mean age, 71 years) with heel pain from plantar
fasciitis who used a heel pad made of Sorbothane (Sorbothane,
Inc., Kent, Ohio) attached to a custom-molded, medium-­
density Plastazote insert reinforced with cork in the medial
longitudinal arch. Duration of pain ranged from 6 months to
several years; 5 of 10 patients previously tried other interven­
tions. Pain was rated by a 10-point Likert pain rating scale.
A  significant difference occurred between baseline pain
­ratings (5.7/10) and postintervention pain ratings (1.85/10).
Morton's Neuroma
Kilmartin and Wallace167 found that orthotic intervention did
not improve symptoms of Morton's neuroma. Twenty-three
individuals with pain of the third and fourth intermetatarsal
space, aggravated by exercise and relieved by rest, were ran­
domly assigned to two groups, with no consideration of foot
type. Those in the supination group wore a Cobra orthosis
with a thicker medial heel and arch filler. Those in the pro­
nation group wore a reverse Cobra orthosis with a thicker
lateral heel. Pain was measured by a visual analog scale.
Sensory impairment and pain were objectively measured by
tests that elicit neuroma pain. Function was assessed with
the McMaster-Toronto Arthritis Patient Function Preference
Questionnaire patient-specific measure of maximal func­
tion. No differences in pain or function occurred between the
supination and pronation groups. Neither orthosis produced
additional symptoms in the lower extremity.
The authors suggested that prescribing a custom ortho­
sis based on foot type would have provided greater relief of
symptoms.
Low Back Pain
Dananberg and Guiliano168 examined the effects of orthotic
intervention in 32 patients with chronic low pain. Patients com­
pleted the Quebec Back Pain Disability Scale at baseline after
wearing foot orthoses for 1 month and after wearing orthoses
for at least 6 months. The Quebec Scale provided a back pain
score and a disability score. Permanent orthoses were fabricated
on the basis of the results of temporary orthoses with modifi­
cations specific to each patient, in-shoe pressure analysis, gait

212
Section II  Orthoses in Rehabilitation
video analysis, and clinical examination. At 1 month, signifi­
cant reduction was observed in the mean pain and disability
scores. Twenty-three of the original 32 patients were contacted
at 6-month follow-up and reported significant improvement in
function and reduction in pain. In comparing their outcomes
to previous work by Kopec and colleagues,169 who used the
Quebec Back Pain Disability Scale to evaluate improvement in
178 patients undergoing standard back care interventions, the
authors suggested that the use of foot orthoses enhanced out­
comes over traditional back care. Of note, the protocol for eval­
uating patients for permanent orthoses was extensive.169
Although few randomized, controlled clinical studies have
been undertaken, and most have been done with a small
sample size in specific patient populations, current evidence
supports that foot orthoses reduce symptoms of pain and
improve function in individuals with overuse injury. Foot
structure and type, orthotic materials, posting methods, and
fabrication methods must be considered in determining who
is likely to respond to orthotic intervention and comparing
the effectiveness of various orthotic interventions.
SUMMARY
Although many components of Root's theory have been ques­
tioned, little doubt is present concerning the importance of
his work in the field of foot biomechanics and orthotic inter­
vention. Root's work provides a foundation for most of the
research performed to gain a better understanding of the
influence of the foot on lower extremity biomechanics and
overuse injuries. Although research has provided some
answers about mechanisms underlying efficacy of orthotic
intervention, many more questions have also been raised.
Additional research is necessary before clinicians will be able
to prescribe orthoses confidently based on likely outcomes.
The effectiveness of biomechanical foot orthoses depends
on a number of factors. An understanding of causes and
effects of aberrant foot motion on pathological conditions of
the foot is essential in determining the appropriate orthosis
prescription and plan of care. Clinicians who do not care­
fully consider biomechanical principles and other factors that
contribute to clinical signs and symptoms are likely to pre­
scribe an ineffective or inappropriate orthosis. Information
gathered from all three components of the biomechanical
examination (non–weight-bearing, static weight-bearing,
and dynamic gait assessment) is critical for orthotic design
and prescription.
Historically, the principles and design of the Root func­
tional orthosis and the biomechanical foot orthosis have had
consistently effective clinical results. Root's model demands
a keen understanding of foot biomechanics, careful prescrip­
tion, and advanced fabrication skills. With this understanding
and attention to detail, the end result may be a lightweight,
durable, cost-effective foot orthosis that substantially reduces
the detrimental effects of aberrant foot motion.
M. L. is an active 50-year-old woman who recently began
to train for a local 10-km race. She is referred by her family
physician for evaluation and intervention because of thick­
ened and painful plantar callus under the second and fourth
metatarsal heads and on the lateral surface of the hallux in
both feet. The discomfort has increased to a point that she is
unable to complete the distances she needs to run to prepare
for the upcoming race.
M. L. is 5 feet, 5 inches tall and weighs 132 lb. In relaxed
standing, no leg-length discrepancy is apparent, although
both patellae are rotated inward, slight hyperextension and
recurvatum at the knee is present (left more than right), and
both feet are markedly pronated.
The following values are recorded in the non–weight-
bearing and weight-bearing examinations:
CASE EXAMPLE 1
Individual with Rearfoot and Forefoot Dysfunction
Non–Weight-Bearing Examination Component
Left
Right
Rearfoot STN position
6 degrees varus
7 degrees varus
Calcaneus inversion
18 degrees
22 degrees
Calcaneus eversion
12 degrees
14 degrees
Ankle dorsiflexion
9 degrees
7 degrees
Rearfoot dorsiflexion
2 degrees
0 degrees
Forefoot STN position
Mild valgus
Moderate valgus
Locking mechanism
Fair
Poor
First ray
Slightly plantar flexed
Slightly plantar flexed
Hallux dorsiflexion
75 degrees
80 degrees
Medial longitudinal arch
Medium height
Medium height

Chapter 8  Foot Orthoses
213
Weight-Bearing Examination Component
Left
Right
Calcaneal/floor alignment
Eversion
Eversion
Tibiofibular position
40 degrees
37 degrees
Navicular drop (STN to relaxed calcaneal stance)
10 mm
12 mm
Navicular position (Feiss)
Slightly below
Moderately below
Toe sign
2.5 toes visible
3 toes visible
Femoral torsion
14 degrees
16 degrees
Tibial torsion
25 degrees
27 degrees
STN, Subtalar neutral.
Questions to Consider
• What are the normative values for non–weight-bearing
range of motion in the rearfoot (STN position, calcaneal
inversion and eversion, dorsiflexion) and forefoot (STN
position, midtarsal joint dorsiflexion, first ray position,
and mobility)?
• What rearfoot and forefoot deformities do M. L.'s exami­
nation findings suggest?
• What are normal findings for the closed chain static
weight-bearing examination?
• How should the findings for M. L.'s weight-bearing
examination be interpreted?
• How do the findings of M. L.'s non–weighting-bearing and
weight-bearing examinations relate to each other? What
deformities are compensated versus uncompensated?
M. L. wants to continue training for her upcoming race
without increasing her pain and further damaging soft tis­
sue in her feet. An appropriate prescription is being created
for M. L. on the basis of the findings of her examination and
the principles of orthotic design.
Examination Findings
Relaxed standing: no apparent leg-length discrepancy, both
patella rotated inward, slight hyperextension and recurva­
tum at the knee (left more than right), marked pronation of
both feet.
CASE EXAMPLE 2
Individual with Rearfoot and Forefoot Dysfunction
Non–Weight-Bearing Examination Component
Left
Right
Rearfoot STN position
6 degrees varus
7 degrees varus
Calcaneus inversion
18 degrees
22 degrees
Calcaneus eversion
12 degrees
14 degrees
Ankle dorsiflexion
9 degrees
7 degrees
Rearfoot dorsiflexion
2 degrees
0 degrees
Forefoot STN position
Mild valgus
Moderate valgus
Locking mechanism
Fair
Poor
First ray
Slightly plantar flexed
Slightly plantar flexed
Hallux dorsiflexion
75 degrees
80 degrees
Medial longitudinal arch
Medium height
Medium height
Weight-Bearing Examination Component
Left
Right
Calcaneal/floor alignment
Eversion
Eversion
Tibiofibular position
40 degrees
37 degrees
Navicular drop (STN to relaxed calcaneal stance)
10 mm
12 mm
Navicular position (Feiss)
Slightly below
Moderately below
Toe sign
2.5 toes visible
3 toes visible
Femoral torsion
14 degrees
16 degrees
Tibial torsion
25 degrees
27 degrees
STN, Subtalar neutral.
Continued

214
Section II  Orthoses in Rehabilitation
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• How frequently should M. L. be followed up during this
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intervention be assessed?

Chapter 8  Foot Orthoses
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1995;20(3):341–352.

219
Principles of Lower Extremity Orthoses
Michelle M. Lusardi
There are many factors to consider when selecting a lower
extremity orthosis for individuals with musculoskeletal or
neuromuscular dysfunction who have difficulty with mobil­
ity and walking. An orthosis may be designed to substitute for
impaired muscle performance in the presence of weakness to
improve foot clearance in the swing phase of gait.1 An orthosis
may be used to provide stance phase stability and support to
enhance alignment of limb segments when there is structural
instability of one or more lower extremity joints.2 An orthosis
may be designed to limit joint motion or unload forces dur­
ing weight bearing to allow healing after surgery or prevent
injury to vulnerable joints.3 For persons with impaired motor
control and abnormal tone, orthoses may enhance mobility by
minimizing the impact of abnormal movement associated with
hypertonicity by positioning limb segments for optimal func­
tion.4,5 Alternatively, an orthosis may be used to minimize the
risk of development of bony deformity and contracture asso­
ciated with longstanding hypertonicity, especially in growing
children.6 Given the many different reasons that an orthosis
might be prescribed, there is no “one size fits all” option: Health
professionals must clearly define what they want an orthosis to
accomplish, consider its practicality and cost, and sort through
the many options available to select the design and compo­
nents that will best meet the patient's needs and goals.
This chapter systematically reviews the design, and the
pros and cons of ankle-foot orthoses (AFOs), knee-ankle-
foot orthoses (KAFOs), and hip-knee-ankle-foot orthoses
(HKAFOs) as a means to improve mobility and function for
children and adults with neuromuscular dysfunction. We will
start with a quick review of the gait cycle and its “rockers” as
a foundation for understanding how an orthosis can provide
stance phase stability or enhance swing phase mobility. Then
we will compare and contrast the various AFO designs, dis­
cuss contemporary KAFO components and design, explore
traditional HKAFOs and their uses, investigate the clinical
use of the parapodium and standing frames, and finally con­
sider orthotic options for reciprocal gait for patients with sig­
nificant neuromuscular disease or disability. We will apply
our growing understanding of lower extremity orthoses in
problem-based cases for children and adults with cerebral
palsy, hemiplegia following stroke, postpolio syndrome, and
spinal cord injury (SCI).
WHAT TYPE OF ORTHOSIS IS BEST?
When an individual with neuromuscular or musculoskeletal
dysfunction has difficulty with mobility and walking, deci­
sions about orthotic options are best made by collaborative
interaction within the framework of an interdisciplinary
team.7 Members of this team include the person who will be
using the orthosis, their family members or caregivers, any
physicians involved in his or her care (e.g., a neurologist,
9
LEARNING OBJECTIVES
On completion of this chapter, the reader will be able to:
1. Define the functional objectives (reasons) that an ankle
foot orthosis (AFO), knee ankle foot orthosis (KAFO),
or hip knee ankle foot orthosis (HKAFO) would be pre­
scribed for persons with mobility dysfunction.
2. Explain the evaluative process used to determine appropri­
ate prescription for individuals requiring a lower extrem­
ity orthosis.
3. Describe the biomechanical control systems for foot,
ankle, knee, and/or hip designed into an AFO, KAFO, or
HKAFO.
4. Describe how each type of lower extremity orthosis is
designed to enhance achievement of stance phase stability,
swing limb clearance, limb prepositioning, adequate step
length, and efficiency of gait.
5. Describe how each of the most commonly prescribed AFO,
KAFO, and HKAFO designs affect transition through the
rockers of stance and swing phase of gait.
6. Compare and contrast the indications and limitations
of prefabricated, custom fit, and custom molded lower
extremity orthoses.
7. Apply knowledge of normal and pathological gait, assess­
ment of impairment, and functional potential in the selec­
tion of an appropriate lower extremity orthosis for patients
with neuromuscular impairments.
8. Identify effective strategies for donning/doffing the ortho­
sis, gait and mobility training, and orthotic maintenance
for children and adults using lower extremity orthoses.
9. Select appropriate outcome measures to evaluate effective­
ness of orthotic intervention and gait training for persons
using lower extremity orthoses.

220
Section II  Orthoses in Rehabilitation
orthopedist, or physiatrist), the physical and occupational
therapists who are likely to be involved in functional train­
ing, and the orthotist who will design, fabricate, deliver, and
maintain the orthosis. The combined knowledge and skills
of all members of the team ensure that the prescription will
best match orthotic design to the patient's functional needs
(Table 9-1).8 If the team is not able to gather in one place as
decisions are being made, there must be effective strategies
for communication in place so that each team member can
contribute his or her unique perspective about why an ortho­
sis is indicated and how the orthosis will facilitate the indivi­
udual's functional ability.
Physical therapists examine the patient to provide infor­
mation about muscle performance and motor control, range
of motion, alignment of the limbs, information about the gait
cycle with attention to both primary impairments and the
compensation strategies the individual uses while ­walking,
as well as how the orthosis might impact biomechanically
TABLE 9-1  Components of the Preorthotic Prescription Examination Organized by ICF Categories
ICF Category
Domain
Concerns
Body structure and function
Joint integrity and stability
Ligamentous instability, joint deformity
Range of motion
Soft tissue contracture, joint deformity
Limb length and alignment
Rotational deformity, unequal limb length
Muscle length
Fixed versus modifiable contracture
Overall flexibility
Ability to don/doff; impact of orthosis
on trunk, back
Motor control
Quality of voluntary motion
Muscle tone
Flaccidity, hypotonicity, hypertonicity,
fluctuating tone
Muscle performance
Strength, power, endurance
Involuntary movement
Impact on tolerance of orthosis
Coordination
Ability to don/doff
Somatosensory function
Ability to detect skin irritation/damage
Perceptual function
Ability to don/doff
Upper extremity function
Ability to don/doff
Postural control, balance
Ability to don/doff
Visual function
Ability to perform skin checks, donning/doffing
Cognitive function
Understanding of how to use orthosis
Cardiovascular endurance
Ability to functionally use orthosis
Activity level
Gait analysis
Observational
Primary gait problems and compensations
Kinematic
Primary gait problems and compensations
Kinetic
Impact of orthosis on moment throughout
gait cycle
Energetics
Impact of orthosis on physical work of walking
Assistive device
Safe function with orthosis and assistive device
Various surfaces
Impact of resistance, unstable surface on gait
Transitions
Sit to/from stand
Preparing to walk and returning to seated
position
To/from floor
Activities on the floor (especially for children/
play)
Managing falls
How to protect self and recover from fall
Inclines/stairs
Degree of mobility in home and public
environment
Activities of daily living
Donning/doffing
Will assistance be necessary? Who will provide
help?
Self care
How will orthosis impact on self-care ability?
Toileting
Will orthosis need to be removed to use the
bathroom?
Dressing
Ability to manage clothes and shoes
Participation level




Home
Ability to take part in family activities, roles
School
Mobility in classroom, hallways, outside
play areas
Work
Mobility in entrance, workspace, common areas
Leisure
Mobility over surfaces, use of tools/devices
Transportation
Ability to drive, use public transportation
ICF, The World Health Organization's International Classification of Functioning, Disability and Health.

Chapter 9  Principles of Lower Extremity Orthoses
221
on other daily motor tasks (e.g., a child's ability to get up and
down from the floor).9 Physicians bring to the team an under­
standing of the specific disease or disorder that the patient is
dealing with, including the condition's natural history and
likely prognosis, types of secondary musculoskeletal problems
that are commonly encountered, and any cognitive, develop­
mental or multisystem involvement that may be associated
with the disease.10 Family members and the individual need­
ing the orthosis are concerned with practical issues, such as
who will be responsible for applying (donning) or removing
(doffing) the device and the ease with which this can be accom­
plished, as well as information about the types of activities that
the individual wants to be involved in while using the orthosis
(lifestyle and leisure activities).11 The orthotist uses knowledge
of materials and biomechanics, information provided by team
and family members, and results of the individual's physical
examination to design and fabricate the orthosis that will best
address the mobility problem that needs to be solved.9
The team must not overlook the significant contribution of
the individual and caregiver in the prescription process. The use
of an orthosis enhances as well as constrains lower limb func­
tion; as such, it requires considerable adjustment on the part of
the person who will be wearing the orthosis. An understand­
ing of the individual's or the caregiver's expectations about what
the orthosis will accomplish is a key component of orthotic pre­
scription and training. Discussion and education about what an
orthosis will and will not do for the wearer can minimize poten­
tial mismatch of expectation versus actual outcome. Acceptance
and functional use of the orthosis depends on just how well it
meets identified needs and goals, as well as the cost of its use in
terms of inconvenience and disruption of lifestyle.12
Careful consideration of the individual's diagnosis is also
critical when selecting materials and designing the ortho­
sis.13 Questions that the team should consider ­during the
decision making process include: Can we reasonably expect
that an individual's musculoskeletal or neuromuscular status
is stable and likely to remain the same over time? Does the
disease typically have a progressive course, such that decline
in function is anticipated over time? Or, as in the case of
traumatic injury, will the person's condition and functional
ability improve with time as healing occurs? What can be
expected in terms of muscle function and strength, range
of motion and joint function, and functional mobility and
gait over time? How might growth and developmental sta­
tus influence future orthotic needs? All of these must be
accounted for in the design of the orthosis.
The selection of any orthotic device must include careful
consideration of four factors:
1. The advantages or positive outcomes expected when using
the orthosis (i.e., how it will improve mobility and gait,
influence tone, or protect a limb or body segment).
2. Any disadvantages or tradeoffs that may be associated
with its use (i.e., the ways in which it may complicate daily
activity, mobility, or preferred activities; the energy cost of
associated with its use; the relative expense of the device).
3. The indications that the orthosis may be useful to the indi­
vidual (i.e., the match between the person's characteristics
and needs, and what the orthosis will provide).
4. The circumstances or characteristics of the individual that
make use of the device detrimental or contraindicated.
Consideration of these four factors guide clinical decision
making when comparing and contrasting the various options
for lower extremity orthoses. Characteristics of an ideal
orthosis are summarized in Box 9-1.
To help an individual use the orthosis most effectively, the
physical therapist must understand how the orthosis should
fit with respect to its design (i.e., what are the optimal trim
lines?) and force control systems (how does it act on the limb
segments?) (Box 9-2). Every orthosis uses force applied to the
FUNCTION
• Meets the individuals mobility needs and goals
• Maximizes stance phase stability
• Minimizes abnormal alignment
• Minimally compromises swing clearance
• Effectively pre-positions the limb for initial contact
• Is energy efficient with the individual's preferred assis­
tive device
COMFORT
• Can be worn for long periods without damaging skin or
causing pain
• Can be easily donned and doffed (e.g., considering cloth­
ing, footwear, toileting)
COSMESIS
• Meets the individual's need to fit in with peers
FABRICATION
• Can be made in the shortest period of time
• Uses a minimally complex design
• Has some degree of adjustability to enhance initial fitting
• For children, responds to growth or change over time
• Is durable: stands up to stresses/strains of daily activity
COST
• Can be made with minimal initial cost, and minimal cost
for maintenance
BOX 9-1  Characteristics of an ‘Ideal’ Orthosis
1. Pressure = Force/Area
2. Torque = Force × distance
3. Control direction of primary force
direction of counter-forces
4. Equilibrium Σforces = 0
BOX 9-2  Principles Underlying Control Systems
in Orthotic Design

222
Section II  Orthoses in Rehabilitation
limb to accomplish the goals of its design. An orthosis is most
comfortable and effective when (Figure 9-1):
1. The forces are distributed over large surface areas to mini­
mize pressure on skin and soft tissue.
2. The forces are applied in such a way that a large moment
arm reduces the amount of force needed to control
the joint.
3. The sum of the primary force and opposing counterforces
of each control system equals zero.
DETERMINANTS OF FUNCTIONAL GAIT
There are five factors that influence how well an individual is
able to walk.14 The first is stance phase stability: The limb in
contact with the ground must be stable enough to support body
weight and respond to the ground reaction forces (GRF) as the
individual moves through stance phase. The second is clear­
ance in swing: The advancing limb must clear the ground ade­
quately during swing phase to minimize risk of stumbling and
trips. Swing limb clearance is influenced by the ability to main­
tain a level pelvis by stance limb abductor muscle as well as by
action of the hip, knee flexors, and dorsiflexors of the swing
limb as they relatively shorten the length of the swinging limb.
The third is swing phase pre-positioning: By the end of swing,
the foot about to contact the ground must be positioned for an
effective initial contact and loading response as stance begins.
The fourth is adequate step length: There must be adequate
motor control and range of motion at the hip, knee, ankle, and
forefoot of both limbs so that optimal step length can occur.
The fifth is energy conservation: If there are problems with tim­
ing, muscle performance, coordination, or postural control
during the gait cycle, the energy cost of walking rises substan­
tially, and efficiency of ambulation is compromised.
If neuromuscular or musculoskeletal dysfunction substan­
tially interferes with these determinants, functional ambula­
tion may be an unrealistic goal without an appropriate orthosis.
Refer to Chapter 5 for greater detail about characteristics of the
normal and pathological gait cycle.
THE ROCKERS OF STANCE PHASE
Orthotists describe three transitional periods, or rockers, during
stance phase of walking as the body progresses forward over the
foot (Figure 9-2).15 During the first (heel) rocker, there is a con­
trolled lowering of the foot from neutral ankle position at initial
contact to a plantarflexed foot flat, as well as acceptance of body
weight on the limb during loading response. When motor con­
trol and muscle performance is efficient, eccentric contraction
of the quadriceps and anterior tibialis prevents “foot slap” and
protects the knee as GRF is translated upward toward the knee.
In the second (ankle) rocker, the tibia begins to rotate over the
weight-bearing foot, from its initial 10 degrees of plantarflex­
ion at the end of loading response, then through vertical into
dorsiflexion as midstance is completed. Eccentric contraction
of the gastrocnemius and soleus muscles “puts on the brakes”
to control the speed of the forward progression of the tibia over
the fixed foot throughout midstance. At the start of the third
(toe) rocker, the forefoot has converted from its mobile adap­
tor function of early stance to a rigid lever for an effective late
stance, and the heel rises off the ground so that body weight has
to roll over the first metatarsophalangeal joint through push-off
in terminal stance. During fast walking and running, accelera­
tion occurs as active contraction of the gastrocnemius-soleus
complex propels the foot and leg into swing phase.
All lower extremity orthoses provide some degree of external
stability to foot and ankle joints; as a result, the smooth transi­
tion through the rockers of stance phase is often compromised.16
CFPosterior
CFPlantar
FPrimary
FIGURE  9-1  Principles underlying the plantarflexion control
system acting during swing phase in a rigid/solid ankle-foot
orthosis (SAFO). The large primary force (FPrimary) is applied in
a posterior-inferior direction over a large surface area (stippled
area) anterior to the axis of the ankle joint, usually by the shoe's
closure or reinforced by webbing across the anterior ankle. The
two counterforces, applied in an upward (CFPlantar) and anterior
(CFPosterior) direction, also over a large surface area, far from the
axis of the ankle joint, create an effective moment arm so that less
force is required to achieve the desired stabilization. The sum of
the primary (large arrow) and two opposing counterforces (small
arrows) is zero in a well-balanced orthosis.

Chapter 9  Principles of Lower Extremity Orthoses
223
Disruption of forward progression during stance negatively
impacts step length, cadence, and single limb ­support time.15
The optimal orthotic prescription must balance the need to
provide external support with the possible compromise on for­
ward progression and mobility: The orthotist strives to select
an orthotic design that provides minimum necessary stabil­
ity so that mobility will be the least compromised.16 In many
instances, modifications of footwear, such as the addition of a
cushion heel (which simulates controlled lowering of the foot
in loading response) or a rocker bottom sole (which simu­
lates forward progression of the tibia over the foot through­
out midstance), can substitute to some degree for the mobility
lost when external control is necessary.17 The rehabilitation
team must weigh the impact of stability provided by an ortho­
sis on progression through stance and its impact on a patient's
functional status: At times compromise is unavoidable if the
patient's functional deficits are to be addressed effectively.
PREFAB, CUSTOM FIT, OR CUSTOM MOLDED?
How does the team determine whether an individual would
benefit from a relatively less expensive prefabricated ortho­
sis versus a more costly (in both time and money) custom-
molded orthosis designed specifically for the person? There
are a number of factors to consider in making this decision.
The effectiveness of an AFO is determined by to the inti­
macy and consistency of its fit. Thermoplastic AFOs can be
very effective in controlling a wide range of orthopedic defor­
mities; however, this requires a total contact, intimate fit in all
three planes of motion. Intimacy of contact between limb and
orthosis is best achieved in custom molded designs.
Mass manufactured, prefabricated orthoses are available in
a wide spectrum of orthotic designs, by shoe size, and made of
a number different of materials. The degree to which they can
be modified or adjusted to fit an individual varies; this may
be problematic for persons with foot deformity, extremely
wide or narrow feet, or large calf muscles. They are attrac­
tive to payers because they are significantly less expensive
that custom-fit or custom-molded orthoses. Many rehabilita­
tion professionals, however, are not satisfied with the ability
of a prefabricated orthosis to provide optimal external sup­
port and control of motion over time: Durability is directly
related to the quality of material used and by the lack of inti­
mate fit to an individual's limb. Even a minimal amount of
pistoning or heel elevation within the orthosis during walking
can lead to skin irritation or breakdown, and in the presence
of hypertonicity, increase of underlying abnormal extensor
tone. Therapists may opt to use a trial run with prefabricated
orthoses as an evaluative tool to determine which orthotic
design might best meet the patient's needs during the time
that a custom orthotic is being prepared or when the patient's
condition requires use of an orthosis for only a short time
period.18 Because prefabricated orthoses do not fit the foot
intimately, they should be used with extreme caution in per­
sons with neuropathic foot conditions whose ability to per­
ceive soft tissue irritation and damage is compromised.19
Another alternative is an orthosis that begins as a manufac­
tured “blank” that is then custom fit using heating or relieving
techniques or the application of additional materials to obtain
as close a fit to the individual's foot and limb as possible. While
custom-fit orthoses provide better control than similar prefab­
ricated versions, they are not as effective in terms of fit and
function as a custom-molded orthosis.20 Custom-fit orthoses
may be appropriate when change in functional status (either
improvement or deterioration) is anticipated, such that the
orthosis will need to be replaced or adjusted frequently.
Custom-molded orthoses provide the optimal control
of the limb and, because of their intimate fit, are especially
important for patients with impaired sensation, significant
hypertonicity, or risk of progressive deformity associated
A
B
C
FIGURE 9-2  Three transitional rocker periods occur as the body moves forward over the foot during
stance. A, During first rocker, the transition from swing into early stance, controlled lowering of the fore­
foot occurs, with a fulcrum at the heel. B, During second rocker, controlled forward progression of the
tibia over the foot occurs, with motion of the talocrural joint of the ankle. C, In the third rocker, transition
from stance toward swing occurs as the heel rises, with dorsiflexion of the metatarsophalangeal joints.

224
Section II  Orthoses in Rehabilitation
with their condition. The orthotist constructs the orthosis
around a rectified model of the person's limb, ensuring ade­
quate pressure relief over vulnerable areas (i.e., bony promi­
nences) and building in the desired stabilizing forces based
on the orthotic prescription.21 Refer to Chapter 6 for more
details about the process of fabrication.
The only true contraindication of a custom-molded ther­
moplastic design is significantly fluctuating limb size, asso­
ciated with conditions that lead to edema of the braced
extremity.22 When limb size fluctuates, intimacy of custom
molded fit is lost: When the limb is at its lowest volume,
excessive movement of the limb within the orthosis occurs,
compromising orthotic control and increasing risk of skin irri­
tation and damage. When the limb is significantly edematous,
the AFO may become constricting, leading to pressure-related
problems. For persons with congestive heart failure, advanced
kidney disease on dialysis, or other conditions associated with
unpredictable fluctuation in limb volume, the total contact of a
custom-molded orthosis may be inappropriate, and a conven­
tional double upright orthotic design should be considered.
APPROPRIATE FOOTWEAR
Whether the decision is to use a prefabricated, custom-fit,
or custom-molded orthosis, the ultimate ability of the AFO
to meet its therapeutic goals depends on the type and con­
dition of the individual's footwear.17 Refer to Chapter 7 for
more information about key characteristics of shoes worn
with an orthosis. Recognition of the need to consider foot­
wear is not always intuitive to the individual, caregivers, or
health professionals working on improving the ability to
ambulate. It may be necessary for the individual to wear a
shoe that is one-half to a whole size larger to accommodate
an orthosis; a shoe that is too short or too tight can interfere
with the biomechanical function of the orthosis. Shoe clo­
sure of an oxford style or athletic shoe (whether tied with
laces or closed with Velcro) often provides the diagonally
directed force that stabilizes the calcaneus in the heel cup
of the orthosis; if the calcaneus moves out of position dur­
ing walking, the effectiveness of orthotic control is compro­
mised. Loafer type shoes and most sandals do not provide
adequate stabilizing forces during the stance phase of gait.
While most thermoplastic AFO designs allow individu­
als to alternate among several pairs of shoes, changing heel
heights dramatically alters the biomechanical function of
the orthosis. The orthotist and therapist share responsibil­
ity for patient and family education about appropriate foot­
wear, monitoring shoe condition to assess impact of wear
and tear on its construction and stability, as well as ongoing
evaluation of the effectiveness of the orthosis in meeting the
individual's functional needs over time.
ANKLE-FOOT ORTHOSES
AFOs are, by far, the most frequently prescribed device
used to control the lower extremity during each phase
of the gait cycle for individuals with neuromuscular or
musculoskeletal impairments that make walking difficult.
It is important to note that the acronyms used to name
lower extremity orthoses describe joints that are posi­
tioned within the orthosis. In reality, AFOs also effectively
address stability of the knee joint (proximal to the orthosis)
during stance.23
AFOs fall into two categories: static orthoses that pro­
hibit motion in any plane at the ankle (e.g., solid ankle AFO,
anterior floor reaction AFO, patellar tendon–bearing/
weight-relieving AFO). In contrast, dynamic orthoses allow
some degree of sagittal plane motion at the ankle (e.g.,
posterior leaf spring or spiral AFOs, articulating ankle
AFOs). Whether static or dynamic, the primary goal of an
AFO is to provide just enough external support for stabil­
ity in stance and clearance in swing with minimal compro­
mise of forward progression through the heel, ankle, and
toe rockers of gait.16 The actions, indications, and contra­
indications for the various AFO designs are summarized
in Table 9-2.
Biomechanical Principles
The biomechanical principles of AFOs are founded on the
functional anatomy of the ankle-foot complex. Dorsiflexion
and plantarflexion of the ankle are multiplanar (i.e., move­
ment occurs in all three planes of motion) as the talus rotates
through the mortise of the ankle in both open chain move­
ment, and when the mortise moves over a relatively fixed
(weight-bearing) talus in a closed chain movement.24 The
proximal surface of the mortise is shaped by the syndesmosis
(fibrous articulation) between the distal tibia and fibula. The
medial wall of the talocrural joint is formed by the medial
malleolus, a downward extension of the tibia. The lateral wall,
formed by the lateral malleolus of the fibula, is both longer
and shifted posteriorly. Because of the shape of the articu­
lar surfaces of the talus in its mortise and the offset position
of the malleoli, the axis of the ankle joint is slightly oblique,
running in an anteromedial to posterolateral direction. As a
result, dorsiflexion is accompanied by some degree of fore­
foot pronation and abduction along with hind foot valgus.
Plantarflexion is accompanied by forefoot supination with
adduction and hind foot varus. Note that during stance,
movement occurs in closed chain situation because the foot
is fixed on the ground by weight-bearing forces, so that the
mortise rolls over the head of the talus.
If an AFO has mechanical ankle joints, the axis of the
mechanical joints should be aligned as closely as possible to
the obliquely oriented anatomical axis of motion (Figure 9-3).
The mechanical joint heads are placed at approximately mid­
line of the malleoli in the sagittal plane. This strategy reduces
likelihood of abnormal torque and shearing between the
orthosis and limb as the individual wearing the orthosis
walks. When there is incongruence between the anatomical
and mechanical axes, excessive motion of the limb within the
orthoses is likely, and action of the mechanical ankle joint is
compromised.

Chapter 9  Principles of Lower Extremity Orthoses
225
TABLE 9-2  Summary of Indications for, Impact on Gait of, and Contraindications for Commonly Prescribed Lower Extremity Orthoses
Type of Orthosis
Category
Actions
Indications
Contraindications
Options
UCBL orthosis
Static
Stabilize subtalar and tarsal
joints in stance
Rearfoot valgus/varus
Flexible pes planus
Rigid foot deformity
Thermoplastic
Gillette modification
DAFO
Dynamic
Stabilize subtalar and tarsal
joints in stance
Flexible pes planus
Mild to moderate spastic diplegic
or hemiplegic CP
Hypotonic CP
Rigid foot deformity
Thermoplastic
Supramalleolar
Dynamic
Stabilize subtalar and tarsal
joints in stance
Preposition foot for IC by heel
Flexible pes planus
Mild to moderate spastic diplegic
or hemiplegic CP
Hypotonic CP
Significant equinovarus
hypertonicity
Thermoplastic
Posterior Leaf Spring
Dynamic
Assist limb clearance in swing
Preposition foot for IC by heel
Dorsiflexion weakness, impaired
motor control, LMN flaccid
paralysis of dorsiflexors
Moderate to severe
hypertonicity
Thermoplastic
Carbon Graphite AFO
Dynamic
Assist limb clearance in swing
pre-position foot for IC by heel
Paralysis or impaired muscle
performance of dorsiflexors
Moderate to severe
hypertonicity
Custom or prefabricated
Neuro-orthoses
Dynamic
Assist limb clearance in swing
Preposition foot for IC by heel
Dorsiflexion weakness or low tone
Flaccid paralysis
Patient intolerance of
electrical stimulation
Functional electrical
stimulation
Articulating ankle







Dynamic







Assist limb clearance in swing
Preposition foot for IC by heel
Permit advancement of tibia
(2nd rocker) in stance




Impaired motor control of ankle
musculature
Potential for recovery of neuromotor
function




LMN paralysis (flaccidity)
or hypotonicity as
primary problem





Thermoplastic or metal
double-upright
Dorsiflexion assist
Plantarflexion stop
Adjustable range into
dorsiflexion can be
incorporated
Often requires shoe with
cushion heel
(Continued)

226
Section II  Orthoses in Rehabilitation
TABLE 9-2  Summary of Indications for, Impact on Gait of, and Contraindications for Commonly Prescribed Lower Extremity Orthoses—cont'd
Type of Orthosis
Category
Actions
Indications
Contraindications
Options
Solid-ankle AFO






Static






Control ankle position throughout
stance
Provide stance phase stability via
ankle-knee coupling
Assist limb clearance in swing
Pre-position foot for IC by heel
Distal trim line behind metatarsal
heads or extended toe-plate
Significant hypertonicity with
seriously impaired motor control
at ankle and knee




LMN paralysis (flaccidity)
or hypotonicity as primary
problem




Thermoplastic
Basis for KAFO and
HKAFO
Requires cushion heel and
rocker bottom shoe



Tone-inhibiting AFO
Static
Control ankle position throughout
stance
Provide stance phase stability via
ankle-knee coupling
Typically extended toeplate
Significant hypertonicity with
seriously impaired motor control
LMN paralysis (flaccidity)
or hypotonicity as primary
problem
Thermoplastic,
Basis for KAFO and
HKAFO
Requires cushion heel and
rocker bottom shoe
Anterior floor reaction
AFO
Static
Provide stability in stance via
ankle-knee coupling
Control ankle position throughout
stance
Weakness or impaired motor
control at knee and ankle
Ligamentous insufficiency
at the knee
Genu recurvatum
Thermoplastic or carbon
composite
Custom-made or custom-fit
Weight-relieving AFO



Static



Protect lower leg and foot during
stance by reducing weight
bearing forces.

Healing soft tissue, ligamentous,
or bone injuries of the lower leg,
ankle, or foot

Mechanical instability of the
knee, or injury to proximal
tibia
Patient intolerance of PTB
weight-bearing forces (rare)
Thermoplastic and metal
hybrid
Custom or prefabricated

AFO, ankle-foot orthosis; CP, cerebral palsy; DAFO, dynamic ankle foot orthosis; IC, initial contact; HKAFO, hip-knee-ankle-foot orthosis; KAFO, knee-ankle-foot orthosis; LMN, lower
motor neuron ; PTB, patellar tendon bearing ; UCBL, University of California Biomechanics Laboratory orthosis .

Chapter 9  Principles of Lower Extremity Orthoses
227
STATIC ANKLE-FOOT ORTHOSES
Static AFOs are the most aggressive of the AFO designs in
providing external support. They restrict ankle and foot
motion is all three planes to provide significant stance phase
stability and swing limb clearance. Because of their rigid­
ity, however, these orthoses greatly compromise transitions
through the first (heel), second (ankle), and to a lesser degree
third (toe) rockers of stance phase. Individuals using static
AFOs do better functionally wearing a shoe with a cushion
heel and rocker bottom to simulate these key transitions. The
decision to recommend a static AFO should be made care­
fully, weighing the benefit of greater stability against the cost
of lost mobility.
Solid Ankle-Foot Orthoses
The solid-ankle AFO (SAFO), also known as a rigid AFO, is
typically fabricated from relatively thick thermoplastic and
aims to hold the ankle and foot in as close to biomechani­
cally neutral position (zero degrees of ankle dorsiflexion,
subtalar and calcaneal neutral, with a balanced forefoot) as
possible given the individual's functional anatomy.25 The
anteroposterior trim line of the SAFO falls at or near the
midline of the medial and lateral malleolus (Figure  9-4).
Medial and lateral corrugations may be incorporated into
the shell of the orthosis to provide additional strength
when hypertonicity or excessive weight creates loading
forces that require a stronger orthosis. The proximal bor­
der is typically trimmed to fall 1.5 inches below the apex of
the head of the fibula. The footplate it either trimmed just
short of the plantar metatarsal heads or can be lengthened
beyond the metatarsal distally into a toe plate if hypertonic­
ity is a concern.26 Some orthotists recommend the addition
of a tone-inhibiting bar if hypertonicity is severe.27 There
is a tradeoff to consider if the footplate is lengthened: It is
much easier to fit into and put on shoes with a shorter foot­
plate; assistance may be necessary to don shoes when the
SAFO has a full toeplate.
SAFO Control Systems
There are four distinct control systems incorporated into the
SAFO design (Figure  9-5). To resist plantarflexion during
swing phase, there is a fulcrum force applied at the anterior
ankle (by strapping or by the shoe's laces or Velcro closure)
opposed by a distal counterforce upward under the metatar­
sal heads and a proximal counterforce at the posterior proxi­
mal surface of the AFO. To resist dorsiflexion during stance
phase, there is an upward and inward compressive force at
the posterior heel, opposed by a distal downward counter­
force delivered by the shoe, and a proximal force applied by
the anterior closure straps just below the knee. It is important
to note that the locked ankle created by an AFO generates
an extensor moment at the knee during stance. In this way,
a SAFO can substitute for impaired motor control or muscle
performance of knee extensors for persons with stroke, cere­
bral palsy, or other neuromotor dysfunction.
To resist varus and inversion of the foot, a medially
directed force is applied just above and below the lateral mal­
leolus with laterally directed counterforces at the proximal
medial tibia and the medial foot. To resist valgus and eversion
of the foot, there is a laterally directed force applied above and
FIGURE  9-3  Alignment of the mechanical ankle joint axes must
reflect the degree of external rotation/tibial torsion that is present in
the transverse plane.
FIGURE  9-4  Custom-molded, solid-ankle ankle-foot orthosis
holds the ankle in as close to optimal static alignment as possible
for a given patient. Mediolateral ankle stability is a result of trim
lines at the midline of the malleoli. Note the high medial border at
the foot and the slight flaring just proximal to the medial malleo­
lus. This strategy is used to counteract an abnormal, flexible subtalar
valgus. The crossed Velcro strap anterior to the ankle helps position
the rear foot appropriately within the heel section of the orthosis.
(Reprinted with permission from Zablotny CM. Use of orthoses for
the adult with neurological involvement. In Nawoczenski DA, Epler
ME [eds], Orthotics in Functional Rehabilitation of the Lower Limb.
Philadelphia: WB Saunders, 1997. p. 223)

228
Section II  Orthoses in Rehabilitation
FP
FP
FD
FC
FD
FC
A
B
C
D
FP
FD
FC
FP
FD
FC
FIGURE  9-5  The four force systems in a molded thermoplastic solid-ankle ankle-foot orthosis
design. A, Plantarflexion is controlled during swing phase by a proximal force (Fp) at the posterior calf
band and a distal force at the metatarsal heads (Fd) that counter a centrally located stabilizing force
(Fc) applied at the ankle by shoe closure. B, For control of dorsiflexion during stance phase (i.e., for­
ward progression of the tibia over the foot), Fp is applied at the proximal tibia by the anterior closure,
Fd at the ventral metatarsal heads by the toe box of the shoe, and counterforce Fc at the heel, snugly
fit in the orthosis. C, The force system for eversion (valgus) locates Fd along the fifth metatarsal, Fp at
the proximal lateral calf band, and Fc on either side of the malleolus. D, To control inversion (varus)
of the foot and ankle, Fd is applied by the distal medial wall of the orthosis against the first metatarsal,
Fp at the proximal medial calf band, and Fc at the distal lateral tibia and calcaneus/talus on either side
of the lateral malleolus.

Chapter 9  Principles of Lower Extremity Orthoses
229
below the medial malleolus, with medially directed counter­
forces just below the fibular head proximally and at the lateral
foot distally.
The degree of control for the foot is also influenced by the
position of the trim lines of the foot section. When there is
midtarsal joint deformity with forefoot abduction or adduc­
tion to contend with, trim lines are adjusted to capture the
shafts of the first and fifth metatarsals. If there is too much
subtalar valgus, the height of the medial wall is increased,
and a flange might be placed proximal to the medial mal­
leolus. These strategies provide greater surface area for dis­
tribution of corrective forces applied by the orthosis, so
that the patient is more comfortable with the external sta­
bility it provides. If knee hyperextension at midstance is a
problem for individuals with impaired motor control, the
orthotist might fabricate the SAFO set in just a couple of
degrees of ankle dorsiflexion, rather than neutral, to mini­
mize excessive extension moment and preserve knee joint
health over time. A Gillette modification can be added to
the outer medial or lateral surface of the heel cup to influ­
ence excessive valgus or varus moment at the knee joint dur­
ing stance. A medial or lateral post (similar to those used in
a biomechanical foot orthosis) can be incorporated into the
foot section to equalize forefoot to rearfoot relationships or
to enhance biomechanical effects on the knee.
Progression Through Stance Phase
The SAFO biomechanically interferes with transitions through
all three rockers of gait in stance phase because of the fixed
ankle position inherent in the design.
The orthosis prevents the controlled lowering of the foot
that usually occurs in the ankle/first rocker during load­
ing response. If the shoe does not have a compressive cush­
ion heel to mimic controlled lowering, the orthosis propels
the tibia rapidly to achieve foot-flat position. The individ­
ual wearing the orthosis needs some eccentric ability of the
quadriceps to counteract the rapid knee flexion moment
that accompanies the SAFOs propulsive force acting on the
tibia. This is especially true if the SAFO has been set in a
few degrees of dorsiflexion to minimize risk of knee hyper­
extension in early stance.
The proximal anterior strapping used to hold the limb in
the upper part of the SAFO acts with the fixed ankle position
to prevent forward progression of the tibia over the weight-
bearing foot during the second/ankle rocker that typically
occurs during midstance. If the individual's shoe does not
have rocker bottom characteristics, this check of forward
momentum compromises effective preparation for push-off
and transition from stance into swing phase and necessarily
shortens stride length achieved by the swinging limb.
In nonpathological gait, there is 60 degrees of extension
at the hallux during the third, or toe rocker of gait. For per­
sons wearing a SAFO with a footplate that extends into a
stiff toeplate, the third/toe rocker of the foot will certainly
be limited. A shoe with rocker bottom characteristics can
assist a smoother rollover when extension of the hallux is
limited.
Indications for SAFO
The SAFO design is often selected for individuals with mod­
erate to severe hypertonicity where equinovarus significantly
impairs the ability to walk.26,28,29 It may also be used for per­
sons with unpredictable fluctuating muscle tone (athetosis) to
provide external stability that makes ambulation possible in
the presence of unpredictable variation in antigravity tone.30
While the SAFO has been used in persons with multiple scle­
rosis with tremor and ataxia, the evidence of its efficacy for
improved coordination during walking is limited.31 It may be
recommended for persons with significant generalized lower
extremity weakness or significant hypotonicity, providing
external support as a substitute for impaired muscle perfor­
mance that would otherwise prevent ambulation.32,33 In both
of these circumstances the SAFO is a substitute for severely
impaired muscle activity. A custom-molded SAFO has also
been used to protect the foot and ankle in the management of
persons who need stabilization after foot or ankle surgery, or
for those with ankle instability and pain secondary to rheu­
matoid arthritis.34,35
The Anterior Floor Reaction Ankle-Foot Orthosis
All static AFO designs use moments that result from the
GRF to provide stability during stance. An orthosis that
has evolved from the basic SAFO design to better address
impaired motor control of the knee and weakness of the
quadriceps is the anterior floor reaction orthosis (FRO)36,37
(Figure 9-6). The FRO is fabricated to hold the ankle in a
few degrees of plantarflexion. This restricts the ability of
the tibia to roll forward over the foot in the second/ankle
rocker of gait, creating an extensor moment that stabi­
lizes the knee during stance (Figure 9-7). If stability is also
needed in late stance phase, a stiff toeplate can be added to
reinforce the extension moment at the knee. The FRO and
SAFO use the same force systems to control foot and ankle
position. Whether the FRO is fabricated in a single piece
(see Figure 9-7A) or as a SAFO with the addition of a ther­
moplastic anterior shell (see Figure 9-7B), padding is added
where the FRO contacts the proximal surfaces of the tibia
to make the extra extension force delivered by the orthosis
more tolerable to the wearer.
The FRO is often used for children with cerebral
palsy who demonstrate “crouch gait,” or for children with
myelomeningocele and persons with postpolio syndrome
who have paralysis or weakness at the knee and ankle.36–38
To be efficacious, the FRO relies on a GRF vector that passes
anterior to the anatomical knee joint. As knee and hip flexion
contractures approach or exceed 10 degrees, the GRF vector
nears or passes posterior to the anatomical knee joint, and the
FRO is less effective in stabilizing the knee during stance.36
The FRO is contraindicated for persons with notable recur­
vatum during stance as well as those with cruciate ligament
insufficiency; in these circumstances, the extra knee exten­
sion moment can further damage joint structure. While the
rigid control of ankle and knee enhances mechanical stabil­
ity in stance, these external restrictions imposed by the FRO
may compromise efficacy of postural responses. In those with

230
Section II  Orthoses in Rehabilitation
balance impairment, an ambulatory assistive device (e.g., a
cane, Lofstrand crutches, or rolling walker) may be needed
for safety, especially if FROs are worn on both limbs.
Weight-Relieving Ankle-Foot Orthoses
The weight-relieving AFO, also known as a patellar tendon–
bearing AFO (PTB-AFO), incorporates the intimate fit and
load-bearing characteristics of a PTB prosthetic socket into a
SAFO or traditional metal double upright AFO (discussed later)
as a means of offloading or unloading weight-bearing forces
during stance phase for individuals with painful, unstable, or
recently repaired ankle or foot (Figure 9-8).39–42 The anterior
shell of the AFO is modified to accept weight-bearing forces via
the medial tibial flare and patellar tendon bar, along with total
contact around the upper calf. As with a PTB prosthetic socket,
the proximal portion of the PTB-AFO is set in approximately 10
degrees of knee flexion (with respect to vertical) to load some
of the body weight onto the anterior shell at the medial tibial
flare and patellar tendon bar during stance. This axial force is
then transmitted to the ground through the medial and lateral
walls of the thermoplastic orthosis, which may be reinforced
with metal uprights or through the medial and lateral uprights
of a traditional double upright AFO. This strategy effectively
reduces axial loading of the ankle and foot during gait.
The weight-relieving AFO is used for persons with
Charcot arthropathy, plantar neuropathic ulcers, slowly
healing fractures, severe rheumatoid or osteoarthritis of
the ankle, surgically repaired ankles after fracture, syno­
vial debridement in hemophilia, and other circumstances
that require protection of the foot and ankle when non–
weight bearing is not possible. A tibial fracture orthosis and
the Charcot restraint orthotic walker (CROW) are adapta­
tions of the weight-relieving AFO; both encase the entire
lower limb to provide maximal reduction of axial loading
while healing takes place.43,44 Individuals wearing a weight-
relieving AFO must have normal anatomical structure of the
knee, adequate muscle performance and motor control of
the quadriceps muscles for stability in early stance, and suf­
ficient skin integrity to tolerate the loading forces applied by
this orthotic design.
DYNAMIC ANKLE FOOT ORTHOSES
Dynamic orthoses allow some degree of sagittal plane
motion at the ankle; many permit dorsiflexion during stance
phase to facilitate the second/ankle rocker of gait, but restrict
plantarflexion during swing phase to facilitate swing limb
A
B
C
FIGURE 9-7  A, When a patient walks in a “crouch gait” pattern, the
ground reaction force vector passes behind the knee at midstance,
creating a flexion moment at the knee, which must be counteracted
to maintain upright position. B, In normal gait, knee stability at mid­
stance is assisted by a ground reaction moment as the body moves
over the foot, and the ground reaction force vector passes anterior to
the knee. C, The solid-ankle ankle-foot orthosis and the floor reac­
tion orthotic designs use a fixed ankle position to harness the ground
reaction force, creating a large extension moment at the knee.
B
A
FIGURE 9-6  A, This floor reaction orthosis (FRO) was fabricated
using carbon graphite and fiberglass in a thermosetting process
because of the desire to provide maximum stiffness. The combina­
tion of a solid-ankle design and an anterior wall produces a knee
extension moment at midstance and enhances stance phase stability.
B, This FRO has a posterior shell much like a solid-ankle ankle-foot
orthosis. The combination of slight plantarflexion at the ankle and
a stiff, long toeplate creates a plantarflexion–knee extension couple
that acts in mid to late stance. The padded anterior shell more com­
fortably captures the resultant extension moment, stabilizing the
knee. Note also the corrugation incorporated in the medial and lat­
eral walls of the ankle-foot orthosis to provide additional rigidity to
the orthosis.

Chapter 9  Principles of Lower Extremity Orthoses
231
­clearance, incorporating some type of orthotic ankle joint.
These dynamic orthoses are available in both thermoplastic
and more traditional metal double-upright designs. These are
reviewed in order from least restrictive to most supportive
designs.
The UCBL Orthosis
In the 1970s, researchers at the University of California
Biomechanics Laboratory developed a custom-molded
shoe insert, now known as the UCBL orthosis, as an orthotic
intervention for subtalar joint instability (Figure  9-9).45
The UCBL controls flexible calcaneal deformities (rearfoot
valgus or varus) as well as transverse plane deformities of
the midtarsal joints (forefoot abduction or adduction) by
“grabbing” the calcaneus and supporting the midfoot with
high medial and lateral trim lines; it realigns the calcaneus,
improving the angle of pull of the Achilles tendon, pro­
viding a more stable foundation for the articular surfaces
of the talus, navicular, and cuboid bones.46 The UCBL is
also used to improve functional alignment of children and
adolescents with flexible pes planus, a longitudinal arch
deformity.47 The Gillette modification, an external post
positioned either on the medial or lateral border of the heel
cup, can be used to apply additional rotatory moments to
the calcaneus during weight bearing. In addition to being
useful when there is flexible structural malalignment of
the rear and midfoot, the UCBL shoe insert may improve
foot performance during stance for persons with hypoto­
nicity. It is important to recognize that the UCBL orthosis
acts primarily at subtalar and midfoot tarsal joints during
weight bearing; it would not be appropriate for persons
with swing phase clearance issues, which require the trim
line of the orthosis placed above the ankle joint.
Dynamic Ankle Foot Orthosis
The dynamic ankle-foot orthosis (DAFO), also known as a
flexible supramalleolar orthosis (SMO), is a custom-molded
orthosis that has evolved from the UCBL shoe insert to
better address sagittal plane control of the ankle and foot
during stance and to facilitate foot clearance in swing.48
Custom-molded from relatively thin thermoplastic, its prox­
imal trim lines are just superior to the ankle joint, and its
A
B
FIGURE 9-8  Lateral views of the PTB AFO (weight relieving orthosis) loads weight bearing onto the
orthosis during stance, offloading the tibia and fibula, carrying some or all of body weight through
the solid-ankle ankle-foot orthosis shell (A) or double uprights (B) to the floor. (A, Courtesy Elite
Orthotics, Zelienople, Penn. B, Reprinted with permission from Edelstein JE, Bruckner J. Orthotics:
A Comprehensive Clinical Approach, Fig. 3-27a. Thorofare, N.J.: Slack Inc., 2007. p. 50.)
FIGURE 9-9  The University of California Biomechanics Laboratory
orthosis is designed to position the calcaneus optimally for effec­
tive subtalar joint function. The deep heel cup, with its high medial
and lateral trim lines, snugly holds the calcaneus. The orthosis also
encompasses the joints of the midfoot, providing support for the
longitudinal arch. In this example, a medial post (Gillette modifica­
tion) has been added.

232
Section II  Orthoses in Rehabilitation
­distal trim lines encase more of the forefoot than the UCBL
(Figure 9-10). By limiting movement of the midfoot and fore­
foot and by holding the foot in functional position, the DAFO
provides a stable base for more effective motor performance
and postural control during standing and ambulation.49,50 The
DAFO is designed to redistribute plantar pressures of spas­
tic equinovarus from the anterior foot to the heel, perhaps
by reducing overall stimulation of reflexes that would other­
wise reinforce extensor hypertonicity in children with mild to
moderate diplegic cerebral palsy.51 By providing a stable base
during stance phase, the DAFO improves swing limb clear­
ance, stride length, cadence, and self-selected walking speed
of children with diplegic cerebral palsy, nearly to that of age-
matched peers without neuromotor impairment.50,52 Parents
of children using DAFOs report improved upright posture as
well as enhanced ability of their children to participate in play
activities, based on perceived changes in stability, agility, and
speed of movement when wearing the DAFO.49 The major
complaint about the DAFO was that there was a need to fre­
quently change socks because confinement of the foot within
the plastic DAFO shell and shoe contributed to sweaty feet.
Posterior Leaf Spring Ankle-Foot Orthosis
The Posterior Leaf Spring (PLS) AFO is a dynamic thermo­
plastic AFO designed to accomplish two things53:
• Support the weight of the foot during swing phase as a
means of enhancing swing limb clearance
• Assist with controlled lowering of the foot during loading
response in stance as part of the first/heel rocker
The PLS is one of the group of AFOs that provide dorsiflex­
ion assistance. In contrast to the SAFO, medial and lateral trim
lines are located well posterior to the midline of both ­malleoli
so that the orthosis is flexible at the anatomical ankle joint
(Figure 9-11).54 The degree of flexibility is determined by the
thickness of the thermoplastic material used to construct the
orthosis and width of the posterior upright in the distal third
of the orthosis.54 In custom-molded PLS orthosis, the orthotist
tailors the stiffness of the orthosis using the trim line pattern
that will best support the weight of the foot during swing as
well as the individual's needs for stability in stance.54
Once the heel contacts the ground at initial contact and
loading response begins, the flexible plastic of the PLS serves
as a proxy for impaired or absent eccentric activity of the
tibialis anterior muscle, slowing but not stopping the foot's
descent toward the ground.53 As stance phase continues, the
flexible PSL allows the tibia to roll forward over the weight-
bearing foot to accomplish a smooth second/ankle rocker of
midstance to terminal stance. As the foot leaves the ground in
initial swing, the PLS is able to hold the ankle at the desired
neutral 90-degree position, which assists swing clearance
and keeps the toes elevated so that next initial contact will
be made at the heel. Compared to the stiffness of the SAFO,
which makes walking up and down inclines even more chal­
lenging than walking on level surfaces, the flexibility inherent
in the PLS provides a notable functional advantage.55–57
Owing to its narrow posterior upright and relatively shallow
heel cup, a PSL is not as effective in stabilizing the ­calcaneus
and talus during stance as are the SAFO, DAFO, or UCBL
designs. This makes it less effective in controlling mediolateral
foot position, especially for persons with flexible deformities of
FIGURE 9-11  The posterior position and arc of the trim lines at
the ankle, as well as the thickness of thermoplastic material used,
determine the degree of flexibility of the posterior leaf spring ankle-
foot orthosis. This design approximates the first and second rockers
of stance phase and assists clearance and pre-positioning of the foot
during swing.
FIGURE 9-10  The dynamic ankle-foot orthosis (DAFO) is a flex­
ible polypropylene brace designed to optimize subtalar joint align­
ment through its supramalleolar design. (Reprinted with permission
from Zablotny CM. Use of orthoses for the adult with neurologi­
cal involvement. In Nawoczenski DA, Epler ME [eds], Orthotics
in Functional Rehabilitation of the Lower Limb. Philadelphia: WB
Saunders, 1997. p. 229.)

Chapter 9  Principles of Lower Extremity Orthoses
233
the forefoot, midfoot, or rearfoot.58 In these circumstances, the
orthotist may opt to place medial and lateral trim lines some­
where between the mid-malleolar position of a SAFO and the
narrower PLS to provide additional stability. This modification
is sometimes referred to as a semisolid AFO. The modification
provides better control of ankle motion, but at the cost of limit­
ing mobility during the second/ankle rocker of gait.59 Note that
the flexibility of a PLS and a semisolid AFO make them inap­
propriate for individuals with significant equinovarus or spas­
ticity of the lower extremity: A high level of abnormal tone will
overpower the control systems in these designs.
Additional Dorsiflexion Assist Options
There are a number of commercially available prefabricated
as well as custom-molded AFO designs available as alterna­
tives for individuals whose primary need is for dorsiflexion
assistance as a substitution for weakness and/or impaired
motor control at the ankle. Three of the more frequently used
options are reviewed here: (1) Dual Carbon Fiber Spring
Orthosis, (2) wearable functional neuromuscular electrical
stimulation units, and (3) novel commercially available alter­
native designs.
Carbon Fiber Spring Orthoses
The Dual Carbon Fiber Spring orthosis (CFO), developed
and tested primarily in Germany, is a modification of the
traditional PLS design that cuts the PLS into a foot and calf
section, then attaches overlapping carbon fiber springs (car­
bon fiber and Kevlar fibers impregnated with epoxy resin)
between the sections (Figure  9-12A).60 Spring resistance is
selected based on the individual's weight. This design aims
not only to substitute for impaired or absent anterior com­
partment muscle activity, but also to enhance the third/toe
rocker of stance phase that is typically compromised by ther­
moplastic AFOs.60 A more powerful push-off is attributed to
loading of the spring during early and midstance as the tibia
moves forward over the foot, and release of the spring in tran­
sition from terminal swing to preswing.61
The CFO design has been adapted to enhance walking
ability of children with myelomeningocele and other neuro­
muscular conditions that contribute to impaired or absent
plantarflexor muscle performance.62,63 In this version, the
carbon fiber spring is L-shaped (see Figure 9-12B) with its
attachment to the foot component (a stiffer version of a supra­
malleolar DAFO) on the plantar surface rather than posterior
heel. The slight distance between the spring and posterior
foot section acts as a dorsiflexion stop during stance, allow­
ing some dorsiflexion for second/ankle rocker until the two
surfaces come into contact. The proximal carbon fiber spring
is fit into a slot in the posterior of a custom-molded section
that resembles the upper half of a total contact prosthetic
socket. A vertical slot drilled into the proximal spring allows
it to slide up and down for several centimeters during stance
phase to minimize potential skin friction. This CFO appears
to enhance transition through both second/ankle and third/
toe rockers of gait, and to provide assistance for push-off.
This design has also been incorporated into a knee-ankle-
foot orthosis for children who require additional support or
control at the knee and hip.64
Both versions of the CFO may require a larger size shoe to
accommodate the orthosis in the shoe.
Functional Neuromuscular Electrical Stimulation
For persons with impaired motor control resulting from
disease or trauma of the central nervous system, several
commercially available, wearable functional electrical stim­
ulation units, also called neuroprostheses, are available
(e.g., WalkAide, Hanger Orthopedic Group, Austin, Texas;
Odstock Dropped Foot Stimulator, Salisbury, UK; NESS
L300 Foot Drop System, Bioness Inc. Valencia, Calif.). The
individual wears a cuff that is positioned snugly just below
the knee, rather than an orthosis that must fit into the shoe
(Figure  9-13). The cuff holds a small stimulator medially
with electrodes positioned laterally over motor end points
of the peroneal nerve.65 Depending on the model, appropri­
ate timing of the functional electrical stimulation for dor­
siflexion activity is determined by a switch worn in the
shoe, an inclinometer, or an accelerometer. Most use sur­
face electrodes to deliver the stimulus for muscle contraction
although cuffless versions with surgically implantable elec­
trodes are available. Studies evaluating the device have dem­
onstrated improved spatial and temporal characteristics and
safety of walking in persons with acute and chronic stroke
when worn as an orthosis alone or when integrated with
rehabilitation interventions.66–68 Similar findings support its
use for persons with traumatic brain injury, multiple sclero­
sis, and Parkinson's disease.69–72
Each of these devices must be adjusted to the individu­
al's typical gait pattern by an orthotist trained to fine-tune
A
B
FIGURE 9-12  A, Note the carbon fiber springs inserted posteriorly
between the foot and calf component of this carbon-fiber orthosis.
The springs provide dorsiflexion assistance for clearance in swing
and pre-positioning of the foot for initial contract, as well as preser­
vation of the second and third rockers of stance phase. B, The Dual
Carbon Fiber Spring orthosis (CFO) designed to provide assistance
with plantarflexion/push-off for the transition from stance to swing
for persons with weakness or paralysis of calf muscles/plantarflexors.

234
Section II  Orthoses in Rehabilitation
the device. To be effective, all of these devices require an
intact and healthy peroneal nerve. They would not be
appropriate for persons with peripheral nerve injury or
neuropathy (e.g., traumatic or compressive dysfunction of
the peroneal nerve, Guillain-Barré syndrome, longstanding
radiculopathy, lower motor neuron SCI, polio, or postpolio
syndrome).
Manufacturers note that such devices are contraindi­
cated in individuals with demand pacemakers or defibrilla­
tors, healing fractures, metal implants in the limb, or history
of phlebitis; the unit should be used with caution in persons
with varicose veins, inflammation in or around the knee,
or sensory impairment. While most devices are resistant to
splashes, immersion in water during bathing or swimming,
or saturation while shoveling snow, for example, will damage
the unit, rendering it nonfunctional.
Commercially Available Dorsiflexion-Assist Designs
A number of manufacturers have developed carbon fiber
orthoses to provide dorsiflexion assistance at the appropri­
ate times in the gait cycle (e.g., Camp ToeOFF series, Allard
USA, Rockaway, N.J.; AFO Dynamic, Ossur Americas,
Foothill Ranch, Calif.; Matrix and Matrix Max, Prolabor­
thotics USA, Napa, Calif.). In contrast to thermoplastic
designs, many of these orthoses use a cushioned anterior
shin or medial shank piece, held in place by strapping, that
transitions into a medial upright and continues into a full
footplate (Figure 9-14). These orthoses are designed to pre-
position the foot for heel strike at initial contact, substitute
for impaired anterior compartment to allow controlled low­
ering of the foot into foot flat position during the first/heel
rocker of loading response, provide some medial-lateral
stability during stance while allowing forward progression
of the tibial during the second/ankle rocker of stance phase,
contribute to push-off in the transition from stance to swing,
and support the weight of the foot for effective swing limb
clearance.73 Although there is some evidence that these dor­
siflexion-assist designs have a positive impact on both the
kinematics and energy cost of walking, there have been few
published studies that directly compare them with traditional
PLS orthoses, or with articulating (hinged) thermoplastic
AFOs or traditional metal double upright AFOs with dorsi­
flexion-assist orthotic ankle joints.73
Hinged Thermoplastic Ankle-Foot Orthosis
The thermoplastic hinged (articulating) ankle-foot ortho­
sis (HAFO) allows sagittal plane motion at the ankle by
incorporating a mechanical ankle joint between the foot
and calf sections of the orthosis. This variation of the SAFO
was designed primarily to allow the tibia to roll over the
weight-bearing foot during stance, for a smooth second/
ankle rocker, at the same time holding the foot in optimal
alignment to control the impact of tone-related equinovarus
forces throughout the gait cycle (Figure 9-15). In children
with cerebral palsy and in adults after stroke, these orthoses
reduce energy cost of walking (compared to barefoot), as well
as improve stride length, cadence, and walking speed.74–76
FIGURE 9-14  An example of a carbon fiber composite dorsiflex­
ion assist ankle-foot orthosis used to substitute for activity of ante­
rior compartment muscles of the lower leg. (Courtesy Trulife USA,
Jackson, Miss.)
FIGURE 9-13  The Hanger WalkAide System, as an example of a
wearable functional electrical stimulation unit, is used to trigger
muscle contraction of dorsiflexors during appropriate points in the
gait cycle. (Courtesy Hanger Orthopedics, Austin, Texas.)

Chapter 9  Principles of Lower Extremity Orthoses
235
As compared with the SAFO, the HAFO also improves mobil­
ity in many ­functional activities, such as rising from the floor
(an important component of play for children), ascending
and descending stairs, and walking up or down inclines.56–58
There is some indication that HAFOs lessen the magnitude
of abnormal muscle activation associated with spasticity in
children with cerebral palsy.77 HAFOs appear to reduce risk
of falls in adults with longstanding hemiplegia after stroke,
improve static postural control, and have less negative impact
on dynamic postural control in standing than SAFOs.78,79 For
some children with moderate to severe spastic diplegic cere­
bral palsy, however, the mobility provided by a HAFO com­
promises stability in early stance, reinforcing crouch gait
pattern, reducing walking speed, and increasing energy cost
as compared to a SAFO.74 Multiple perspectives on function,
as well as the desired impact on quality of gait, must be con­
sidered when deciding which orthosis is best.
The shape, dimensions, and force control systems of
the HAFO are almost exactly the same as those of a SAFO,
except it has two separate pieces linked by an orthotic ankle
joint rather than being a single, solid piece. The HAFO has a
larger width at the ankle than the SAFO to accommodate the
mechanical ankle joint; this may require larger or wider shoe
size to accommodate the orthosis.
Hinged AFOs can be fabricated to allow free motion at
the ankle, to allow limited range of motion (i.e., allow dor­
siflexion and stop plantarflexion, or the inverse), or to pro­
vide some assistance to dorsiflexion, depending on what
orthotic ankle joint option motion best meets the individu­
al's needs and maximizes the resources they bring to the task
of walking. A variety of mechanical thermoplastic joints are
commercially available (Figure 9-16). Those with true articu­
lations (e.g., the Oklahoma joint) have a single axis of motion
that should be aligned as closely as possible to the anatomic
ankle joint; other orthotic joints (e.g., the Gillette joint) are
flexible and nonarticulating.
Traditional metal orthotic ankle joints have been incor­
porated into thermoplastic HAFOs as well; These designs
are referred to as hybrid orthoses. Simple single axis joints
provide mediolateral stability without restriction of avail­
able dorsiflexion or plantarflexion; a motion stop can be
A
B
FIGURE  9-15  A, This hinged ankle-foot orthosis (AFO), with
Camber Axis Hinges as the orthotic ankle joint, allows forward
motion of the tibia through the second/ankle rocker of stance phase.
B, This hinged AFO, with Oklahoma orthotic ankle joints, has a
built-in plantarflexion stop (when the posterior edges of the foot and
calf section come into contact) and posterior strapping that can be
adjusted to limit the amount of dorsiflexion available, based on the
wearer's motor control and need for stability in stance. (A, Courtesy
Becker Orthopedic, Troy, Mich.)
FIGURE  9-16  Examples of thermoplastic ankle joints used in
hinged ankle foot orthosis. The overlap joint (A) and Oklahoma
joint (B) are single axis joints, whereas the flexible Gillette mech­
anism (C) allows movement into dorsiflexion and plantarflexion
without an actual articulation.
A
B
C

236
Section II  Orthoses in Rehabilitation
incorporated if there is need to limit plantarflexion beyond
neutral (for stability in early stance) or dorsiflexion (to limit
weight bearing on the forefoot in later stance) as the indi­
vidual's needs dictate. A bi-channel adjustable ankle joint
(also referred to as a double action ankle joint or a double
Klenzak joint) (Figure 9-17) can be used to provide assis­
tance and/or limit motion based on an individual's capabil­
ities and needs for support. If motion assistance is desired,
a coil spring is placed in the channel, and a screw is used
to adjust compression until the desired level of assistance
is achieved. If motion is to be blocked, a solid steel pin is
inserted instead of the spring, to stop motion beyond a
particular point in the range of motion. Because of its ver­
satility and adjustability, the double action ankle joint is
often chosen when change in a patient's functional status
(improvement or deterioration) is anticipated. Orthotic
ankle joints such as the Camber Axis Hinge® allow the
orthotist to adjust the available range of motion from none
(as in a SAFO) through an array of limited anteroposterior
stop settings. This would be an advantage when motor con­
trol around the ankle and knee is expected to improve over
time, for example, in individuals who are recovering from
an acute stroke.
For many adults with stroke and for some children with
cerebral palsy, the HAFO allows free dorsiflexion; however,
when motor control is compromised, such that additional
support is needed during stance, the orthotist may choose
to incorporate a mechanism, such as a check strap, to adjust
the amount of dorsiflexion allowed (see Figure 9-16B). If the
check strap is maximally tightened, the orthosis functions like
a solid-ankle AFO. The check strap can be loosened, length­
ened, or elasticized as neuromotor control improves, thus
allowing only as much forward progression of the tibia in the
second rocker as is safe and functional for the individual. This
adaptation makes the HAFO versatile and useful when return
of neuromotor control or function is anticipated.
It is important to note that a prerequisite for using this
orthosis is at least 5 degrees of true ankle dorsiflexion, accom­
plished without compromise of subtalar or midtarsal joint
position; for this reason, a HAFO may not be an appropri­
ate choice for persons with severe spasticity that limits ankle
motion or those with significant instability or malalignment
of the midfoot.
Conventional Dorsiflexion-Assist Ankle Foot Orthosis
The conventional double upright counterpart to the PLS
uses a spring mechanism incorporated into the mechanical
ankle joints of the orthosis (Figure 9-18). The uprights are
connected to the distal stirrup at the mechanical ankle joint,
and the stirrup is fixed between the heel and sole of the shoe.
A coiled spring and small ball bearing are placed in a channel
in the distal uprights that runs toward the posterior edge of
the stirrup. When the spring is compressed at initial contact
and early loading response, it resists plantarflexion, allowing a
controlled lowering of the foot to the floor, substituting for the
second/heel rocker of early stance. Recoil of the spring when
the foot is unloaded in preswing and initial swing assists dor­
siflexion for swing phase toe clearance.74 The amount of dorsi­
flexion assist provided is determined by adjustment of a screw
placed in the top of the channel to compress or decompress
the spring further. Another option is the dual channel (double
Klenzak) orthotic ankle joint (see Figure 9-17); by placing a
spring in one channel and a rod in the other, this mechanical
ankle joint can provide adjustable dorsiflexion assistance and
plantarflexion stop (in persons with impaired dorsiflexion
muscle performance) or plantarflexion assistance and dorsi­
flexion stop (for those with motor control or muscle perfor­
mance impairment of the gastrocsoleus complex).
Traditional or conventional double upright orthoses are
typically used when the individual who needs dorsiflexion
assistance and plantarflexion control has a comorbid condition
Set
screw
Pin
Spring
Ball
bearing
A
B
FIGURE 9-17  A, The double-action joint can be used in a conven­
tional double-upright, metal ankle-foot orthosis and a thermoplastic-
metal hybrid ankle-foot orthosis. Motion is assisted if a spring is
compressed within the channel or can be blocked by placement of a
steel pin within the channel. B, The internal anatomy of the double
adjustable ankle joint. Ankle joint mobility restrictions (e.g., plan­
tarflexion stop) result from the locations of the pins in the anterior
and posterior channels of the orthotic joint. A spring may occupy
one of the channels, as depicted here, to assist motion (e.g., dorsi­
flexion assistance). The ball bearings allow the brace uprights to
pivot with ease over the brace stirrup. The set screw can be adjusted
to change the relative positions of the rods in each of the channels.
(B, From Zablotny CM. Use of orthoses for the adult with neuro­
logical involvement. In Nawoczenski DA, Epler ME [eds], Orthotics
in Functional Rehabilitation of the Lower Limb. Philadelphia: WB
Saunders, 1997. p. 227.)

Chapter 9  Principles of Lower Extremity Orthoses
237
that causes fluctuation in limb size (edema), such as conges­
tive heart failure or the need for kidney dialysis, that would
compromise the intimate fit of a thermoplastic orthosis. The
downside of the double upright AFO is its less effective con­
trol of abnormal foot position and risk of skin irritation as
the foot moves within the shoe. For persons with neuro­
pathic foot conditions who are unable to directly perceive
abnormal pressures and the discomfort of tissue stress, a cus­
tom-molded AFO that is intimately fit for the individual's
foot would be the orthosis of choice unless significant fluc­
tuating edema precludes this choice.
AFO Designs, Tone, and Postural Control
Although some AFOs are described as having tone-reducing
(TR-AFO) or tone inhibiting (TI-AFO) effects and are pre­
scribed for persons with hypertonicity (spasticity) from
upper motor neuron diseases (stroke, cerebral palsy, trau­
matic brain injury), the evidence of this effect is primarily
based on cross-sectional studies and case reports, rather
than randomized controlled clinical trials.80 Historically,
such AFO designs have their roots in the principles of serial
casting, which sought to lessen the impact of tonic plantar
reflexes that reinforce extensor tone of the lower extremity in
children with cerebral palsy.81,82 An early review of how these
principles were applied to AFO designs suggested that the
orthosis incorporate the following83:
• A metatarsal bar or dome to alter loading on metatarsal
heads
• A mechanism to encourage toe extension
• Additional loading on either side of the distal point of
attachment of the Achilles tendon
• An ankle held in neutral subtalar and dorsiflexion position
Tone-reducing principles have been applied to SAFO,
DAFO, and HAFO designs, and studied in children with cere­
bral palsy and in adults with stroke or traumatic brain injury.
This variation makes comparison of efficacy across studies
challenging.80 The impact of TR- and TI-AFO use on kine­
matic measures of gait (e.g., speed, stride length, cadence)
and on posture is similar to, rather than consistently superior
to, other AFO designs.52 The forecasted positive influence of
TR-AFO on abnormal muscle activity of the gastrocnemius
muscle (as measured by EMG and Hoffman reflex amplitude)
during walking, while challenging to measure, has not been
well supported in children with cerebral palsy or adults with
stroke or spinal cord injury.52,84,85
How does this evidence affect the decision making of the
team about whether to incorporate tone reducing charac­
teristics into an AFO? At this point, it appears that TR- and
TI-AFOs are equivalent in effect on function in children with
cerebral palsy and perhaps in adults with stroke. We do not
understand the effect of TR-AFOs on muscle tone. Current
evidence does not support a positive neurophysiological con­
sequence, and there is no alternative means to quantify muscle
tone (the modified Ashworth Scale is a categorical measure,
rather than a continuous measure).86 Consensus statements of
the International Society for Prosthetics and Orthotics sug­
gest that the terms tone-reducing or tone-inhibiting should
not be used to describe AFOs until stronger evidence of their
efficacy for specific patient groups become available based on
randomized controlled trials.87,88
While all AFO designs have a positive impact on quality
and efficiency of walking (speed, stride, joint kinemat­
ics, kinetics, and energy cost), they vary in their impact
on efficacy of postural responses, and balance during
functional activities while walking, standing, or moving
between sitting and standing.89,90 Because many individu­
als whose walking would improve if they used AFOs also
have deficits in motor control that impact the efficacy of
balance and postural responses, and because risk for fall­
ing is high, it is important to consider the interaction of the
orthosis with the individual's own movement resources.91
A key question to consider is how the orthosis influences
an individual's ability to dynamically control the body's
center of mass within his or her base of support in stand­
ing, and while transitioning and walking. Does the ortho­
sis constrain, maintain, or improve the individual's limits
of stability during functional tasks that are meaningful and
important for that person? For some persons with motor
control dysfunction, the limitation of ankle motion may
enhance stability in stance enough to improve ability to
perform functional tasks while standing. For others, the
FIGURE  9-18  Conventional double-upright dorsiflexion assist
ankle-foot orthosis, with a single-channel orthotic ankle joint.
Tightening the screw at the top of the channel compresses a spring
to increase the amount of dorsiflexion assistance provided. This split
stirrup would be fit into a shoeplate positioned between the sole and
heel, making it possible for the patient to use the ankle-foot orthosis
with more than one shoe.

238
Section II  Orthoses in Rehabilitation
same AFO design may impair the ability to respond effec­
tively to both internally generated and external perturba­
tions that shift the center of mass toward the edges of the
individual's limits of stability.
Studies evaluating the impact of AFOs on static and
dynamic postural control are challenging to interpret
because of variation in the AFO designs being evalu­
ated, the outcome measures used to assess balance, and
the patient groups included in the sample.89 In general,
the SAFO and semisolid AFOs positively impact on static
balance but appear to delay or impair response to pertur­
bations.92–94 For persons with stroke using a PLS ortho­
sis, evidence is relatively convincing that both static and
dynamic postural control improve with use of the orthosis
(when compared to no orthosis or to SAFO) as measured
by Timed Up-and-Go times, Berg Balance Scale score, and
limits of stability testing.95–97 There is little evidence about
the impact of HAFOs and DAFOs on balance: The few
available studies suggest a modest improvement in both
static and dynamic postural control.98
How does this evidence impact clinical decision making
when selecting an orthotic design for a particular patient? The
team must weigh the potential positive and negative influences
of the orthosis on the ability to walk, as well as on postural
control during all activities that are important to the individ­
ual who will be wearing the orthosis. There is not a clear best
or worst AFO; instead the team must match the pros of the
orthosis with the person's neuromuscular resources, physical
characteristics, and abilities and desired activities, tempered
by the prognosis associated with the condition or diagnosis.
CASE EXAMPLE 1
A Child with Spastic Diplegia/Cerebral Palsy
P. M. is a 7-year-old child with a primary diagnosis of spastic
diplegic cerebral palsy. He is anxious to keep up with his non­
impaired peers at school, but his moderate “crouch gait”
(despite using Lofstrand crutches as assistive devices) limits
his mobility and endurance. He is referred by his neurolo­
gist for evaluation in the interdisciplinary “brace clinic” at
the local children's medical center.
On physical examination, P. M. is found to have moderate
tightness and soft tissue shortening of his plantarflexors, dis­
tal hamstrings, adductors, and hip flexors. While he exhibits
moderate extensor-pattern spasticity in both lower extremi­
ties, sagittal and coronal plane motions of his hip, knee, and
ankle are within 10 degrees of normal. Structurally, he exhib­
its 25 degrees of femoral anteversion and 15 degrees of inter­
nal tibial torsion. Upon barefoot weight bearing, however, his
foot progression angles appear to be normal, at approximately
10 degrees external (outward) angle.
Questions to Consider
• W.hat are the most likely gait problems in each subphase of
gait that might be effectively addressed by an AFO?
• What musculoskeletal (alignment and flexibility) and
neuromuscular (control) impairments or character­
istics, as well as developmental issues will have to be
considered by the team as they sort through orthotic
options for this child?
• Which of the orthotic options (static vs. dynamic)
might you choose for this child? What are the possible
benefits and trade-offs of each?
• How might you assess if the orthosis chosen is accom­
plishing the desired outcomes?
Recommendations of the Team
Given the finding of dynamic pes planus and valgus defor­
mity, and the boy's propensity to crouch during stance, the
team recommends bilateral polypropylene solid ankle AFO
be custom molded for P. M. When P. M. receives his AFOs,
he attends several sessions of outpatient gait training. His
gait pattern demonstrates improved plantarflexion–knee
extension couples, with virtually all of the preorthosis knee
persistent knee flexion eliminated. Subtalar joint alignment
is also improved, with an effective support of the medial
longitudinal arch.
Follow-up Care
Three weeks later, the patient's mother schedules a follow-
up visit because she observes, “The AFO is causing P. M.'s
feet to turn in.” On this return visit, observational gait assess­
ment reveals an apparent 30-degree internal (inward) foot
progression bilaterally. This is causing difficulty with clear­
ance of the advancing limb during swing phase. Examination
of the fit and alignment of the AFOs reveal appropriate
design and fit, with effective subtalar neutral position.
The team recommends computerized gait analysis to
be performed to determine the underlying factors leading
to this significant change in foot progression angle despite
appropriately fit and designed SAFO. The team suspects that
this altered foot progression angle is most likely the result
of underlying musculoskeletal deformities (tibial torsion
and femoral anteversion) unmasked when compensatory
motion of the subtalar and midtarsal joints during stance is
restricted by the AFOs. In effect, when foot alignment is well
supported by the AFO, the effect of excessive tibial torsion
and femoral anteversion during gait become more evident.
It is not possible for an AFO to effectively address or con­
trol gait problems arising from existing underlying trans­
verse plane (rotational) deformity. The team and family
begin to consider the possibility of femoral/tibial derota­
tion osteotomy as a solution to the gait problems that have
emerged.

Chapter 9  Principles of Lower Extremity Orthoses
239
WHEN SHOULD A KAFO BE CONSIDERED?
The rehabilitation team considers a knee ankle-foot orthoses
(KAFOs) only when stability during stance cannot be effec­
tively provided by one of the AFO options.99,100 KAFOs are
often prescribed when in addition to impairment of ankle
control there is the presence of (1) hyperextension or recur­
vatum that jeopardize structural integrity of the knee joint,
and/or (2) abnormal or excessive varus or valgus angulation
that occurs during weight bearing in stance phase.101 If not
recognized and addressed appropriately, both threaten joint
function and structure during walking and, with repeated
abnormal loading, increase risk of permanent damage to
supporting structures within the knee and development of
degenerative joint disease. KAFOs can be used unilaterally
(e.g., for individuals with polio affecting one limb) or bilater­
ally (e.g., for those with SCI or myelomeningocele).
The KAFO metal and leather design was used during the
1950s to make ambulation possible for those recovering for
polio.16 The weight of the orthosis, however, increased energy
cost of ambulation significantly, and ultimately made use of a
wheelchair the preferred method of mobility for those ­requiring
bilateral KAFOs to walk.102 The development of the lighter
weight Craig Scott orthosis in the 1970s, the advent of thermo­
plastic custom-fit or custom-molded components in the 1980s,
and emergence of stance control orthotic knee joints since 2000
have contributed to reduction in energy cost of ­ambulation with
KAFOs; walking while wearing these orthoses has became more
reasonable.100 Even now, however, many individuals decide that
walking with bilateral KAFOs is too slow and requires too much
effort to be truly functional for daily use.
Many KAFO designs use a SAFO or HAFO as the distal
component, one or more thermoplastic thigh bars or cuffs as
proximal components, with metal uprights with a variety of
orthotic knee joints to interconnect them.101
Challenges to KAFO Use
The key issues that must be addressed for safe ambulation
with KAFOs are the same as those discussed earlier in the
chapter for AFOs102:
• To provide stance phase stability with minimal disruption
of forward progression (especially through the second/
ankle rocker of stance)
• To minimize disruption of swing limb clearance
• To prepare for an effective initial contact by holding the
ankle in a neutral position
Once the knee joint is encased in an orthosis, however,
meeting these goals can be challenging, especially for persons
who require bilateral KAFOs. These individuals typically have
more proximal deficits in muscle performance, motor con­
trol, and postural control than those whose need for stability
in stance and mobility in swing are addressed by any of the
AFO designs.103
CASE EXAMPLE 2
An Adult with Recent Stroke
Mrs. O is a 74-year-old woman who has just been admit­
ted to an inpatient rehabilitation facility following a 4-day
hospitalization for a thromboischemic stroke of one of the
penetrating branches of the right middle cerebral artery.
MRI indicated most of the damage involved the right inter­
nal capsule and fibers to and from the motor cortex in the
frontal lobe. Mrs. O presents with left hemiplegia, positive
Babinski reflex of the left foot, and several beats of clonus
at the left Achilles tendon on reflex testing. Movement of
the left lower extremity (LLE) occurs in a generalized exten­
sor synergy pattern. She is unable to isolate ankle or knee
motion in the LLE at the present time. Spatial perception
appears to be grossly intact at proximal and mid-extremity
joints of the LLE. She is able to mimic hip and knee posi­
tion with her right lower extremity when her LLE is pas­
sively positioned but does not accurately mimic ankle and
foot position. Static postural control in unsupported sitting
on firm surfaces is intact; however, when sitting at the edge
of the bed, reach distances are less than 10 inches in both
directions. She comes to standing with moderate assistance
of one person. Once standing, she is able to maintain the
position with contact guard. In standing, Mrs. O can reach
­forward and to the right 6 inches, but is very reluctant to
reach to the left. In the parallel bars, she demonstrates a
step-to gait pattern, requiring minimal assistance to advance
LLE. Her relevant past medical history includes a right total
hip arthroplasty 2 years ago and recent diagnosis of type 2
diabetes controlled by oral hypoglycemic medication. She
lives (with her golden retriever) in a ranch style home with
four steps to enter and hopes to eventually return to inde­
pendent living. Before her stroke she was an avid walker,
participating in an informal walking group that trekked in
various local and state parks twice a week.
Questions to Consider
• What are the most likely gait problems, in each subphase
of gait, that you expect to observe in Mrs. O as she begins
her rehabilitation program?
• How will these gait problems change as she recovers
from her stroke?
• What musculoskeletal (alignment and flexibility) and
neuromuscular (control) impairments or characteris­
tics will have to be considered by the team as they sort
through orthotic options for Mrs. O?
• Which of the options for AFOs (static vs. dynamic) might
you choose for Mrs. O? Why have you selected the par­
ticular design or components you are recommending?
• What are the possible benefits and trade-offs of each?
• How might you assess whether the orthosis chosen is
accomplishing the desired outcomes?

240
Section II  Orthoses in Rehabilitation
The movement of transitioning from sitting to standing
while wearing bilateral KAFOs is a complex and demanding
motor task. The stability provided by KAFOs may constrain
dynamic anticipatory and reactionary postural responses
during activities in standing, especially on uneven, high resis­
tance, or slippery surfaces. Many persons who use KAFOs for
ambulation also need to use an ambulatory assistive device
(e.g., crutches, walkers). Fear of falling and fall-related injury
while walking with the KAFOs may be an important con­
cern for those who use them, as well as for their caregivers.
Primary and comorbid conditions that limit cardiovascular
fitness and effectiveness of exercise response may further
reduce endurance, making true functional ambulation with
KAFOs unlikely. The combination of fewer resources that
the individual has to use for walking, an orthosis that may be
challenging to don and wear (given disease-related impact on
activities of daily living and self-care), and the energy cost of
walking even with the current lighter weight KAFO designs
can contribute to an individual's abandonment of walking
with his or her KAFOs after an effort-filled trial period.104,105
This becomes a consideration when the cost of fitting, fabri­
cation, and training for KAFO use is factored in.
Knee Function and Alignment
In early stance, under normal gait conditions, the GRF passes
through the ankle, behind the knee, and through the hip,
­creating an external flexion moment at the knee (Figure 9-19).
To counteract this GRF-related flexion moment, the quadri­
ceps muscles contract to prevent the knee from collapsing into
further flexion, the hamstrings and hip abductors contract to
stabilize hip position and maintain a level pelvis, and the gas­
trocnemius prepares to eccentrically control forward progres­
sion of the tibia.14 This combination of muscle activity provides
an internally generated knee extension moment that balances
the external flexion moment at the knee generated by the
GRF.14 When musculoskeletal or neuromuscular impairment
alters limb position or muscle activity at any lower extremity
joint, the internal/external force system is no longer in equi­
librium, and efficiency of walking and stability in stance will
be compromised.106 The magnitude of disruption of the equi­
librium between externally and internally generated moments
determines whether the individual will be able to use his or her
own resources (often in compensatory patterns or deviations)
to address the imbalance, or if an AFO or KAFO is necessary
for functional walking. Consideration of the magnitude of dis­
ruption of this equilibrium helps the team determine whether
an AFO can effectively influence the position of the GRF as
it crosses the knee, or if instead a KAFO is needed to restore
equilibrium. If there is evidence of ligamentous instability that
threatens anteroposterior or medial lateral stability at the knee,
or markedly abnormal varus or valgus of the knee, a KAFO
would clearly be indicated.
As when collecting data during the clinical examination,
when an AFO is being considered, the evaluation process for
KAFOs includes documentation of the individual's height
and weight, the status of circulation and sensation in lower
extremities, the condition and integrity of the skin, soft tis­
sue density and bony prominences, and living, school, work­
ing, and leisure environments, in which the KAFO is likely to
be used. Specific attention is given to determination of avail­
able range of motion, ligamentous activity, fixed contractures,
muscle performance, muscle and antigravity tone, leg length,
and limb girth. The use of observational gait analysis, walking
speed, other kinematic parameters, and if appropriate kinetic
analysis is used to document preorthotic gait pattern. The
team synthesizes this information to make a recommendation.
The orthotist selects appropriate materials and components,
then fabricates and fits the orthosis, making adjustments as
necessary.103 The physical therapist and individual using the
orthosis begin the process of gait training, initially concentrat­
ing on walking, but eventually adding transitions and manage­
ment of falls.105
KAFO DESIGN OPTIONS
KAFOs, much like the AFOs that form their distal component,
can be made of primarily metal materials (e.g., steel, alumi­
num, titanium alloys, carbon fiber), primarily thermoplastics,
or as a hybrid combining both types of materials. Historically,
the orthotic knee joints of a KAFO were locking or free
swinging; the development of stance-control (SC) knee units
in the early 2000s have significantly changed function and
FIGURE 9-19  The ground reaction force passes through the ankle,
behind the knee, and through the hip as loading response moves
toward midstance, creating an external flexion moment at the knee.
To achieve stability, muscle activity of the quadriceps, hamstrings,
and gastrocnemius/soleus combine to create an internal extension
moment to counterbalance the flexion moment of the ground reac­
tion force.