soft tissue coverage of the lower extremity

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is Assistan t Professor of Surgery, Division of Plastic and

Reco nstructive Surgery, at the Univers ity of Pittsburgh

School of Medicine. After graduating from Dartm outh

Medical School in 1970 and the Univers ity of Colorado

Schoo l of Med icine in 1972, he trained in general surge ry

at the Dartm outh Hitchc ock Affi liated Hosp itals and con-

cluded his plastic surgery training at Brown Univers ity

Affi liated Hosp itals. His fel lowship training in microvas-

cular surgery was taken with Dr. Harry Buncke at the

Ralph K. Davies Hospital at San Francisco . Dr. Swa rtz is

a diplomat of the American Board of Plastic Surgery, and

consulting editor for the Journals of Reco nstructive Mi-

crosurgery and Microsurgery. His cl inical intere sts in-

clude hand surgery and reconstructive microsurgery.

is Assistan t Professor of Plastic and Reco nstructive Sur-

gery at the Univers ity of Pittsburgh. A graduate of Ox-

ford Unive rsity, he trained in general surgery in Great

Britain and then completed a residency in plastic and re-

constructive surgery at the Univers ity of Michigan in

Ann Arbor. Dr. Jones continued training in plastic sur-

gery at the Regional Plastic Surgical Unit at the London

Hospital in England, fol lowed by a further fel lowship in

hand surgery and microsurgery at the Ma ssach usetts

General Hospital in Boston. His major f ield of cl inical

practice is hand surgery and microsurgery.

TREATMENT of the injured lower extremity has been improved

significantly by recent advances in reconstructive surgical tech-

niques. Chief among these are the development of muscle and

musculocutaneous flaps and the parallel development of micro-

vascu lar surgical techniques for free tissue transfers. Each of

these techniques brings an augmented blood supply into the

area of injury, thereby improving the conditions for primary

healing of soft tissues and underlying fractures. The approach to

the management of significant soft tissue and osseous injuries to

the lower extremity outlined in this monograph represents the

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combined efforts of the plastic surgeons and the orthopedic sur-

geons at the University of Pittsburgh. It is essential that the

plastic surgeon and the orthopedic surgeon have a common un-

derstanding of the priorities of wound management and work

toward a common goal from the time of the initial injury. Al-

though the management of osseous defects, including fractures,

nonunions, and segmental bone loss, is beyond the scope of this

monograph, the techniques of soft tissue coverage have a direct

bearing on these more complex wounds.

Briefly, the principles of wound care include (1) a thorough

assessment of the magnitude of the injury, including a detailed

examination of motor and sensory function and vascular status;

(2) anatomical alignment of fractures with appropriate fixation

techniques; (3) thorough debridement of all nonviable tissues,

followed by a second or third reassessment and additional de-

bridement if necessary; and (4) definitive wound repair consist-

ing of soft tissue coverage and bone reconstruction in selected

patients. When these principles are carried out it is possible to

achieve wound closure and primary reconstruction within 5-7

days of the original injury.

Within the f&t few days of injury, the surgeon and patient

alike should have a thorough understanding of the magnitude of

the injury, the reconstructive procedures required, and the like-

lihood of restoring the patient to an ambulatory status within a

reasonable period of time. It is our opinion that for this plan to

be successful, efficient management of these problems should re-

store the patient to a functional status within 1 year of injury.

Patients with protracted disabili ty beyond this period of time

generally have not resumed their preinjury way of life and

might be better served by amputation.

Despite the most careful initial management of traumatic and

other injuries to the lower extremity, chronic problems such as

unstable burn scars, chronic osteomyelitis, and fracture non-

unions present additional special problems that may be resolved

by the application of soft tissue based on a safe vessel network.

A common theme in the following discussion on the techniques

of soft tissue coverage is preservation of blood supply and the

reliable application of this new supply to ischemic or chronically

infected wounds.

This monograph outlines principles in the management of soft

tissue injuries of the lower extremity and delineates the tech-

niques that have been most efficacious in their treatment. The

general methods of soft tissue coverage, including skin grafts,

muscle flaps, and free tissue transfers, wil l be discussed, with

particular emphasis on their relevance in the lower extremity.

Finally, specific procedures for coverage of defects beginning in

the upper leg and extending to the foot and ankle will follow,

with emphasis on those procedures that have been most success-

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ful in our experience. This discuss ion is neither encyclopedic nor

esoteric. Its purpose is to provide surgeons with a practica l and

rational basis for flap selection for a variety of common clin ical

problems.

EVALUATION OF THE INJURED LOWER EXTREMITY

Evaluation of the patient begins with a complete understand-

ing of the mechanism of injury. Previous classifications of lower

extremity injuries are of benefit in predicting the severity of the

injury. Gustillo and Anderson classified fractures into three

types: type I is an open fracture with a wound less than 1 cm

long, type II is an open fracture with extensive soft tissue dam-

age, and type III is either an open fracture or segmental frac-

tures with extensive soft tissue damage that may require vas-

cular repair.l Type III fractures have been further class ified

based on the energy involved to cause them. It is possible to

make recommendations for the treatment based on this classi fi-

cation2 Type III-A fractures are those in which there i s an ac-

curate demarcation between injured and noninjured tissues. The

extent of injury is limited to the area of the defect. Local muscle

flaps or free tissue transfers with a short vascular pedicle can be

employed to treat these open wounds. Type III-B fractures are

those in which abrasion injury produces more significant soft tis-

sue damage and a less distinct line of demarcation between nor-

mal and injured tissues. While the application of a larger flap

may be required, the deeper structure, notably the principal ves-

sels supplying the region, are not severely injured. Type III-C

fractures are high-energy crush injur ies involving widespread

damage to soft tissue, bone, and microvasculature. These inju-

ries necessitate the use of flaps with long vascular pedicles, so

the vascular anastomoses can be performed well outside the zone

of injury. The use of local muscle flaps in such wounds is con-

traindicated.

EVALUATION OF VASCULAR INJURIES

The initia l evaluation of the traumatized lower extremity re-

quires a careful examination of major blood vessels. Injuries to

these vessels portend a significant risk for subsequent tissue ne-

crosis or limb loss. It is therefore of the utmost importance that

an early diagnosis of major arterial injuries be made and appro-

priate treatment provided at the outset. A delay of more than 6

hours in the management of the arterial injury may render an

otherwise salvageable extremity incapable of functional recov-

ery. Even after a successful arterial repair has been performed,

prolonged ischemia may result in diminished or absent capillary

flow, which in turn prevents reestablishment of nutrient blood

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flo~.~ Most arterial injuries can be diagnosed on physical ex-

amination. The cardinal signs of an arterial injury include di-

minished or absent pulses, loss of nerve function, hematoma,

bruit at the site of injury, and persistent arterial bleeding. In

addition to these findings, the presence of an injury in close

proximity to a major vessel is justification for further arterial

evaluation. In several recently reported series4-6 the absence of

pulses distal to the site of the soft tissue injury had a high cor-

relation with a proximal vascular impairment. The dorsalis

pedis and posterior tibia1 pulses should be easily palpable in a

patient without a vascular injury. Diminished or absent pulses,

compared to the opposite uninjured extremity, should raise the

suspicion of vascular compromise and is an indication for arte-

riography. The presence of distal pulses

does not rule out a ma-

jor arterial injury. The dorsalis pedis pulse may be reconstituted

from the first dorsal metatarsal artery communication with the

posterior tibia1 artery through the plantar arch. The reconstitu-

tion of pulses distally through collateral circulation about the

knee has been documented in popliteal artery injuries.7

Transcutaneous ultrasonic Doppler imaging is useful for eval-

uating the acute vascular injury, particularly when peripheral

pulses are difficult to assess. By using the flow-directed device,

the examiner may detect reversed flow through collateral circu-

lation in the foot. Hard copy tracings allow a comparison of nor-

mal and abnormal flow patterns indicative of complete and/or

partial obstructions.8’ ’

Low flows on Doppler imaging without

palpable pulses may indicate spasm or external compression, in

which case the flow should improve over time. In most cases of

acute traumatic injury, the Doppler examination confirms the

clinical findings.

Careful examination of the sensory distribution of nerves in

the lower extremity wil l give clues to potential arterial injuries

immediately adjacent to these nerves. In the popliteal region,

the tibia1 nerve lies immediately adjacent to the popliteal ar-

tery. Sensory loss in both the dorsal and the plantar aspect of

the foot as well as motor paralysis below the knee would be ex-

pected in a patient with complete nerve injury at this level. In

the anterior compartment the anterior tibia1 artery lies imme-

diately adjacent to the deep peroneal nerve, whose sensory dis-

tribution includes the dorsum of the foot. Injuries below the

take-off of the anterior tibia1 artery may be diagnosed by the

finding of sensory loss only on the plantar aspect of the foot,

indicating a potential posterior tibia1 artery injury. Serious ar-

terial injuries ma7 be anticipated in 14 -33 of patients with

nerve deficits.4, ‘, Major hemorrhage or hematoma should alert

the surgeon to the probability of major arterial injury in addi-

tion to nerve deficits.

Displaced fractures or dislocation of the knee and ankle are

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frequent causes of vascular compromise. Prompt reduction of the

fracture or correction of the dislocation wil l result in restoration

of normal pulses, precluding the need for operative intervention.

Vasospasm associated with these problems generally resolves in

a short period of time. Failure of the pulses to return suggests

significant lacerations or intimal tears of the vessel and requires

further intervention.

Angiography is an important adjunctive procedure that pro-

vides the surgeon with the information necessary to make a de-

cision about vessel injury. Primary indications for angiography

include the presence of the clin ical signs of vascular injury,

namely, weak or absent pulses, neurologic deficits, bruits, or ex-

panding hematomas. Even when the decision is made to explore

an extremity for a probable vascular injury, angiography may

help in identifying the exact location of the injury and aid in

planning an approach to the vesseL7, lo Arteriography should be

performed expeditiously so as not to prolong the ischemia time

unnecessarily. Percutaneous transfemoral arteriography may be

performed while the patient is on the operating table and being

prepared for operation. Done by the surgeon, it is rapid and pro-

vides satisfactory films. Patients without significant signs of

ischemia may undergo arteriography under more ideal circum-

stances in the radiology suite without detrimental effects. It is

our practice to perform angiography whenever physical findings

suggest an acute arterial injury; otherwise we observe the pa-

tients with satisfactory distal pulses and circulation.

Al l patients undergoing acute or delayed microvascular recon-

structive procedures should undergo femoral arteriography be-

fore reconstruction is performed. It is of utmost importance that

the surgeon have a clear understanding of the vascular status of

the extremity before undertaking dissections of local or regional

muscles or attempting free tissue transfers that depend on the

presence of intact vessels. Failure to appreciate the extent of

vascular injury is the most frequent cause of flap necrosis when

local muscle flaps are used in the severely injured extremity.

Intraoperative problems of vasospasm, vascular occlusion, and

unrecognized damage to the vessels can be expected if these

basic tenets are not observed.

SIGNIFICANCE OF NERVE INJURIES

Injuries to the major branches of the popliteal nerve below the

knee have additional significance, beyond the potential injury of

vascular structures. Accurate diagnosis of nerve injuries allows

the surgeon to repair these at the time of initial operative inter-

vention, with the potential for partial motor reinnervation and

partial restoration of sensation. Isolated nerve injuries are gen-

erally compatible with limb salvage and preservation of func-

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TABLE l . -FINDINGS IN PATIENTS WITH ISOLATE S INJURIES OF POPL~TEAL NER VE BRANCHES

ARTERY LOCATlON

ADJACENT

NERVE

SENSORY LOSS

MOTOR LOSS

Superf icial

femoral artery

Popliteal artery

Anterior t ibia1

artery

Posterior t ibia1

artery

Adductor

CXId

Popl i tea l

fossa region

Anterior

compartment

lower leg

Posterior

compartment

lower leg

Saphenous

Tib ia1

Deep peroneal

I lelTe

Posterior t ibia1

nerve

Anteromedia l

lower leg

Plantar foot

dorsum oi

foot

Dorsum of foot

Plantar

surface of

foot

NOM

Plantar f lexion

dorsif lexion of

foot, toes

Dorsif lexion of

foot

tion. Table 1 lis ts the findings in patients with isolated injuries

of the branches of the popliteal nerve. In our experience patients

with absence of plantar sensation in combination with severe

osseous and soft tissue injuries have a poor prognosis for resto-

ration of function. In these patients, serious consideration

should be given to primary amputation. Injuries to the anterior

tibia1 nerve with paralysis of extensors of the foot and ankle can

be successfully treated with appropriate tendon transfers or or-

thosis and are compatible with a functionally useful extremity.

A more complete discussion of the role of soft tissue restoration

where sensation is desirable is found later in this monograph.

INITIAL WOUND MANAGEMENT

Initial management of a patient with a severely traumatized

lower extremity is carried out in the operating room under gen-

eral anesthesia. Tetanus prophylaxis is provided according to

the guidelines of the Trauma Care Committee of the American

College of Surgeons.ll Patients in whom a history of tetanus

prophylaxis is unclear are given 500 units of human hyperim-

mune globulin (Hyper-Tet) along with an initia l immunizing

dose of 0.5 cc of adsorbed tetanus toxoid. A broad-spectrum an-

tibiotic with activ ity against penicillinase-resistant staphylo-

cocci is begun, generally a cephalosporin. In the operating room

thorough and complete wound debridement is carried out. Skin

flaps may be evaluated for capillary refi ll and any questionable

skin may be further evaluated with the use of intravenous fluo-

rescein dye. One to 2 gm of dye are injected after a test dose of

1 cc to ensure that there is no allerg ic reacti0n.l’ While the use

of fluorescein is helpful in determining skin viability, its value

in the determination of muscle viab ility is less certain. At pres-

ent there is no clinically useful vital dye that delineates necrotic

from living muscle tissue. In the future the use of the magnetic

resonance imaging techniques may be useful in this regard.

Debridement is based on clin ical judgment. Viable muscle

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blood supply muscles with a single dominant vessel and one or

more secondary vascular pedicles are most safely transferred,

with the dominant vessel being the point of rotation. If the dom-

inant vessel is divided and the muscle is rotated on its distal

vascular supply, significant muscle necrosis may occur. This

method is less reliable but occasionally useful-for example, a

vastus lateralis muscle flap based on its distal blood supply may

be used for knee coverage, and a soleus muscle flap based on the

posterior tibia1 artery may be used for distal tibia1 coverage.

Functional Considerations

It is important to understand the functional loss incurred

when a muscle is chosen for a rotation flap. Frequently more

than one muscle contributes to a given motion. For example, the

soleus and gastrocnemius muscles both contribute to plantar

flexion, and the use of either for soft tissue coverage does not

result in a functional deficit. The use of both, however, would

result in inabil ity to flex the foot in a plantar direction and

would not be suitable for reconstruction. When a muscle has a

special function, as in the case of the tibialis anterior, and its

use for reconstruction is indicated, the muscle belly may be dis-

sected away from the tendon to the musculotendinous insertion

and rotated to cover the defect. In this manner the integrity of

the muscle tendon unit is preserved. Additionally, a larger mus-

cle such as the soleus may be spli t and only a portion of it used

to cover the defect, leaving the remaining muscle functionally

intact.24

Muscle Flaps

When muscle flaps are used for soft tissue coverage along with

split-thickness skin grafting, some muscle atrophy may be ex-

pected, due to muscle denervation and divis ion of insertion and/

or origin. Flaps that are init ially bulky at the time of recon-

struction ultimately settle into an acceptable contour over the

injured tibia and malleolar areas. Latissimus and gracilis free

flaps, for example, show a 30 ~50 decrease from the initia l

flap thickness. Skin grafts placed directly over muscle have been

shown to be quite durable in the lower extremity.25 We and oth-

ers have found this to be an acceptable method of coverage over

non-weight-bearing areas, with long-term durability. This tech-

nique is especially useful in extensive defects where the har-

vesting of a skin flap of necessary dimension would create an

unacceptable donor site deformity.

Occasionally it is possible to use local muscle flaps for soft

tissue coverage and preserve their function aa well. With the

nerve supply to the muscle preserved and its tendon reattached

in a new location, the muscle wil l continue to function, provid-

ing its length has been maintained. The vastus medialis muscle

may be rotated anteriorly for coverage of defects about the su-

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compartment may be released through a midline posterior inci-

sion, an extension of the incision used for vascular access to the

popliteal space. Further release of the deep posterior compart-

ment may be carried out through this incision. Fibulectomy for

complete

Kauper,15

compartment decompression, advocated by Ernst and

while affording adequate decompression, is contrain-

dicated when severe fractures or segmental bone loss are pres-

ent. Following release of the fascia l compartments, temporary

coverage of the wound is carried out with moist dressings, bio-

logic dressings, or skin grafts where indicated. Our preference is

to use adaptic gauze covered with a thick layer of bacitracin

ointment on all exposed wounds. This prevents wound desicca-

tion and provides a bacteriostatic atmosphere.

Following this initia l debridement the patient is returned to

the operating room in 24 or 48 hours for wound inspection and

further debridement as needed. Any remaining devitalized mus-

cle or bone is removed. A thorough inventory of the wound is

carried out and plans for definitive reconstruction are made.

Further debridement is carried out as necessary, should the first

reoperation not be sufficient.

DEFINITIVE SOFT TISSUE COVERAGE

Definitive wound closure is the first step in the reconstructive

process, ultimately leading to full rehabilitation of the patient

with lower extremity trauma. Wound closure is achieved only

after thorough debridement and control of bacterial contamina-

tion have been achieved.

REQUISITES OF SOFT TISSUE COVERAGE

The goal of soft tissue replacement on the lower extremity is

to provide a well-healed, stable wound in the most expeditious

manner. For anatomical areas with little or no padding, such as

the anterior tibia1 region, the malleoli, and the patella, the tis-

sues chosen must provide durable coverage. In addition, the tis-

sues must be supple and able to conform to such regions as the

knee and the ankle joints. In weight-bearing areas, tissues must

be able to withstand the trauma imposed by ambulation or the

wearing of shoes. In each of these conditions, the blood supply to

the tissues must be adequate to prevent long-term ischemic

changes and eventual tissue breakdown.

A second requirement is the restoration of contour. The choice

of reconstruction must take into account the necessity of provid-

ing thin conforming tissue for coverage in the regions of the

malleolus and the foot so that shoes may be worn comfortably.

In addition, the cosmetic aspects with respect to leg contour

should be taken into account when one chooses tissue. While

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aesthetics may not be the primary consideration in lower ex-

tremity reconstruction, if other factors are equal, acceptable con-

tour is achievable.

Third, tissue chosen for reconstructive purposes should pre-

serve function whenever possible. It is unacceptable to sacrifice

a functionally important muscle or muscle skin flap merely be-

cause of its proximity to the wound. Only those muscles or mus-

culocutaneous units that are not essential for normal function

should be utilized. By preserving the musculotendinous junc-

tions, a muscle like the tibia lis anterior, an essential dorsiflexor

of the foot, can be used for covering the anterior tibia while pre-

serving its functional integrity. Similarly , the function of the

latissimus dorsi can be preserved by intramuscular dissection

that preserves the remaining nerve and blood supply to the

functional portion of the muscle. These technique wil l be de-

scribed later in greater detail. These factors take into consider-

ation the appropriate reconstructive method for each patient’s

wound and may be chosen on the basis of a broad armamentar-

ium of reconstructive methods.

CONDIT ION OF THE WOUN D

In choosing the appropriate reconstructive method for soft tis-

sue coverage, the surgeon must take into consideration the

wound itself. The nature of the injury plays a great role in de-

termining the amount of soft tissue and bone destruction that is

present. To a variable degree the tissues in the area of trauma

will have become relatively devascularized. If the devasculari-

zation is minor, the underlying soft tissue vasculature may be

well maintained, thereby allowing the application of a split -

thickness skin graft as the method of choice. Degloving injuries

also generally provide a suitable wound base for split-thickness

skin grafts. More severe trauma, such as crush avulsion injuries

or grade III open fractures with crushing injuries to the under-

lying muscle, significantly decrease the local blood supply, par-

ticularly in the area of fracture. The choice of reconstructive

method here must take into account these vascular changes.

The surgeon must also consider the desirability of increasing

the blood supply to an ischemic wound. The use of a highly vas-

cularized muscle tissue in a free tissue transfer satisfies this re-

constructive requirement. Final ly, the patient’s overall condi-

tion, age, and concomitant medical and surgical problems may

dictate whether the simplest possible method of reconstruction

or a more complicated endeavor is attempted. Temporary wound

closure with a biologic dressing or skin grafts wil l allow the sur-

geon to further evaluate the patient before undertaking more

complex procedures.

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BACTERIOLOGIC CONTROL

Bacterial contamination or gross infection may be adequately

controlled with seria l debridement and systemic antibiotics.

Continued wound infection reflects residual necrotic tissues, ei-

ther muscle or bone, and their complete debridement is essen-

tial. Topical antimicrobials such as Sulfamylon or the less pain-

ful silver sulfadiazine may be used to treat the open wound prior

to coverage. The use of biologic dressings allows the surgeon to

further assess bacterial contamination. An initia l “take” of por-

cine heterografts or the actual take of homografts indicates suc-

cessfu l control of bacterial proliferation.

The suitab ility of a heavily contaminated wound for grafting

may be determined by quantitative bacterial analysis. The rapid

slide technique is a useful method for determining whether the

bacterial count i s less than lo5 per cubic millimeter of tissue.16

TIMING OF COVERAGE

Coverage of open wounds of the lower extremity is basically

divided into three time periods. Immediate coverage means clo-

sure of the wound within 24 hours of the time of injury. Defini-

tive coverage at this time depends on a thorough evaluation of

the wound and confidence that the underlying tissues have not

sustained severe trauma or further necrosis.

Delayed primary closure is performed a short period of time

following injury, generally within 5-7 days. This technique is

the most useful and allows a more thorough evaluation of the

wound, including seria l debridement, complete vascu lar assess-

ment with arteriography, and a thorough plan of reconstruction

that the surgeon and the patient have had time to consider

along with its alternatives. Delayed primary closure may be

combined with definitive bone reconstruction or other recon-

structive procedures as needed with a greater measure of safety

than one might have in the acute setting immediately following

injury.

The third category of wound closure is secondary closure.

Many patients in whom secondary closure is necessary have in-

curred severe injury with major soft tissue loss, crush injuries,

or segmental bone loss. These wounds have been treated open

for a period of time and frequently are heavily contaminated

with bacteria, if not grossly infected. Coverage of these wounds

presents a significant problem in infection control, particularly

if bone is involved. Soft tissue coverage alone might be chosen

rather than definitive bone and soft tissue reconstruction in or-

der to prevent the loss of bone grafts or nerve grafts due to sec-

ondary infections. Additional difficulties encountered in these

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wounds are significant fibrosis and induration of tissues with

loss of normal tissue planes. In general, the simpler the method

of soft tissue closure in these wounds, the more successful it has

been.

METHODS OF SOFT TISSUE COVERAGE

In evaluating a wound that needs soft tissue coverage, the

surgeon should consider methods in order of simple to complex.

The simplest method that meets the reconstructive goals should

be chosen in preference to more complex, risky methods. In in-

creasing order of complexity, the reconstructive methods are pri-

mary closure, skin grafts, local muscle flaps, free tissue trans-

fers, and cross-leg flaps.

SKIN GRAFTS

Split-thickness skin grafts taken from the thigh or the buttock

may be safely applied to most wounds in the lower extremity

with a high degree of success. They have been used successfully

for closure of fasciotomy wounds and for skin loss over underly-

ing muscles and the periosteum. They take well over the para-

tenon and on granulating wound beds. An essential requirement

is an adequate blood supply to the underlying tissues. Skin

grafts have also been used in less ideal locations, such as over

the Achil les tendon and over bare bone. A time-honored tech-

nique for grafting over bone is to drill holes through the bone

cortex and allow granulation tissue to cover the bone before

placing the skin graft. In the Achilles tendon region as well,

granulation tissue is required to support a skin graft. These

techniques require meticulous wound care and patience on the

part of both surgeon and patient for successful completion of

wound closure. Skin grafts are indicated for closure of heavily

contaminated wounds, particularly in the chronic wound setting.

The use of a meshed split-thickness skin graft over freshly de-

brided tissue is particularly useful. Meshing permits wound ex-

udate and bacterial accumulation to be collected in the overlying

cotton dressing, passing through the interstices of the graft

without lifting it from its bed.

A special indication for the use of split-thickness skin grafts

is in degloving injuries of the extremities (Fig 1). Replacing

these full-thickness skin flaps on the traumatized wound is uni-

formly unsuccessful and most of the time results in necrosis of

the skin flap and infection of the underlying tissues.17 If the tis-

sue is available, split-thickness skin grafts may be taken from

the degloved specimen with an electric dermatome. Skin grafts

may be used to close extensive wounds as a temporary measure

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Fig 1.-A and 6, a large thigh flap resulting from a degloving injury. The flap was

debr ided and a split-thickness skin graft harvested from the flap was used to cover

the wound. Add itional skin grafting was necessary. Replacing such a flap in its

wounded bed generally results in necrosis of the flap and underlying infection.

when the patient’s condition does not allow a complicated sur-

gical procedure to be carried out safely. Use of a skin graft under

these conditions allows homeostasis to be regained and gives the

surgeon and patient added time to plan more definitive complex

reconstructive procedures.

LOCAL MUSCLE FLAPS

Significant improvements in soft tissue coverage of the lower

extremity have been achieved with the development of muscle

flaps in reconstructive procedures.18-20 This work has renewed

interest in studying the blood supply to the muscles and has

increased our knowledge of and ability to use muscles in recon-

structive procedures.21-23

Local flaps are indicated for soft tissue

coverage of important structures such as the patella, the knee

joint, the exposed tibia1 bone, and weight-bearing areas of the

foot. Generally these are areas in which split-thickness skin

grafting does not provide stable wound coverage or preservation

of joint mobility. A necessary condition for the use of local mus-

cle tissues is an adequate blood supply to these tissues. A thor-

ough understanding of this blood supply allows the surgeon to

make a judgment with regard to the use of these procedures.

Vascular trauma in the region of the major blood supply to the

intended muscle is a contraindication to the use of a local muscle

flap. Similarly, an extensive crush injury to the region would

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make the transfer of local muscle hazardous. In sections to fol-

low, individual muscle and myocutaneous flaps will be described

in detail for specific regions.

Principles of Muscle Flap Transposition

The reconstructive surgeon must be familiar with the basic

principles of muscle flap transposition. These include an under-

standing of the blood supply to the individual muscles con-

cerned, the location of that blood supply with regard to the mus-

cle’s arc of rotation, and the functional deficits incurred with the

use of the muscle for soft tissue coverage. Finally, in using mus-

cle flaps, preservation of function is an essential part of the re-

constructive plan.

Classification of Muscles by Their Blood Supply

Mathes and Nahai have classified the blood supply of the mus-

cles after extensive dissections and radiographic study with in-

jection of contrast material.23 This information is extremely im-

portant in planning the transfer of local muscle tissues either as

a pedicle transfer or a free tissue transfer. A summary of this

classification is presented here, along with a brief discussion of

the more useful muscles for reconstruction of lower extremity

defects (Fig 2).

Type I blood supply to muscle is defined by the presence of a

single vascular pedicle as the primary blood supply for the mus-

cle or muscle skin unit. In general, the dominant blood vessel

enters the muscle proximally. In the lower extremity muscles

with a type I blood supply include the medial and lateral gas-

trocnemius muscles, supplied by the sural arteries, and the rec-

tus femoris muscle and tensor fascia lata, both supplied by the

lateral femoral circumflex artery. A type II blood supply is that

in which there are two vascular pedicles to the muscle, a domi-

nant more proximal pedicle and a smaller minor pedicle, gener-

ally in its distal portion. This blood supply is the most frequent

vascular type in human anatomy. The dominant blood supply is

used in transfer of the flap, and the entire muscle survives di-

vision of the minor distal pedicle. Muscles with a type II blood

supply include the gracilis, the vastus lateralis, the soleus, the

biceps femoris, and the peroneus longus and brevis. The type III

blood supply to muscle is defined by two equally dominant ped-

icles. The muscle may be transferred on either of its vascular

pedicles. Generally there is a rich anastomotic network between

the two pedicles. The rectus abdominis muscle, based on the

deep inferior epigastric or the superior epigastric artery, is a

muscle with a type III blood supply. A type IV blood supply is

found in muscles which have a multiply segmented blood supply

over the length of the muscle belly. Division of more than two

or three of these blood vessels results in necrosis of that segment

of the muscle. These muscles are generally unreliable as flaps

16 JUNE CPS


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*r?rer/iYr

tibia / - -

wt.

II soLEt.

Ip TIBIALIS ANTERIOR P LATISSIMUS

Fig 2.-Classification of the blood supply to muscles and musculocutaneous

flaps: type I, single proximal domina nt pedicle; type II, proximal dominan t pedicle

and distal minor pedicle; type Ill, two equally dominan t pedicles; type IV, mdtiple

segmental pedicles; type V, one dominan t proximal pedicle and segmental second-

ary vascular pedicles .

when based on their more proximal segmental blood supply.

Muscles with a type IV blood supply include the tibialis ante-

rior, the flexor digitorum longus, and extensor digitorum longus.

Lastly, muscles with a type V blood supply have one dominant

vascular pedicle and segmental secondary vascular pedicles.

These muscles are exemplified by the latissimus dorsi muscle

and the pectoralis muscle. The significance of this blood supply

is that a portion of the muscle may be transferred using one of

the dominant blood vessels while the remainder of the muscle

will survive, based on the lesser segmental blood supply.

Arc of Rotation

The use of muscles in rotation flaps depends on an under-

standing of the point at which the major blood supply enters the

muscle. This pivot point is fixed. Tissue distal to this point is

rotated into the defect, preserving that blood supply. Additional

arc of rotation may be achieved by releasing the muscle from its

origin and carefully mobilizing the vascular pedicle. The gas-

trocnemius muscle, for example, will reach farther around the

knee or above the knee when this technique is used. Type II

JUNE CPS 17


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perior portion of the knee, and the tendon may be reattached to

the patella tendon for preservation of terminal knee extension.26

MUSCULOCUTANEOUS FLAPS

The principles of the musculocutaneous flap were developed b&

McGraw and Dibbell” from work that dates back to Manchot.

They recognized the importance of perforating blood vessels

from underlying muscle as a principa l means of blood supply to

the overlying skin. There are, of course, other routes by which

blood vessels enter the skin, including the direct cutaneous ar-

teries and fasciocutaneous arteries; these routes will be de-

scribed in greater detail later. From experimental injections in

human cadavers and extensive clin ical use, the vascular terri-

tories of underlying muscles have been well described.20, 22 Mus-

culocutaneous units in the upper thigh include the rectus fe-

moris muscle and the skin overly ing the anterior portion of the

thigh,28 the tensor fascia lata muscle, including a long fasciocu-

taneous extension covering the anterior lateral thigh, ’ and the

gracilis muscle with the skin overlying the proximal muscle.22

These muscles w ill safely supply the overlying skin when they

are transferred for reconstructive purposes. Below the knee the

most useful myocutaneous flap is the medial and lateral gastroc-

nemius musculocutaneous flap. The skin overlying the medial

and lateral aspect of the calf may be elevated based on the per-

forating vessels through the gastrocnemius muscle.30’ 31 Fre-

quently the skin territory extends beyond the muscle itself to a

variable degree. This area is considered to be the random skin

territory of the musculocutaneous flap. These flaps share certain

advantages over underlying muscle flaps alone. They include an

extended territory for greater coverage, and a potentially

greater durability and, in certain circumstances, sensibil ity

(e.g., the tensor fascia lata musculocutaneous flap). A potential

disadvantage with the use of these flaps is that often skin grafts

are required on the donor sites, leaving a less than acceptable

donor site deformity. The skin and subcutaneous tissues do not

undergo atrophy as do muscle tissues with sp lit-thickness skin

grafts. In such areas as the ankle and distal third of the tibia,

the use of musculocutaneous flaps require secondary defatting

procedures for an acceptable contour.

FASCIOCUTANEOUS FLAPS

As our understanding of the blood supply to the skin has in-

creased, a wide variety of flaps have been developed, based on

this new information.3 ’ 33 Flaps based on blood vessels emerging

from between muscles giving circulation to the overlying sub-

cutaneous tissue and skin have recently been developed on the

JUNE CPS 19


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medial and lateral thigh.34 The skin of the medial aspect of the

knee, based on the sural artery,35 is another example. This flap,

however, has not found wide acceptance owing to significant do-

nor site deformity. Finally, the skin on the posterior calf, also

supplied as a musculocutaneous flap, may be elevated on a fas-

ciocutaneous vessel emerging from between the two heads of the

gastrocnemius muscle.36 The success of many of our reconstruc-

tive efforts has probably been due to the redundancy in blood

supply of the skin envelope. As our study of these flaps pro-

gresses, new methods of transferring tissue will be developed.

FREE TISSUE TRANSFERS

Free tissue transfers are indicated when local flaps are un-

available or additional specialized reconstructive procedures are

required, such as bone reconstruction and transfer of composite

tissues. Free flaps have wide application in a variety of recon-

structive problems and have been shown to significantly shorten

hospitalization and reduce the number of operative procedures

required as compared to conventional techniques in the lower

extremity.37* 38 For problems of soft tissue coverage, these in-

clude the use of muscle flaps alone with split-thickness skin

grafts, musculocutaneous flaps, and free skin flaps.

Evaluation of Recipient Vessels

Successful reconstruction using free tissue transfers requires

healthy recipient arteries and veins for microvascular anasto-

moses. A thorough evaluation of the vascular system must be

carried out before such procedures are undertaken. Initial eval-

uation includes palpation of the dorsalis pedis, posterior tibial,

and popliteal pulses. Doppler ultrasound imaging may aid in de-

termining the suitability of these vessels for free tissue transfer,

particularly in obese individuals. At the ankle, the dorsalis

pedis and posterior pulses should be palpable; if they are not,

the vasculature will probably be inadequate. Since the dorsalis

pedis artery may be reconstituted by collateral circulation from

the posterior tibia1 and peroneal vessels and vice versa, arteri-

ography is performed with the use of intra-arterial vasodilating

agents prior to using these vessels. In the severely traumatized

extremity major distal vessels may be injured, and circulation to

the foot may depend on a single vessel. Knowledge of this situ-

ation will prevent the sacrifice of that vessel and influence the

selection of an end-to-side vascular anastomosis.3g’ 4o Flow stud-

ies in the extremity will also determine which of the patent ves-

sels in the distal extremity has the greater flow and therefore

the least chance of intraoperative complications.

The venous system must also be evaluated prior to the use of

free tissue transfers. Venography has been helpful in identifying

20 JUNE CPS


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unsuspected deep vein thrombosis which may occur in both the

acute and the chronic posttraumatic situation. In long-standing

deep vein thrombosis, lower leg edema is generally observed and

the superfic ial venous system would be chosen as a recipient

vein for transferred tissues. Impedence plethysmography is use-

ful in identifying this condition. Finally, intraoperative evalua-

tion of the vessels must show them to be free of fibros is and

scarring. Vessels encased in fibrotic tissues frequently undergo

severe irreversible vasospasm when dissection of the vessels is

carried out. This situation can be avoided by more proximal dis-

section of the vessels in healthy uninjured tissues. An alterna-

tive strategy is to use a flap with a long vascular pedicle, such

as the latissmus dorsi flap, in order to place the vascular anas-

tomoses in the popliteal fossa, where vasospasm is less of a prob-

lem.

Flap Selection

To meet the requirements for soft tissue coverage in lower ex-

tremity defects, the appropriate flap must be selected. Large de-

fects requiring substantial bulk may be treated successfully

with the latissimus dorsi myocutaneous flap, the scapular flap,

the tensor fascia lata flap, and the groin flap. Each of these flaps

has specific advantages and disadvantages. Smaller defects are

best treated with a gracil is muscle or musculocutaneous flap, an

internal oblique muscle flap, or a rectus abdominis muscle flap.

When

used with a split-thickness skin graft, these muscles atro-

phy to give the most acceptable contour for distal third defects.

Planning and Execution of Free Tissue Transfers in the Lower

Extremity

The success of free tissue reconstruction requires an orderly,

planned approach to the recipient vessel dissection and flap dis-

section, with planned alternatives should conditions prevent use

of the firs t selection. Both the surgeon and the patient should be

prepared for the use of alternative flaps or vein grafts for ex-

tending vascu lar pedicles, should this become necessary. When

possible, two teams simultaneously dissect the recipient vessels

and the flap. It is our practice initially to identify the recipient

vascu lar bundle before the flap dissection and decide whether it

is an acceptable vessel for free tissue transfer. Further prepara-

tion of the vascular pedicle with meticulous dissection of the ar-

tery and vein is performed while the second team is raising the

flap. Once recipient vessels are adequately prepared, the wound

is temporarily closed with skin clips after the vessels are bathed

in a solution of 2 lidocaine to relieve vasospasm. After the flap

is isolated on its vascular pedicle, the flap is allowed to perfuse

for 20 minutes prior to division of the vessels. If there is any

question about the viability of the flap at this time, it may be

sutured back into place and the wound temporarily closed until

JUNE CPS 21


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the flap may be safely transferred. At each step along this path

a planned retreat is sti ll possible.

When it is clear that the flap is well perfused on its vascular

pedicle, the defect in the lower extremity is thoroughly debrided

of all marginally viable tissue in preparation for the transfer of

the flap. This is the point of no return. The vascular pedicle of

the flap is then divided and the flap transferred into the defect.

The second team closes the donor site while the first team insets

the flap, ensuring adequate vessel length and positioning before

the microvascular anastomoses are begun. If vein grafts are re-

quired to extend the vascular pedicle, anastomosis of the vein

graft to the flap vessels may be carried out prior to insetting the

flap or passing the vascular pedicle beneath skin bridges.

Final ly, the vascular anastomoses are performed. Conserva-

tion of major vessels of the lower extremity is an essential part

of the planning in microvascular procedures.40 The end-to-side

anastomosis is routinely chosen for arterial anastomosis into the

anterior tibia1 and posterior tibia1 vessels. This maintains opti-

mal blood flow to the remainder of the lower extremity. Venous

anastomoses are generally performed end to end. In selected

cases the superficial veins, such as the greater or lesser saphe-

nous vein, may be utilized when deep vein thrombosis is sus-

pected. To ensure proximal patency, gentle irrigation of the vein

is performed prior to vascular anastomosis. Recent evidence sug-

gests that end-to-side venous anastomoses may be preferable in

preventing venous thrombosis at the anastomotic site.41

Postoperative Care of Patients Undergoing Free Tissue

Transfers

Unlike muscle flaps and skin grafts in the lower extremity,

free tissue transfers require hour-by-hour observation in the

first 5 postoperative days to detect vascular thromboses. Throm-

bosis in the flap vessels means certain flap necrosis unless im-

mediate measures are taken to correct the problem. The moni-

toring of microvascular free tissue transfers is primarily carried

out by the surgeon and specially trained nursing personnel.

Changes in the appearance of the flap with regard to capillary

refil l and color are extremely important signs of partial or com-

plete vascular occlusion. An additional clinical sign is the color

of bleeding from a small wound made by a No. 11 blade scalpel.

Recently developed monitoring techniques such as surface tem-

perature monitoring, transcutaneous Po2 sensors, plethysmog-

raphy, and quantitative IV fluorescein analysis are useful in

monitoring the flap postoperatively.41-44 Each of these methods

indirectly measures the circulation at the anastomotic site. More

direct monitoring of the flap vessels, both artery and vein, by

pulsed Doppler ultrasound, currently under investigation, may

ultimately prove to be the optimal method.45

22 JUNE CPS


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Pharmacologic Manipulations and Free Tissue Transfers

The essential ingredient of successful free tissue transfers is

the technically perfect anastomosis. The sk ill is developed

through progressive laboratory exerc ises in animal models.

Careful attention to selection of recipient vessels, prevention of

vasospasm, and meticulous surgical technique wi ll assure a

thrombosis-free anastomosis. In most cases vascular thrombosis

is the result of technical errors due to inadequate resection of

the injured vessel segment, preexisting vascular disease result-

ing in elevation of an intimal flap, or improper placement of su-

tures. Despite the best of technique, occas ionally vascular

thromboses continue to occur. Low-dose aspirin given as a 5-

grain rectal suppository at the beginning of the operation and

continued on an alternate-day basis is the only prophylactic an-

tiplatelet medication employed in our free tissue transfers.

There is no general agreement as to the appropriate dose of as-

pirin to give for this purpose. Experimental evidence suggests

that doses in the range of 1.7 mg/kg inhibit platelet aggegation

without depressing prostacycline on the vessel wall. Higher

doses inhibit both prostacycline and thromboxane. To date there

is no conclusive experimental evidence that the routine use of

antithrombotic medication is beneficial.47 When platelet thrombi

are seen to occur intraoperatively, however, a full anticoagulant

dose of heparin is given IV.48 Reoperation for thrombosed vessels

is also managed by heparinizing the patient following explora-

tion and repair of the thrombosed vessels. Continuous IV hepa-

rin at the rate of 1,000 units/hour in a 70-kg adult is carr ied out

for 5 days and the dose tapered over a 2-day period.

Postoperative elevation is maintained for 7 days, after which

time gradual, progressive leg dependency is allowed. The flap

must be monitored carefully for signs of venous congestion dur-

ing this period. When ambulation is finally permitted, gentle

support with stockings or ace bandages is maintained for 6-12

weeks postoperatively.

SOFT TISSUE COVERAGE OF DEFECTS ABOUT THE KNEE

Exposure of the knee joint and patella as a result of trauma

or wound complications following prosthetic knee replacement

requires flap closure for the preservation of knee motion. Occa-

sionally reconstruction of the extensor mechanism or ligaments

that provide medial and lateral knee stabil ity wi ll depend on

adequate soft tissue coverage. Requirements of tissue in this

area are that it be supple, allowing full range of motion, and be

able to withstand the pressure from underlying structures as

well as external pressure during routine activities. In general,

muscle flaps with skin grafts and cutaneous flaps satisfy these

requirements.

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22/56

Fig 3.-Medial gastrocnemius muscle flap. The gastrocnemius muscle is elevated

alone on its proximal vascular pedicle and used to cover defects of the proximal

third of the tibia . A meshe d split-thickness skin graft is place d directly on the muscle.

scored to allow further stretching of the muscle unit and direct

application of the highly vascu lar muscle to the underlying de-

fect. The muscle is sutured in place and the donor incis ion closed

over suction drains. A meshed spl it-thickness skin graft is then

used to cover the muscle (Figs 3 and 4).

USE OFTHE LATERAL HEAD OFTHE GASTROCNEMIUS

The lateral head of the gastrocnemius muscle may be used for

coverage of lateral and anterolateral defects of the tibia and

knee joint. The muscle is 2-3 cm shorter than the medial head

and, as a result, has a more limited arc of rotation. Dissection

and elevation are performed in a manner sim ilar to that for the

medial gastrocnemius, with care taken to avoid the common pe-

roneal nerve in the region of the fibular head. Again, additional

pedicle length may be obtained by detaching the muscle origin

from the lateral femoral condyle, carefully preserving the lateral

sural artery.

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Fig 4.-A media l gastrocnemius muscle flap used to treat chronic osteomyelitis

of the proximal third of the tibia of 10 years’ duration. A, chronic osteomyelitic cavity.

B, muscle flap elevated. C, closure of the wound prior to split-thickness skin grafting.

D, fina l result at 1 year.

GASTROCNEMIUS MUSCULOCUTANEOUS FLAP

The medial gastrocnemius musculocutaneous flap is indicated

for soft tissue defects over the middle third of the tibia and for

extensive defects about the knee. Since a skin graft is required

at the donor site, there is a significant cosmetic deformity. The

flap extends from the midline posteriorly to within 2 cm of the

anterior tibia1 crest. Its maximum length is to within 5 cm of

the medial malleolus. The flap is elevated by including the un-

derlying fascia to the level of the gastrocnemius muscle. This is

necessary because the blood supply to the skin is from fasciocu-

taneous vessels derived from the last perforating vessel through

the gastrocnemius muscle. Once the skin flap is elevated to the

edge of the gastrocnemius, the skin-muscle unit is elevated as

previously described for elevation of the muscle alone. The mus-

cle is mobilized until coverage of the defect is achieved, and the

donor site is closed with a split-thickness skin graft (Fig 5). The

lateral head of the gastrocnemius muscle may also be used as a

musculocutaneous flap. Its skin territory extends to within 10

cm of the lateral malleolus and therefore is somewhat limited in

its arc of rotation compared to the medial flap (Fig 6).

Several additional maneuvers are available to increase the

usefulness of the gastrocnemius muscles for coverage of knee de-

fects. These include division of the origin of the muscle and mo-

bilization of the vascular pedicle to allow more proximal exten-

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Fig S-Med ial gastrocnemius musculocutaneous flap. The flap may be elevated

to within 5 cm of the media l malleolus. The gastrocnemius muscle is included with

the flap and provides perforating vessels that connect with the fascial extension. A

skin grafl is necessary for closure of the donor site.

sion of the mu scle, spl i tt ing the mus cle longitudinally and

placing portions of the muscle within small osseous defects or

marrow cavity defects, and advancing the gastrocnemius muscle

and overlying skin as a V-Y advancement flap to cover below-

knee amputation stumps (Fig 7).30

THE TURN-DOWN VASTUS LATERALIS FLAP

The vastus lateralis muscle, based on a distal blood supply,

may be turned down to cover lateral defects of the knee in its

superior portion. Because the major blood supply to this muscle

is the descending branch of the lateral femoral circumflex ar-

tery, the most proximal portion of this muscle is subject to ne-

crosis when the muscle is based on its more tenuous distal blood

supply. Nevertheless, the muscle regularly covers the superior

lateral portion of the knee when the more reliable gastrocne-

mius muscle flap is unavailable (Fig 8). A longitudinal incision

is made over the anterior aspect of the upper thigh and the ten-

sor fascia lata is divided. The vastus is mobilized with blunt and

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Fig 7.-Gastrocnemius muscle may be split longitudin ally and used to fill cavities

within the knee joint. A, Charcot joint in a paraplegic patient with septic arthritis and

chronic osteomyelitis. B, med ial he ad of the gastrocnemius muscle is split longitu-

dinally. C, after the knee joint has been thoroughly debrided, the muscle is passed

through the join t and covered with a split-thickness skin graft. D, fina l result at 6

weeks. Long-term healing of the wound resulted.

Fig E.-Turned-down vastus lateralis muscle flap. The proximal dom inant blood

supply to this muscle, the latera l femo ral circumflex artery, must be sacrificed when

basing the muscle on its distal secondary blood supply, branches of the geniculate

arteries.

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Fig 9.-A turned-down vastus lateralis muscle flap used for coverage of lateral

defects of the tibia. A, cornminuted fracture of the proximal tibia with fixation plate

exposed. Cancellous bone grafts are packed into the depth of the wound. B, the

muscle flap is left attached in its distal on e quarter to ensure its blood supply. C,

fullness in the lateral aspect of the knee at the muscle pedicle requires closure with

a split-thickness skin graft. D, result at 6 months with primary healing and a united

fracture.

simus is as an innervated muscle flap when medial knee stabil-

ity is desired (Fig 10) or for dynamic reconstruction of the quad-

riceps muscle (Fig 11). Alternatives include the scapular flap or

groin flap, which can carry cutaneous flaps of large dimensions.

Vascular access for these procedures is generally from the

popliteal fossa. This necessitates a graft with a vascular pedicle

of adequate length to prevent kinking of the pedicle due to ten-

sion and sti ll provide adequate coverage of the knee region.

SOFT TISSUE COVERAGE OF BELOW-KNEE AMPUTATION

STUMPS

A recurrent problem in patients with below-knee amputations

is breakdown of skin overlying the bone ends when soft tissue

padding is not adequate. Coverage of these defects presents a

considerable problem, often challenging the ingenuity of the

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Fig lo.-Innervated latissimus dorsi musculocutaneous free flap for coverage and

stability of the knee. A, traumatic injury of the leg and loss of stable soft tissue in

the med ial and posterior aspects of the knee. B, latissimus dorsi musculocutaneous

free flap used to provide both soft tissue coverage and innervated muscle stability

to the region.

surgeon. When shortening the bone is not a satisfactory option,

several others are available. These include turn-down muscle

flaps from the thigh, V-Y advancement of the remnant of the

gastrocnemius muscles and overlying skin, free tissue transfers,

and cross-leg flaps.

Each of these procedures may have particu-

lar indications in individual patients.

The vastus lateralis muscle, based on its precarious distal

blood supply, is occas ionally useful in covering below-knee am-

putation stumps, particularly in the prepatellar and lateral as-

pect. This muscle used in this fashion with overlying skin grafts

has proved to be durable (Fig 12).

V-Y ADVANCEMENT OF THE GASTROCNEMIUS REMNANT

The proximal portion of the gastrocnemius muscle may be de-

tached from its origins on the femoral condyles and the muscle

and overlying skin advanced in a V-Y fashion.30 Use of this

technique allows advancement of the full-thickness muscle and

skin approximately 3 cm, with primary closure of the distal

wound beyond the area of pressure, and V-Y closure of the donor

site in the popliteum. Sensation to the skin is maintained with

this procedure, which is a significant advantage. It is important

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Fig 11 .-innervated latissimus dorsi musculocu taneous free flap. A, chronic trau-

matic osteomyelitis of the femur w ith loss of rectus femoris muscle. B, muscle flap

provides both coverage and dynamic extension of the knee.

to ascertain that the sural arteries, branches of the popliteal ar-

tery, have not been damaged.

FREE TISSUE TRANSFERS

When local muscles are not available for distal coverage of the

amputation stump, free tissue transfers have provided a reliable

method of obtaining adequate soft tissue coverage. The latissi-

mus dorsi muscle, or musculocutaneous, flap can provide stable

Fig 12.-Distally based vastus

lateralis muscle used for coverage of

below-knee stump. A , chronic

recurring wound breakdown on the

weight-bearing surface of the

amputation stump. B, flap, based on

its distal bloo d supply, reaches to the

tibia1 area. C, stable wound achieved

.-.:a. -2 --..-.- --A-1:-^

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Fig

13.-Latissimus dorsi muscle free flap used for coverage of below-k nee am-

putation stump.

A,

exposed tibia and chronic nonhe aling wound in a patient with

bilateral am putations. B, healed wound with adequate padding over amputation

stump. The vascular anastomoses were performed in the poplitea l fossa.

soft tissue coverage. The length of the vascular pedicle allows

vascular anastomoses to be created in the popliteal fossa. This

flap, however, does not provide cutaneous sensation, and pa-

tients must be diligent in preventing pressure ulceration. The

tensor fascia lata flap, when used as a free flap, allows sensory

reinnervation, utilizing the lateral femoral cutaneous nerve su-

tured to the saphenous nerve.52 Free tissue transfers may be in-

dicated in patients with bilateral leg amputations, in whom

cross-leg flaps would be unavailable and local muscle flaps un-

reliable (Fig 13).

USE OF CROSS-LEG FLAPS

Finally, the medial gastrocnemius fasciocutaneous flap may

be utilized as a cross-leg flap for below-knee amputation stump

coverage in situations where free tissue transfers are not possi-

ble and local muscles are damaged. As in other applications of

the cross-leg flap, this requires a 3-week period of flap attach-

ment to the stump followed by careful flap pedicle division. In

lower extremity wounds with poor vascularity, cross-leg flaps do

not allow improved nutrition to the area and do not provide cu-

taneous sensibility. Nevertheless, they may be useful in selected

patients.

SOFT TISSUE COVERAGE OF TIBIAL DEFECTS

Soft tissue coverage of the lower leg may be conveniently di-

vided into three regions, the proximal third, the middle third,

and the distal third of the tibia. Local muscle flaps are useful for

coverage of proximal and middle third defects when their blood

supply is intact. Free tissue transfers are recommended for dis-

tal third defects.

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PROXIMALTHIRD

The gastrocnemius muscle flap described above is the flap of

choice in the proximal third of the tibia. When it is covered with

a split-thickness skin graft the muscle provides a minimal donor

site defect. The medial head of the gastrocnemius has a longer

muscle belly than the lateral head; however, both will cover de-

fects of the anterior tibia. For lateral proximal tibia1 defects, the

lateral head of the gastrocnemius muscle is chosen (see Fig 5).

The soleus muscle, discussed below, wil l also reach the proximal

third of the tibia. However, this is a second choice.

MIDDLE THIRD

The Soleus Muscle

The soleus muscle is most useful for covering soft tissue de-

fects in the middle third of the tibia. It is a broad muscle which

extends from the popliteal fossa to the Achil les tendon in the

. proximd b&d

sup

P

&

peroned

ar ery

Fig 14.-Vascular anatomy of the soleus muscle. The proximal domina nt blood

supply of the soleus muscle is the peroneal artery. A secondary distal blood supply

OOmes from branches of the posterior tibia 1 artery. The muscle may be transferred

on either its proximal or its distal blood supply.

34 JUNE CPS


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posterior calf and lies immediately beneath the gastrocnemius

muscles. Its blood supply comes from branches of the peroneal

artery in its proximal portion and the posterior tibia1 artery in

its distal portion (Fig 14). When based proximally, the distal

vascular pedicles must be divided prior to rotating the muscle

for coverage of the middle third of the tibia. Following rotation

and inset, it is covered with a split-thickness skin graft. The

muscle will cover the middle third of the tibia, and with more

extensive dissection, the proximal third (Fig 15). The primary

advantage of using this muscle is that its use does not cause a

significant contour deformity such as may occur when the gas-

trocnemius muscle is employed. Also, because of its rich vascu-

lar supply the muscle is frequently available for transfer in the

injured extremity. The muscle is best approached from the me-

dial aspect of the leg through an incision from the medial con-

dyle of the tibia to just above the medial malleolus. The muscle

is identified immediately beneath the gastrocnemius muscle. In

the proximal third of the leg, there is an avascular plane sepa-

rating the gastrocnemius from the soleus. In the distal portion

of the leg, however, these muscles fuse to form the Achil les ten-

don. Additionally, the deep surface of the soleus muscle must be

sharply divided from the flexor digitorum muscle in the middle

third of the leg. The minor vascular pedicles arising from the

peroneal artery are divided only to the point at which the mus-

cle can be rotated into the defect. If a small area is to be covered,

the soleus muscle may be split longitudinally in the midcalf and

only a portion of the muscle transferred (Fig 16). In larger de-

fects, the entire soleus muscle may be used. The muscle is skin

Fig

15.-Cadaver dissection of the

soleus muscle.

A,

the muscle flap is

raised, based on the proximal peroneal

artery. One may elevate only the lateral

or the media l half of the muscle. 8, arc

of rotation includes the region of the

patella. C, distal arc of rotation includes

AL- -:

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Fig 16.-Left,

soleus mu scle flap used for coverage of exposed tibia1 fracture

(middle third o f tibia).

Right,

use of the soleus mu scle and a spl i t-thickness skin

graft over a midtibial fracture.

grafted primarily and the donor site is closed over suction drain

catheters. If the lateral aspect of the tibia requires coverage, a

lateral approach to the soleus muscle may be made. The inter-

posed fibula makes difficult the visualization of the minor pedi-

cles, which must be divided and ligated to assure adequate mo-

bilization of the muscle and good hemostasis.

The second choice for coverage of soft tissue defects in the

middle third of the tibia is a gastrocnemius musculocutaneous

flap. An extended skin flap based on the medial gastrocnemius

Fig 17.-Medial gastrocnem ius musculocutan eous flap for coverage of the middle

third of the tibia. A, open wound of the m iddle third of the tibia. 6, rotation of the

gastrocnem ius musculocutan eous flap. The donor site requires a spl i t-thickness skin

graft.

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muscle can be elevated to within 5 cm of the medial malleolus.

This provides excellent soft tissue coverage in the middle third

of the tibia but requires split-thickness skin grafting in the do-

nor defect (Fig 17).

Use of the Gastrocnem ius Myo fascial Flap as a Bipedicled Flap

Bipedicled gastrocnemius musculocutaneous flaps may be

used to cover defects of the anterior tibia in the middle and dis-

tal thirds.53 Keeping intact the distal attachment above the mal-

leolus increases the blood supply to the “fascial extension.” This

attachment limits the amount of flap mobility, however. The bi-

pedicled flap is elevated by making a midline posterior incision

and splitting the raphe between the two heads of the gastrocne-

mius muscle. The incis ion is carried to within 2 cm of the mal-

leolus. The medial or lateral head of the gastrocnemius muscle

is separated from the underlying soleus muscle and elevated

with the skin and subcutaneous tissue along with the underly-

ing fascia. Care is taken to preserve the posterior tibia1 neuro-

vascular bundle as well as the short saphenous vein and sural

nerve. A back cut is required distally just above the malleolus

to achieve adequate rotation. Skin grafts are required for the

donor defect. In our opinion, these flaps risk the creation of fur-

ther wound healing problems in an already compromised area,

particularly for the distal third of the tibia, and instead we pre-

fer free tissue transfers.

In addition to the soleus muscle and the gastrocnemius mus-

culocutaneous flap, smaller muscles may be useful in augment-

ing soft tissue coverage in the distal portion of the middle third.

The tibialis anterior muscle and the extensor digitorum muscle

based proximally may be combined with the soleus muscles for

covering larger defects. When using these muscles it is possible

to preserve their function by separating a portion of the muscle

belly from the tendon. Caution must be exercized in selecting

these muscles in the traumatized extremity. Because of their

tenuous blood supply (type IV), extensive mobilization fre-

quently leads to muscle necrosis.

DISTALTHIRD

The distal third of the tibia presents a difficult problem for

the use of local muscle flaps. In this region, the extensors and

flexors of the foot have largely become tendinous and there is

little muscle useful for soft tissue coverage. Although the use of

several muscles based on their segmental distal blood supply has

been described, including the tibialis anterior, extensor digito-

rum longus,

and the soleus, it must be emphasized that the

blood supply is marginal for survival of the muscle. Muscle ne-

crosis occurs in a significant percentage of cases, rendering these

techniques unreliable.56 Rotation of dista lly based muscle flaps

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is contraindicated in patients with severe local trauma to the

distal third of the leg and in patients with absent posterior tibia1

or anterior tibia1 pulses. When the proximal blood supply of

these muscles is ligated, the smaller secondary blood supply

must be adequate for survival of the muscle. Preoperative arte-

riography is recommended before the use of distally based mus-

cle flaps. The technique of elevation of these muscles is similar

to that of proximally based muscles. The proximal portion of the

muscle is elevated and its major blood supply ligated. The

smaller, distal blood-supplying vessels are ligated only as nec-

essary to allow adequate rotation of the muscle flap.

The Distally Based Soleus Muscle

The inferiorly based soleus muscle derives its blood supply

from secondary segmental vessels that are branches of the pos-

terior tibia1 artery. A muscle is exposed for incision over the

medial lateral border and is divided from the Achilles tendon

with sharp dissection. It is easily divided from the overlying gas-

trocnemius muscle. The distal vascular pedicles are seen approx-

imately 12 cm from the medial malleolus and should be pre-

served if possible. The donor site is closed primarily and the

muscle is skin grafted (Fig 18).55

Free Tissue Transfers

The use of free tissue transfers for distal third soft tissue cov-

erage is particularly appropriate for the reasons given in the

preceding paragraphs. Because of the nature of severe local

trauma, distally based muscle flaps are generally unreliable.

Consequently we favor free tissue transfers as the primary mode

of therapy for these injuries.57

Indications for Free Tissue Transfer

Open fractures of the distal tibia, exposure of the ankle joint,

and extensive soft tissue defects are indications for microvascu-

Fig 18.~-Dista lly based soleus muscle flap for coverage of defects of the distal

third of the tibia. A , open wound of the tibia in the distal third. B, soleus muscle has

bee n split and rotated to cover the distal third. Use of this muscle in a freshly trau-

matize d patie nt is risky because of the precarious nature of the secondary bloo d

supply.

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lar free tissue transfer. The one-stage transfer of muscle on mus-

culocutaneous flaps has provided a reliable solution to these

problems. Muscle flaps and skin grafts provide the most desir-

able contour for both large and small defects. A meshed skin

graft is placed immediately over the muscle, and with subse-

quent shrinkage of the muscle an acceptable contour is ob-

tained 25, 58 A large skin island may be included for larger de-

fects or when greater bulk is required. Advantages of the

latissimus flap are that one can cover a distal third of the ex-

tremity defect and place the microvascular anastomosis in the

popliteal artery well out of the zone of injury.5g Larger vessels

are not as prone to spasm as are the more distal anterior and

posterior tibia1 vessels. This has been a useful technique in our

hands. The dissection is rapid and the vessels are extremely ac-

cessible. In such cases we have been able to obtain a latissimus

flap with pedicle lengths of up to 35 cm (Fig 19).

For smaller defects, the gracilis muscle, or musculocutaneous,

flap, based on the medial femoral circumflex artery, is both con-

venient and reliable.20 The muscle is located in the medial thigh

between the sartorius and the vastus medialis. It originates on

Fig lg.-Use of the latissimus dorsi musculocu taneous flap for coverage of de-

fects of the distal third of the tibia. A, chronically infected nonun ion in the distal third.

Local blo od vessels were unsatisfactory for vascular anastomos is. B, design of the

latissimus flap based low in the back, a llowing vascular pedicles up to 30 cm in

leng th. C , Hea led wound . The vascular anastomosis was constructed at the trifur-

cation of the poplitea l artery and vein.

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the pubis and inserts on the medial tibia1 tubercle. The vascular

pedicle enters the muscle approximately 10 cm distal to the pu-

bic tubercle. Its length is approximately 6-7 cm, with an arte-

rial diameter of 1.5-2.0 mm. The flap may be used as muscle

alone with skin graft, or the skin island over the proximal half

may be safely included. For defects about the ankle and distal

tibia, muscle alone is preferred, as it gives the most acceptable

contour. The primary advantages of this muscle are its ease of

access in the supine patient, its convenient size for smaller de-

fects, and the well-tolerated donor scar on the medial thigh (Fig

20).

In addition to the gracil is muscle, the internal oblique and the

rectus abdominis are smaller muscles with dependable vascular

pedicles for use in the distal third of the lower extremity. The

internal oblique muscle, based on the deep circumflex iliac ar-

tery, is elevated through an extended herniorraphy incision. The

vascular pedicle is 8-10 cm long and has an arterial diameter

of 1.5-2.0 mm. The muscle is flat and can be easily tailored to

fit difficult contours. Its primary indication is for surface defects

of the ankle. The donor scar is well hidden in brief underwear.

No patient in our experience has developed abdominal laxity

when this muscle flap has been used (Fig 21).60

The rectus abdominis muscle, based on the deep inferior epi-

gastric artery, provides yet another useful muscle for coverage

in an extremity. The vascular pedicle is very long (lo-12 cm)

and its external arterial diameter is 2-3 mm. The muscle is eas-

Fig 20.-The gracilis

musculocutaneous flap for small defects

of the distal tibia and ankle. A, open

wound following comminuted fracture of

the distal tibia. 8, design of the gracilis

musculocutaneous flap. The blood supply

is based on the med ial circumflex femoral

artery. The skin island is reliable only

over the proximal third of the muscle. C,

healed wound followkig microsurgical

transfer. Vessel anastomoses were

constructed in the posterior tibia 1 artery

and vein.

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Fig 21 .-Internal oblique muscle free flap and skin graft for smaller defects about

the distal tibia and ankle. A, chronically nonhe aling posttraumatic wound of the distal

third of the tibia. 6, design of the internal obliqu e muscle free flap based on the

ascending branch of the deep circumflex iliac artery. C, muscle flap elevated on the

deep circumflex iliac artery. Note that the muscle flap is centered directly over the

ascending branch, ensuring complete survival of the muscle. D, healed wound at

1

year with acceptable contour of the distal third of the tibia.

ily dissected through a transverse suprapubic incision, is suited

for intermediate-sized defects, and may be contoured as

needed.61

With free tissue transfers, the appropriate tissue for the indi-

vidual defect may be selected. These flaps are reliable in expe-

rienced hands, with a success rate of 95 or greaterIn the dis-

tal third of the leg and foot, free tissue transfers are the resort

of choice and have largely replaced the older methods of tubed

pedicle flaps and cross-leg flaps.62

Cross-Leg Flap

The cross-leg flap may be useful in distal third coverage when

a free tissue transfer is not possible or has failed. The donor flap

must be skin grafted, as previously described. The gastrocne-

mius fasciocutaneous flap has provided a useful, reliable fascio-

cutaneous unit for use as a cross-leg flap when other methods

are not available. The advantages of this flap over the conven-

tional cross-leg flap are that it does not require a preliminary

delay, and that because the gastrocnemius muscle is not ele-

vated in the procedure, it causes no impairment of this muscle.

In the previously described musculocutaneous flap, the distal

skin over the medial distal leg to within 5 cm of the medial

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Fig 22.-Gastrocnemius musculocu taneous flap used as an unde layed cross-leg

flap. Inclusion of the gastrocnemius muscle with its perforators allow s secure ele-

vation of the flap witho ut prior delay. T he donor site requires a split-thickness skin

graft for closure.

malleolus is elevated in a subfascial plane. As one approaches

the border of the gastrocnemius muscle, a significant perforating

artery will be observed. This artery should be left intact and

marks the extent of the proximal dissection of the flap. The do-

nor site is skin grafted and then the flap is set into the recipient

defect in the opposite leg (Fig 22). Division of the flap is begun

at 3 weeks by cross-clamping the vascular pedicle and injecting

fluorescein to ensure adequate vascularization from the recipi-

ent bed. There is some concern that due to the axial-patterned

blood supply, a delay in revascularization might occur in these

flaps. It is our preference to base the judgment for division of the

flap on the fluorescein test. If there is any question, a partial

transection of the pedicle is carried out and the procedure is re-

peated in 3-5 days (Fig 23). The Hoffman external fixation de-

vice is a useful adjunct for immobilizing patients undergoing the

cross-leg flap procedure. It allows ease of access to flap dressings

and is more comfortable then the plaster and cross brace tech-

nique.57

RECONSTRUCTION OF SOFT TISSUE DEFECTS ON THE

FOOT

Reconstruction of soft tissue defects of the foot remains a com-

plex and challenging problem despite the recent developments

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Fig

23.-The

medial gastrocnemius

musculocutane ous cross-leg flap for

coverage of the middle

and distal thirds

of the tibia. A, cross-leg flap can be

elevated to within 5 cm of the med ial

malleolus.

8,

time of division of the

mus cle pedicle is determined by use of

IV fluoroscein dye. The extent of dye

penetration ma y be seen by the second

line

drawn on the flap at 30 days. C,

comp lete survival of the cross-leg flap

after division of the pedicle and insetting

in musculocutaneous flap and free flap surgery. Defects of the

foot may be divided arbitrarily into three geographic areas: the

dorsum of the foot, the medial and lateral malleoli, and the

plantar, weight-bearing surface. The etiology of soft tissue de-

fects in the foot may also be divided into three general catego-

ries. Trauma is the most frequent cause and may range from

degloving injuries and burns to pressure ulcerations. In the sec-

ond category, diminished sensibil ity of the plantar skin may

lead to the development of a neurotrophic ulcer in conditions

such as paraplegia, myelodysplasia, and diabetes. Fin

soft tissue coverage of the lower extremity

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