Operative Technique in Plastic Surgery – Kevin C.Chung

of the dorsum of the foot and courses superficially at
the lower leg. Around the knee, it courses dorsal to
the medial femoral condyle before it runs anteriorly at
the thigh and penetrates the fascia in the groin where
it enters the femoral vein.
■ Flap and Anastomosis
■ If muscle flaps are performed, these should be harvested together with skin
islands to allow postoperative supervision of perfusion. These skin islands
can be dissected based on one perforator and can therefore be removed after
7 to 10 days just by ligation of the perforator and to not require a second
procedure.
■ After flap harvest (TECH FIG 4A), the flap is provisionally secured to the
thigh, and the recipient vessels are approximated to the femoral vessels.
■ End-to-side anastomoses should be preferred over end-to-end anastomoses
to side branches for the arterial system, because the flow is higher and
consecutive complication rates are reduced. Venous anastomosis is routinely
performed in end-to-end fashion to side branches of the (TECH FIG 4B–E)
femoral vein using coupler devices or standard suture. In cases of insufficient
venous branches, direct end-to-side anastomosis to the femoral vein or end-
to-end anastomosis to the saphenous vein is applicable.
■ After the anastomoses are finished, it is useful to secure the anastomotic site
using fibrin glue to prevent postoperative repositioning and subsequent vessel
kinking.
■ Adequate perfusion of the flap is either checked by capillary refill or by
brisk capillary bleeding from the flap margins.

TECH FIG 4 • A. A combined latissimus (A) and
parascapular (B) flap was harvested to reconstruct an
extensive traumatic defect after a motor bike accident
(C). The vascular pedicle was dissected to the
subscapular artery and vein B. End-to-side
anastomosis (arrow) was performed of the
subscapular artery to the femoral artery. C. Venous
anastomosis (arrow) was likewise done to the femoral
vein. D. An extensive traumatic defect at the thigh with
exposed femur required reconstruction using free
tissue transfer because the femoral vessels were
exposed (arrow). E. After anastomosis to the femoral
vessels.

■ Flap Inset, Skin Grafting
■ After flap reperfusion, manipulation to the anastomotic side should be
avoided for some minutes. During this period, anastomotic flow is
established and minor anastomotic bleeding terminates.
■ Flap inset is the performed temporarily using suture clips. The anastomotic
site and flap pedicle are then checked for optimal positioning before the flap
is definitely sutured to the defect. Skin-to-skin closure is preferred in
fasciocutaneous flaps, whereas muscle flaps are fixed under the defect
margins that should be elevated. Here, running sutures using absorbable
monofilament material are preferred over nonresorbable sutures.
■ Muscle flaps should be covered using split-thickness skin grafts (TECH FIG
5). In these cases, it can be useful to provide vacuum-assisted closure therapy
to the skin-grafted area (using low pressures such as 75 mm Hg) to allow
optimal wound healing.
■ Split-thickness skin grafting can be performed under monitor skin islands
already, if these are harvested based on perforators.
■ Care has to be taken to prevent any compression to the anastomosis or flap
pedicle when wound dressings are applied.
TECH FIG 5 • A,B. Flap inset was performed, and the
latissimus flap as well as the proximal thigh
musculature were skin grafted (A, proximal thigh
muscles; B, parascapular flap; C, latissimus dorsi flap
with split-thickness skin grafts).

PEARLS AND PITFALLS
Preoperative
planning
■ A detailed analysis of the defect is necessary prior to surgery to
identify every structure that needs to be reconstructed.
■ For flap choice, the distance from the anastomotic site to the most
distant part of the defect has to be considered.
■ The bulk of the flap has to be considered, when skin-to-skin
closure is attempted.
Arterial
disease
■ If the patient suffers from peripheral arterial disease or varicosity,
a vascular surgeon or interventional radiologist should be involved
in the treatment team.
Patients’
needs
■ The patients’ needs have to be evaluated prior to surgery. The
reconstructive aim significantly varies if the patient is ambulating
normally or if he is chair- or bed-bound.
■ Palliative surgery vs curative attempts in oncologic patients.
Anastomosis
■ End-to-side anastomoses to the femoral vessels are preferred over
end-to-end anastomoses to side branches, because blood flow is
greater and complication rates are reduced.
Postoperative
care
■ Flap perfusion has to be monitored on a regular base for the first
postoperative days.
■ Monitoring is possible clinically in fasciocutaneous flaps, or
monitor skin islands of muscle flaps. The latter can be harvested
based on a perforator to allow removal without additional surgery.
POSTOPERATIVE CARE
■ Postoperative positioning of the patient can be crucial. Compression of the
pedicle or flap has to be avoided. Here, postoperative positioning has to be
discussed with the patient preoperatively. This increases the patients’
understanding and compliance.
■ External fixators can be helpful to allow adequate postoperative positioning.
■ Postoperative anticoagulation is part of an ongoing debate.2 In general, less
intervention is preferred over aggressive anticoagulation. The authors only
prescribe low molecular weight heparin for thromboembolic prophylaxis.
Higher doses or intravenous heparin are only applied in bypass free flaps or
after revision surgery. If patients develop thrombocytosis or arterial clots,
acetylsalicylic acid can be useful.
■ Flap perfusion has to be monitored on a regular base (hourly) to allow

immediate revision surgery if arterial inflow or venous drainage is
compromised.
■ After 5 to 7 days, the flap should be exposed to gravity (so-called dangling
procedure), and the patients should be mobilized.3
■ Physical therapy has to be applied from the first postoperative days.
■ Compression garments are usually required to avoid bulky flaps and scars as
well as contractures. Scar massage is beneficial in most patients.
■ Physical therapy and rehabilitation have to be planned in most patients.
However, these are mostly defined as the individual defect and rarely depend
on the microsurgical procedure itself (FIG 2).
OUTCOMES
■ Outcomes after free flap surgery to thigh defects mostly depend on the
underlying condition rather than on the microsurgical procedure itself.
■ Outcomes in traumatic patients mainly depend on wound healing, osseous
healing, and long-term function due to scarring or post-traumatic arthritis.
■ Prognosis in oncologic patients depends on the tumor itself and is
determinated by size, location, tumor biology, immunology, and distant
metastases.
FIG 2 • Results after 2 months with uneventful wound
healing (medial view (A), lateral view (B)).
■ Infectious control is of utmost importance in consecutive patients. Here, flap
perfusion is as important as postoperative antibiotic treatment that can be
required for long periods, when osteomyelitis is evident.
COMPLICATIONS
■ Flap failure rates vary significantly depending on defect causes and
localization. Failure rates between 1% and 10% are described internationally.4

■ Other complications include wound infection, incomplete healing or ongoing
infection, as well as partial flap loss. The latter can be as detrimental as a
complete flap loss und should therefore be prevented if possible. Here, flap
dimensions should not be extended as much as possible. If large defects have
to be reconstructed, flaps should be combined, or microsurgical effort has to be
increased for maximum safety (eg, inclusion of multiple perforators with in-
flap anastomoses, use of arteriovenous loops, bypass free flaps, combined or
chimeric flaps).
REFERENCES
1. Bains R, Magdum A, Bhat W, et al. Soft tissue sarcoma—a review of
presentation, management and outcomes in 110 patients. Surgeon.
2016;14(3):129-135.
2. Kremer T, Bauer M, Zahn P, et al. [Perioperative management in microsurgery
—consensus statement of the german speaking society for microsurgery of
peripheral nerves and vessels]. Handchir Mikrochir Plast Chir.
2016;48(4):205-211.
3. Neubert N, Vogt PM, May M, et al. Does an early and aggressive combined
wrapping and dangling procedure affect the clinical outcome of lower
extremity free flaps?—A randomized controlled prospective study using
microdialysis monitoring. J Reconstr Microsurg. 2016;32(4):262-270.
4. Xiong L, Gazyakan E, Kremer T, et al. Free flaps for reconstruction of soft
tissue defects in lower extremity: a meta-analysis on microsurgical outcome
and safety. Microsurgery. 2016;36(6):511-524. doi:10.1002/micr.30020.

41
CHAPTER
Nerve Repair and
Reconstruction—Sciatic
Nerve and Femoral Nerve
Gabrielle B. Davis and Catherine Curtin
Sciatic Nerve
DEFINITION
■ The sciatic nerve is the largest peripheral nerve in the body.
■ Its role is critical for lower extremity protective sensation and ambulation.
■ Sciatic nerve injury in the setting of lower extremity trauma was historically
an indication for amputation.
■ Recent advancements in microsurgical techniques have led to improved
outcomes and viability of the extremity.
ANATOMY
■ The origin of the sciatic nerve is from the ventral divisions of L4, L5, S1, S2,
and S3.
■ The confluence of nerve fibers joins in the pelvis and exits via the greater
sciatic foramen and below the piriformis muscle (FIG 1).
■ In the buttocks, the sciatic nerve is located posterior to the gluteus maximus
muscle and anterior to the superior gemellus, obturator internus, inferior
gemellus, and quadratus femoris.
■ It courses inferiorly, midway between the greater trochanter and the ischial
tuberosity.
■ In the posterior thigh, it travels deep to the long head of the biceps femoris.
■ There are two distinct divisions of the sciatic nerve traveling within the same

sheath, the peroneal and tibial divisions.
■ In the upper thigh, the tibial division gives off braches to all of the hamstring
muscles (semitendinosus, semimembranosus, biceps femoris) except for the
short head of the biceps femoris (FIG 2).
■ The peroneal nerve distribution innervates the short head of the biceps femoris
and the ischial portion of the adductor magnus muscle.
■ The two divisions will separate completely at the level of the popliteal fossa.
■ The posterior tibial nerve continues its course posteriorly to innervate the
muscles in the posterior leg compartment.
■ The common peroneal nerve will course laterally around the head of the fibula
to innervate the muscles of the anterior and lateral compartments.
■ The inferior gluteal artery provides majority of the blood supply to the sciatic
nerve.
FIG 1 • Course of the sciatic nerve as it exits the pelvis

below the piriformis muscle.
Innervation/Function
■ In the upper thigh, the sciatic nerve is responsible for motor function to the
hamstrings muscles, which allow for flexion at the knee.
■ The common peroneal and tibial branches are responsible for all of the motor
function below the knee.
■ It provides cutaneous sensory innervation to the posterior thigh.
■ Its terminal branches provide sensation to the lateral aspect of the knee, lateral
lower leg, and the dorsal and plantar surfaces of the foot.
Mechanisms of Injury
■ The sciatic nerve is at risk for entrapment as it passes through the sciatic
notch, especially in the setting of pelvic fractures.
■ Traumatic injuries, particularly in penetrating trauma, can occur at any level
with variable grades of severity.
■ Iatrogenic injuries are not uncommon and result from pelvic and hip surgery,
as well as injection site injuries.
■ Revisional hip surgeries and patients with developmental dysplasia are at
higher risk.1
■ Direct compression neuropathy is rare but has been described in comatose
patients during prolonged anesthesia or long periods of sitting on a hard
surface.2 Piriformis syndrome is a compressive neuropathy of the sciatic nerve
as it travels underneath the piriformis muscle.

FIG 2 • A,B. The sciatic nerve path in the posterior thigh
as it divides in the popliteal fossa into the peroneal and
tibial divisions.
PATIENT HISTORY AND PHYSICAL EXAM
■ Detailed history and physical examination must be obtained prior to the
decision for operative management.
■ Documentation of muscle strength using the Medical Research Council

(MRC) scale and sensory deficits by two-point discrimination along the
cutaneous distribution of the nerve.
■ The extent of sensory deficit can also be measured by the “ten-test for
sensation.” The patient grades the level of sensation to touch on the injured
side using a scale from 1 to 10. This number is compared to the level of
sensation to similar touch on the uninjured side.
■ Physical manifestations will be dependent on the level of injury, extent of each
nerve division involved, and if it is a partial or complete injury.
■ High injury can lead to significant morbidity, as buttock-level sciatic nerve
lesions will result dysfunction of knee flexion, foot extension, flexion,
inversion, eversion, and all movement of the toes.
■ Sensory losses of variable degrees result in the posterior thigh and the entire
foot and lower leg except for the medial aspect of the lower leg, which is
supplied by the saphenous nerve.
■ Injuries below the level of the hamstring can allow ambulation with an intact
femoral nerve as the patient can have active flexion, extension, and locking of
the knee.
■ Patients with piriformis syndrome complain of buttock pain and numbness.
This can also result in pain radiating down the leg and thigh “sciatica.”
■ Patients with piriformis syndrome may have a history of buttock trauma, and
symptoms are exacerbated by prolonged sitting or activities resulting in
adduction and internal rotation of the leg.
■ On physical exam, the proximal sciatic is tested by asking the patient to flex
the knee against resistance with the lower leg extended.
■ The peroneal branch is tested by assessing foot extension, eversion, and
abduction of the toes against resistance.
■ The tibial branch is tested by assessing foot plantar flexion and flexion of the
toes against resistance.
■ To test for piriformis syndrome, the “AIF” maneuver should be performed.
The AIF maneuver consists of adduction, internal rotation, and flexion of the
hip.
■ Pain on AIF maneuver is diagnostic for piriformis syndrome.
IMAGING
■ Detailed physical exam detailing sensory and motor deficits will help delineate
the level of injury.

■ Nerve conduction studies can also assist with localization of the injury.
■ Of note, electromyography (EMG) has limited utility in the acute setting, as
muscles may not demonstrate signs of denervation for several weeks.
■ For piriformis syndrome, imaging may demonstrate hypertrophy of the
piriformis muscle, anomalous vessels, or bands around the muscle.
FIG 3 • MRI neurogram showing bright fascicles of the
sciatic nerve.
■ Magnetic resonance (MR) neurogram is an emerging technique in which
edema or inflammatory changes around a nerve could help identify location of
injury (FIG 3).
NONOPERATIVE MANAGEMENT
■ If the injury is closed or due to compression, a trial of conservative
management should first be attempted.
■ Physical therapy should be initiated early, focusing on ambulation with
bracing and orthotics.
■ Pain management for relief of neuropathic pain includes pharmacologic
modalities and therapy for desensitization.

■ If no significant return of function is noted by 3 months, then surgical
exploration is warranted.
■ Unrelenting pain could indicate neuroma formation and may warrant surgical
exploration even if signs of spontaneous recovery are evident.
■ Treatment for piriformis syndrome is typically conservative including
stretching of the muscle and image-guided steroid injections.
■ If conservative treatment fails, then surgical release of the piriformis can be
considered.
FIG 4 • Patient prepared for surgery of distal sciatic
injury after knee dislocation. Arrow marks the area of
nonadvancing Tinel. Note the needles in place for
baseline motor responses during the intraoperative
nerve monitoring.
SURGICAL MANAGEMENT
■ Concern for laceration to one or both branches as demonstrated by significant
motor or sensory deficits warrant early operative exploration.3
■ Intraoperative electrophysiologic studies can serve as a guide to determine the
area of injury for compression, stretch, or blunt injuries that have not
spontaneously recovered (FIG 4).
■ If nerve action potentials are detected across the injured site, external
neurolysis should be performed.
■ Nerve repair or reconstruction should be performed in the setting of a nerve
not in continuity or intraoperative nerve testing that finds no recovery across

the zone of injury.
■ Primary repair should always be attempted if there is not significant tension on
the repair.
■ If primary repair without tension cannot be performed, reconstruction should
be performed with nerve grafting.
■ Neuropathic pain is a common concern. The use of antineuropathic pain
medications should be part of the patient’s multimodal treatment.
T E C H N I Q U E S
■ Upper Sciatic Nerve: Hip and Buttock Pathology
■ The patient should be placed in the prone position.
■ A bump can be placed beneath the pelvis to provide flexion at the hips.
■ The contralateral lower extremity should also be prepped and draped in the
event a sural nerve graft is required for repair.
■ A curvilinear incision is made starting at the posterior superior iliac spine,
traveling laterally to the greater trochanter, and inferiorly to the gluteal
crease.
■ The dissection is carried down to the level of the gluteus maximus muscle.
■ The superior and lateral aspect of the gluteus maximus muscle is released
from the iliotibial tract.
■ A 2- to 3-cm cuff of the muscle is left to the superolateral attachment to
facilitate closure.
■ An avascular plane below the gluteal maximus muscle should be developed
by retracting the muscle medially to expose the sciatic nerve.
■ Careful hemostasis using bipolar electrocautery is critical for good
visualization.
■ Care must be taken not to injure the hamstring branches as they typically run
superior and medial to the main sciatic trunk.
■ The gluteal neurovascular structures travel along with the sciatic nerve, and
care must be taken to preserve these vessels.
■ In some cases, the piriformis muscle will need to be detached from the femur
laterally and retracted medially for improved exposure of the nerve at the
sciatic notch.

■ Lower Sciatic Exposure: Thigh Pathology
■ The patient is placed in the prone position.
■ An incision is made over the suspected level of injury.
■ Tourniquet may not be feasible, given proximal lesion and need for nerve
monitoring; therefore, preinject suspected site prior to prepping with
bupivacaine with epinephrine.
■ Dissection can be carried down to the popliteal fossa for full exposure of the
nerve depending on the level of injury (TECH FIG 1A).
■ A plane is developed between the biceps femoris and the semitendinosus
muscle.
■ Careful hemostasis using bipolar electrocautery is critical for good
visualization.
■ The sciatic nerve can be exposed running deep to the biceps femoris (TECH
FIG 1B).
■ The sheath should be divided exposing the two divisions of the nerve for full
inspection of injury.
■ Further isolation of the nerve should be performed under an operating
microscope, with adequate exposure of the nerve proximal and distal to the
lesion.
■ The nerve should be resected to healthy nerve fascicles.
TECH FIG 1 • A. Nerve-to-nerve monitoring of the
sciatic nerve to tibial nerve to assess for neuroma in
continuity. The black arrow represents the division
becoming the tibial nerve, the blue arrow the peroneal

nerve. B. Lacerated sciatic nerve exposed in the
posterior thigh. Note the large caliber of this nerve.
■ Primary Nerve Coaptation
■ Nerve repair should be performed via end-to-end epineural coaptation with
9-0 monofilament permanent sutures.
■ Fibrin sealant can also be used to reapproximate and seal nerve ends.
■ A sural nerve graft can be interposed between the two ends if primary repair
is not possible.
■ The peroneal and tibial components should be repaired separately aligning
their respective fascicles.
PEARLS AND PITFALLS
Hemostasis
■ Preinject incision with bupivacaine with epinephrine.
■ A solution of 1 amp of epinephrine diluted in 100 cc of saline can
be used to moisten a gauze, which is then dabbed in the wound to
help with visualization.
Technique
■ In the thigh, there are numerous branches of the sciatic nerve to
the hamstring muscles, and care must be taken not to injure these
branches during dissection.
Intraoperative
monitoring
■ Communication between neurology and anesthesia teams is
critical to ensure that patient does not receive medications that will
hinder intraoperative monitoring.
■ The machines for the sequential compression device and warming
blankets can cause background that interferes with intraoperative
monitoring.
■ Do not use tourniquet if planning intraoperative monitoring as
ischemia of the nerve can result in neuropraxia.
Diagnosis
■ Must determine sciatic nerve injury vs pelvic plexus trauma, as
repair of the latter may be contraindicated.
POSTOPERATIVE CARE

■ If there is concern for tension across the nerve repair, range of motion
exercises should wait for at least 3 weeks.
■ Physical therapy should be initiated early focusing on ambulation with the use
of braces and orthotics.
■ Early therapy for desensitization and scar management are useful to minimize
postoperative pain.
■ If pain is severe, a multidisciplinary approach with pain management,
psychology, and therapy should be initiated.
OUTCOMES
■ Factors associated with worse outcomes include delay in repair of more than 4
months, length of nerve defect, and division of nerve involved.4
■ One of the largest series evaluating outcomes of civilian sciatic nerve injuries
was performed at Louisiana State University Health Science Center:5
■ They evaluated outcomes of 353 patients with buttock-level and thigh-level
sciatic nerve injuries over a 24-year period.
■ Mechanisms of injury included injection injuries, hip surgeries, fracture
dislocations, blunt ant penetration trauma, and compression.
■ Patients with partial nerve deficits without severe pain or with significant
spontaneous recovery were treated with conservative management and
achieved good recovery of motor and sensory function.
■ Patients with detectable nerve action potentials intraoperatively only
underwent neurolysis.
■ Overall, they found thigh-level sciatic nerve injuries achieved better
outcomes than buttock-level injuries (Table 1).
■ In addition, for peroneal nerve injuries, both primary repair and nerve
grafting had worse outcomes in comparison to tibial nerve injuries.
■ It is postulated that worse outcomes for peroneal nerve injuries results from
less robust blood supply and connective tissue padding between fascicles
compared to the tibial nerve.6,7
COMPLICATIONS
■ Neuropathic pain. There is a higher incidence of neuropathic pain with delayed
repairs.6
■ Development of complex regional pain syndrome (CRPS)
■ Neuroma
■ Rupture

Table 1 Percent of Patients Who Achieved At Least a Medical Research
Council strength of at least 3
Level of Injury
All patients
Suture Repair
Nerve Graft
Repair
Buttock
87%
73
62
Thigh
96%
93
80
Tibial
71%
30
24
Peroneal
79%
69
45
Kim DH, et al. Management and outcomes in 353 surgically treated
sciatic nerve lesions. J Neurosurg. 2004;101(1):8-17.
Femoral Nerve
DEFINITION
■ Femoral nerve injuries are more common than sciatic nerve injuries.
■ Most injuries are iatrogenic, resulting from abdominal and pelvic surgeries.
■ In general, femoral nerve injuries have a better prognosis than other lower
extremity nerve injuries.
■ Most patients typically maintain the ability to ambulate with the use of
orthotics.
■ Early identification and treatment are critical for prevention of muscle atrophy
and the need for long-term rehabilitation.
ANATOMY
■ The femoral nerve forms in the pelvis from the ventral rami of L2, L3, and L4
spinal roots (see TECH FIG 1B).
■ The nerve travels in the retroperitoneum, anterior to the psoas muscle and
medial to the iliacus.
■ It enters the thigh deep to the inguinal ligament and travels through the
femoral triangle, which is bordered superiorly by the inguinal ligament,
laterally by the sartorius, and medially by the adductor longus muscle.
■ In the femoral triangle, it runs lateral to the femoral artery.
■ Approximately 1 to 4 cm distal to the inguinal ligament, it divides into the

anterior and posterior branches (FIG 5).
■ The lateral circumflex femoral artery typical runs between the two divisions.8
■ The anterior division provides motor innervation to the sartorius muscle and
sensory innervation to the anterior and medial upper thigh.
■ The posterior division provides motor innervation to the quadriceps muscles.
FIG 5 • Course of the femoral nerve in the anterior
thigh.
■ Its terminal division is the saphenous nerve, which runs with the greater
saphenous vein and provides sensory innervation to the medial lower leg and
foot.
■ The blood supply to the femoral nerve is derived from the iliolumbar artery in

the pelvis and the deep circumflex iliac artery and lateral circumflex femoral
artery in the thigh.
Innervation/Function
■ In the pelvis, it provides motor innervation of the psoas and the iliacus
muscles, which contributes to flexion at the hip.
■ It also gives off a branch in the pelvis or upper thigh to innervate the pectineus
muscle that aids in adduction of the hip.8
■ In the thigh, it provides motor function to musculature of the anterior
compartment including the quadriceps (rectus femoris, vastus lateralis, vastus
medialis, and vastus intermedius) and the sartorius muscle.
■ The quadriceps functions to extend the knee, and the sartorius contributes in
flexion, abduction and lateral rotation of the hip, as well as flexion of the knee.
■ The femoral nerve does not provide any motor innervation below the knee.
■ Sensory innervation of the femoral nerve includes the anterior thigh.
■ Its terminal branch, the saphenous nerve, provides sensory innervation to the
medial knee and medial lower leg, as well as the medial aspect of the foot.
PATHOGENESIS
■ Majority of the published femoral nerve injuries are the result of iatrogenic
injury from abdominal and pelvic procedures, primarily from compression by
self-retaining retractors.8
■ The saphenous nerve especially the infrapatellar branch can be injured during
knee surgery. This can result in chronic pain after total knee arthroplasty.9
■ At the inguinal ligament, the femoral nerve can become compressed
particularly with flexion, abduction, and external rotation of the legs, such as in
lithotomy position.
■ Inadvertent injury during arterial cannulation for cardiovascular procedures
has also been described.
■ Retroperitoneal hematomas, pelvic lymphadenopathy, and colon or rectal
malignancies can lead to femoral nerve compression in the pelvis.
■ Femoral nerve stretch injuries can also be caused by hip hyperextension in
dancers or yoga instructors.
■ Ischemic injuries can lead to nerve devascularization, such as in aortic or iliac
surgeries.
PATIENT HISTORY AND PHYSICAL EXAM

■ Motor and sensory exam techniques are same as sciatic nerve.
■ Evaluation of a patient with femoral nerve injury employs the same principles
as for sciatic nerve injury.
■ Injury to the intrapelvic femoral nerve results in weakness with hip flexion,
knee extension, and an absent or diminished patellar reflex.
■ Sensory deficits can include numbness, paresthesias, or hyperesthesia along
anteromedial thigh and medial lower leg.
■ Hip flexion should be tested by supporting and flexing the knee while
requesting the patient to flex hip against resistance.
■ Loss of quadriceps function can result in knee hyperextension if there is a
functional tensor fascia lata or gracilis muscle.
■ On reflex examination, the patient will have loss of knee jerk.
■ The saphenous nerve can be compressed at the adductor hiatus: tenderness,
Tinel, and positive scratch collapse at the adductor hiatus can help identify this.
IMAGING
■ Similar evaluation as for sciatic nerve injury
NONOPERATIVE MANAGEMENT
■ Contusions, compression, traction, or partial injuries are initially managed
with conservative strategies to determine the amount of spontaneous recovery.
■ Early ambulation is encouraged with the use of knee or knee to ankle orthotics
for weakness of quadriceps muscles.
■ All patients should participate in aggressive physical therapy to prevent
muscle atrophy and the development of deep venous thrombosis.
■ Joints can also be maintained supple by dynamic and static splinting to prevent
contractures, in the event early ambulation cannot be performed.
■ If there is no recovery of motor or sensory function within 3 months, surgical
intervention is warranted.
SURGICAL MANAGEMENT
■ Complete lacerations require early surgical exploration and repair.
■ If the patient’s medical condition is stable, neurorrhaphy should be performed
within the first 3 to 7 days of injury.
■ Primary repair should be attempted when possible, and autologous nerve grafts
from the sural nerves is an alternative.
■ For high femoral nerve palsies, a transfer of the obturator nerve has been

described. These transfers have demonstrated good functional outcomes;
however, there are limited data.10
T E C H N I Q U E S
■ Retroperitoneal Femoral Nerve Exposure: Pelvic
Pathology
■ The patient should be placed in the supine position.
■ Surgical bumps should be placed under the hip to elevate the affected side.
■ Dissection is carried down to the level of the external and internal oblique
muscles.
■ The muscle-splitting technique is utilized to separate the muscles in the
direction of their fibers.
■ The transversalis fascia is opened and the peritoneum retracted superiorly
away from the retroperitoneal fat.
■ The retroperitoneal fat is carefully mobilized for exposure of the femoral
nerve, just lateral to the femoral artery.
■ The iliac vessels and ureter will be coursing medially to the nerve.
■ Dissection can be carried superiorly to the iliopsoas muscle for high
exposure of the nerve.
■ Care should be taken not to injure the lateral femoral cutaneous nerve and
ilioinguinal or genitofemoral nerves.
■ The inguinal ligament can be divided if needed to facilitate exposure.
■ Lower Femoral Nerve Exposure: Thigh-Level
Pathology
■ The patient is positioned supine with the knee flexed 30 to 45 degrees.
■ The femoral artery is palpated midway between the anterior superior iliac
spine and the pubic symphysis.
■ A longitudinal incision is made lateral to the femoral artery or the midaspect
of the inguinal ligament.
■ The incision is carried inferiorly to the midthigh, following the course of the

femoral nerve.
■ Painful Saphenous Neuroma
■ The patient has had nerve blocked preoperatively, has had at least a 70%
pain reduction, and is comfortable with the trade of decreased sensation for
decreased pain.
■ Identify area of pain and look for nerve proximally (TECH FIG 2A).
■ If discrete nerve injury is identified, resect neuroma and reconstruct defect
with allograft (TECH FIG 2B).
■ If there is any question as to the extent of the zone of injury, it is advised to
resect nerve proximally so it does not cross a joint and bury the end of the
nerve within the muscle under no tension.
TECH FIG 2 • A. Patient with a painful neuroma in the
saphenous nerve distribution after a laceration: circle
denotes painful area and dotted line area of
decreased sensation. B. Neuroma resected and
defect reconstructed with nerve allograft.
■ Nerve Repair
■ The nerve is identified using the existing wounds or the approaches
described above.
■ The nerve can be directly coapted if a tension-free repair is possible.
■ If there is tension on the repair, a bridging nerve graft is required.
■ Nerve coaptation is done using microsurgical technique.

■ Use 9-0 suture with minimal amount of sutures placed.
■ Fibrin sealants can be used to seal the repair site and to hold cabled nerve
grafts together.
■ Repairs are protected for 3 weeks with splints/braces to limit mobility at
adjacent joints.
PEARLS AND PITFALLS
Pathogenesis
■ Similar to sciatic nerve injury.
■ The femoral nerve travels with the femoral artery and femoral
vein, and concomitant vascular injuries are common.
Surgical
management
■ Vascular injury must be performed prior to nerve repair.
POSTOPERATIVE CARE
■ Physical therapy should be initiated early focusing on ambulation with the use
of braces and orthotics.
■ Therapy should also focus on desensitization and scar management.
OUTCOMES
■ There is a paucity of robust studies on outcomes of femoral nerve repairs.
■ For the majority of compression, stretch, or partial lacerations, good outcomes
in motor function have been reported; however, most patients have residual
sensory deficits.8,11
■ The Louisiana State University Health Science Center series published
outcomes of 119 operative repairs of femoral nerve injuries over a 32-year
period.11
■ Mechanisms of injuries included iatrogenic, hip or pelvic fractures, gunshot
wounds, and lacerations.
■ They demonstrated good functional recovery regardless of mechanism of
injury, level of the lesion, or primary vs nerve grafting.
■ In addition, they reported that the majority of patients who had neurolysis
regained almost complete function, for both thigh- and pelvic-level lesions.

■ They concluded that femoral nerve injuries overall have a good prognosis,
consistent in other smaller series.6
COMPLICATIONS
■ Chronic pain
■ Development of complex regional pain syndrome
■ Neuroma
■ Rupture
REFERENCES
1. Liu R, et al. Sciatic nerve course in adult patients with unilateral
developmental dysplasia of the hip: implications for hip surgery. BMC Surg.
2015;15:14.
2. Wang JC, et al. Bilateral sciatic neuropathy as a complication of craniotomy
performed in the sitting position: localization of nerve injury by using
magnetic resonance imaging. Childs Nerv Syst. 2012; 28(1):159-163.
3. Topuz K, et al. Early surgical treatment protocol for sciatic nerve injury due to
injection—a retrospective study. Br J Neurosurg. 2011; 25(4):509-515.
4. Burks SS, et al. Challenges in sciatic nerve repair: anatomical considerations.
J Neurosurg. 2014;121(1):210-218.
5. Kim DH, et al. Management and outcomes in 353 surgically treated sciatic
nerve lesions. J Neurosurg. 2004;101(1):8-17.
6. Secer HI, et al. The clinical, electrophysiologic, and surgical characteristics of
peripheral nerve injuries caused by gunshot wounds in adults: a 40-year
experience. Surg Neurol. 2008;69(2):143-152.
7. Aydin A, et al. The results of surgical repair of sciatic nerve injuries. Acta
Orthop Traumatol Turc. 2010;44(1):48-53.
8. Moore AE, Stringer MD. Iatrogenic femoral nerve injury: a systematic review.
Surg Radiol Anat. 2011;33(8):649-658.
9. Kinghorn K, et al. Case scenario: nerve injury after knee arthroplasty and
sciatic nerve block. Anesthesiology. 2012;116(4):918-923.
10. Tung TH, Chao A, Moore AM. Obturator nerve transfer for femoral nerve
reconstruction: anatomic study and clinical application. Plast Reconstr Surg.
2012;130(5):1066-1074.
11. Kim DH, et al. Intrapelvic and thigh-level femoral nerve lesions: management
and outcomes in 119 surgically treated cases. J Neurosurg. 2004;100(6):989-
996.

42
CHAPTER
Keystone and Related
Perforator Flaps
Michael W. Findlay
DEFINITION
■ Keystone flaps encompass a group of related fasciocutaneous flaps first
devised by Behan that share a common geometric design (a keystone shape
similar to the keystone of stone arches) but can vary in the following ways:1
■ Blood supply (perforator vs direct vs neurovascular vs composite)
■ Degree of islandization (complete vs incomplete, cutaneous or
fasciocutaneous)
■ Method of transfer into the defect (advancement, transposition, combination)
■ Whether used alone or along with another keystone flap on the opposite side
of the defect (double opposing keystone flaps).
■ The classification of keystone flaps is based on the method of transfer and the
number of keystone flaps involved (FIG 1).
ANATOMY
■ Keystone flaps close defects by transferring fasciocutaneous tissue from an
adjacent donor site to the defect while maximizing use of cutaneous arteries,
superficial and deep venous drainage, and lymphatics without being defined by
a specific form of the transfer (eg, transposition vs rotation).
■ Human skin is well supplied with perforators and direct vessels for supply of
keystone flaps with established patterns of cutaneous supply in the limbs
(longitudinally oriented septocutaneous and musculocutaneous perforators), the
trunk (segmental perforators with intercommunications in well-defined
intermuscular planes), and the head and neck (profuse cutaneous supply
dominated by direct cutaneous vessels in the head and perforators and direct
vessels in the neck).2

■ Conjoint supply to flaps refers to the incorporation of both cutaneous vessels
and neurovascular supply within the flap (eg, incorporation of saphenous or
sural nerves and their vasa nervorum) so as to augment blood supply.
Codevelopment of arteries and nerves during development result in conjoint
flaps that have a very strong axial blood supply that improves their robustness.
An additional benefit is that blood supply from the vasa nervorum can be
significant in some areas (eg, posterior thigh), further contributing to flap
vascularity.
■ Certain sites do not contain cutaneous perforators (eg, pretibial border, scalp)
and hence represent problem areas for keystone flap elevation. Keystone flaps
can be raised either side of the pretibial border for mobilization of tissue over a
pretibial defect, but cannot reliably be designed directly over the pretibial skin
as the basis for its blood supply due to the lack of direct cutaneous perforators.
■ Superficial and deep venous drainage can be incorporated in most keystone
perforator flaps through preservation of deep venous system along with arterial
perforators and the subcutaneous veins by blunt dissection of subcutaneous
tissues and islandization of the underlying fascia (if necessary) via the use of
scissors through small windows in the subcutaneous tissue. Superficial veins
are often numerous, and some may need to be divided to permit sufficient
mobilization, but their division is performed sequentially, stopping once
sufficient mobilization is achieved.

FIG 1 • Basic design and types of keystone flaps. A. An
ellipse is formed as though the defect is to be closed
primarily. Then, a keystone flap is designed beside it
with sharp dissection undertaken through the skin and
deep fascia. B. V-Y closure is performed at the flap
margins during flap advancement. C. A skin graft may
be used for closure of the secondary defect. D. Double
opposing keystone flaps may be used on either side of

the defect. E. This is particularly useful for midline
defects, for which the flaps can form mirror images. F.
Yin-yang variant of double opposing keystone flaps. G.
When one end of the keystone flap is transposed to fill
a defect, skin grafting of the secondary defect may be
necessary.
■ The longitudinal orientation of fascial planes in many areas of the body (eg,
limbs, paraspinous region) predispose to a longitudinal orientation for keystone
flaps (slightly oblique orientations may help in limbs; see below), with the
most appropriate mobilization of longitudinal keystone flaps being in a
transverse direction. That is, the longitudinal orientation of the paraspinous
musculature makes medial and lateral movement of keystone flaps relatively
easy to cover central back defects, whereas the fibrous attachments between
the skin and underlying spinous processes make superior or inferior movement
problematic.
■ Where there is circumferential limitation for flap mobilization and direct
closure of the secondary defect (eg, distal limbs), orienting keystone flaps
oblique to the long-axis provides an oblique (longer) circumference, thereby
maximizing available donor tissue for closure.
■ Placement of incisions in relaxed skin tension lines where possible is very
helpful. The keystone shape is one that naturally hides well. Caution should be
exercised in selection of any island flap in patients prone to abnormal scarring
(eg, hypertrophic/keloid scarring). Partial flap islandization is a good option
where feasible in such individuals or in patients very sensitive about the scar
burden.
■ Undermining and skeletonization of the perforator/direct vessel pedicle to the
flap can be undertaken but is unnecessary in the vast majority of cases, and
therefore, only the division of structures felt absolutely necessary for elevation,
mobilization, and inset of the specific keystone flap are undertaken, thereby
ensuring both surgical efficiency and safety.
■ The design and flexibility in the blood supply, venous drainage, and
mobilization of the keystone flap make it readily suitable for application in
most areas of the body with local variation to optimize the outcome in specific
areas.

PATIENT HISTORY AND PHYSICAL FINDINGS
■ An understanding of the etiology of the defect to be reconstructed and relevant
patient factors (health, comorbidities, activity levels, mobility, nutrition) help
direct the most appropriate form of reconstruction in any potential flap case.
■ As with all forms of flap reconstruction, particular interest should be focused
on removal of the causative factor (eg, cancer, infection), identification and
optimization of locoregional blood flow, selection of the best possible flap
based on the needs of the defect and locoregionally available tissue, and
optimization of the patient in the perioperative period.
■ Any past history of conditions that affect local blood flow and wound healing
should be elicited and mitigated where possible (eg, irradiation, peripheral
vascular disease (micro and/or macroangiopathy), diabetes mellitus, smoking,
and previous surgery/trauma.
■ Examination findings of note include quality of surrounding donor sites for
skin and tissue quality (including presence of radiotherapy tattoos, scars,
fibrosis).
IMAGING
■ The vast majority of patients do not require preoperative imaging or the use of
intraoperative Doppler ultrasound to achieve reliable and timely reconstruction
using the keystone flap or its variants as long as normal design principles are
followed (see FIG 1).
■ Computed tomography, angiography, and similar imaging modalities are the
most useful to answer what direct or perforating vessels are available to the
locoregional tissues, and delayed views can show the venous drainage to the
area of interest.
■ Fluorescence microscopy is invaluable for pre- and intraoperative imaging of
the perforators and direct vessels to the skin but is rarely indicated for keystone
flap elevation and has anaphylaxis as a risk factor.
■ Imaging can be of use where previous surgery or trauma may have damaged
the normal blood supply of the donor skin, or if there is significant arterial
disease, and therefore, the selection of the most appropriate local vessels is
necessary to ensure success.
NONOPERATIVE MANAGEMENT
■ As with any fasciocutaneous defect, careful consideration should be given to
the potential of the defect to be closed directly (under physiologic tension and

utilizing biological and mechanical creep as tolerated) or healed by secondary
intention.
■ The progression to flap reconstruction is considered where these options are
either not possible or lead to unacceptable risks/complications.
SURGICAL MANAGEMENT
■ Keystone flap reconstruction is reliable as long as a sequence of steps is
undertaken in which the primary goal is sufficient mobilization of the flap to
close the recipient and donor sites, while preserving as much arterial input,
venous output, and lymphatic drainage as possible.
■ No additional maneuvers are undertaken once recipient and donor-site closure
can be achieved.
■ If further mobilization of tissues is needed, then the flap can be fully
islandized where the cutaneous vessels have been followed back through deep
fascia and or freed where they exit muscles to facilitate mobilization; however,
one must be cautious not to damaging perforating vessels as this can lead to
tissue ischemia and necrosis.
Preoperative Planning
■ The defect is assessed for its suitability for fasciocutaneous reconstruction,
with a consideration of locally available tissue, including potential vascular
pedicles, as the basis for the flap.
■ Keystone flaps can be performed in irradiated tissue1 or even in the setting of
lymphedema,2 but caution should be exercised with flap planning in these
settings so as to ensure adequate perforators/direct vessels and avoid
unnecessary tension across suture lines.
■ Where primary closure is unachievable, consider a keystone design and
determine the form of mobilization that will work best to close the defect and
match the local tissue shape (eg, transposition flaps are best for convex
surfaces and advancements are best for flat surfaces).
■ There are circumferential limitations in the limbs (where the defect size
represents over 30% to 40% of the circumference of the limb), as these
defects may require grafting of the secondary defect or an alternate form of
reconstruction.
■ Defects are marked out as though they are to be closed directly as part of an
elliptical excision/closure, and keystone flaps can be designed on one or both
sides of the ellipse with the best side (or sides) chosen based upon local tissue

availability, suitability of local vessels, and the needs of the defect.
■ The ellipse does not need to be excised. It simply gives a guide to the best
orientation for the flaps.
■ It is good practice to mark every excision or defect as though it will be closed
by a keystone flap and then perform one if the defect cannot be closed
primarily (if indicated). This maximizes experience with keystone planning.
Positioning
■ Patient positioning is entirely dependent upon the ensuring easy access to the
operative site. This is usually supine or lateral with circumferential draping in
the limbs.
■ Prone positioning is most useful for midline defects of the back that require
bilateral keystone flaps.
Approach
■ The design and mobilization of keystone flaps can be tailored to suit the needs
of the defect and the area to be reconstructed, including variations in the
following:
■ Design—eg, asymmetrical keystone in the calf
■ Mobilization—advancement, rotation, transposition, sliding
■ Grafting of the secondary defect
■ Single or double flaps—eg, yin-yang flap variant
■ Placement of V-Y points (best over convexities)
■ Keystone flaps provide fasciocutaneous coverage of defects.
■ As a group, fasciocutaneous flaps are poorly suited to the reconstruction of
complex three-dimensional defects where it is essential to obliterate dead
space with filling with well-vascularized tissue.
■ Keystone flaps are excellent at providing a simple and reliable approach to
locoregional coverage and are sufficiently robust that they can be performed in
conjunction with other flaps that will sit under the keystone flap (and can be
tunneled under if necessary); thereby, providing vascularized soft tissue to fill
a three-dimensional defect along with locally matching skin coverage.
T E C H N I Q U E S

■ Keystone Flap Reconstruction of the Lower Leg
Markings
■ Mark out the planned design that incorporates local pedicles and consider
how the design will capture suitable venous drainage for the flap (TECH FIG
1A,B).
■ Modify the design as required to maximize the potential for closure of both
the defect and donor site (eg, the cone shape of the leg responds well to
asymmetrical Keystone flaps (that are wider superiorly than inferiorly).
■ Determine the nature of flap mobilization into the defect and plan in reverse
around any pivot points.
Islandization of the Flap
■ Apply a tourniquet to facilitate flap elevation where appropriate.
■ Full islandization of the keystone flap promotes even tension across the flap
(avoiding linear or point tension) and may augment cutaneous perfusion
within the flap3 but must be weighed against the added scar burden.
■ Where significant skin elasticity is present, it may be possible to minimize
incisions on the donor defect side of the flap while still performing V-Y
advancement of the rest of the keystone flap.
■ The skin is sharply incised while preserving underlying neurovascular
structures (particularly venous drainage) (TECH FIG 2A).
■ Blunt dissection and targeted release of fascial or skin retaining ligaments
and similar fibrous structures are undertaken as necessary while maintaining
the integrity of the vasculature and lymphatics (TECH FIG 2B).
■ Islandization of the fascia is undertaken if necessary, by sharp incision with
scissors through small windows in the subcutaneous tissue (TECH FIG 2C).
■ Islandization is undertaken only to the degree to which is it required to
achieve flap mobilization and closure.
■ Dissection of perforators is rarely necessary but, when performed, care to
should be taken to divide supporting connective tissue structures that might
otherwise impede blood flow following mobilization of the flap.

TECH FIG 1 • A. A complex defect of the left leg
involving an exposed plate for fixation of a compound
tibial plateau fracture. Flap reconstruction is planned
following debridement, washout, and confirmation of
minimal bacterial contamination through wound swabs
for microscopy, culture, and sensitivity. The anterior
tibial artery was injured in the fracture, but the
peroneal and posterior tibial vessels were intact.
There was obvious undermining superiorly and
inferiorly to the defect. Lateral tissues would be most
appropriate as the basis for a keystone flap in this
setting. B. An asymmetrical keystone perforator flap is
designed to take advantage of cutaneous perforators
from the peroneal and posterior tibial vessels. The flap
makes good use of the lateral calf tissue but does not
cross the axis of knee movement superiorly (on the
right) and the diameter of the flap is larger than the
defect width to ensure capture of perforators and
ready availability of soft tissue to close the wound.

TECH FIG 2 • A. Islandization of the skin is performed
by sharp incision while preserving the underlying soft
tissues that contain important superficial venous
drainage, lymphatics, and nerves. B. Blunt dissection
is performed to retain important subcutaneous
neurovascular structures (particularly superficial
venous drainage seen on the right of the flap). The
deep fascia is intact here with the exception of the
existing defect. Flap closure of the defect was still not
possible at this point; therefore, fascial islandization
was performed. C. Fascial islandization is performed
using partially open scissors and a pushing technique
so as to minimize the risk of injuring nearby structures.
This can be performed through small windows in the
subcutaneous tissue so that neurovascular structures
can be maintained. The leading edge of the flap is
also mobilized (at the edge of the defect).
Assess Flap Viability and Achieve Definitive Hemostasis
■ Following mobilization of the flap, the tourniquet is released so the viability
of the keystone flap can be assessed.
■ The site and contribution of individual perforators can be assessed at
tourniquet release as blood flows back into the flap.
■ It is typical for keystone flaps to demonstrate hypervascularity initially and
they may display a 3% to 5% increase in cutaneous perfusion secondary to
changes in blood flow from the process of flap islandization.
■ Initially, the flap may resemble venous congestion, but venous changes
should not be present beyond 10 to 15 minutes following release of the
tourniquet (as assessed by the presence of rapid capillary return).
■ It is ideal to achieve hemostasis at this time and consider whether a drain
should be placed.
Strategic Suturing
■ Even physiological wound tension is one of the key elements to the success
and good long-term aesthetic results seen with well-performed keystone

flaps.
■ Skin is normally under tension, and keystone flaps are typically under some
tension upon closure.
■ Single lines of tension or point tension should be avoided as these are not
tolerated well by the skin, including keystone flaps.
■ Islandization can be helpful to ensure even tension across the flap.
■ Excess flap tissue (common at the obtuse angles of the flap beside the
defect) can be trimmed safely to facilitate wound closure.
■ The generation of even tension begins with the placement of strategic sutures
across both the defect and the donor site to induce creep across both wounds
and the flap (TECH FIG 3A,B).
■ Creep results in some relaxation of the tissues and promotes a more even
tension at final closure.
■ Mattress sutures are ideal as these provide for the induction of creep
alongside wound eversion to improve the resulting scar.
■ A fine continuous suture helps ensure eversion and even tension.
■ The “hemming suture” (two horizontal mattress sutures followed by a simple
suture) may be used as a means of closure (TECH FIG 3C,D).

TECH FIG 3 • A. Following release of the tourniquet
and hemostasis, strategic mattress sutures are
placed, including tacking closure of the defect and the
opposite side of the flap to induce creep and maximize
even tension. The residual flap tissue at the leading
edge of the flap has been trimmed. B. V-Y closure has
been performed and further strategic mattress sutures
have been placed to produce even physiological
tension on the wound. C. A continuous skin suture
(eg, Hemming mattress) is placed to ensure even
tension and a nicely everted suture line for optimal
aesthetic results. A suction drain is noted in the left of
field, and this helped to minimize dead space in the
otherwise planar defect. D. Anterior view of the flap at
the point of V-Y closure to demonstrate even
physiological tension and good contour following
wound closure. Minor wound edge cones will resolve

on the convex surface of the leg in the following
weeks to months without the need for revision.
■ Keystone Flap Reconstruction of the Axilla
■ TECH FIG 4 is the case of a patient with medically refractory hidradenitis
suppurative of the left axilla who underwent excision of the involved axillary
tissue and reconstruction with a lateral intercostal perforator-based keystone
island flap (see TECH FIG 4).
TECH FIG 4 • A. Medically refractory hidradenitis
suppurative in the left axilla prior to excision. B. The
area to be excised is marked along with a lateral
intercostal perforator-based keystone perforator island
flap. The breast base is marked anteriorly with a
dotted line to ensure that the reconstruction does not
involve the breast directly. C. Following excision,
partial closure is performed in the arm, analogous to a
brachioplasty, leaving a defect that is 15 cm by 10 cm
and not able to be closed directly while still
maintaining should movement. D. The skin of the flap
is incised to form an island with elevation of the

tissues as necessary to facilitate transposition into the
defect. E. Blunt dissection is performed to the
undersurface of the flap to divide fascial attachments
to the lateral chest wall, yet preserving all
neurovascular structures where possible. F.
Placement of strategic deep sutures begins with those
for closure of the primary defect. G. Strategic suturing
around the periphery ensures even tension before
skin sutures are placed. Potential delays in wound
healing are anticipated in the axilla, so interrupted
sutures are used in this area. H. Full closure is
completed with deep dermal and subcuticular sutures
for the rest of the wound. Note that all of suture lines
run around the perimeter of the breast, including into
the lateral aspect of the inframammary fold and V-Y
closures in the periphery, have maintained good
contour and shoulder movement despite the size of
the primary defect.
PEARLS AND PITFALLS
Poor donor
sites
■ The subcutaneous border of the tibia has no perforators and few
direct vessels. Keystone flaps may be designed on either side of
pretibial defects, but should not be designed directly over the
tibia if possible. The scalp has direct vessels, but no perforators,
and therefore, is not generally suitable for keystone flaps.
Flap
mobilization
■ Understanding the underlying muscle and fascial arrangements
will facilitate ease of flap movement into the defect (eg, coverage
of spinal defects using flaps on either side of the spine, but not
above or below).
Aesthetics
■ Consider modification of keystone flap margins to lie in natural
skin creases or within aesthetic units as this improves their

appearance and minimizes scar burden.
Dissection
■ Avoid overdissection of vascular structures. Only mobilize
sufficiently to achieve wound and donor defect closure. Further
dissection wastes time and puts important neurovascular
structures at risk.
Skin grafting
■ Retain all skin trimmed from the keystone flap until the end of
the case as this can be useful as donor skin for any skin grafting
that might be necessary toward the end of the case.
Design
experience
■ Plan a keystone flap for every defect but only use it if necessary
and/or appropriate. This will rapidly increase experience with
keystone flap planning.
Distal
extremities
■ Use an oblique flap orientation to increase the available
circumference for closure and have a low threshold for skin
grafting of secondary defects.
Contour
■ Mobilization by transposition or elements of rotation produce a
convexity, whereas advancement produces a more planar
reconstruction. Consider matching the type of mobilization to
suit the needs of the defect to enhance esthetics.
Documentation
■ An operative note that includes a diagram or photo of the flap
planning and eventual closure is very useful.
■ In some circumstances, it may be difficult to identify the scars of
keystone flaps, since scar generation is minimal in older
individuals and the keystone design is not an obvious geometric
pattern recognized by the human eye.
■ Where the defect was from oncologic surgery, positive margins
may require a thorough understanding of the nature of flap
mobilization so that further resection can be performed
effectively if necessary.
POSTOPERATIVE CARE
■ Following closure, if movements across joints adversely impact the integrity
of the flap closure, then splinting is recommended.
■ Splinting is rarely needed for more than 3 to 5 days.
■ If the reconstruction is associated with an underlying musculoskeletal injury
that requires immobilization, this takes precedence.
■ Keystone flaps are very robust and are tolerant of being dependent for short
periods in the immediate postoperative setting.
■ Keystone flaps are suitable to ambulatory surgery.

■ Encourage elevation of the limb to limit postoperative swelling, but it is rare to
need to immobilize patients.
■ If closure is tight, then splinting will limit the risk of wound dehiscence during
the period of postoperative edema (3 to 5 days).
■ Keystone flaps do not require specific monitoring in general.
OUTCOMES
■ Keystone flap reconstruction is a straightforward approach to fasciocutaneous
reconstruction that is well tolerated by patients and has a low complication
profile relative to other forms of flap reconstruction.
■ A retrospective analysis of 200 consecutive keystone flaps for head and neck
reconstruction demonstrated a 2% flap revision rate for partial flap necrosis
and a single complete flap loss.4 This compares very favorably to other forms
of fasciocutaneous flap reconstruction in the head and neck.
COMPLICATIONS
■ Keystone flaps are robust as evidenced by their relatively low partial and total
flap loss rates.
■ Minor complications can occur in up to 15% of cases in the head and neck
with local wound issues including suture abscess, cellulitis, and wound
dehiscence being the most common forms.4
■ Donor site morbidity is very low, secondary to the conservative nature of flap
dissection, including minimal dissection of muscle.
REFERENCES
1. Behan F, Sizeland A, Porcedu S, et al. Keystone island flap: an alternative
reconstructive option to free flaps in irradiated tissue. ANZ J Surg.
2006;76(5):407-413.
2. Behan FC, Lo CH, Shayan R, Findlay M. The keystone technique for
resolution of chronic lower limb wound with lymphoedema. J Plast Reconstr
Aesthet Surg. 2009;62(5):701-702.
3. Rubino C, Coscia V, Cavazzuti AM, Canu V. Haemodynamic enhancement in
perforator flaps: the inversion phenomenon and its clinical significance. A
study of the relation of blood velocity and flow between pedicle and perforator
vessels in perforator flaps. J Plast Reconstr Aesthet Surg. 2006;59(6):636-643.
4. Findlay MW, Sinha S, Rotman A, et al. The Keystone perforator island flap in
head and neck reconstruction: indications and outcomes from 200 flaps. Plast

Reconstr Surg. 2013;132(4S):8-9.

43
CHAPTER
Section V: Amputation and
Replantation
Amputation of the Lower
Extremity: Toes, Foot, Ankle
Kedar S. Lavingia and Jason T. Lee
INTRODUCTION
■ Partial foot amputation (PFA) is a common sequel to advanced vascular
disease secondary to diabetes and its complications.1
■ PFA may also occur due to injury, infection, cancer, or birth defect.
■ PFA affects approximately 2 per 1000 patients in western countries, making it
the most common type of amputation surgery.2
■ PFA is associated with a significant failure rate and numerous complications
including skin breakdown, ulceration, and equinus contracture, which can lead
to subsequent and more proximal amputation.
■ Thoughtful patient selection, early involvement of neuropsychiatry and
physical medicine and rehabilitation (PM&R) are fundamental to a successful
outcome.
BACKGROUND/CONSIDERATIONS
Forefoot Amputation
■ Toe disarticulations are quite challenging when dealing with the remaining
cartilage of the involved metatarsal head and possible complications of residual
osteomyelitis.
■ Ray amputation, which involves the excision of the toe and part of the
metatarsal, provides a more viable option of ensuring an adequate surgical

debridement of the septic margins if that is the indication.
■ Indications may include a wet or dry gangrene of a toe, osteomyelitis of the
metatarsal head and/or proximal phalanx, septic arthritis of the
metatarsophalangeal joint, and gross infection of the toe.
■ Suggested inclusion criteria by a variety of authors for this type of amputation
may include one or two palpable pedal pulses, ankle brachial index (ABI) ≥
0.8, and toe brachial index ≥ 0.7.3
■ In recent studies, absence of pulses, delayed capillary filling, high erythrocyte
sedimentation rate, high creatinine, and high neutrophil counts were found to
be predictive factors for a poor clinical outcome.4
■ Indications for transmetatarsal amputation may include wet or dry gangrene
involving only the forefoot and/or infection involving the forefoot, whereas the
inclusion criteria are the same as those mentioned above required for a ray
amputation.
■ Amputation at the metatarsal level causes a muscular imbalance due to
resultant equinovarus deformity from unopposed action of gastrocnemius,
tibialis anterior, and tibialis posterior tendons, which is coupled with the
deficiency of the muscular tension of the extensor tendons.5,6
Midfoot Amputation
■ Lisfranc disarticulation is a disarticulation through the tarsometatarsal joint,
whereas Chopart disarticulation is a disarticulation through the talonavicular
and calcaneocuboid joints leaving only the hindfoot (talus and calcaneum)
behind (FIG 1).
■ These amputations are rarely performed in diabetic foot infections due to high
failure rate and the proximity of infected tissue to the heel pad.7
Hindfoot/Ankle Amputation
■ This category included the amputations such as Syme amputation and has the
indications and inclusion criteria as mentioned in the forefoot amputation
category (FIG 2).
■ Syme amputation has been advocated for trauma cases; however, Syme
amputation can give good results in patients with diabetic foot infections.8
■ Syme amputation should be reserved for patients with at least a palpable
posterior tibial pulse and an ankle-brachial index of more than 0.5.
SURGICAL MANAGEMENT

Preoperative Planning
■ All patients undergoing an amputation should be evaluated by both
neuropsychiatry and PM&R early.
■ Prevention and early detection of future disease should be discussed with the
patient.
■ Education on pressure-area pathogenesis is important as part of a strategy to
encourage the patient to prevent further problems.
■ Cardiac optimization is important given the high incidence of cardiac disease
among this patient population.
■ If discussing limb viability from trauma, a multidisciplinary approach
involving vascular, orthopedics, and plastics should take place prior to
proceeding with amputation.
FIG 1 • Midfoot amputation.

FIG 2 • Hindfoot/ankle amputation.
T E C H N I Q U E S
Toe Amputation
■ Place the patient supine with a small bump under the ipsilateral foot if
desired.
■ Incision lines are marked on the skin as appropriate for the planned
amputation.
■ For a partial toe amputation, a plantar-based flap is commonly used.
However, several other possibilities exist (eg, dorsal flap, side-to-side flap,
and fish-mouth flap).9
■ The most important principles are to ensure that the flap is viable before
closure and to perform a tension-free repair.
■ All necrotic tissue is debrided. If infection is present, the tendon sheaths
must be drained of any purulent material, which often tracks along them.
■ Microbiology samples may be sent for culture and sensitivity testing.
■ Neurovascular bundles are ligated or cauterized as they are dissected.
■ If the wound is left open, many dressing options are available. Commonly,
the wound is loosely packed with gauze soaked in saline or povidone-iodine.
Generous amounts of cotton dressing and ACE bandages are then applied.

■ If conducting an osteotomy, dissection is carried down to the periosteum,
and a bone cutter or pneumatic saw is used to perform the osteotomy at the
appropriate level.
■ It is important to be mindful of tendon insertions and to consider the
biomechanical effects that sacrificing these will have; disruption may
predispose to further surgical intervention in the future.
Transmetatarsal Amputation
■ A curved fish-mouth incision is made just proximal to the infected tissue of
the foot (TECH FIG 1).
■ The incision runs from the midshaft of the fifth metatarsal laterally to the
midshaft of the first metatarsal medially through a midplane axis and carried
circumferentially. The plantar flap is left longer to allow for closure. Also,
the residual flap should be little longer on the medial side than on the lateral
side again to aid with closure.9
■ The incision is again circumferential and extended downward to bone. As
the incision is deepened, hemostasis is achieved by means of cautery and/or
vessel ligation with ties. The bony landmarks of the metatarsals are identified
and presented by means of a periosteal elevator. The metatarsals are cut with
a saw, and the bony ends are rounded with a bone file.10
■ The wound is copiously irrigated and adequate hemostasis is achieved.
■ Standard synthetic braided suture is used for closure of muscular and
subcutaneous layers. Skin closure with synthetic nonbraided suture results in
low skin tension and good approximation. Staples may also be added and
dressing applied.
TECH FIG 1 • A–D. Transmetatarsal amputation.

■ Midfoot Amputation (Lisfranc/Chopart)
Lisfranc Amputation
■ The proximal incision passes over the dorsum of the foot at the base of the
metatarsals. The plantar incision is placed distally so that the infected
material is removed, but the flap is long enough that it may be tailored later
to cover the ends of the resected bones.
■ The tarsometatarsal joints are disarticulated at the first, second, and third
metatarsal bases. The fourth and fifth metatarsal bases are cut through with a
motorized saw and left in the residual foot.
■ On occasion, it may be necessary to leave the third metatarsal base in place
to provide a better surface to support the local soft tissues.
■ The residual foot is then dissected from the plantar surface, starting at the
level of the short flexor muscles. The flap is then beveled to the distal edge.
■ The wound is then checked for any residual infectious tissues and for
hemostasis. It is tailored to close without tension.
Chopart Amputation
■ Amputation of the forefoot at the talonavicular and calcaneocuboid joints
closely resembles that of amputation at the tarsometatarsal joints.
■ The plantar flap is long enough to fold up to the dorsum of the foot. In
infected cases, no bone trimming is performed. In noninfected cases, the
distal surfaces of the calcaneus are rounded to relieve potential pressure
points.
■ Ankle Amputation (Syme Amputation)
■ The anterior incision of the Syme amputation extends across the ankle just
distal to the tip of each malleolus.
■ The posterior incision extends from the malleoli vertically and also
transversely across the heel.
■ The extensor tendons are all divided at the level of the skin incision.
■ The dorsalis pedis artery and vein are then identified, ligated, and divided.
■ The ankle joint capsule is incised while plantar-flexing the foot. The medial
and lateral ankle ligaments are divided.
■ The tendons of the posterior tibialis and flexor hallucis longus are transected,

taking care to avoid injury to the posterior tibial artery. This will be the sole
blood supply to the flap.11
■ The heel fat pad is carefully dissected by staying close to the calcaneus to
avoid creating a buttonhole, which can doom the operation. The ankle joint is
disarticulated and the foot is passed from the table.
■ In a single-stage amputation, the malleoli are divided with a saw at the level
of the articular surface of the tibia and the width is reduced by vertical bone
excision. Holes are drilled in the medial, anterior, and lateral parts of the
distal tibia and fibula to secure the heel pad directly under the tibia.12
■ In a two-stage Syme amputation, the wound is closed by suturing the heel
flap to the dorsal fascia. Six weeks later, the malleoli are removed through
separate vertical incision.13
PEARLS AND PITFALLS
Indications
■ A careful and complete history and physical examination are
essential. Preoperative studies are necessary to plan the resection
and reconstruction. Vascular supply to planned reconstruction and
amputation must be assessed prior to procedure.
Surgical
incision
■ A long plantar flap leads to a better end-bearing stump. Leaving a
flap to short will lead to complications and wound break down.
Infections/flap
necrosis
■ Intravenous antibiotics and surgical debridement may be
necessary to treat deep infections. Early diagnosis and treatment
can affect outcome. Do not delay treatment if suspected infection
after amputation.
Postoperative
management
■ Keep the wound wrapped in sterile soft dressings and a pressure
wrap for 3–5 days and physical therapy and rehab should be
consulted early in the course.
POSTOPERATIVE CARE
■ Keep the wound wrapped in sterile soft dressings and a pressure wrap for 3 to
5 days.
■ Staples/sutures will remain in place for approximately 2 weeks.
■ Physical therapy and PM&R should be consulted early.