Operative Technique in Plastic Surgery – Kevin C.Chung

and tourniquet
children—the Esmarch bandage works better. The surgeon must
be careful not to make the tourniquet too tight.
Release
■ The most proximal extent of release is the bifurcation of the
arteries. A distal nerve bifurcation can be teased apart with
gentle intraneural dissection and splitting of the fascicles.
Occasionally, one will encounter an arterial bifurcation that is
too distal. In these instances, the smaller branch can usually be
sacrificed depending on the blood supply to the other side of the
digit. One can place a microvascular clamp, release the
tourniquet, and assess vascularity before dividing any branches.
Postoperative
■ Adequate compression and immobilization is critical to
successful skin graft take and predictable healing. Children
between 9 and 12 months of age occasionally will slip out of
long-arm casts; these should be reapplied promptly.
POSTOPERATIVE CARE
■ Immobilize the arm for 3 weeks as noted previously. If the cast falls off, it
should be replaced.
■ Remove the cast in the office and assess healing of skin grafts. Sutures, old
clots, and debris can be removed from the wounds at this time.
■ Occupational therapy to make nighttime volar resting thermoplast splints with
web space conformers at this time. The conformers put pressure on the scars
and allow them to soften and settle more quickly. These should be worn for
about a month after the cast is removed.
OUTCOMES
■ Functional outcomes after syndactyly release depend mostly on the
preoperative status of the digits and the hand.
■ In simple cases where the joints are not involved, full range of motion of the
involved digits should be expected postoperatively (FIG 6).
■ In complex cases, reconstruction is difficult and common postsurgical
functional issues include rotational and angular deformity and nail deformity.5
COMPLICATIONS
■ Web creep (loss of initial depth of the web space) can occur over time, with
incidence ranging from 2% to 24% (FIG 7).4
■ Web scars are best corrected right before the child starts school, around 5 or 6
years of age, after a significant growth spurt has occurred and the scars have

had ample time to soften.
■ Most webs scars respond well to Z-plasty, but occasionally, skin grafting
may be necessary.
■ Skin graft loss or flap loss, partial or complete
■ Vascular compromise—especially in complex and complicated cases
■ Nail deformity
■ Rotational and angular deformities
■ Dense scars
FIG 6 • Long-term postoperative dorsal (A) and web
space (B) views of the patient with complete third web
space syndactyly in TECH FIGS 1B and 2B. Patient has
a pliable web space with no limitations in range of
motion or function. Three-month postoperative dorsal

(C) and web space (D) views of the patient with
incomplete fourth web space syndactyly in TECH FIGS
1A and 2A. Early healing with good maintenance of web
and normal function.
FIG 7 • Web space scar after syndactyly release. A.
Three years after syndactyly release, this child has a
scar that tethers the web space and prevents full
extension of the ring finger. B. Twenty years after
syndactyly release, this adult patient has a web scar
that is bothersome but does not interfere with function.
Note desquamation of scarred skin.
REFERENCES
1. Oberg KC, Feenstra JM, Manske PR, Tonkin MA. Developmental biology and
classification of congenital anomalies of the hand and upper extremity. J Hand
Surg [Am]. 2010;35:2066-2076.
2. Hynes SL, Harvey I, Thomas K, et al. CT angiography-guided single-stage
release of adjacent webspaces in non-Apert syndactyly. J Hand Surg Eur Vol.
2015;40:625-632.
3. Deunk J, Nicolai JP, Hamburg SM. Long-term results of syndactyly
correction: full-thickness versus split-thickness skin grafts. J Hand Surg Br.
2003;28:125-130.
4. McCarroll HR. Congenital anomalies: a 25-year overview. J Hand Surg [Am].

2000;25:1007-1037.
5. Goldfarb CA, Steffen JA, Stutz CM. Complex syndactyly: aesthetic and
objective outcomes. J Hand Surg [Am]. 2012;37:2068-2073.

64
CHAPTER
Hypoplastic Thumb
Reconstruction
Amir H. Taghinia
DEFINITION
■ A thumb is considered hypoplastic if any of its osseous, musculotendinous, or
articular components is deficient or missing or if the web space that it forms
with the index finger is shallow.
ANATOMY
■ The normal thumb is broad with osseous and articular structures that allow
ample movement in multiple planes. Its intrinsic muscles provide a short
moment arm, powering the motion enabled by the osseoarticular column. The
normal first web space has a gentle curve spanning from the thumb
metacarpophalangeal (MP) joint to the index finger MP joint.
■ The modified Blauth classification system1 provides a surgically useful basis
for categorizing thumb hypoplasia.
■ Type I thumbs have minimal shortening and narrowing. No surgical
intervention is needed.
■ Type II thumbs have narrowing of the first web space, hypoplastic intrinsic
thenar muscles, and laxity of the MP joint. Reconstruction is recommended.
■ Type IIIA thumbs have features seen in type II thumbs, but they also have
extrinsic tendon anomalies and a hypoplastic metacarpal. Reconstruction is
recommended.
■ Type IIIB thumbs have features seen in type IIIA thumbs, but they also have
an absent proximal metacarpal and instability of the carpometacarpal (CMC)
joint. Pollicization is the treatment of choice.
■ Type IV (pouce flottant, floating thumb) and V (aplasia, complete absence)
thumbs are also best treated with pollicization—these thumbs are discussed

in the chapter on Index Finger Pollicization.
■ Specific anatomic deficiencies in types II and III thumbs include the
following1–3:
■ Laxity of the MP joint ulnar collateral ligament (UCL). The radial collateral
ligament (RCL) may also be lax, as may the entire joint capsule (global
laxity).
■ Hypoplasia or absence of the thenar muscles manifested as poor opposition
■ The flexor pollicis longus (FPL) tendon may be eccentrically attached to the
distal phalanx. But it also may be absent, may follow an abnormal path
(usually radially transposed), may have a very distal muscle belly, or may
anomalously attach to the proximal phalanx.
■ The extensor pollicis longus (EPL) tendon may also be eccentrically attached
to the distal phalanx. It may also be absent or follow an abnormal, more radial
path.
■ Abnormal radial interconnections between the EPL and FPL lead to a
characteristic radial deviation of the thumb termed pollex abductus. These
connections are usually present at the MP joint and prevent active
interphalangeal (IP) joint motion.
■ The distinction between type II and IIIA may not bear strongly on the choice
of surgical intervention, as there can be some overlap. If the thumb requires
web space deepening, collateral ligament reconstruction, and opponensplasty,
then there is usually some degree of extrinsic tendon abnormality present.2 The
surgeon should focus on treating the individual deficiencies that are present in
a given thumb.
PATHOGENESIS
■ Thumb hypoplasia occurs as a result of multiple potential factors—including
genetic (associated syndromes), environmental, teratogenic (thalidomide), and
idiopathic causes.
■ It is considered to be a malformation, based on the Oberg, Manske, and Tonkin
classification of 2010.4
NATURAL HISTORY
■ Thumb hypoplasia occurs in 1 out of 100 000 live births. A large number of
patients with thumb hypoplasia will have associated conditions such as cardiac
or hematologic anomalies.
PATIENT HISTORY AND PHYSICAL FINDINGS

■ Patients with type I to IIIA can present anytime in life. In milder cases, the
differences can be so subtle that parents do not notice a mild deficiency (in
function or appearance) until much later in life, especially if the nondominant
side or both sides are involved.
■ Physical findings:
■ Intrinsic thenar muscle hypoplasia (FIG 1A). This finding is usually evident
early, especially if there is a comparative normal contralateral side. Patients
lack strong opposition.
■ MP joint instability (FIG 1B,C). The stability of this joint is difficult to
assess in an infant because of global joint laxity. However, as the child grows,
the laxity becomes more evident on examination. Patients sometimes use a
“metacarpal grasp”—when an object is held between the fingers and the
thumb metacarpal head, thus avoiding the distal thumb.

FIG 1 • A. Palmar view of hand with thumb hypoplasia.
The thumb is short with flattening of the thenar
eminence and lack of flexion or extension creases at
the IP joint. The RCL (B) and UCL (C) are lax, allowing
significant deviation of the joint. D. The first web space
is shallow; radially deviating the thumb any more to
widen the web space would result in deviation at the
MP joint rather than splaying of the metacarpals.
■ Shallow web space (FIG 1D). This finding is also evident early, though the
degree of involvement is assessed subjectively. An incompetent UCL can
sometimes mask a shallow web space. It is best to assess the web space by the
angle achieved between the index and thumb metacarpals.
■ Extrinsic muscle abnormalities. These include abnormal size, length,
strength, and insertion of the thumb flexor and extensors. These anomalies are
typically manifested as joint deviations (MP joint) and/or lack of flexion or
extension creases (IP joint).
■ The functional ability of the CMC joint is often not obvious on the infant’s
plain film radiograph. Functional differentiation can be made by allowing the
child to grow and watching the toddler at play. If the thumb is bypassed in
favor of the index finger, the joint is likely nonfunctional.
■ The hand surgeon should be aware of the conditions associated with thumb
hypoplasia (eg, VACTERL, Fanconi anemia, and Holt-Oram syndrome) and
have a low threshold to refer if suspicions arise.
■ In particular, Fanconi anemia is a fatal disease that occurs mainly in those
with thumb hypoplasia and is easily diagnosed with a simple blood test.
IMAGING
■ Plain radiographs (FIG 2) help to determine the status of the metacarpal, CMC
joint, any abnormalities of the index finger, and the status of the distal radius
and ulna (presence of radial longitudinal deficiency).
NONOPERATIVE MANAGEMENT
■ Most patients with Blauth type I thumb hypoplasia do not need surgical
intervention.

FIG 2 • Plain radiographs of both hands demonstrate a
comparatively shorter right thumb with thinner first
metacarpal.
SURGICAL MANAGEMENT
■ The author performs hypoplastic thumb reconstruction around 2.5 to 3 years of
age, particularly if MP joint ligament reconstruction is needed. The metacarpal
head should be big enough to allow creation of a tunnel without fracturing. Key
procedures are outlined below.
■ Opponensplasty
■ In congenital cases, opponensplasty is done using the flexor digitorum
superficialis (FDS) tendon to the ring finger or the abductor digiti minimi
(ADM).
■ The FDS is advantageous because it provides simultaneous opponensplasty
and ligament reconstruction.
■ The ADM is used in patients who have had previous pollicization procedures
(and have weak opposition) or those with thumb hypoplasia who do not need
ligament reconstruction.

■ MP joint ligament reconstruction
■ This procedure is done with tightening of the existing capsular tissues or
extrinsic reconstruction with either the FDS to the ring finger (in cases that
need simultaneous opponensplasty) or the palmaris longus tendon. In cases of
global laxity, chondrodesis or epiphyseal arthrodesis is advocated, though
both of these procedures have significant downsides.
■ The author errs toward stability. Thus, for most cases, both UCL and RCL
are reconstructed using a tendon graft. The tendon is split, and one-half is
routed through a tunnel made in the metacarpal head to reconstruct the UCL.
The tendon is then passed underneath the adductor aponeurosis and routed
from dorsal to palmar through a tunnel in the periosteum in the proximal
phalanx. It is then passed under the aponeurosis once again before being
sutured back to itself at the metacarpal head. The RCL is reconstructed on the
radial side using a similar method.
■ Web space deepening.
■ This procedure is best done with a four-flap Z-plasty.
■ Multiple other procedures have been proposed, but the Z-plasty remains the
workhorse for this condition.
■ Other adjunct procedures include correction of MP and IP joint deviation by
division of the tendinous attachments of the flexor to the extensor (pollex
abductus), division of the musculus lumbricalis pollicis, step-lengthening of the
extrinsic flexor tendon, and detachment and reinsertion of the EPL and/or FPL
tendon.
■ Pin fixation is advocated after these procedures.
■ Depending on the degree of involvement and interventions planned, it is
important to establish a logical sequence for performing these procedures. For
example, performing the web space release first releases the investing tight
fascia of the intrinsic muscles, thus allowing better palmar abduction prior to
opponensplasty.
Preoperative Planning
■ Discuss risks, benefits, and expectations with parents on the day of surgery.
Positioning and Approach
■ The patient is positioned supine with the arm out on a small hand table.
■ Incisions are planned carefully prior to use of the tourniquet.
■ Plan all incisions before exsanguinating the upper extremity.

■ In toddlers, an Esmarch bandage is used as a tourniquet as it provides better
hemostasis. In older children, a pneumatic tourniquet works best.
T E C H N I Q U E S
■ Four-Flap Z-Plasty for First Web Space
■ Splay the web with the help of an assistant and draw a transverse line across
the tightest area of the web. On the thumb side, draw a perpendicular line
dorsally. On the index finger side, draw a perpendicular line palmarly. Bisect
these 90-degree angles with two additional lines at 45 degrees.
■ The five lines that are drawn should be the same length (TECH FIG 1A–
C).
■ Incise the limbs and raise the flaps with a few millimeters of fat to preserve
the blood supply.
■ Spread in the web space, and define and protect the neurovascular structures.
Bluntly dissect the muscles and sharply divide their investing fascia to widen
the distance between the index and thumb metacarpals (TECH FIG 1D).
■ Releasing the fascia of the adductor pollicis and first dorsal interosseous
muscle is critical to obtaining a wide web space.
■ If designed correctly, the flaps should transpose into their new respective
positions.
■ If performing a ligament reconstruction, extend the ulnar skin incision to
fully expose the MP joint.

TECH FIG 1 • A–C. Designing the four-flap Z-plasty.
The dorsal incision perpendicular to the web should
be next to the thumb; the alternative approach would
place the incision on the volar thumb and cause a
flexion contracture. D. The investing fasciae of the
adductor pollicis and first dorsal interosseous are seen
in the first web space. These should be sharply
divided or excised to allow optimal widening of the
web.
■ Opponensplasty and Ligament Reconstruction
Using FDS
Markings
■ Design a radial mid-lateral incision on the thumb MP joint, just dorsal to
where the glabrous skin meets the nonglabrous skin.
■ Design a transverse incision over the distal wrist flexion crease; this incision
should be long enough to gain access to the flexor carpi ulnaris (FCU) tendon
ulnarly and the ring finger flexor digitorum superficialis (FDS) tendon
radially.

■ Finally, design a longitudinal A1 pulley incision in the distal palm over the
ring finger ray (TECH FIG 2).
TECH FIG 2 • Design of the incisions, palmar view.
Exposure and Tendon Harvest
■ Incise the wrist crease incision. Find and isolate the FCU tendon while
identifying and protecting the ulnar artery and nerve.
■ Find and isolate the FDS tendon to the ring digit at the wrist. It is usually the
most palmar and ulnar flexor tendon.
■ Retract the tendon and confirm that it flexes the ring proximal
interphalangeal (PIP) joint. Free its distal attachments.
■ Incise the A1 pulley incision over the ring finger, spread down to the tendon
sheath, and sharply divide the A1 pulley. Using a small retractor, pull the
FDS up into the wound with the finger in maximal flexion.
■ Obtain maximal exposure in the wound, and free the FDS from the FDP in
both directions. Incise the two limbs of the FDS as distally as possible,

leaving its insertion intact.
■ Occasionally, the FDS tendons of the ring and little digits are joined
proximally. If pulling on the ring FDS causes flexion of the little digit PIP
joint, a separate incision to release the little finger FDS may be necessary
(TECH FIG 3A).
■ Deliver the FDS into the wrist wound, and wrap with moist gauze so it does
not desiccate.
■ Incise the radial thumb incision and dissect to the extensor mechanism.
■ If present, release the pollex abductus and free the extensor from the flexor
(TECH FIG 3B,C).
■ It is crucial to divide these attachments, as they will otherwise act as a
deforming force, stressing the MP ulnar collateral ligament (UCL)
reconstruction.
■ Once released, pull the extensor and flexor proximally to ensure that the
MP joint does not deviate radially.
■ Correct any extrinsic tendon abnormalities. Depending on the anatomy,
options include realignment of tendons with pulleys, step-lengthening, and/or
reinsertion of eccentrically attached tendons. (None were performed in the
example case.)

TECH FIG 3 • A. The first web space has been
released and the FDS tendon has been isolated and
delivered through the wrist wound. The fourth and fifth
digit FDS tendons were joined up to the mid-palm, so
a separate A1 pulley incision was needed on the fifth
ray. B. Pollex abductus is radial deviation of the thumb
caused by attachments of the extensor pollicis longus
(EPL) tendon to the flexor pollicis longus (FPL) tendon
present at the MP joint level. C. Extrinsic tendons can

be radially transposed and attached to each other via
tendinous bands. In addition, the extrinsic tendons can
have eccentrically placed insertions (radially) on the
distal phalanx.
Tunnel Creation
■ Retract the extensor dorsally and identify the metacarpal head on the radial
side without entering the joint.
■ Define the metacarpal head in the ulnar incision as well. Create a tunnel
underneath the adductor aponeurosis in the proximal to distal direction. The
tendon will be routed underneath the aponeurosis.
■ To create the tunnel in the metacarpal head, incise the periosteum over the
metacarpal head and strip off a small area. Clearly define the dorsal and
palmar aspects of the metacarpal head and mark a spot exactly in the middle.
TECH FIG 4 • Multiple drill holes using a K-wire
through the metacarpal head allow for creation of an
elliptical tunnel through which the tendon can be

passed for ligament reconstruction.
■ Make one wide tunnel by drilling multiple holes side by side using a 0.035-
in. Kirschner wire (TECH FIG 4), then drilling in between these holes.
■ The tunnel may also be created with a single pass of a drill, appropriately
selected for size.
■ Ensure that the tunnel is generous and visibly larger than the tendon. Pulling
the tendon through a small tunnel causes it to fray.
■ The thumb metacarpal’s physis is located proximally, in contrast to the
physes for the finger metacarpals, which are located distally. Therefore, there
are no concerns about growth arrest when this bone tunnel is created.
■ Create two vertical (dorsal to palmar) tunnels in the periosteum on the radial
and ulnar aspects of the proximal phalanx just distal to the physis. These
tunnels should be centered volarly to best mimic the normal collateral
ligaments.
■ The author does not bore vertical bone tunnels in proximal phalanges of
small children. This technique is technically difficult, threatens the physis,
and has not been found to be necessary.
Passing the Tendon
■ Create a subcutaneous tunnel from the distal wrist incision to the radial
thumb incision.
■ Loop the FDS tendon around the FCU tendon and pass it through the
tunnel into the radial thumb wound.
■ Pass one limb of the distal FDS through the metacarpal head tunnel from
radial to ulnar (TECH FIG 5A).
■ Split the FDS proximally and keep pulling the tendon limb through until
palmar abduction reaches about 70 degrees.
■ Suture the tendon to the periosteum on the radial and ulnar sides of the
metacarpal head to secure the opponensplasty.
■ On the ulnar side, pass the tendon under the aponeurosis, then dorsal to
palmar through the periosteal tunnel, and then under the aponeurosis again
(TECH FIG 5B) and suture it to the tendon itself at the metacarpal head
(TECH FIG 5C).
■ Repeat this procedure on the radial side; there is more tendon length on this
side and there is no aponeurosis in the way.

■ Trim any excess tendon and place additional securing sutures if necessary
(TECH FIG 5D,E).
■ Test the integrity of the ligament reconstruction to assure there is no laxity.
Usually, pins are not necessary.
TECH FIG 5 • A. The FDS limbs are separated, and
one is passed through the bone tunnel to create the
UCL, while the other creates the RCL. B. The UCL is
reconstructed in the shape of a triangle. The tendon is

passed superior to inferior in the periosteal tunnel and
sutured back to itself. C. The UCL reconstruction is
done under the adductor aponeurosis. D. RCL
reconstruction is demonstrated. E. UCL reconstruction
performed under the adductor aponeurosis.
Completion
■ Close the wrist wound using several deep dermal 4-0 Monocryl sutures
followed by a running 5-0 Monocryl intracuticular suture. Close the palm and
radial thumb wounds with interrupted simple or horizontal mattress 6-0
chromic gut sutures.
■ Transpose the Z-plasty flaps, and close the web space wounds using simple
interrupted 6-0 chromic gut sutures (TECH FIG 6).
■ Place antibiotic-impregnated petroleum gauze (Xeroform) on the wounds
and apply compression gauze.
■ Deflate (or remove) the tourniquet and assess perfusion.
■ Apply dressings and a well-padded long-arm cast for 3 to 4 weeks.

TECH FIG 6 • Immediate postoperative palmar view
shows good opposition (A) and a wide web space
after four-flap Z-plasty (B).
■ Opponensplasty With Abductor Digiti Minimi
(Huber)
■ Design an L-shaped incision on the ulnar side of the hand (TECH FIG 7A).
■ The long limb of the incision should be a high mid-lateral ulnar incision
extending from just distal to the fifth digit MP joint to the pisiform.
■ The short limb is a transverse volar incision on the distal wrist crease just
proximal to the pisiform. This second incision helps to free the proximal
origin of the abductor digiti minimi (ADM) muscle if needed for additional
mobilization of the muscle. Note: The transfer can also be raised as a
myocutaneous flap thus avoiding tunneling and adding more bulk to the
thenar area.5
■ Incise the mid-lateral ulnar marking and dissect down to the ADM muscle.

Isolate and protect any branches of the dorsal sensory ulnar nerve.
■ Incise the fascia and dissect the muscle free (TECH FIG 7B), following it
distally until its insertion is encountered on the fifth digit proximal phalanx.
■ Disinsert the muscle, leaving a long cuff of periosteum attached to the
muscle to facilitate subsequent reinsertion.
■ Dissect the muscle proximally and identify and protect its neurovascular
bundle. If additional length is needed on the muscle, the short limb of the L-
incision can be made and the origin mobilized off the pisiform and flexor
carpi ulnaris. The author does not transfer the origin.
■ Make a high mid-axial incision on the radial aspect of the thumb MP joint
and dissect down to the distal metacarpal.
■ Create a generous subcutaneous tunnel between the thumb MP joint and the
proximal aspect of the ulnar wound (TECH FIG 7C). Tunnel the muscle
through.
■ There are multiple sites where the muscle can now be attached: the extensor
hood, the proximal aspect of the proximal phalanx, or the distal aspect of the
metacarpal.
■ The author typically attaches the muscle to periosteum near the metacarpal
head. This insertion site gives the most direct pull without taxing the MP
joint UCL. It also avoids radial pull on the extensor mechanism, which may
disrupt the learned prehensile patterns in postpollicization cases or translate
the (already radially displaced) extensor tendon in hypoplastic cases.
■ Attach the muscle and secure with several sutures to obtain maximal palmar
abduction under moderate tension. Ensure that the pedicle is not kinked.
■ Close the wounds with absorbable sutures (TECH FIG 7D). The ulnar
incision is closed with a running intradermal suture.
■ Place antibiotic-impregnated petroleum gauze (Xeroform) on the wounds
and apply compression gauze.
■ Deflate (or remove) the tourniquet and assess perfusion.
■ Apply a well-padded long-arm cast for 3 weeks.

TECH FIG 7 • A. A 6-year-old boy who underwent left
index finger pollicization for type IV thumb hypoplasia
presented with weakness of palmar abduction and
opposition. A high midlateral ulnar incision is planned
with a transverse extension at the distal wrist crease,
just proximal to the pisiform. B. The ADM muscle is
seen as the most ulnar/palmar structure deep to the
skin. C. The ADM muscle has been mobilized. A
generous tunnel housing a Penrose drain connects
the ulnar incision to the mid-lateral incision on the
radial aspect of the neothumb “MP joint.” D. The
muscle has been tunneled and inset in maximal
palmar abduction/opposition. The wounds have been
closed.

PEARLS AND PITFALLS
Anatomy
■ There are numerous variations of extrinsic and intrinsic
muscle/tendon anatomy, including a lumbrical emanating from the
flexor (so-called musculus lumbricalis pollicis), flexor that inserts
partially on the proximal phalanx, joined flexor and extensor
proximally, eccentric insertions, and various degrees of attachment
of the FPL to the EPL. Not all of these abnormalities need to be
surgically repaired.
Technique
■ Radial deviation at the MP and IP joints can be improved by
releasing the pollex abductus with or without step-lengthening of
the flexor tendon and reinsertion of the EPL and/or FPL into a more
ulnar position on the distal phalanx. Pin fixation may be necessary
after this procedure to keep the joints straight.
Surgical
management
■ Although many parents ask the surgeon to restore active IP joint
motion, this is possible only in a small subset of patients who have
preoperative passive but not active IP joint motion.
■ On occasion, the MP joint laxity is so severe (global) that one
should consider MP joint chondrodesis or epiphyseal arthrodesis.
Chondrodesis does not heal predictably, and epiphyseal arthrodesis
is only possible if there is enough epiphysis to allow fusion. Both
techniques shorten the thumb and stress the CMC joint.
FIG 3 • A. Two months postoperatively, the patient was
using the opposition transfer for grasping food. Three
years postoperatively, he demonstrates a stable MP
joint with strong opposition (B) and a wide first web

space (C).
POSTOPERATIVE CARE
■ Remove the cast after 3 or 4 weeks of immobilization.
■ Fashion a thumb spica thermoplast splint that can be worn for 2 or 3 weeks at
night for protection.
■ Start range of motion exercises with hand therapy.
OUTCOMES
■ Functional outcomes for hypoplastic thumb reconstruction are satisfactory if
the anatomic abnormalities are appropriately treated (FIG 3).
■ There is a lack of good long-term data on functional outcomes, especially
data that have been controlled for severity of involvement.
■ The reconstructed thumb remains smaller and less powerful than the normal
thumb.
COMPLICATIONS
■ Immediate complications are rare. Long-term functional concerns relate to the
degree of hypoplasia, correct preoperative diagnosis, and appropriate treatment.
■ Persistent lack of active IP joint motion can be seen despite adequate release of
the tendon adhesions.
■ Inadequate release of pollex abductus attachments can cause a deforming
radial force and weaken the MP joint UCL repair in the long term.
■ If the collateral ligament is reconstructed dorsal to the axis of rotation,
hyperextension of the MP joint may result. Ensure that the vertical tunnel on
the proximal phalanx is centered volarly.
REFERENCES
1. Manske PR, McCarroll HR Jr, James M. Type III-A hypoplastic thumb. J
Hand Surg [Am]. 1995;20:246-253.
2. Tonkin M. Surgical reconstruction of congenital thumb hypoplasia. Indian J
Plast Surg. 2011;44:253-265.
3. Light TR, Gaffey JL. Reconstruction of the hypoplastic thumb. J Hand Surg
[Am]. 2010;35:474-479.
4. Oberg KC, Feenstra JM, Manske PR, Tonkin MA. Developmental biology and
classification of congenital anomalies of the hand and upper extremity. J Hand
Surg [Am]. 2010;35:2066-2076.

5. Upton J, Taghinia AH. Abductor digiti minimi myocutaneous flap for
opponensplasty in congenital hypoplastic thumbs. Plast Reconstr Surg.
2008;122:1807-1811.

65
CHAPTER
Reconstruction of Radial
Polydactyly
Amir H. Taghinia
DEFINITION
■ Polydactyly refers to the presence of extra digits. Most surgeons prefer this
term to duplication, as the latter implies that the partners are exactly identical,
which is the exception rather than the rule.
■ Radial polydactyly is the presence of extra digits involving the thumb ray. This
terminology is preferable to preaxial polydactyly because the term preaxial
encompasses the thumb through ring rays.
ANATOMY
■ Radial polydactyly is most commonly classified using the Iowa classification
system.1 The system divides polydactyly based on longitudinal level of bone
and/or joint arborization but does not account for soft tissue differences (FIG
1).
■ Not considering small soft tissue–only (nubbin) polydactyly cases, type IV is
the most common radial polydactyly (approximately 45% of cases) and type II
is the second most common (approximately 20% of cases).
■ Type VII radial polydactyly, which has a triphalangeal component, is further
subdivided into six types.
■ The Iowa classification does not include soft tissue differences and certain
types of radial polydactyly. Accordingly, additional classification systems have
been proposed.
■ The Rotterdam system gives broader classification possibilities (including
triplicate thumb) but introduces more complexity.2
■ Although the thumb partners may be nearly identical, the ulnar partner is
usually the more dominant one; it is larger and better developed and has greater

range of motion and strength.
■ Nevertheless, both partners may exhibit findings of thumb hypoplasia,
including smaller stature, poorly developed joints and tendons with lack of
flexion or extension creases, joint deviations, eccentrically inserting extrinsic
tendons, and abnormal or deficient intrinsic muscles.
PATHOGENESIS
■ The exact etiology of radial polydactyly remains unknown. The literature
suggests an imbalance between the apical ectodermal ridge (AER) and the
underlying mesoderm as one cause.
■ Based on the Oberg, Manske, and Tonkin classification,3 polydactyly is
considered to be a malformation with abnormal formation/differentiation of the
hand plate in the radioulnar axis.
NATURAL HISTORY
■ Radial polydactyly occurs more commonly in those with Caucasian and Asian
descent, with an incidence of 1 in every 3000 live births.
PATIENT HISTORY AND PHYSICAL FINDINGS
■ Patients are usually seen in infancy.
■ Radial polydactyly may run in families.
■ Associated conditions may occur, even Fanconi anemia, a rare condition that
can be fatal if not diagnosed early.
■ Examine the thumbs for flexion and extension creases, passive and active
range of motion, joint stability, and strength.
■ During late infancy, the child usually starts to use the more dominant thumb. It
is worthwhile to see the child at play to better understand the developing
prehensile patterns.

FIG 1 • Iowa classification of radial polydactyly. The
distinctions are based on increasing levels of proximal
divergence. The radial partner tends to be smaller and
less developed.
IMAGING
■ Plain radiographs are the study of choice and should be obtained for most
polydactyly cases involving bone.
■ Radiography resolves all uncertainty about the level and involvement of a
polydactyly that may not be clear on physical examination.
SURGICAL MANAGEMENT
■ Small pedunculated (“nubbin”) polydactyly is treated in the office before a
month of age. Young infants are not strong enough to resist small procedures,
and they can be soothed easily with a pacifier or sugar water.
■ Suture ligation can leave a small bump, so two alternatives are preferred,
both using local anesthesia in the clinic treatment room: excision and suture
closure or clipping at base with a hemoclip and excision. Both options are
offered to the parents in this early age.
■ The advantage of the clipping is that it is quick, but the clip can stay several
weeks and cause local skin irritation, and there is a small risk of ingestion
(especially on the radial side) if not covered with a dressing at all times.
■ The excision and closure option takes more time but with likely fewer
potential complications.
■ For older infants or those in whom the polydactyly has a wide base, the author
prefers excision in the operating room under general anesthesia at about 9 to 12

months of age.
■ General anesthesia is also required in cases with more extensive involvement.
No clear consensus exists regarding timing of repair. The risk of anesthesia in a
small child should be weighed against early repair that takes advantage of brain
plasticity. Other medical comorbidities should be taken into account.
■ Small object grasp in the infant starts around 9 months of age; accordingly, the
author prefers to correct polydactyly between 9 months and 1.5 years of age.
■ For very complex cases, it is worthwhile to delay repair until the structures
are large enough to conduct a more technically precise operation. An example
is a small trapezoidal or delta phalanx that requires a closing wedge
osteotomy (eg, triphalangeal thumb).
Surgical Options
■ There are three methods for repair of radial polydactyly: resection and
reconstruction, the sharing technique, and acral transposition (“on-top plasty”).
■ The surgeon should not apply one technique to one type of polydactyly based
purely on algorithm.
■ Instead, a careful analysis of the clinical and radiographic findings, as well as
expected functional outcome and patient factors, should dictate the choice of
reconstruction.
■ The main principles for repair are ablation of nonfunctional structures,
creation of the best functional and aesthetic single digit from parts of both
partners, and preservation of length, stability, and a wide first web space.
Resection and Reconstruction
■ Resection and reconstruction involves resecting the more hypoplastic partner
and augmenting the better developed one (see Technique section).
■ This technique is indicated when the dominant partner alone is sufficient to be
a thumb with good appearance and function.
■ It is the easiest and the most favored approach. It can be applied to all types of
polydactyly and is the most common operation for types IV to VI.
■ The main sequence of this procedure is as follows:
■ Disarticulation of the discarded partner but preservation of a
ligamentoperiosteal flap and (if present) muscle insertion
■ Shaving of redundant proximal articulation
■ Osteotomies to correct angulation, if needed

■ Reattachment of the ligamentoperiosteal flap and muscle insertions
■ Rebalancing of eccentrically aligned extensor and flexor tendons, if needed
Sharing Technique
■ The sharing technique uses parts from both partners to create a single digit.
The most common expression of this technique is the Bilhaut operation, which
removes central tissues and combines two digits into one.
■ The procedure is indicated for nearly symmetrical but hypoplastic partners
when removal of one partner only would leave a small thumb.
■ The original Bilhaut technique removed equal parts from symmetrical partners
but resulted in unsatisfactory outcomes including nail ridging, growth
disturbance, and stiffness.
■ The modified Bilhaut technique proposed by Baek4 shows more promising
results. It removes extra-articular unequal parts from symmetrical partners,
thus avoiding articular reconstruction and creating a well-contoured distal
phalanx for the nail.
■ The technique is typically performed for types II and III thumbs when the
two partners are small but nearly equal in size.
■ It can also be applied to type IV thumbs, but because the phalanges are
usually asymmetrical, articular step-offs and bony misalignment are more
likely to occur, resulting in less satisfactory outcomes.5
■ Dorsal and volar incisions are made, the central soft tissue is excised, and the
phalangeal components are identified. The dominant phalanx’s articular
surface is preserved. Similarly shaped extra-articular osteotomies are
performed in each phalanx such that the defect in the dominant distal phalanx
will be matched by a small nonarticular, soft tissue–bearing bone segment of
the nondominant distal phalanx (FIG 2). The phalanges are then opposed and
secured with Kirschner wires or sutures.

FIG 2 • In the modified Bilhaut operation for type II
radial polydactyly, an extra-articular portion of each
distal phalanx is shared to reconstruct one distal
phalanx. Typically, a greater portion of the more
dominant partner is preserved. Kirschner wires (shown)
or sutures provide fixation for the osteotomy.
FIG 3 • In the original Bilhaut operation, half of each
distal phalanx was used to reconstruct the thumb. A.
The contour was suboptimal, leading to a groove in the
nail. B. In the modified Bilhaut technique, slight volar
axial rotation of the distal phalanges prior to fixation

ensures a smoother nail contour.
■ Slight volar axial rotation of the distal phalanges prior to fixation will ensure
a smoother nail contour without a groove, avoiding the so-called seagull
deformity (FIG 3).
■ The nail bed and skin are then repaired using fine sutures.
Acral Transposition
■ On-top plasty is performed when one digit has better proximal components
and the other has better distal components.
■ This reconstruction is more common for cases with metacarpal or
carpometacarpal arborization such as in types V to VII radial polydactyly.
■ The procedure involves moving the better distal component of one partner
onto the better proximal component of the other.
■ The better distal component is isolated as a neurovascular island flap, and an
osteotomy is performed at the desired level of transfer. The lesser distal
component is excised and an osteotomy of the better proximal component is
done at the desired level of transfer (FIG 4).
■ The transfer is then performed and fixed with pins or interosseous wires. The
intrinsic muscles are rebalanced and the skin is closed.
■ Joint and bone deviations should be corrected (to the greatest extent possible)
in the first operation with osteotomies and tendon rebalancing as needed.
Subsequent repairs may be needed with growth.6
■ In more proximal cases (eg, type V and VI), the surgeon should carefully
consider the first web space. Because the ulnar partner is the one that is most
commonly preserved and it is usually ulnarly deviated, the surgeon should
perform maneuvers necessary to make sure that the first web space will be
sufficiently wide.
Preoperative Planning
■ Discuss risks, benefits, and expectations with parents on the day of surgery.
■ Specifically outline the risks of scarring, joint deviations, stiffness, and bulges.
Positioning
■ The patient is positioned supine with the arm out on a small hand table.
Approach

■ Incisions are planned carefully prior to use of the tourniquet. The author
prefers mid-lateral incisions to dorsal incisions, since they produce the best
appearance.
■ In infants and toddlers, an Esmarch bandage is used as a tourniquet.
FIG 4 • Acral transposition (“on-top plasty”) is usually
indicated in more proximal radial polydactyly where one
partner is dominant distally and the other is dominant
proximally. A. In this case, the dominant ulnar distal
partner will be transferred to the dominant proximal
radial partner. Osteotomy sites are indicated in blue
highlighting. The shaded portion of the ulnar partner’s
metacarpal will be discarded. The skin incisions are
planned such that plenty of skin is preserved on the
hand from the radial partner. The goal is to dissect the
ulnar partner as a vascularized island flap and translate
it into the soft tissue sleeve of the radial partner. The
wound where the ulnar partner resided will then be
closed linearly, thus constructing a wide first web space.
B. During the operation, the distal radial partner is
discarded while any intrinsic muscles that attach to it
are preserved for subsequent attachment onto the
transferred partner. C. After the ulnar partner is isolated
as a vascularized island flap, osteotomy is performed,

and it is transferred onto its new position and secured
with interosseous wires or Kirschner wires. The intrinsic
muscles are reattached, and the skin is closed,
resulting in an improved web space.
T E C H N I Q U E S
■ Reconstruction of Type IV Radial Polydactyly
Markings and Exposure
■ The case of a 9-month-old boy with type IV polydactyly is presented with
step-by-step surgical treatment (TECH FIG 1A–C).
■ Draw the markings for a mid-lateral closure. Leave excess skin on the
preserved partner and trim the skin later to create a custom closure (TECH
FIG 1D,E).
■ The closure takes extra time but improves appearance.
■ Once the tourniquet is applied, incise the dorsal markings and dissect sharply
to the extensor tendon (TECH FIG 1F).
■ Develop a plane above the extensor mechanism to just beyond the
metacarpophalangeal (MP) joint (TECH FIG 1G).
■ Incise the extensor tendon distal to its bifurcation and dissect under the
extensor above the MP joint capsule.
■ Incise the palmar markings; dissect and divide the neurovascular bundle
(TECH FIG 1H).
■ Dissect a plane over the flexor mechanism and the intrinsic abductor of the
thumb (TECH FIG 1I). The abductor usually inserts on the radial and volar
aspects of the proximal phalanx, but the anatomy is quite variable.
Flap Creation
■ Design a proximally based periosteal flap on the radial aspect of the
proximal phalanx (TECH FIG 2A).
■ Incise the markings and elevate this flap with the radial partner’s MP joint
radial collateral ligament and the abductor muscle (TECH FIG 2B).
■ This flap will be used for subsequent reconstruction of the retained partner.

■ Isolate and divide the extrinsic flexor tendon (TECH FIG 2C).
Disarticulation, Osteotomy, and Fixation
■ Disarticulate at the MP joint. A bifid metacarpal head will now be visible
(TECH FIG 3A).
■ Cut the metacarpal head that articulated with the discarded partner (see
TECH FIG 2B).

B Abductor pollicis brevis Adductor pollicis

TECH FIG 1 • Type IV radial polydactyly in a 9-month-
old boy. A,B. Anteroposterior clinical and radiographic
views demonstrate a smaller, less developed radial
partner. The ulnar partner is inline (parallel) to the
metacarpal, and so an osteotomy of the metacarpal
will not be needed. C. Simplified anatomy of radial

polydactyly. The abductor pollicis brevis muscle can
have variable, and potentially multiple, insertion sites,
such as onto the extensor, the bone, and the flexor
tendon. If on-top plasty is planned, the insertion of the
adductor pollicis should be considered. D,E. Dorsal
and palmar views of the operative markings for
planned excision of radial partner. A mid-lateral
closure is planned. Excess skin is left on the retained
partner for subsequent closure. F. The dorsal skin
incision has been incised, the dorsal veins are
cauterized, and a plane is developed over the
extensor mechanism. G. The dorsal skin flap is
elevated proximal to the MP joint. H. The volar incision
is made, and the neurovascular bundle to the radial
partner has been identified. I. The volar skin flap is
elevated to expose the flexor tendon and the intrinsic
abductor musculature.
■ If only cartilage is involved (in minor cases), a knife will be sufficient to
complete this task (TECH FIG 3B).
■ In most cases, however, a retrograde osteotomy with a saw or a fine bone
cutter is needed (TECH FIG 3C).
■ Assess the need for closing wedge metacarpal osteotomy. When MP joint
ulnar angulation of the retained partner is prominent, a closing wedge
osteotomy is needed (TECH FIG 3D).
■ Pin fixation is necessary after osteotomy (TECH FIG 4). Insert a retrograde
0.028 in. Kirschner wire from the ulnar side.
Tendon Correction in Type IV Polydactyly
■ In divergent-convergent (rhomboid) type IV polydactyly, the extensor and
flexor tendons can have eccentric insertions onto the distal phalanges (TECH
FIG 5).

TECH FIG 2 • A. A proximally based periosteal flap is
designed. The flap will include the radial collateral
ligament and the abductor muscle insertion. Note that
the muscle is inserting onto the bone (periosteum) and
the flexor tendon. B. Technical maneuvers necessary
for reconstruction of type IV radial polydactyly. The
periosteal/muscle flap has been lifted, the dotted area
showing the previous area of flap adherence. It is
ideal to leave a long periosteal cuff on the flap to
make subsequent repair easier. The radial head of the
bifid metacarpal is cut, and a closing wedge
osteotomy is performed if there is deviation of the
ulnar partner. C. The flexor tendon is isolated. Note
the periosteal/muscle flap reflected proximally and
held with forceps.

TECH FIG 3 • A. The radial partner has been
disarticulated at the MP joint, and the bifid metacarpal
head is noted. B. In minor cases, such as this one, the
radial head of the metacarpal is mostly cartilaginous
and can be excised using a blade. C. In most cases,
the radial head of the metacarpal has an osseous
component and a retrograde osteotomy with a saw is
needed. D. Illustration demonstrates result after
closing wedge osteotomy (secured with a pin) and
reattachment of the periosteal/muscle flap.

TECH FIG 4 • A,B. A different patient is demonstrated
with type IV radial polydactyly and more significant
ulnar angulation of the ulnar partner at the MP joint.
Improvement in angulation is noted after closing
wedge osteotomy and pin fixation intraoperatively (C)
and 3.5 weeks postoperatively (D).

TECH FIG 5 • In rhomboid type IV polydactyly, the
extrinsic tendons can attach eccentrically on the distal
phalanges, thus exaggerating the deviation. If these
abnormal insertions are not addressed, deviation can
recur with growth.
■ If left alone, these abnormal tendons can contribute to long-term
misalignment and deviation of the thumb.
■ They should be detached and reattached at the proper location on the distal
phalanx.
Reattachment and Closure
■ Reattach using sutures the flap of periosteum, collateral ligament, and
muscle to the radial aspect of the retained proximal phalanx (TECH FIG
6A).
■ After removal of the radial metacarpal head, the radial aspect of the

remaining metacarpal is bare and not attached to the collateral ligament;
however, the collateral ligament heals well to the metacarpal.
■ Additional reinforcing sutures to the metacarpal may be necessary.
■ There will be excess skin in multiple dimensions. In most cases, the excess
skin can be trimmed and “cheated in” and a mid-lateral closure completed.
■ If there is abundant excess, a better approach is to make a separate palmar
incision along the MP joint flexion crease to excise skin in an orthogonal
dimension (TECH FIG 6B,C).
■ Apply a soft dressing and a long-arm cast for 3 to 4 weeks.
TECH FIG 6 • A. The periosteal, collateral ligament,
and muscle flap have been reattached to the proximal
phalanx with additional reinforcing sutures onto the
radial aspect of the metacarpal. B. Final appearance
after closure. C. Note that the “dog ear” has been
ablated via a separate incision in the volar MP joint
flexion crease.
PEARLS AND PITFALLS
Surgical
management
■ It is the author’s opinion that, when possible and especially in more
proximal polydactyly cases, resection and reconstruction give a

better aesthetic outcome than does the Bilhaut “sharing” technique.
The downside is that the thumb is usually smaller.
■ The surgeon should have a well-defined stepwise approach for each
case.
Technique
■ When developing muscle and/or collateral ligament flaps, leave a
long periosteal sleeve to allow easier subsequent reattachment.
■ In polydactyly cases that have multiple levels of joint deviation (eg,
rhomboid type IV), multiple simultaneous osteotomies should be
undertaken.
POSTOPERATIVE CARE
■ Immobilize the extremity with a long-arm cast with the elbow at 90 degrees of
flexion for 3 or 4 weeks. The author immobilizes longer in those patients who
have undergone osteotomies.
■ Remove the cast (and pins) and refer to hand therapy for fabrication of a
thermoplast thumb spica splint.
■ Start range-of-motion exercises.
■ Wear the splint for 2 or 3 weeks at night.
■ See patients once every 1 to 2 years to assess function, growth, and joint
deviation.
OUTCOMES
■ Although multiple different outcome scoring systems have been proposed,
reliability appears highest for the scoring system proposed by the Japanese
Society for Surgery of the Hand.7
■ The results after polydactyly repair are generally satisfactory but depend
greatly on the initial deformity.
■ Results of type III, V, and VI repairs are less satisfactory.
■ The affected side is weaker than the normal side and revisions are common,
but patients have favorable scores on objective outcome measures.6
■ Long-term unfavorable outcomes after repair include deviations and
angulations (with associated pain), bony prominences, stiffness, and nail
deformity. Deviations maybe the result of trapezoidal or delta phalanges,
canted or unstable joints, or asymmetrical growth and can occur long term
despite an adequate initial repair.
■ The Bilhaut procedure has had unfavorable results including stiffness and nail
deformity. Many prefer resection and reconstruction to this technique,5

although the aforementioned modification of the Bilhaut technique for more
distal polydactyly cases4 has shown promising results and gained support.
COMPLICATIONS
■ Immediate complications are rare and include bleeding, infection, and wound
dehiscence.
■ Wound dehiscence is almost always due to inadequate immobilization and can
be prevented with a long-arm cast.
REFERENCES
1. Wassel HD. The results of surgery for polydactyly of the thumb. Clin Orthop
Relat Res. 1969;64:175-193.
2. Zuidam JM, Selles RW, Ananta M, et al. A classification system of radial
polydactyly: inclusion of triphalangeal thumb and triplication. J Hand Surg
Am. 2008;33:373-377.
3. Oberg KC, Feenstra JM, Manske PR, Tonkin MA. Developmental biology and
classification of congenital anomalies of the hand and upper extremity. J Hand
Surg Am. 2010;35:2066-2076.
4. Baek GH, Gong HS, Chung MS, et al. Modified Bilhaut-Cloquet procedure
for Wassel type-II and III polydactyly of the thumb. J Bone Joint Surg Am.
2007;89:534-541.
5. Dijkman RR, Selles RW, Hülsemann W, et al. A matched comparative study
of the Bilhaut procedure versus resection and reconstruction for treatment of
radial polydactyly types II and IV. J Hand Surg Am. 2016;41:e73-e83.
6. Stutz C, Mills J, Wheeler L, et al. Long-term outcomes following radial
polydactyly reconstruction. J Hand Surg Am. 2014;39(8):
1549-1552.
7. Dijkman RR, van Nieuwenhoven CA, Selles RW, Hovius SER. Comparison
of functional outcome scores in radial polydactyly. J Bone Joint Surg Am.
2014;96:463-470.

66
CHAPTER
Index Finger Pollicization for
Hypoplastic Thumb
Amir H. Taghinia, Brian I. Labow, and Joseph Upton
DEFINITION
■ The thumb is the functional keystone of the hand. The basic hand unit has
three main elements: a thumb, a web space, and a prehensile post. Severe
hypoplasia or aplasia of the thumb leads to significant functional impairment.
■ Index finger pollicization is the procedure of transposing the index finger into
the position of the thumb. It is the quintessential operation of hand surgery,
incorporating key principles and requiring meticulous technique and execution.
■ The methods outlined herein include further refinements1 to the techniques
initially proposed, developed, and refined by D. Buck-Gramcko2 and J. W.
Littler.3
ANATOMY
■ The normal thumb is perfectly adapted for pinch and grasp. It is broad with
osseous and articular structures that move in multiple planes. Its intrinsic
muscles provide a short moment arm, powering the movement enabled by the
osseoarticular column.
■ The normal first web space has a gentle curve spanning from the thumb
metacarpophalangeal (MP) joint to the index finger MP joint.
■ A thumb is considered hypoplastic if any of its osseous, musculotendinous, or
articular components is deficient or if the web space that it forms with the
index finger is shallow.
■ The modified Blauth4 classification system provides a surgically useful basis
for categorizing thumb hypoplasia. Most surgeons agree that Blauth types I, II,
and IIIA thumbs can be reconstructed, whereas Blauth types IIIB, IV (pouce
flottant), and V (aplasia) hypoplastic thumbs require index finger pollicization.

■ The differentiating factor between Blauth type IIIA and IIIB thumbs is the
presence (IIIA) or absence (IIIB) of a functional carpometacarpal (CMC) joint.
■ The preoperative state of the index finger is the greatest determinant of long-
term postoperative function after pollicization.1,5 Patients with normal index
fingers will have the best function. Abnormal index fingers are typically seen
in patients with radial longitudinal deficiency. Abnormalities include stiffness,
joint hypoplasia, incomplete intrinsic muscles and/or extrinsic tendons, and
hypoplastic or anomalous vessels and nerves.
PATHOGENESIS AND NATURAL HISTORY
■ Thumb hypoplasia occurs as a result of multiple potential factors, including
genetic (associated syndromes), environmental, teratogenic (thalidomide), and
idiopathic causes.
■ It is considered to be a malformation, based on the Oberg, Manske, and Tonkin
classification of 2010.6
■ Thumb hypoplasia occurs in 1 out of 100 000 live births.
■ A large number of patients with thumb hypoplasia have associated conditions
such as cardiac or hematologic anomalies.
PATIENT HISTORY AND PHYSICAL FINDINGS
■ Patients are usually seen in infancy. In severe cases such as type IV or type V,
the diagnosis is clear. Nevertheless, the difference between type IIIA and IIIB
can be difficult to ascertain in a newborn. The integrity of the CMC joint is
sometimes not obvious on plain film radiographs. Functional differentiation
can be made by allowing the child to grow and watching the toddler at play—if
the thumb is not used, the joint is likely nonfunctional.
■ Indeed, most children with severe thumb hypoplasia will scissor pinch using
the index and middle fingers in lieu of the nonfunctional thumb. With time, the
web space between the index and middle fingers widens and the index finger
starts to pronate. These patients are ideal candidates for pollicization.
■ The hand surgeon should be aware of the conditions associated with thumb
hypoplasia, and have a low threshold to refer if suspicions arise.
■ In particular, roughly 50% of patients with Fanconi anemia (an inherited
defect in DNA repair leading to bone marrow failure and premature
malignancy) manifest thumb hypoplasia, along with a variety of other
anomalies. The diagnosis of Fanconi anemia can be made via a blood test
early in life.

■ Other associated conditions include Holt-Oram syndrome, VACTERL
association, radial longitudinal deficiency, and thrombocytopenia-absent
radius (TAR).
IMAGING
■ Plain radiographs help to determine the status of the CMC joint, any
abnormalities of the index finger, and the status of the distal radius and ulna
(presence of radial longitudinal deficiency).
■ The authors do not routinely perform angiography.
DIFFERENTIAL DIAGNOSIS
■ Differentiate type IIIA and IIIB thumbs by functional assessment of the child.
SURGICAL MANAGEMENT
■ The authors perform index finger pollicization in toddlers around 2 years of
age, but the timing is more dependent on size, weight, and other medical
comorbidities that may delay intervention.
■ The procedure is technically easier if performed in a toddler, rather than an
infant.
■ Manske5 has shown that pollicization can be functional and effective even if
performed later in childhood.
■ The main objective of the operation is to shorten and reposition the index
finger into a recessed, pronated, and palmarly abducted position, as well as to
simultaneously create a well-contoured web space.
■ The main steps of the procedure are as follows:
■ Make incisions in a modified Y to V fashion that will allow the index finger
to be recessed and rotated.
■ Isolate the index finger as a neurovascular island.
■ Disinsert and isolate the intrinsic muscles of the index finger.
■ Excise the metacarpal, ablate the metacarpal growth plate, and secure the
metacarpal head in a hyperextended position into the cut metacarpal base.
■ Rebalance the extensor tendons.
■ Rebalance the intrinsic muscles.
■ Adjust skin flaps to create an aesthetically pleasing outcome.
■ Almost always, there is sufficient skin to transpose the index finger and close
all the wounds without needing skin grafts.
■ Any open wounds or flaps under tension are the result of poor incision

planning or execution.
■ Simultaneous bilateral index finger pollicization is not performed.
Preoperative Planning
■ Again discuss risks, benefits, and expectations with parents on the day of
surgery.
■ Specifically outline the risks of flap loss (partial or complete), ischemia of
the digit, poor positioning, and suboptimal function and the potential need for
revisional or adjunct procedures later in childhood.
■ The surgeon needs fine surgical instruments and vessel loops for tagging and
dissection of important structures.
Positioning
■ The patient is positioned supine with the arm out on a small hand table.
Approach
■ Incisions are planned carefully prior to use of the tourniquet. Dorsal and
palmar approaches are needed.
T E C H N I Q U E S
■ Index Finger Pollicization
Markings and Dissection
■ Place two small round marks, one at the base of the index finger and the
other at the position where the new thumb base will be placed. Mark a
racquet-shaped incision around the base of the index finger. Extend these
markings onto the proposed new thenar flexion crease; this will be the
recession incision.
■ The markings for the incisions should be planned so they extend through
the round marks (TECH FIG 1A, B).
■ The back-cut incision is not made until the ray has been transposed.
■ Exsanguinate the upper extremity and inflate a tourniquet in the upper arm.
■ Incise transversely on the dorsum of the index finger (TECH FIG 1C).
(Note that the patient shown in the clinical photographs has radial