Plastic surgery

PART IX

TRUNK AND LOWER EXTREMITY

CHAPTER 94  LOWER EXTREMITY RECONSTRUCTION

ARMEN K. KASABIAN AND NOLAN S. KARP

The lower extremity has a mechanical component and must bear weight. These functional requirements make an effective reconstruction difficult. The mechanism of lower extremity defects includes trauma, diabetes and vascular disease, cancer ablation, and other disease processes. Reconstruction of the lower extremity requires the knowledge of all plastic surgical tools, such as skin grafting, local flaps, perforator flaps, muscle flaps, microvascular free flaps, and arterial, nerve, and bone repair.

LOWER EXTREMITY TRAUMA

Treatment of high-energy lower extremity trauma with soft-tissue and bone injuries remains a formidable problem. These injuries often occur in the multiply injured trauma patient, making management even more difficult. Initial motor vehicle air bag designs reduced mortality and the incidence of facial fractures, but did not offer adequate protection of the lower extremities. Newer designs with multiple airbags now protect the lower extremities. Pedestrian motor vehicle accidents, falls from heights, and sporting injuries result in open tibial fractures that require the management of complex bone and soft-tissue injuries and may be associated with vascular and nerve injuries.

The management of lower extremity trauma has evolved to the point that many extremities, except for severely mangled extremities, are now routinely salvaged. Treatment requires a team approach consisting of orthopedic, vascular, and plastic surgeons. Fracture management utilizes techniques of external fixation, intermedullary rodding, and internal plating. Bone grafting now includes vascularized bone grafts, Ilizarov bone lengthening, artificial bone matrix and bone growth factors, and nonvascularized bone grafts. Soft-tissue management includes microvascular free tissue transfers, local muscle flaps, fasciocutaneous and perforator flaps, and skin grafts. Techniques of vascular and nerve repair have been further refined.

The goal in the treatment of open tibial fractures and lower extremity salvage is to preserve a limb that will be more functional than if it were amputated. If the extremity cannot be salvaged, the goal is to maintain the maximum functional length. The management of these injuries is a topic of debate in the literature. A severely mangled extremity may require multiple operative procedures and it may be months to years before it can be used for weight bearing and the patient can return to employment.

In a review of 72 patients with Gustilo grade IIIB open tibial fractures, Francel et al. found that despite a 93% successful limb salvage rate, a majority of patients had problems with ankle motion or leg edema. Only 28% returned to work after 42 months of mean follow-up compared with 68% of patients who had a below-knee amputation.1 Similarly, Georgiadis et al. compared 27 patients who had attempted limb salvage with 18 patients who had primary below-knee amputation. They found that patients who had limb salvage took longer to achieve full weight bearing, were less willing to return to work, and had higher hospital charges than those who had primary amputation.2

Other reviews have shown more successful outcomes with extremity salvage. Laughlin et al. reviewed the functional outcome in eight patients with grade IIIB and six with grade IIIC injuries. He found that despite a long recovery period, eight of nine patients returned to work.3 In a series of 128 patients treated at Bellevue Hospital for open tibial fractures, 66 were available for follow-up for at least 5 years. More than 60% of the patients returned to work after extremity salvage. For some patients, the delay in returning to work was as long as 10 years after the original injury. A significant cause for the delay to return to work was social factors, such as pending litigation. No patients required further reconstruction more than 5 years after their microvascular free tissue transfer. All but three patients were satisfied with their reconstructions and would do it again if they had the chance. Of the three who were dissatisfied, none were willing to convert the reconstruction to an amputation.4 In a series of 42 patients, Rodriguez et al found that of 42 patients who had lower extremity salvage with free flaps, 93% of the patients would go through the limb salvage process again to avoid amputation.5

These results appear to be favorable compared with average return to work rates of 66% for patients after lower limb amputation, with only 22% to 67% of these returning to the same occupation and the remainder changing their occupation as reported in the literature in a review by Burger et al.6 Although McKenzie et al. found that outcomes based on the Sickness Impact Profile (SIP) was equivalent at 2 and 7 years for amputees versus salvage patients,7,8 20% of patients with lower extremity fractures, not extremity salvage procedures, were not working at 30 months post injury despite low SIP scores.9 This indicates that return to work rates and SIP scores are not accurate in determining the value of lower extremity salvage. Objective functional studies need to be done to compare outcomes.

Extremity salvage is a long, complicated process. Patients must be made aware of the expected course and the anticipated functional outcome. Patient selection is an important variable in evaluating the final outcome. Although normal function is rarely achieved, most patients are grateful for their salvaged limb.

History

Amputation was practiced early in the history of man. One of the earliest writings is that of Hippocrates (460–370 BC), who described amputation as the method of last resort when faced with ischemic gangrene.

Ambroise Pare (1509–1590) described the basic rules of amputation still followed today. He recommended amputation through viable tissue and closure of amputation stumps to fit prostheses. He went on to describe phantom pain and stump revision.

The concept of immobilization was introduced by Ollier (1825–1900), who introduced the plaster cast. During the U.S. Civil War, the mortality of lower extremity injuries was 50%, secondary to sepsis. The advent of antiseptics and antibiotics decreased this mortality rate through World War I.

The “closed plaster technique” for open tibial fractures was introduced by Orr. It was further advanced during the Spanish Civil War by Trueta, who performed surgical debridement prior to placement in plaster.

During World War II, no new techniques were developed. However, improvement in aseptic technique and antibiotics decreased the mortality of wound complications from 8% in World War I to 4.5% in World War II. Nonetheless, the increased destructive capacity of military equipment in World War II resulted in a 5.3% amputation rate compared with 2% in World War I. The incidence of postfracture osteomyelitis decreased from 80% in World War I to 25% in World War II.

The next major advance in lower extremity salvage came during the Korean conflict. Lower extremity injuries during this war involved injuries to the major arteries in 59% of the cases. The concept of artery repair as opposed to artery ligation was introduced. This practice decreased the amputation rate from 62% at the beginning of the war to 13% at the end of the war, with wound mortality dropping to 2.5%.

In the late 1960s, plastic surgeons discovered the transfer of regional flaps to cover soft-tissue defects of the lower extremity. With the advent of microsurgery in the 1970s, improved techniques of bone coverage with soft tissue and of nerve repair further advanced the ability to salvage traumatic lower extremity injuries. Rates of osteomyelitis have been decreased by up to 95% in most series. The free fibular flap also solved the problem of bone gaps in these devastating injuries. The concept of bone lengthening was discovered by Codivilla much earlier and advanced by Ilizarov. It was popularized in the Western world only in the 1980s. This concept provided additional techniques to solve both bone and soft-tissue deficiencies.

The concept of negative pressure dressings was introduced in the 1990s by Argenta et al.10 It was found that negative pressure on a wound would decrease edema, decrease bacterial count, promote contraction of the wound, and, with the help of a sponge dressing, promote granulation.

Perforator flaps have become more effective in covering many defects of the lower extremity which once required microvascular free flaps. Many wounds that were difficult to manage now were easier to manage and enabled simpler reconstructions. Management of many lower extremity wounds requires careful evaluation to use the simplest and most effective methods.

Anatomy

The leg has several characteristics that make it unique. Humans are bipedal, thus full weight bearing in the erect position is on the two lower extremities. The full force of the weight of the body is transmitted through the legs. The muscles of the leg provide ankle function with plantarflexion, dorsiflexion, eversion, and inversion. Additional leg muscle functions include toe flexion, knee extension, and knee flexion. If the ankle were fused, the functional needs of the leg muscles are greatly unnecessary. Therefore, significant muscle loss of the leg can be tolerated with maintenance of bipedal ambulation. Consequently, muscle loss of the leg is not a contraindication to reconstruction and salvage.

The hydrostatic pressures imposed on the leg increase the incidence of edema, deep venous thrombosis, and venous stasis problems. These problems are rare in the upper extremity, but common in the lower extremity. The lower extremity is also much more commonly afflicted with atherosclerosis than the upper extremity. Therefore, both venous and arterial problems are more common in the lower extremity and must be considered when developing a reconstructive plan.

The anteromedial portion of the tibia is covered by the skin and subcutaneous fat only. This relatively unprotected anatomy leads to many instances of bone exposure, which require specialized soft-tissue coverage.

Because the full force of the body is transmitted to the feet, sensibility on the plantar aspect of the foot is necessary for normal ambulation. Normal sensibility is required for tactile sensation, position sensation, and protection of the vulnerable pressure-bearing portion of the body. Loss of the tibial nerve, with loss of sensibility on the plantar aspect of the foot, is a relative contraindication for lower extremity salvage. However, many patients with peripheral neuropathy are able to ambulate. They must remain cognizant of the potential problems; motivated patients can reasonably enjoy normal ambulation without soft-tissue breakdown. Thus, in selected patients, loss of sensation of the plantar aspect of the foot may not be an absolute contraindication for lower extremity salvage.

Bones

The bones of the leg are the tibia and the fibula. The tibia provides 85% of the weight-bearing capacity of the leg, whereas the fibula serves as a structure for muscle and fascial attachments and as a significant structural portion of the ankle joint.

The tibia is the second longest bone in the body. It articulates with the femur at the knee joint on two condyles and joins the fibula to articulate with the talus to form the ankle joint. It articulates with the fibula proximally at the tibiofibular joint and distally at the tibiofibular syndesmosis. The tibia is connected to the fibula in its midportion with the interosseous membrane. It is a classic long bone with a diaphyseal shaft with a thick cortical bone surrounding a marrow cavity. The tibia is wide proximally where it articulates with the femur and narrows to the shaft. The diaphyseal portion is usually described as three surfaces: medial, lateral, and posterior. The medial border is subcutaneous, and thus most prone to exposure during injury. The lateral surface is one of the origins of the tibialis anterior muscle and is protected by the anterior compartment muscles. The posterior surface is well protected by the soleus and gastrocnemius muscles.

The fibula is the smaller bone of the leg. It originates slightly posterior and distal to the tibia and it articulates with the posterolateral tibia. The shaft of the fibula serves as the origin of many of the muscles of the leg. Distally, it articulates with the talus and forms the lateral malleolus. Because the fibula is not weight bearing and is in a relatively protected position, it is of less concern in trauma, except when the lateral malleolus is involved. Only the proximal and distal portions of the fibula are required, and because of an independent blood supply from the peroneal artery, the central portion of fibula is an excellent source of vascularized long bone and can be sacrificed readily.

Compartments

The anatomy of the leg is best understood by dividing it into its four muscle compartments: anterior, lateral, posterior, and deep posterior. The deep fascia of the leg forms discrete areas or compartments (Table 94.1 and Figure 94.1).

The anterior compartment is comprised of four muscles: the tibialis anterior, the extensor hallucis longus, the extensor digitorum longus, and the peroneus tertius. All four muscles dorsiflex the foot, but the primary dorsiflexor is the tibialis anterior, which also inverts the foot. The extensor hallucis longus primarily extends the great toe; further contraction causes foot dorsiflexion. The extensor digitorum longus extends the phalanges of the lateral four toes and dorsiflexes the foot. The peroneus tertius dorsiflexes and everts the foot. All four muscles are innervated by the deep peroneal nerve, and their blood supply is from muscular branches of the anterior tibial artery.

The lateral compartment is comprised of the peroneus longus and peroneus brevis muscles. Both muscles plantarflex and evert the foot. They are both innervated by the peroneal nerve. The vascular supply of the peroneus longus is the muscular branches of the anterior tibial and peroneal arteries. The vascular supply of the peroneus brevis is muscular branches from the peroneal artery.

The superficial posterior compartment is comprised of the gastrocnemius, soleus, plantaris, and popliteus muscles. They are all innervated by the tibial nerve. The gastrocnemius muscle plantarflexes the foot and flexes the knee. Its blood supply is from sural branches of the popliteal artery. The soleus muscle plantarflexes the foot and is supplied by the muscular branches of the posterior tibial, peroneal, and sural branches of the popliteal artery. The plantaris muscle plantarflexes the foot and is supplied by the sural branches of the popliteal. The popliteus flexes the knee and rotates the tibia and is supplied by genicular branches of the popliteal.

The deep posterior compartment is comprised of the flexor hallucis longus, flexor digitorum longus, and tibialis posterior muscles. They are all innervated by the tibial nerve. The flexor hallucis longus flexes the great toe and aids in plantarflexion of the foot. It is supplied by muscular branches of the peroneal artery. The flexor digitorum longus flexes the phalanges of the lateral four toes and aids in plantarflexion of the foot. It is supplied by the branches of the posterior tibial artery. The tibialis posterior plantarflexes and inverts the foot. It is supplied by muscular branches from the peroneal artery.

Compartment Syndrome

Compartment syndrome is an increase in interstitial fluid pressure within an osseofascial compartment of sufficient magnitude to cause a compromise of the microcirculation, leading to myoneural necrosis. Any crush injury to a closed compartment may lead to compartment syndrome. The literature indicates an incidence of compartment syndrome of 6% to 9% in open tibial fractures. It is important to realize that a laceration with an open fracture may not provide adequate decompression to prevent compartment syndrome.

FIGURE 94.1. Cross-sectional anatomy of the leg. Note the paucity of soft tissue over the anteromedial tibia.

The cardinal signs of compartment syndrome are pain disproportionate to the injury, pain on passive flexion or extension, and palpably swollen or tense compartments. Loss of pulses is a late sign and the presence of pulses does not rule out compartment syndrome. The definitive diagnosis is made by measuring the compartment pressure.

Various methods have been used to measure the intercompartmental pressure, including slit catheters and saline injection techniques. Although commercially produced units are available, an 18G needle flushed with saline and connected to a transducer is usually adequate. The threshold for fasciotomy is controversial. Some surgeons consider a pressure >30 mm Hg in any compartment as an indication for fasciotomy. Allen et al. considered fasciotomy when the compartment pressure was >40 mm Hg for 6 hours or was >50 mm Hg for any length of time.11 Four-compartment fasciotomy should be performed when there is any index of suspicion of compartment syndrome, as the morbidity of a fasciotomy is far less than the morbidity of ischemic necrosis of the lower extremity secondary to an untreated compartment syndrome.

Fracture Classification

Classification of open tibial fractures in relation to fracture pattern and soft-tissue injury is useful in describing injuries and prognosis. The most commonly quoted classification for open fractures is that of Gustilo (Table 94.2).

A grade IIIA injury is an open fracture with soft-tissue damage. Because it is classified as having adequate soft-tissue coverage of the fracture, it rarely requires complex plastic surgical procedures. These injuries are usually treated with local wound care, debridements, skin grafts, or simple local flaps. A grade IIIB injury involves an open fracture with periosteal stripping and bone exposure. A grade IIIC injury is an open fracture associated with an arterial injury requiring repair. Although this is the most commonly quoted classification, it remains woefully inadequate to describe the injury or to evaluate the prognosis of an open tibial fracture for which the plastic surgeon is involved. An open tibial fracture with 3 cm of periosteal stripping and exposed bone (Figure 94.2A) is not the same as an open tibial fracture with an 8-cm bone gap, 12 cm of exposed bone, and necrosis of 16 cm in all four-compartment muscles (Figure 94.2B), though they would be both classified as grade IIIB injuries. Similarly, the phrase “arterial injury requiring repair” in the classification of a grade IIIC injury is ambiguous. Some surgeons may believe it is necessary to repair a second vessel in a one-vessel leg, whereas others believe that a single vessel is an adequate blood supply to the foot. In the first case, the injury would be classified as grade IIIC; in the second case, as grade IIIB. The classification does not tale nerve injury into consideration, which is crucial in the assessment of prognosis.

In an attempt at a better classification, the Mangled Extremity Syndrome Index, Mangled Extremity Severity Score, Predictive Salvage Index, and Limb Salvage Index were created. Even these indices have proved imperfect in predicting outcome.12 A more precise classification system awaits development to predict the outcome of salvage efforts for mangled extremities.

MANAGEMENT OF THE MANGLED EXTREMITY

Management of the mangled extremity requires the combined expertise of the trauma, vascular, and plastic surgeons. For the management of the mangled extremity, we use the protocol presented inFigure 94.3 at Bellevue Hospital.

Initial Evaluation

High-energy lower extremity injuries are usually associated with other life-threatening injuries. The priority in multisystem injuries is to salvage the life of the patient, not necessarily to salvage or treat the limb. The advanced trauma and life support guidelines are followed prior to fracture management. The priorities are the ABCs: airway, breathing, and circulation. If the patient has other life-threatening injuries, treatment of the extremity injury should be limited to stabilization of the extremity and control of bleeding. Amputation of a mangled extremity in a clinically unstable patient may be more prudent than an extensive reconstructive course and should be considered in the initial evaluation of the patient.

Once the patient’s other injuries have been addressed, an assessment is made to determine if the extremity is salvageable. Limb viability is assessed by examining the wound and then assessing vascular, bone, soft-tissue, and nerve injuries.

FIGURE 94.2. Grade IIIB fractures vary tremendously in severity. A. Grade IIIB open tibial fracture with periosteal stripping and soft-tissue defect. B. Grade IIIB open tibial fracture with extensive bone and soft-tissue loss.

Vascular examination includes evaluation of the pulses, color, temperature, and turgor of the foot. One must realize that an ischemic limb does not necessarily indicate a vascular injury. The vessels may be in spasm or may be kinked secondary to the injury. Pulses may return after fracture reduction. Doppler examination of the vessels may help to evaluate patency when pulses are not palpable. Angiograms are usually performed if the extremity remains ischemic or requires a free-flap reconstruction.

Bony evaluation is made by visual examination of the open wound. Radiographs are mandatory for evaluation of the fracture. More thorough evaluation of the fracture fragments and accurate assessment of bone loss, fragment vascularity, and periosteal stripping of the bone require assessment in the operating room.

Soft-tissue evaluation includes examination of the skin subcutaneous tissue, muscle, and periosteum. Avulsed and crushed soft tissues can be assessed in the emergency room, but soft-tissue and muscle viability usually cannot be evaluated except in the operating room during the debridement. In complicated cases, even experienced surgeons have difficulty assessing soft-tissue viability. Serial debridements may be necessary to make that determination.

Neurologic evaluation includes motor and sensory evaluation of the peroneal and tibial nerves. Significant nerve injury is a relative contraindication for extremity salvage, as nerve repair in the lower extremity has poor functional results, and a below-knee amputation may be preferable to an insensate foot.

The initial assessment determines if the limb is salvageable, if the extremity revascularization is necessary, if a free flap will likely be required, if there is bone loss, and if there is nerve injury and if so, if it precludes a functional limb. If the extremity is unsalvageable, an amputation is indicated. If the extremity is salvageable, the reconstructive protocol is followed.

FIGURE 94.3. Algorithm for the treatment of lower extremity trauma.

Reconstructive Plan

After the patient is stabilized and the decision for limb salvage has been made, the first issue to address is whether or not there is a vascular injury. If so, a decision is made as to whether an angiogram should be obtained in the angio suite or in the operating room. If there is quick access to a high-quality angiogram, that is preferable. If there may be a several-hour wait for the angio suite, the patient is taken to the operating room and an on-table angiogram is obtained.

In general, the skeleton is stabilized first. If the extremity requires revascularization, the stabilization is performed quickly or temporary vascular shunts are placed until stabilization is achieved. Once the bone is stabilized, the vascular injury is repaired if indicated. Significant ischemia may result from spasm, which can be corrected by fracture reduction. If the foot is viable, there may be adequate collateral circulation, or a single intact vessel to the foot may be adequate for extremity viability. If revascularization is performed, fasciotomy to prevent compartment syndrome is always necessary.

Once bony stability and vascular integrity are established, all nonviable tissue is debrided. If blood vessels are exposed and an adequate debridement has been performed, immediate soft-tissue coverage is indicated with a microvascular soft-tissue transfer. If there are no vital structures exposed and/or the zone of injury is not clear, the patient is brought back for a second, or even a third, debridement before definitive soft-tissue coverage is achieved. Most authors agree that early soft-tissue coverage is associated with a lower complication rate. Byrd et al. found that the overall complication rate of wounds closed within the first week of injury was 18% compared with a 50% complication rate for wounds closed in the subacute phase of 1 to 6 weeks.13 In a review of Godina’s work, closure of wounds within the first 72 hours after injury was associated with the lowest complication rate and highest success rate (Table 94.3).14 Yaremchuk et al. believe that serial, complete debridement is more important than the absolute timing of soft-tissue coverage.15 Platelet counts increase nearly fourfold in the subacute phase after injury, which may play a role in the increased complication rate seen during this period.16 Recent reviews have had conflicting results. Although Steirt et al found that the free flap coverage of open fractures could be delayed by initial treatment with vacuum-assisted closure (VAC) therapy without significantly increased complication rates,17 Hou et al. found that the VAC therapy decreased flap size requirements but use beyond 7 days showed higher infection and amputation risks.18 The surgeon is best guided by the principle that early complete debridement and early soft-tissue coverage improve the results of extremity salvage.

Special Problems

Soft-Tissue Avulsion. Soft-tissue avulsion is a unique condition. Massive areas of skin and subcutaneous fat may be avulsed that initially appear viable, and it is tempting to suture the avulsed tissue back in place. This avulsed tissue is always injured much more extensively than initially appreciated and progressive thrombosis of the subdermal plexus ensues, followed by necrosis of nearly the entire flap of soft tissue. It is more prudent to remove the entire avulsed soft tissue, remove the skin as a skin graft, and reapply it to the soft-tissue defect. It always seems radical at the time, but nothing is more wasteful than necrosis of the entire flap with its skin, requiring additional donor defects for later skin grafting.

Vascular Injuries. Injury to the popliteal vessels or vessels more proximal requires immediate repair or reconstruction. Posterior dislocations of the knee are prone to disruption of the popliteal vessels and represent a vascular emergency. The best treatment for more distal injuries is somewhat more controversial. Certainly, if all three vessels distal to the trifurcation are injured, reconstruction of at least one vessel is indicated. If one vessel is injured, then ligation of that vessel may be more prudent than the attempted repair. If two vessels are injured, it is usually preferable to repair at least one vessel. There are, however, no studies that demonstrate any difference in outcome whether or not a second vessel is reconstructed. Sound surgical judgment is necessary to determine whether the extremity will benefit from a second distal vessel and whether the morbidity of the additional surgery to reconstruct the second vessel is warranted.

Vascular injury is initially assessed with physical examination of palpable pulses, color, capillary refill, and turgor of the extremity. Doppler examination is added for equivocal physical examinations. An angiogram is indicated for massive injuries, an ischemic injury that will probably require reconstruction, or an injury that may require microvascular reconstruction. In the ischemic extremity, angiography must be done emergently, with reconstruction to follow. Often, if a vascular bypass is required to revascularize the extremity, an immediate microvascular free flap may be required to cover the bypass graft, further complicating the emergent treatment of the wound. If the extremity is not ischemic, angiography may be delayed after initial treatment of fracture fixation and wound debridement followed by delayed soft-tissue coverage. If pulses are palpable, recent studies show that preoperative angiography may not be necessary prior to microvascular free tissue transfer.

Nerve Injury. Injuries to the lower extremity often have associated nerve injuries. Although microvascular techniques allow for nerve repair and nerve grafting, the results of nerve reconstruction in the lower extremity are poor. These poor results are in part a result of the long distance from the spinal cord to the motor endplates, the complex distribution of nerve fascicles, and the long distance required for the nerve to grow to the motor endplate, resulting in end-organ atrophy. Recent experience with nerve grafting shows some promising results in selected patients. Trumble found an average return of strength of 11% and protective sensation in all of nine patients treated with nerve grafts for repair of the peroneal and sciatic nerves.19 However, most of these patients were in the pediatric age group.

Disruption of the peroneal nerve results in foot drop and loss of sensation on the dorsum of the foot. Although not crippling, lifelong foot splinting or tendon transfers are required to offset the foot drop. The loss of sensation of the dorsum of the foot does not cause much morbidity. The loss of the tibial nerve is more devastating. It results in the loss of plantarflexion of the foot, a function that facilitates the step off in ambulation. The most devastating loss is that of sensibility of the plantar aspect of the foot, which results in the loss of some position sense and in chronic injury and wounding of the plantar aspect of the foot. Atrophy and vasomotor changes complicate the injury and often result in amputation. Although not an absolute indication for amputation, it is certainly a relative contraindication and is not much different from the foot of the patient with diabetic neuropathy.

Nerve injuries to the lower extremity should be repaired at the time of injury, if primary repair can be achieved. If nerve grafts are necessary to bridge nerve gaps, they are perhaps best delayed until a healthy soft-tissue bed is established. The prognosis of nerve repair is guarded at best, and most patients require tendon transfers or lifetime splinting.

FRACTURE MANAGEMENT

Before vascular or nerve repair can be performed or adequate debridement attempted, a stable framework must be constructed. It is the basis for early fracture management. If a vascular anastomosis is performed prior to fracture fixation, the maneuvering during fracture reduction may disrupt the anastomosis, or the interposition grafts may be found to be too short or redundant after fracture reduction. Consequently, our protocol is to perform fracture fixation first.

The techniques available for fracture fixation include traction, casting/splinting, intramedullary nailing, internal fixation, and external fixation.

Traction fixation is rarely used, when the patient is too sick to undergo fracture stabilization. It necessitates immobilization of the entire patient and does not rigidly fix the fragments. Traction is employed more commonly in the upper leg; however, it may be used in the lower leg as a temporary measure for the unstable patient until the patient’s medical condition allows more stable fixation.

Cast immobilization is appropriate for closed leg injuries or for open tibial fractures once the wound is stable, but it provides poor fracture immobilization and difficulty with wound care if there is an active wound. Although the “closed plaster technique” was introduced by Orr and popularized by Trueta, newer techniques are currently available. Occasionally, an open plaster technique is used. A window is cut in the cast to allow for dressing changes and wound debridement. This open cast technique can be used until wound control is achieved and definitive wound management is approached.

Intramedullary nailing with reamed or nonreamed nails has many advantages in fracture fixation. Reamed nails provide rigid fixation by providing a tight fit in the medullary canal with proximal and distal fixation. Reamed nails allow early ambulation. Intramedullary nails, however, can only be used for minimally comminuted fractures without significant bone loss. The disadvantage of this technique is the obliteration of the entire endosteal blood supply by stripping out the medullary canal. In bone that already has a compromised blood supply, devascularization of the injured bone may result; thus, the technique is not indicated for the massively traumatized lower extremity.

Nonreamed nails do not take up the entire intramedullary canal and do not require complete stripping of the endosteal blood supply. They share the advantage of relatively stable fixation and allow early mobilization. They also require relatively stable fracture patterns. When used for Gustilo grade IIIB or IIIC injuries, immediate coverage of the exposed bone and hardware is required. Exposure of the hardware runs the risk of a progressive, rapid infection up the intramedullary canal. Consequently, serial debridements and delayed soft-tissue coverage are contraindicated with this technique. Although it is generally agreed that nonreamed locked nails are effective in open grades I, II, and IIIA tibial fractures, their use in grade IIIB fractures is less clear. Trabulsy20 and Tornetta21 showed that nonreamed locked nails combined with early soft-tissue coverage and early bone grafting were more effective than external fixation.

Internal fixation of diaphyseal tibial long bone injuries with plates and screws provides relatively rigid fixation. Application of the fixation devices, however, requires extensive soft-tissue and periosteal stripping and introduces a significant amount of foreign body into the wound. Compromised tissue may be further devascularized. The plates and screws must be covered immediately with soft tissue using local or free flaps. Again, serial debridement and delayed flap coverage are not indicated once the hardware has been introduced.

External fixation is the fixation of choice in the most severely traumatized lower extremities with massive soft-tissue and bone injury. External fixation allows rigid fixation without additional soft-tissue trauma and bone devascularization and allows access to the wound for additional debridement. External fixators may obstruct microvascular surgery however. Such problems can be limited with proper planning of pin and rod placement. In addition to the disadvantage of bulkiness, another potential complication is pin tract infections. External fixators can be used with the Ilizarov technique for bone lengthening in situations of bone gaps, or they may be left in place after cancellous or vascularized bone grafting until additional stability of the fracture is obtained. Because of the wide zone of injury in grade IIIB and IIIC injuries and contamination at the fracture site, external fixation is usually the fixation of choice.

Management of Bone Gaps

For managing bone gaps, three techniques are available: nonvascularized cancellous bone grafts, Ilizarov bone lengthening, and vascularized bone grafts. The timing of bone grafting remains controversial. At the time of soft-tissue coverage, bone gaps may be filled with antibiotic beads or cancellous bone grafts. Early bone grafting relies on adequate debridement and soft-tissue coverage with adequate vascularity to support the bone grafting. Many surgeons prefer to get wound control prior to bone grafting, avoiding the risk of losing valuable bone stock. We prefer to postpone bone grafting until 6 to 12 weeks after soft-tissue wound coverage has been achieved.

Nonvascularized cancellous bone grafts are best used for nonunions or small bone gaps of less than a few centimeters. In well-vascularized beds, union rates >90% can be achieved with nonvascularized bone grafts in these limited situations.

With larger bone gaps, the success of nonvascularized bone grafts decreases, and vascularized bone grafts or Ilizarov bone lengthening is required. The Ilizarov technique uses the concept of distraction osteogenesis to fill bone gaps (see Chapter 24). The Ilizarov technique can theoretically bridge gaps of large dimensions, but for practical purposes, it is best used for gaps of 4 to 8 cm. Two strategies are possible. The gap can be obliterated with bone graft and then lengthened subsequently, or the bone gap can be left as is and distraction osteogenesis is employed to distract one or both segments to meet at the fracture site. The former, shortening of the bone and later lengthening, offers the advantage of easier soft-tissue management. When the bones are left out to length, soft-tissue coverage by microvascular free flaps followed by distraction osteogenesis is also possible. Complications include leg-length discrepancies, axial deformities, refracture, pin track infections, and incomplete “docking” requiring secondary bone grafting.

Vascularized fibular grafts can bridge gaps of ≤24 cm. In harvesting the fibula, it is necessary to preserve the proximal and distal 6 cm of fibula in the donor leg in order not to interfere with knee or ankle function; thus, the limit of fibula harvest is the native fibular length minus 12 cm. The use of the fibula assumes the availability of the contralateral fibula as a donor and of a recipient vessel in the injured leg. The fibula will never achieve the strength of the original tibia because of its markedly smaller mass. The fibula is prone to fracture, but after healing, the fibula hypertrophies and increases in strength. Weiland reported an 87.5% success rate in 32 free fibular grafts, with average time to full weight bearing of 15 months.22 Fyajima et al. reduced the time to weight bearing to 6 months by the use of a twin-barreled vascularized fibular graft.23

Soft-Tissue Management

The choice of soft-tissue coverage of open tibial fractures depends on the extent and the location of the injury.

Split-Thickness Skin Grafts. Split-thickness skin grafts will cover exposed muscle or soft tissue, and occasionally they can be used to cover the bone with healthy periosteum or tendon with healthy paratenon. In most circumstances, however, subcutaneous tissue or muscle is recommended to cover vessels, nerves, bone, and tendon, even with healthy periosteum or paratenon. Skin grafts may be adequate to cover Gustilo grade IIIA open tibial fractures, but they are inadequate coverage alone for Gustilo grade IIIB or IIIC injuries.

Local Flaps. Local fasciocutaneous or muscle flaps are useful for small to moderate defects of bone-exposed vessels or tendons. It is generally accepted that local flaps are available in the proximal or middle third of the leg, but local flaps in the lower third of the leg do not exist. The defects of the lower third of the leg nearly always require free tissue transfer.

Fasciocutaneous flaps may be proximally based and cover small defects of the bone, exposed vessels, or tendons; however, general principles of rotation flaps must be considered. A small defect will require a large flap and the donor site will always require a split-thickness skin graft. In a series of 67 fasciocutaneous flaps to the lower extremity, Hallock found an 18.5% complication rate. Distally based flaps had a 37.5% complication rate, although wound closure was ultimately achieved in 97% of patients.24 Local fasciocutaneous flaps are usually not available in Gustilo grade IIIB or IIIC injuries in which the local soft tissue is within the zone of injury and unavailable for transfer.

With better understanding of the blood supply to the skin and subcutaneous tissue, pedicled perforator flaps have become more popular as local soft-tissue flaps and represent a new era for reconstruction of the lower extremity. In a series by El-Sabbagh et al., 32 of 34 perforator flaps to the lower extremity survived completely. One flap failed and one had tip necrosis. There were 13 peroneal artery perforator flaps, 16 posterior tibial artery perforator flaps, and 5 medial sural artery perforator flaps in their series.25

Local muscle flaps are quite useful to cover defects of exposed bone, artery, nerve, or tendon in the proximal or middle third of the leg. The lateral or medial gastrocnemius flap is useful for defects of the proximal third of the leg (Figure 94.4). Defects of the knee can be covered easily. The middle third can be covered by the soleus flap (Figure 94.5). A hemisoleus muscle can be taken, preserving function of the remaining half of the soleus muscle. Again, it is important to note that large flaps are required to cover even small defects because of the arc of rotation. A considerable donor-site defect that requires skin grafting may be encountered. Functional deficits of muscle harvest are real, but have not been adequately studied. Smaller defects may be covered by the tibialis anterior muscle or other muscles of the anterior and lateral compartments; however, these muscles have a less reliable blood supply and may be less readily expendable. The tibialis anterior, for example, is an important muscle for dorsiflexion of the ankle. It should be transferred as a bipedicle flap for small defects. The main problem with the use of local muscle flaps is that they are usually in the zone of injury of high-energy grade IIIB or IIIC injuries. High-energy injuries may result in bone, soft-tissue, arterial, nerve, and significant muscle injury. The muscles in these high-energy injuries with significant associated crush injury may not be available for local transfer.

Free Tissue Transfer

Microvascular free tissue transfer has revolutionized the treatment of high-energy lower-extremity injuries with the associated bone, soft tissue, and muscle loss and with exposure of the bone and vital structures. Once debridement of all devitalized tissue has been completed, and if an available recipient artery is available, abundant, healthy muscle, and soft tissue can be supplied to cover the exposed vital structures. The rectus muscle or the latissimus dorsi muscle, or the latissimus dorsi combined with the serratus muscle, can cover large defects (Figure 94.6). In a review of 304 cases of microvascular free flap reconstruction of the lower extremity, Khouri and Shaw reported a 92% success rate.4 Reported success rates by many authors with early wound coverage with microvascular free flaps have been 85% to 100%. The anterolateral thigh perforator free flap has recently become a popular choice for the coverage of lower extremity defects.

Negative Pressure Dressings. Some wounds may be difficult to manage despite the options of skin grafting, local flaps, or microvascular free tissue transfers. Some patients may not be candidates for operative procedures. Chronic wounds may not be amenable to these treatment options because of poor wound beds and inadequate granulation. Argenta et al. described a VAC using a foam dressing with controlled negative pressure on the dressing sponge and thus the wound. This method of wound care promotes granulation, promotes wound contracture, and decreases bacterial count. The technique has been successful in treating even grade IIIB open tibial fractures that may have required a local muscle flap or a microvascular free tissue transfer.18,26 Surgical debridements are still necessary as an adjunct to the dressing changes. Though some wounds may be treated with this technique until complete closure has occurred, many wounds require additional surgery, such as a skin graft or flap. The significant improvement in the wound bed, however, makes the reconstructive procedure easier. This technique is not effective for ischemic wounds.

Chronic Osteomyelitis

Chronic osteomyelitis after grade III tibial fractures occurs in approximately 5% of open tibial fractures. Early and adequate debridement of open fractures is key to prevention of osteomyelitis. Once osteomyelitis occurs, the mainstay of treatment is debridement of all devitalized tissue and necrotic bone (Figure 94.7) and replacement with healthy, well-vascularized tissue, followed by treatment of the bone defect. Anthony et al. treated 34 patients with chronic osteomyelitis with debridement and immediate muscle flap coverage and antibiotics. They had an overall success rate of 96%.27 May reviewed a 13-year experience with treatment of chronic traumatic bone wounds with microvascular free tissue transfer.28 He had a 95% success rate in his series of 96 patients. The treatment of choice for chronic osteomyelitis remains radical debridement of necrotic tissue and coverage with well-vascularized tissue.

FIGURE 94.4. Open knee wound with necrotic patella. A. Pre-op appearance. B. The wound covered with a gastrocnemius rotation flap. C. The healing wound 6 weeks postoperation.

FIGURE 94.5. Middle third tibial fracture. A. Pre-op appearance B. Hemisoleus flap to cover tibial fracture. C. The healing wound 10 days postoperation.

Most recent studies also show excellent overall success rate in the treatment of chronic osteomyelitis with fasciocutaneous free flaps. Khan et al. showed a 100% survival and boney union in 20 patients treated with radial forearm free flaps.29 Hong et al. showed a 100% success rate in 28 consecutive patients with chronic osteomyelitis treated with the anterolateral thigh flap.30 Musharafieh et al. had success in 21 out of 22 patients treated for chronic osteomyelitis with free flaps.31 However, Gonzalez et al. had a 22% failure rate in patient treated for chronic osteomyelitis with free flaps.32Successful treatment of chronic osteomyelitis of the lower extremity with free tissue transfer can be expected to be from 80% to 95%.

FIGURE 94.6. Mangled extremity with severe IIIB fracture and multiple areas of exposed bone. A. Pre-op appearance B. Salvage after multiple debridements, bone grafting and rectus free flap.

FIGURE 94.7. Chronic IIIB tibia fracture with exposed bone. A. Pre-op appearance B. Radical debridement of all devitalized bone and soft tissue. C. The wound after extensive debridement. D. After coverage with parascapular free flap. E. 24-year follow-up.

Salvage of Below-Knee Amputation Stumps

When limb salvage is not possible, every attempt should be made to preserve as much limb length as possible. This is particularly important with respect to the knee joint. If the knee unit is salvageable, a below-knee amputation is performed. The work of ambulation is significantly reduced in patients with below-knee amputations when compared with patients with above-knee amputations. Patients with below-knee amputations have a more normal gait and a greater ability to perform more physical activities than patients with above-knee amputations. The development of microvascular surgery has allowed salvage of extremities at a more distal level. This is particularly true when the main problem is inadequate soft-tissue coverage.

Advantages of More Distal Amputations. Ambulation with a below-knee amputation requires 25% more energy and oxygen consumption than ambulation without an amputation. Above-knee amputations necessitate 65% more oxygen and energy consumption compared with nonamputees. Patients with bilateral below-knee amputations have a 45% increased oxygen and energy consumption requirement for ambulation when compared with nonamputees. The amputee will walk more slowly to compensate for the increase in energy required. The higher the level of the amputation, the more energy required, and the slower and less effective the ambulation.

Quality of life is also significantly affected by the level of amputation. The daily distance walked is significantly less in above-knee amputation patients as compared to below-knee amputation patients. More above-knee amputation patients walk only in the house or do not walk at all. Above-knee amputation patients have more trouble with stairs and ramps and often require hand controls to drive.

Free Flap Salvage of Below-Knee Amputation Stumps. If the distal limb is nonsalvageable but the knee joint is functional, every attempt should be made to preserve a below-knee amputation. Although the ideal below-knee amputation stump has >6 cm of tibia below the tubercle, any length of tibia should be preserved as the benefits of a below-knee amputation are great compared with above-knee amputation. If adequate soft-tissue coverage is present, the stump may either be closed primarily or closed in a delayed fashion. If insufficient soft tissue exists to cover the bone, free flap reconstruction is considered. If the foot on the amputated part is uninjured, the plantar surface can be removed and transferred to the stump as a free flap. If the foot on the amputated part is not usable, then a standard free flap can be performed shortly thereafter. In dirty wounds, the free flap is delayed until wound conditions are optimized. Figure 94.8 summarizes the decision- making tree.

In a study by Kasabian, 22 patients achieved stable coverage of below-knee amputations with free flap coverage.33 The most common flap was the parascapular flap, used in 11 patients. A foot fillet flap was used in six cases. The other free flaps employed were the latissimus dorsi,4 lateral thigh,1 tensor fascia lata,1 and groin.1 The patients in the study required an average of 4.9 operations related to their injury. There were 1.3 operations after the free flap. Most patients had long hospitalizations as a result of the combination of their injuries and their overall situations.

The foot fillet flap offers several advantages over other flaps. It is the only flap available from the amputated part and as such has no donor-site morbidity. In addition, sensory innervation is provided by the tibial nerve, peroneal nerves, and sural nerves. The tibial nerve is used most commonly and provides sensibility to the plantar surface of the foot, which is usually inset at the end of the below-knee amputation stump. Neurorrhaphy may be accomplished to a proximal nerve stump or the nerve may be left in continuity. Finally, the foot fillet has glabrous skin that is durable and not prone to ulceration (Figure 94.9).

Muscle free flaps with skin graft coverage tend to heal slowly. There are often areas of partial graft survival. In addition, as the muscle atrophies and the flap shrinks, revisions are required for both the stump and the prosthesis. The additional surgical procedures lengthen the time to the fitting of the final prosthesis when compared with patients with fasciocutaneous flaps.

Oncologic Lower Extremity Reconstruction

Defects of the lower extremity caused by oncologic resection, involving bone and soft tissue, can be salvaged in a similar fashion. Numerous reviews show high success rates in tibial reconstruction with fibula free flaps as well as soft-tissue reconstruction with muscle and fasciocutaneous free flaps. Chen et al. reviewed 25 patients who had reconstruction of long bone defects with vascularized fibula flaps. All flaps survived. After 6 months, 11 of 14 patients had uncomplicated bony union and 13 of 14 patients had bony union after a second procedure.34 Moran et al. reviewed reconstruction of long bone defects salvaged with massive bone allografts and intramedullary free fibular flaps. All flaps survived. Four of seven patients had primary bone union and the other two had bony union with a second procedure.35

Barner-Rasmussen et al. reviewed 75 free flaps for reconstruction after resection of soft-tissue sarcomas of the leg. Success rate was 95%.36 Success rate in reconstruction for oncological resection remains high. The problem remains disease free survival after oncologic resection (Figure 94.10).

FIGURE 94.8. An algorithm for amputation in lower extremity injuries.

FIGURE 94.9. Foot fillet coverage. A. A large zone of injury in proximal tibia area with a long segment of exposed tibia. B. The foot is relatively uninjured. C. Foot fillet dissection performed. D and E. The final result.

FIGURE 94.10. Soft-tissue sarcoma of the lower extremity. A. Pre-op appearance. B. After wide excision of the tumor. C. Tumor specimen. D. After reconstruction with latissimus flap and skin graft.

FIGURE 94.11. Ischemic lower extremity with exposed tibia. The saphenous veins had previously been harvested for coronary bypass grafts. A. Pre-op appearance. B. Angiogram shows inadequate donor vessel for free flap. C. Simultaneous revascularization with polytetrafluoroethylene graft and rectus free flap. D and E. Postoperative result.

Lower Extremity Reconstruction in Vascularly Compromised Patients

Numerous authors have shown that lower extremities may be salvaged even in those patients with severe vascular disease. Colen showed a success rate of nine free flaps in 10 patients with severe vascular disease.37 Serletti et al. reviewed 30 patients with combined vascular bypass and free flap reconstruction. Eighteen patients had simultaneous bypass and flap while 12 had delayed soft-tissue reconstruction. Eight of the 30 reconstructions were unsuccessful with 3 early graft and flap failures and 5 with new areas of ischemia. All required amputation. But 73% were salvaged.38 Most of these salvage attempts were for defects of the foot, which will be discussed in the next chapter. However, revascularization may be required for salvage of defects of the leg. Kasabian et al. described the salvage of a tibial defect with a microvascular free flap using simultaneous polytetrafluoroethylene graft for inflow39 (Figure 94.11).

SUMMARY

Lower extremity reconstruction requires a team approach that carefully assesses the costs, technical considerations, functional results, and psychosocial aspects of the treatment plan.

References

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3.  Laughlin RT, Smith KL, Russell RC, et al. Late functional outcome in patients with tibia fractures covered with free muscle flaps. J Orthop Trauma. 1993;7:123-129.

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24.  Hallock GC. Complications of 100 consecutive local fasciocutaneous flaps. Plast Reconstr Surg. 1991;88:264.

25.  El-Sabbagh AH. Skin perforator flaps: an algorithm for leg reconstruction. J Reconstr Microsurg. 2011;27(9):511-523.

26.  Greer S, Kasabian A, Thorne C, et al. The use of subatmospheric pressure dressing to salvage a Gustilo grade IIIB open tibial fracture with concomitant osteomyelitis to avert a free flap. Ann Plast Surg. 1998;41(6):687.

27.  Anthony JP, Mathes SJ, Alpert BS. The muscle flap in the treatment of chronic lower extremity osteomyelitis: results in patients over 5 years after treatment. Plast Reconstr Surg. 1991;88:311.

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34.  Chen CM, Disa JJ, Lee HY, et al. Reconstruction of extremity long bone defects after sarcoma resection with vascularized fibula flaps: a 10-year review. Plast Reconstr Surg. 2007;119(3):915-924.

35.  Moran SL, Shin AY, Bishop AT. The use of massive bone allograft with intramedullary free fibular flap for limb salvage in a pediatric and adolescent population. Plast Reconstr Surg. 2006;118(2)413-419.

36.  Barner-Rasmussen I, Popovc P, Bohling T, et al. Microvascular reconstruction after resection of soft tissue sarcoma of the leg. Br J Surg. 2009;96(5):482-489.

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38.  Serletti JM, Deuber MA, Guidera PM, et al. Atherosclerosis of the lower extremity and free-tissue reconstruction for limb salvage. Plast Reconstr Surg. 1995;96(5):1136-1144.

39.  Kasabian AK, Glat PM, Eidelman Y, et al. Limb salvage with microvascular free flap reconstruction using simultaneous polytetrafluoroethylene graft for inflow. Ann Plast Surg. 1995:35(3):310-315.