Surgical reconstruction of the lower extremity

INTRODUCTION — Reconstructive surgery may be needed to correct dysfunction and the form of the lower extremity caused by a variety of etiologies including trauma, nonhealing wounds, infection, malignancy, degenerative disease, or congenital deformities.

The principles of surgical reconstruction of the lower extremities are reviewed. Although the discussion focuses largely on the management of the severely traumatized lower extremity, the basic concepts that guide reconstruction are similar regardless of the antecedent etiology. In the lower extremity, it is important to embrace amputation as an integral element of the treatment algorithm; amputation should not be regarded as a loss or failure to treat an injury, and it may represent the best treatment option depending on the severity of disease/injury and the critical status of the patient.

Severe upper extremity injury and reconstruction are reviewed separately. (See "Severe upper extremity injury in the adult patient" and "Surgical reconstruction of the upper extremity".)

INDICATIONS — Multiple etiologies may threaten a patient's lower extremity, including acute trauma, nonhealing wounds due to underlying peripheral vascular disease or diabetes, infection, degenerative disease, osteonecrosis, resection for malignancy, and congenital deformities.

●Traumatic injuries – Acute lower extremity injury is a result of significant traumatic force, and patients should be initially evaluated and cared for within Advanced Trauma Life Support (ATLS) guidelines, including assessment of the patient's airway, appropriate resuscitation, and management of life-threatening torso injuries, which take precedence over limb injuries. Traumatic lower extremity injuries that require reconstructive techniques include open fractures, vascular injuries, crush injuries, traumatic amputations, and severe nerve injuries [1]. Open long bone fractures occur at a rate of 11.5 per 100,000 persons per year, and many of these fractures occur in the tibial shaft [2-4]. Lower extremity trauma is very morbid for the patient and quite expensive to treat though overall less expensive if the limb can be salvaged. In one review, the projected total lifetime costs for a patient whose severely injured leg was able to be salvaged was USD $163,282, while the costs associated with amputation for a comparable injury were $509,275 [5]. (See "Surgical management of severe lower extremity injury".)

●Nonhealing wounds – Nonhealing wounds due to peripheral artery disease (PAD), venous stasis, or diabetes may improve when the systemic disease/disorder is better controlled. As an example, improved diabetes management including proper nutrition and glucose control may help with the healing of related wounds. If wounds persist despite conservative management, lower extremity revascularization may be necessary. Subsequent wound management may require debridement with local flap or free tissue transfer to provide a soft tissue surface for pain-free weight bearing. (See "Management of chronic limb-threatening ischemia" and "Management of diabetic foot ulcers".)

●Infection/osteomyelitis – Antibiotics tailored to the cultured organisms and local wound care are the standard treatment for local/superficial infection of the soft tissue. For deeper infections and osteomyelitis, thorough debridement of all nonviable tissue is required. The duration of antibiotics is often determined in conjunction with infectious disease specialists according to the severity of the infection. Reconstructive surgery is performed once infection is cleared to aid functional recovery. Bone biopsy of any ongoing wound with exposed bone or nonunion may be recommended to exclude osteomyelitis prior to definitive reconstruction. (See "Necrotizing soft tissue infections" and "Surgical management of necrotizing soft tissue infections" and "Nonvertebral osteomyelitis in adults: Treatment".)

●Degenerative disease – Degenerative diseases are mainly caused by repetitive stress and aging. The primary degenerative disorder that affects the lower extremities is osteoarthritis, for which mainly joint replacement is performed, but various other reconstructive surgeries can also be used. Early consultation with a plastic surgeon is prudent to ensuring successful outcomes, particularly in high-risk patients, such as in patients who continue to smoke, patients with PAD, or those who require revision surgery [6-9]. (See "Total hip arthroplasty" and "Total knee arthroplasty" and "Complications of total hip arthroplasty" and "Complications of total knee arthroplasty".)

●Osteonecrosis – Osteonecrosis results from inadequate perfusion to the bone tissue and may be a complication of traumatic injury, radiation, or chronic steroid use. The femoral head is one of the most common locations for osteonecrosis and can affect young, active adults or those with a history of corticosteroids [10]. (See "Clinical manifestations and diagnosis of osteonecrosis (avascular necrosis of bone)" and "Treatment of nontraumatic hip osteonecrosis (avascular necrosis of the femoral head) in adults".)

●Malignant tumors – Surgical treatment of long bone tumors may involve radical resection of the tumor, including en bloc resection of bone, neurovascular structures, and soft tissue. Limb salvage is the standard of care following lower extremity oncologic resection [11]. Often, local flaps or pedicled flaps can be used for soft tissue coverage of the resulting defects. For more extensive wounds, free tissue transfer is necessary. Free fibula reconstruction first can be used with or without allograft for long bone reconstruction of the lower extremity [12-15]. The fibula can also be transferred with its epiphysis for future growth potential [16]. Following lower extremity amputation for malignant tumor, fillet flaps from the amputated extremity have been used for reconstruction as pedicled or free flaps (eg, coverage for hip disarticulation) [17,18]. (See "Surgical resection of primary soft tissue sarcoma of the extremities" and "Flap reconstruction of the lower extremity", section on 'Fillet of sole flap'.)

●Congenital disease – The goal of reconstruction of congenital disease affecting the lower extremity is to preserve future growth and reduce the risk of limb-length discrepancies. Severe limb defects can be treated with lengthening operations. Amputation with prosthetic reconstruction is also an option; however, prostheses are associated with potential infection and exposure and are without future growth potential.

PLANNING AND DECISION-MAKING

Orthoplastic approach — Owing to the complexity of lower extremity wounds and overall critical state of the patient in the setting of trauma, reconstruction of the lower extremity should be undertaken with a multidisciplinary team approach. For acute wounds, this team generally includes trauma and orthopedic surgeons as well as plastic surgeons. First described in the early 1990s, the collaborative orthoplastic approach between orthopedic and plastic surgeons in limb salvage resulted in a unique field of reconstructive surgery [19]. With time, orthoplastic surgery became known as "the principles and practices of both specialties applied to a clinical problem either by a single provider, or teams of providers working in concert for the benefit of the patient" [19-21]. Successful reconstruction of chronic or other wounds may similarly require a team approach, including vascular and plastic surgeons, wound care including hyperbaric oxygen therapy specialists, and endocrinologists.

For traumatic wounds, the reconstructive surgeon should be involved in the immediate evaluation of the wound given their set of concerns in planning ongoing management and reconstruction [1]. When planning reconstructive options, the plastic surgeon should approach the wound critically, breaking the wound down into sections.

●What in the wound must be covered with vascularized tissue? As an example, exposed bone, joint, and tendon must be covered with tissue that has a robust blood supply. Areas such as the sole of the foot must also be covered with enough soft tissue padding to allow for pain-free ambulation and weight-bearing. Exposed hardware from an infection or trauma necessitates well-vascularized soft tissue coverage.

●What areas of the wound can be allowed to granulate and what areas will tolerate a skin graft?

Similarly, orthopedic surgeons should also be involved in the initial wound assessment diagnosing and stabilizing fractures. When fractures or bone loss is present, the reconstructive surgeon should speak specifically with the orthopedic surgeon regarding planned method and timing of fixation and definitive reconstruction. Open lower extremity fractures are commonly classified by the Gustilo system (table 1) [22,23]. The system categorizes open fractures based on wound size, degree of soft tissue damage, and the amount of contamination. The Gustilo classification has some limitations. It does not account for nerve injury or vascular injuries that do not result in a dysvascular extremity [24]. Perhaps more importantly, it does not consider the exact location on the extremity, which plays a major factor in reconstruction. As an example, more proximal injuries are generally more amenable to local/regional flaps, while distal wounds will likely require free flap placement due to the relative paucity of soft tissue covering the bony structures of the distal extremities. For wounds requiring free flap coverage, a large amount of periosteal stripping may necessitate an osteocutaneous flap rather than a fasciocutaneous or musculocutaneous flap. Nevertheless, the Gustilo system facilitates communication between team members and is a useful way to initially categorize an injury and assess the extent and timing of reconstructive procedures needed.

Patient evaluation — Together with the primary surgical team, the required extent of resection or debridement is determined, and the reconstructive surgeon begins planning reconstructive steps based on the patient's history, physical examination, and imaging studies.

A complete medical history and social history are essential, as comorbidities (eg, diabetes, peripheral artery disease) and social factors such as tobacco use and even level of education affect the outcome of patients with lower extremity wounds [25-27]. Data suggest that the modified frailty index (calculated based on functional status, diabetes, chronic obstructive pulmonary disease, congestive heart failure, and hypertension) is the strongest predictor of outcomes in lower extremity flap reconstruction [28]. For traumatic injuries, details of the trauma are essential and will likely guide later care and should include mechanism of injury, timing (especially important for amputated extremities), and length of entrapment or crush injury.

Clinical assessment varies depending upon the specific indication for lower extremity reconstruction.

●Lower extremity trauma (see "Severe lower extremity injury in the adult patient" and "Severe crush injury in adults")

●Chronic wounds and infection (see "Risk factors for impaired wound healing and wound complications" and "Clinical assessment of chronic wounds" and "Overview of treatment of chronic wounds")

●Degenerative disease (see "Preoperative evaluation and perioperative management of patients with rheumatic diseases")

●Malignancy (see "Preoperative evaluation and management of patients with cancer")

Limb assessment — For traumatic lower extremity wounds, evaluation of the lower extremity can proceed once the patient is clinically stable and other life-threatening injuries have been addressed. In practice, the reconstructive surgeon asked to evaluate a traumatized limb often works concurrently while the primary team completes their initial Advanced Trauma Life Support (ATLS) assessment and management. The reconstructive surgeon should keep in mind that crush and shear forces affect the soft tissue and blood vessels peripheral to the obvious site of trauma, creating a "zone of injury." In addition, all clinicians evaluating a traumatized lower extremity should rule out compartment syndrome. (See "Pathophysiology, classification, and causes of acute extremity compartment syndrome" and "Acute compartment syndrome of the extremities" and "Lower extremity fasciotomy techniques".)

Whether evaluating a patient with an acutely traumatized limb, a patient with a chronic lower extremity wound, or the potential defect following elective tumor resection, physical evaluation of the limb should proceed from an overall gestalt to individual clinical details. Limb assessment should include:

●Identification of any gross limb abnormality.

●Identification of any tissue injury or loss, including laceration, abrasions, open areas, or avulsion injuries.

●Documentation of the femoral, popliteal, posterior tibial, and dorsalis pedis pulses using Doppler assessment. Diminished or absent pulses or Doppler signals should be noted. With traumatic injuries, these often improve with bony reduction unless significant vasospasm or vessel injury is present. In the setting of trauma, the presence of vascular injury is a marker of worse trauma severity and also impacts long-term function [24,29].

●Evaluation for signs and symptoms of compartment syndrome. (See "Pathophysiology, classification, and causes of acute extremity compartment syndrome" and "Acute compartment syndrome of the extremities" and "Lower extremity fasciotomy techniques".)

●Evaluation of skin turgor and temperature, which are important clues to the current and long-term perfusion of the limb. Lack of hair and shiny skin may indicate chronic ischemia. (See "Clinical features and diagnosis of acute lower extremity ischemia" and "Clinical features and diagnosis of lower extremity peripheral artery disease".)

●Documentation of a complete motor and sensory neurological examination. Motor examination should include hip flexion/extension, adduction/abduction, knee flexion/extension, foot plantar/dorsiflexion, eversion, and inversion. Sensory examination should include crude touch, pinprick/temperature, and a 10 gram (5.07 Semmes-Weinstein) sensory testing nylon filament. The extent of functional deficit of each neuromuscular unit is evaluated based on anatomic relationships. (See "Traumatic peripheral neuropathies" and "Overview of lower extremity peripheral nerve syndromes".)

•The sciatic nerve branches into the common peroneal nerve (branches into superficial peroneal nerve and deep peroneal nerve) and the tibial nerve in the popliteal fossa. (See "Overview of lower extremity peripheral nerve syndromes", section on 'Sciatic nerve'.)

•Injury to the tibial nerve is often a result of trauma, entrapment, or compression and results in loss of plantar flexion, weakened inversion, and loss of toe flexion. (See "Overview of lower extremity peripheral nerve syndromes", section on 'Tibial nerve'.)

•The superficial peroneal nerve is the main nerve of the lateral compartment of the leg. Injury results in loss of foot eversion and loss of sensation over most of the dorsum of the foot. However, superficial peroneal nerve injuries are uncommonly symptomatic to the point of seeking surgical treatment. (See "Overview of lower extremity peripheral nerve syndromes", section on 'Fibular (peroneal) nerve'.)

•Injury to the motor branches of the common/deep peroneal nerve can result in symptoms of "foot drop." As a result, loss of ankle dorsiflexion (tibialis anterior, peroneus tertius), foot eversion (peroneus longus, peroneus brevis), and toe extension (extensor hallucis longus, extensor digitorum longus) reduce function in everyday life. (See "Foot drop: Etiology, diagnosis, and treatment".)

The extremity should be photographed, and measurements of the wound, including width, depth, tunneling, undermining, and exposed vital structures should be documented. Acute soft tissue injuries to lower extremities are like burn injuries in that tissue that appears viable on first evaluation may demarcate in subsequent days because of an injured zone of stasis that progresses to partial- or full-thickness tissue loss. This is particularly true with avulsion injuries for which the underlying subcutaneous pedicle is significantly undermined. Moderately perfused tissue on initial debridement is likely to progress to full-thickness loss and should therefore be debrided but may be allowed to demarcate if serial debridement is planned.

Vascular imaging — Any concern for vascular injury during extremity evaluation (diminished pulses, abnormal ankle-brachial index) warrants additional imaging and consultation with a vascular surgeon. Duplex ultrasonography and computed tomographic (CT) angiography are useful for general planning when selecting recipient vessels for free tissue anastomoses. However, digital subtraction angiography (DSA) is superior for identifying intimal injury, calcifications, and distal (infragenicular) runoff. DSA can also help differentiate between vasospasm and thrombus formation. The use of duplex ultrasound has increased in popularity as high-resolution and handheld ultrasound devices have become more available. These devices put the relevant vascular anatomy directly into the hands of the reconstructive surgeon for evaluation of the donor and recipient site. With this tool, the reconstructive surgeon to can locate a dominant perforator when designing a flap for free tissue transfer and use of duplex ultrasound may even reduce operative times when used for preoperative perforator mapping [30,31].

Limb salvage versus amputation — In addition to critically approaching the wound and recognizing what vital structures must be covered, the reconstructive surgeon also bears a large responsibility in deciding whether the available reconstruction options are preferable to amputation. Key questions to pose in weighing these two options include:

●What does the limb do now and what does it need to do in the future?

●What are the goals of reconstruction (maintenance of independent ambulation, structural support for transfers, coverage of a chronic wound)?

●Given the goals of reconstruction, does the limb need to be sensate?

●How much motor function is necessary to meet the goals of reconstruction?

●Are the other injuries so severe that limb salvage is not safe?

For patients with traumatic injuries, the reconstructive surgeon should be in close communication with the trauma team about how the severely injured limb fits into the patient's overall clinical status, which may be facilitated using clinical scales based on anatomic and physiologic derangements such as the Glasgow coma scale, Injury Severity Score (ISS), and APACHE (Acute Physiology and Chronic Health Evaluation) [32-34].

Clinical scoring systems for trauma — In the trauma population, clinical scoring systems have been developed to identify patients who would be better served by limb salvage efforts versus amputation. These have included the Mangled Extremity Severity Score (MESS, 1990), Limb Salvage Index (1991), Predictive Salvage Index (1987), and Nerve, ischemia, soft tissues, skeletal, shock and age (NISSSA, 1994) [35-37]. However, a landmark study in 2001 using the Lower Extremity Assessment Project (LEAP) data was not able to validate any of these scoring systems in terms of predicting outcomes [38].

Lower Extremity Assessment Project (LEAP) — LEAP is largest study of limbs threatened by acute injury and involved 569 patients from eight Level 1 trauma centers [25]. The main goal of LEAP was to provide data to guide limb salvage in patients with severely traumatized lower extremities (defined by Gustilo-Anderson Grade IIIB or Grade IIIC fractures (table 1), select Grade IIIA fractures, dysvascular limbs, major soft tissue injuries, or severe foot and ankle injuries). The LEAP data demonstrated that high-energy trauma is very morbid whether the limb was managed with reconstruction or amputation (49.4 and 53 percent respectively). Roughly half of patients were able to return to work at two years. Patients who underwent reconstruction were more likely to be rehospitalized after their initial trauma compared with those who underwent amputation (47.6 versus 33.9 percent) and to require a subsequent surgery (19.1 versus 5 percent). Both groups self-reported similarly poor scores on the Sickness Impact Profile. Factors that contributed to a poor outcome in both groups included being rehospitalized for a major complication, lower education level, lower income, having no insurance, having a poor social support network, smoking, or being involved in an ongoing legal case for injury compensation.

Over the remaining life expectancy of a trauma patient, economic cost and utility analyses using the raw LEAP data have reported that reconstruction for limb salvage is probably less expensive overall and more satisfying to patients than amputation [39]. However, because the data are observational, it does not account for the possibility that patients who underwent amputation inherently had more severe injuries that required more costly treatment and that would have led to decreased utility if salvage had been attempted.

Surprisingly, a review of LEAP reported that plastic surgeons were directly involved in only 14 percent of cases [25,40]. The decision to amputate may have been related to medical comorbidities or socioeconomic factors perceived to have the potential to impede the long recovery process following complex limb salvage. Proceeding with amputation may also have been related to providers being less familiar with complex reconstructive techniques, lack of access to multidisciplinary techniques/strategies, or the assumption that nerve injury precludes successful salvage [41]. Perhaps with the use of an orthoplastic approach, more patients would have undergone attempted salvage with potentially higher success rates [42,43].

The presence or absence of plantar sensation often assumes a prominent role in decisions about amputation versus reconstruction. One study found that nerve integrity, plantar sensation, soft tissue injury, and initial pulse (vascular injury) were major factors used when considering amputation [44]. However, LEAP showed that patients with an initially insensate foot who underwent salvage treatment did not report or demonstrate significantly worse outcomes compared with the initially insensate patients who were amputated or the patients with an initially sensate foot that underwent reconstructive management [41]. In the salvage group (insensate and sensate), an equal proportion (about 55 percent) had normal plantar sensation two years later, regardless of whether plantar sensation was present at admission. At two years after injury, only one patient in the insensate salvage group had absent plantar sensation. The authors concluded that initial plantar sensation is not prognostic of long-term plantar sensory status or functional outcomes and that it should not be considered in the decision-making for amputation versus salvage.

Patient triage and Lower Extremity Guide for Salvage (LEGS) — Equally important to specialized multidisciplinary care, expediting early diagnosis, treatment, and transfer, when necessary, for patients with traumatic lower extremity injuries improves outcomes [42,45-47]. Rehabilitation and psychosocial needs must also be addressed to offer these patients the best chance for recovery [25]. Protocolizing the triage of severe lower extremity injuries to include quicker and more specialized management with microvascular expertise also decreases unnecessary resource utilization [45]. As an example, the American Society for Surgery of the Hand and the American College of Surgeons have had tremendous success in an initiative to regionalize the care of severe mutilating upper extremity injuries via the National Hand Trauma Center Network [48].

Although studies have urged immediate transfer and early combined surgery for patients with open tibial fractures, proposals on how this is best accomplished are lacking. Following lower extremity trauma, a major factor delaying soft tissue coverage is transfer from another hospital [46]. Patients directly admitted to a tertiary trauma center have fewer surgical procedures overall compared with those who are transferred from other facilities. Other studies have corroborated these findings, demonstrating increased morbidity and mortality associated with transfer delays [49-51], including increased risk of venous thromboembolism [52], osteomyelitis, and nonunion [53].

We have created the Lower Extremity Guide for Salvage (LEGS) (figure 1) that may help this oftentimes challenging decision-making process based on expert opinion and available evidence [54]. The guide demonstrates factors that should result in transfer to a specialized center with limb salvage and microvascular capabilities. However, transfer should be encouraged/initiated based on the triaging physician’s judgement of the capabilities of that hospital.

These factors include, but are not limited to:

●>2 cm of bone loss

●Compartment syndrome (after initial decompression)

●Open fracture or exposed bone/joint with soft tissue loss not amenable to primary closure (ie, requiring microvascular reconstruction)

●Massive burns with open long bone fractures

●Open fracture with serious comorbidities (eg, diabetes, peripheral vascular disease)

●Absent pedal pulses, concern for dysvascular limb

●Absent plantar sensation, concern for nerve injury

●Significant foot/ankle soft tissue loss, including any plantar soft tissue loss

●Fracture with associated compartment syndrome

●Crush or blast mechanism injury involving multiple fascial compartments

●Patients who will require special social, psychologic, or rehabilitative intervention

●Polytrauma with limb injury meeting above criteria following initial stabilization in a trauma center as necessary based on the triaging physician's judgement

Similar to the American Burn Association (ABA) criteria for burn center referral [55], guidelines such as these can help facilitate immediate transfer of patients with severe lower extremity injuries to centers with orthoplastic expertise. As an example, LEAP disproved a common misconception that an insensate traumatic limb should be amputated; LEGS shows that these patients should be transferred [41]. Rather than any one criteria/guideline being considered a hard indication for transfer, LEGS should serve as a guide and offer comfort to providers at institutions with less resources to reach out to tertiary centers in consultation when considering transfer. As examples, patients with compartment syndrome and those with greater than 2 cm of bone loss have an increased risk of infection and may benefit from early transfer and admission to a specialized limb salvage center after emergency management of their initial presentation (eg, revascularization, compartment syndrome decompression) [56]. Also, consideration should also be given for transfer of lower extremity injuries (even if less severe) in patients with comorbidities such as diabetes and peripheral artery disease who would benefit from specialized multidisciplinary input. Despite best efforts, there is a risk of secondary amputation after lower extremity free flap reconstruction, and this is mostly attributable to infection [57].

Replantation — Replantation attempts of traumatically amputated lower extremities are rare, given that shear and crush forces are often a factor. When traumatic amputation does occur, amputated parts should be collected and wrapped in moist gauze placed in a bag over ice prior to transport from the field. Regardless of potential for replantation, components of the amputated limb (eg, soft tissue) may be used in reconstruction [58,59]. As an example, the fillet of sole flap can be used as a pedicled flap or free tissue transfer to cover exposed tibia or femur. When indicated, replantation should only be attempted at specialized centers with appropriate expertise, facilities, equipment, and personnel; otherwise, referral is prudent.

Absolute indications for replantation cannot be equivocally established in children and adults given the high risk for complications and complexity of the process. However, in children, indications are looser, and specialized surgeons with microvascular training may be more inclined to attempt replantation/reconstruction for more severe injuries [60]. Replantation should be considered in guillotine-like injuries in children and young adults in which a "clean-cut" vector leaves arteries and veins amenable to microsurgical anastomosis [61]. Other factors to take into consideration when faced with the dilemma of lower limb replantation include the patient's desire, ischemia time, type of injury, and general condition of patient [62].

Frequently cited contraindications to lower extremity replantation include [62]:

●Significant bone loss (approximately 18 to 20 cm)

●Massive crush injury of the extremity

●Anatomic destruction of the sole of the foot (eg, severe comminution and mangled structures)

●Concurrent destruction of the knee joint in a young patient

●Sacral root avulsion

●Prior nonambulatory status

●Extended ischemia time (>8 to 10 hours)

●Concomitant other life-threatening injuries

In addition, the combination of older age, severe peripheral artery disease, or other comorbidities contraindicates replantation. Heel, calcaneal, and sole amputation should be replanted as long as the extent of destruction does not preclude safe replantation, since the reported results are superior to any available reconstruction [63,64]. The outcome or replantation is more favorable in the absence of severe contamination, comminution, and mangled structures and is more likely to be successful in the hands of an experienced microvascular surgeon.

Initial wound management — The first step in managing acute lower extremity wounds is wound bed preparation beginning with initial debridement, which typically takes place in the operating room. The wound is copiously irrigated with a warm lavage solution, and all foreign debris and devitalized tissue are removed. The wound must be debrided aggressively so only viable tissue remains; any remaining necrotic tissue only serves as a nidus for infection. However, areas of questionable perfusion may be left intact for a "second look" procedure for additional debridement, as needed, in one to two days. Although immediate or near-immediate soft tissue coverage is advocated by some [39], given the inflammatory response of tissue in the "zone of injury," it is not unusual for a patient to require several trips to the operating room. The wound should be photographed following each debridement and wound measurements recorded. Once the wound is clean, definitive coverage can proceed. In preparation for initial debridement of acute wounds, any fractures of the lower extremity can be stabilized, which corrects some of the systemic effects of the fracture and eases the patient's pain. Definitive fixation may be delayed depending on the nature of the patients' trauma and their overall clinical status; quick skeletal stabilization can be achieved with external fixators [65]. (See 'Bone stabilization and reconstruction' below.)

Chronic wounds should be managed in much the same way as an acute traumatic wound. Debridement effectively changes a chronic wound into an acute wound to allow for reinitiation of the wound healing process. Subacute presentations may be associated with varying levels of tissue inflammation with reduced mobility/pliability of the soft tissues, favoring delayed reconstruction. If the clinician suspects infection, tissue culture aids in distinguishing infection from colonization. While all chronic open wounds are colonized with bacteria, not all open wounds are infected. (See "Clinical assessment of chronic wounds", section on 'Signs of infection'.)

Any patient with nonpalpable pedal pulses or signs of chronic arterial or venous changes warrants vascular evaluation. Noninvasive duplex ultrasound is very helpful in the setting of suspected chronic lower extremity arterial or venous insufficiency. Inadequate blood flow or venous incompetence warrants a referral to a vascular surgeon for possible intervention prior to any reconstructive efforts [66]. (See 'Vascular imaging' above and "Noninvasive diagnosis of upper and lower extremity arterial disease".)

Chronically devascularized tissue should only be debrided after revascularization procedures are complete to minimize tissue loss. Of note, maximal tissue oxygenation after open bypass surgery occurs at 6 to 10 days and at roughly 28 days after endovascular procedures.

Timing of debridement — It makes intuitive sense that open fractures should be thoroughly irrigated and debrided as soon as possible. Traditionally, the standard of care for open fractures has been debridement within six hours. However, as part of the LEAP project, this somewhat arbitrary timeframe was questioned. In a review of open fractures that went to the operating room within 24 hours, time from injury to operative debridement was not a significant independent predictor of infection [56]. In a separate review, there was significant difference in rates of infection for patients who were debrided within six hours of injury compared with those who went to the operating room between 6 and 24 hours [67]. However, the incidence of infection was increased for those with prolonged time to admission at a trauma center (greater than two hours) compared with admission to a trauma center within two hours (55.8 percent and 20.4 percent, respectively). The increase in infection increased linearly for patients who were transferred from outside hospitals in a delayed manner (4 to 24 hours) when compared with patients who were transferred more promptly (within three hours). This relationship between time of injury and admission to a definitive trauma center and subsequent risk of infection may be a surrogate for and correlate with the time between injury and initial antibiotic administration [56,67,68]. Thus, broad spectrum intravenous antibiotics should be administered as soon as possible to a patient with an open fracture.

Timing of reconstruction — The timing of closure and/or reconstruction of soft tissue defects is related to the severity of fractures, when present, the amount of tissue loss, the quality and location of the remaining tissue, and wound classification (table 2). The clinician should remember, though, that the blood supply to the leg and foot is not as robust as in the upper extremity or face. If there is any doubt regarding the amount of tension or contamination level of the wound, the wound should not be closed. Multiple techniques are available that can be used as part of a delayed closure strategy.

At the authors' institution, the orthopedic surgeons stabilize the fracture, and we, as reconstructive surgeons, participate in and advise the initial debridement. Depending on the fracture pattern, an external fixator technique is often used acutely, rather than providing definitive fixation. In relatively clean open fractures with minimal bone loss, the orthopedic surgeon may plate the fracture, although they are aware that periosteum may be devascularized in the process of plate placement. Depending on location and provided there will not be undue tension on the remaining soft tissues, Gustilo grade I and potentially grade II injuries can possibly be closed primarily.

If a large bony defect is encountered, definitive management is postponed. The orthopedic surgeon may elect to leave antibiotic impregnated beads in the bony defect, but cadaveric bone or avascular bone grafts should not be introduced into an acute wound that is contaminated or dirty, and management should be deferred until all devascularized bone and tissue have been removed through serial debridement and the wound is able to be covered with well-perfused soft tissue.

Exposed bone and tendon are covered with a moist dressing to prevent desiccation. Various topical agents and dressings are available for interim dressing care (eg, petrolatum impregnated gauze, mafenide acetate, silver sulfadiazine, calcium alginate dressings, other biosynthetic wound dressings) (table 3). The selected dressing should be nonadherent to the underlying tissues, noncytotoxic, and should prevent desiccation.

In the management of lower extremity trauma, the authors have had much success with negative pressure wound therapy (NPWT). While NPWT is contraindicated in grossly infected wounds, it is useful for reducing the size of soft tissue defects (eg, acutely swollen legs that have undergone fasciotomy), preparing wounds for split-thickness skin grafting, and as a way of managing large wounds in the interim period between operative debridement and definitive soft tissue coverage. If bone or other delicate structures are exposed in the wound bed, nonadherent dressings can be placed overlying to prevent desiccation. The indications, contraindications, and techniques for placement of NPWT dressings are reviewed separately. (See "Negative pressure wound therapy".)

The timing of definitive lower extremity soft tissue coverage is dictated by the patient's overall clinical picture and the condition of the wound [69]. Acute coverage by five to seven days is generally the standard of care for preventing infection and aiding in fracture healing. A microsurgical pioneer in limb salvage (Marko Godina) showed the importance of early coverage of traumatic lower extremity injuries with free tissue transfer [70,71]. Decreased rates of nonunion and osteomyelitis were observed in patients who had soft tissue coverage in fewer than three days since time of injury compared with a later timeframe [71]. However, since this early report, significant advances in surgical techniques, antimicrobial therapy, and temporary wound coverage adjuncts have been made [72]. Contemporary data suggest that the optimal period of microsurgical soft tissue coverage can be safely extended without an adverse effect on outcomes [73-75].

GOALS AND INFORMED CONSENT — Before proceeding with lower extremity reconstructive surgery, realistic goals must be set. The discussion should include the patient's desire for limb salvage versus amputation, as well as the likelihood of each based on best available data. In some cases, the available tissue for reconstruction will be limited, and this may necessitate free tissue transfer to help approach normal form and function. Unexpected problems can be encountered during any surgery, and the surgeon must have alternative plans to accommodate for them. It is important that the patient is informed beforehand about all possible treatment paths. (See "Informed procedural consent".)

An orthoplastic approach is critical, and any subsequent treatment and rehabilitation plan should be well-organized [76]. While it is always desirable to avoid multiple surgeries, some situations will require multiple operations because of the patient's age, the extent of the patient's injury or defect, or the nature of the reconstruction.

Expectations for recovery should be discussed to avoid disappointment, particularly if there are any anticipated residual aesthetic or functional deficits [77]. Older patients and those with multiple comorbidities are likely to have longer recovery periods. Equally important is the availability of psychosocial support mechanisms in place to facilitate recovery.

BONE STABILIZATION AND RECONSTRUCTION — Bony stabilization constitutes the foundation of reconstructive surgery of the extremity. The Arbeitsgemeinschaft für Osteosynthesefragen (AO) was formed in 1958 with a focus on patients with musculoskeletal injuries and related disorders to provide care that will allow a patient to return to function and mobility [78]. The founding management principles include fracture reduction to restore anatomic relationships, fracture fixation to provide absolute or relative stability, preservation of blood supply to soft tissues and bone by careful handling and gentle reduction techniques, and early mobilization and rehabilitation.

Fractures — Quick stabilization of lower extremity fractures can be achieved with external fixators in preparation for initial debridement. Stabilization of fractures eases the patient's pain and corrects some of the systemic effects of the fracture. Definitive fixation may be delayed depending on the nature of injuries and their overall clinical status [65]. (See 'Initial wound management' above.)

Simple fractures can be easily stabilized with intramedullary rods or external fixation with the plating, when necessary (algorithm 1). Management of specific lower extremity fractures are reviewed separately. If emergency revascularization is also necessary, external fixation can be used for initial bony stabilization, keeping in mind the exposure necessary for vascular reconstruction.

●Femur fracture (see "Midshaft femur fractures in adults")

●Tibial/fibular fracture (see "Overview of tibial fractures in adults" and "Tibial shaft fractures in adults" and "Proximal tibial fractures in adults" and "Fibula fractures")

●Ankle fracture (see "Ankle fractures in adults")

●Foot fracture (see "Talus fractures" and "Calcaneus fractures")

Closing bony gaps — Bone defects and avascular bone fragments are often seen in severe injuries and can cause nonunion of the fracture and osteomyelitis. For the success of the bone reconstruction, the reconstructive surgeon should preserve vascularized bone fragments, aggressively debride avascular, contaminated/infected fragments, and compensate for bony gaps by using bone grafts or bone transport.

Bone grafting — Bone grafting is the most commonly used procedure to close bony gaps [79]. Several types of bone grafts are available, including autologous grafts (or autografts), allogeneic grafts (or allografts), and synthetic grafts. All bone grafts are used to serve as a scaffold to fill gaps with new bone growth, a process referred to as osteoconduction. In addition, autografts and some allografts trigger osteoinduction, which is the formation of new bone through the differentiation of osteoprogenitors into osteoblasts. For allografts, the success rate is 60 to 80 percent for appropriately sized defects, but there remains a risk for nonunion, infection, and fracture [76].

Autografts, which include nonvascularized and vascularized bone grafts, are commonly used for their osteoinductive and osteoconductive properties. With nonvascularized bone grafting, the surgeon harvests only the bone, whereas with vascularized bone grafting, the bone is harvested along with an artery and vein, which are anastomosed with the arteries and veins at the recipient site.

●Nonvascularized bone grafts for extremity reconstruction are mainly harvested from the iliac crest. Nonvascularized bone grafting is accomplished by filling the gap between bone fragments with the harvested corticocancellous bone. For a long bone defect that is less than 6 cm in length, a staged approach with the use of an antibiotic-impregnated spacer followed by nonvascularized corticocancellous bone graft to the spacer induced membrane can be used for reconstruction (ie, Masquelet technique). (See 'Other options' below.)

●For vascularized bone grafting, bone is harvested along with an artery and vein, which are anastomosed with the arteries and veins at the recipient site. Vascularized autografts are generally preferred for defects greater than 6 cm. For lower extremity reconstruction, the free fibula graft is the most-used vascularized autograft. This involves transfer of bone with its native blood supply to the defect and anastomosing the artery and vein. When used for these large defects, the osteocutaneous fibula flap can provide up to 18 to 20 cm of vascularized bone. Other options include the vascularized autografts obtained from the iliac crest, rib, radius, medial femoral condyle, or scapula. (See 'Osteocutaneous free flaps' below.)

To aid in harvesting autografts, as well as debridement of necrotic bone and clearing and sizing the medullary canal, a "reamer-irrigator-aspirator" (RAI) system, which provides continuous irrigation and suction during long bone reaming, can be used [80,81].

Osteocutaneous free flaps — Two commonly used osteocutaneous flaps include the medial femoral condyle (MFC) flap, also known as medial genicular artery flap, as well as the free fibula flap.

Medial femoral condyle flap — Given the rich vascular supply of the medial femoral condyle flap and reliability of its pedicle, it was first described as a pedicled flap. The flap is based upon the descending genicular artery, a branch of the superficial femoral artery, and on the superomedial genicular artery. It has been used for larger bone grafting procedures as well as for osseous defects measuring up to 4 cm in largest dimension, although there is anatomic data that a much larger cortical segment can be safely harvested [82-84]. It can be harvested as an osteogenic periosteal, an osteoperiosteal, or a cutaneous osteoperiosteal flap. In lower extremity reconstruction, the medial femoral condyle flap has been described as a method of supplying well-vascularized corticoperiosteum in treating recalcitrant nonunion of the femur, tibia, and foot/ankle [85]. (See 'Repair of nonunions' below.)

Fibula osteocutaneous flap — The vascularized fibula bone flap has been used extensively due to its large size (up to 18 to 26 cm in length), predictable dissection, and acceptable donor site morbidity. It is the most commonly used vascular bone flap for bony reconstructions of the femur and tibia (picture 1) [16]. The fibula has a reliable vascular supply from peroneal artery perforators and can be harvested with a skin paddle and/or part of soleus muscle, making it particularly useful in patients with combined bony and soft-tissue defects. Including a skin paddle also allows for post-operative monitoring via doppler checks and/or clinical exam (eg, skin color, temperature, capillary refill). With its strength and long-cylindrical shape, this flap serves as a suitable autograft for reconstruction of the mid-tibia and will reliably hypertrophy with axial loading (ambulation) within the confines of a multiplanar external fixator [16]. Reconstruction can be combined with an endoprosthesis if the tibial defect involves the articular surface [86]. An ipsilateral, pedicled fibula flap is a reasonable technique for tibial shaft reconstruction or knee arthrodesis. The fibula may also be used in a "double-barrel" fashion to reconstruct bony pelvic defects (picture 2).

The fibula should also be considered the first choice for autologous vascularized reconstruction of the femur. Additional cross-sectional strength for this purpose may be obtained by making a double-barrel fibular segment. We typically resect 1 to 2 cm of bone if fashioning a double-barrel fibula to avoid having too much tension on the pedicle when the segment is folded. Also, combination of free fibula transfer and distraction osteogenesis has been used effectively over the past 15 years [87]. In a retrospective review of vascularized fibular flaps used in patients with immediate femur reconstructions, intramedullary fibula placement was associated with a lower complication and metallic implant conversion rates compared with onlay fibular vascularized bone flaps [88].

The Capanna technique of massive allograft combined with free fibular reconstruction is a well-established technique with long-term success >90 percent and should be considered in cases of large bony resection, such as following oncologic surgery [13,14]. Such a technique offers a quicker recovery, as there is no requisite wait period for fibular hypertrophy.

Open fractures — For open fractures in the lower extremity, definitive fixation and defect coverage with a soft tissue flap is aggressively performed (algorithm 1). This approach facilitates fracture repair and helps prevent nonunion, deformity, and infection with the vasculature provided by the flap.

Repair of nonunions — The treatment of nonunion depends on how the initial injury occurred (algorithm 2). Causes of nonunion include inadequate fixation of bone fragments, poor bone healing, or a combination of both.

●Hypertrophic nonunion – Hypertrophic nonunion is due to inappropriate fixation in the presence of adequate biologic wound healing capability, and radiography demonstrates a hyperplastic callus. Hypertrophic nonunion can be treated adequately with internal fixation fortified with extra plating or by exchanging an existing intramedullary rod for a thicker one.

●Oligotrophic nonunion – Oligotrophic nonunion (or atrophic nonunion) is due to poor bone healing, with imaging demonstrating atrophy of bony structures around the injury site. Fracture healing stops because surrounding soft tissue fills in the gaps between the bone fragments, disrupting bone healing. Tissue curettage and bone grafting are performed to stimulate healing.

Osteonecrosis — Osteonecrosis (image 1) can lead to severe and debilitating arthritis and commonly affects young, active adults [10]. The use of free vascularized fibular grafts for femoral-head osteonecrosis is well reported [89], but other bone grafts from the iliac and greater trochanter have been described with similar success [10,90]. A core decompression of the femoral head is performed with removal of any nonviable bone and replacement with a free vascularized bone graft with or without additional bone graft. The ascending or transverse branch of the lateral circumflex system is typically the recipient for the microvascular anastomoses. The transferred bone should be fixed firmly in place, and an absorbable screw, buttress plate, or wire construct may be used [91]. (See "Treatment of nontraumatic hip osteonecrosis (avascular necrosis of the femoral head) in adults".)

Other options

●Ilizarov technique – When free vascularized bone is not favored/possible, the Ilizarov technique has been used successfully for severe lower extremity defects >5 cm with good long-term outcomes [92,93]. However, this technique is not often performed in the lower extremity, since the required distraction period may be prolonged, which creates issues with patient compliance. The Ilizarov technique corrects extremity deformities through the slow extension of bone and soft tissue, including nerves, blood vessels, and muscles, which would not tolerate rapid extension over such a long distance [93]. The Ilizarov external fixator is multiplanar, which allows for simultaneous correction in multiple axes while distracting at a pace of approximately 1 mm per day (figure 2). Although surrounding soft tissue lengthens along with the bone in the distraction technique, in a traumatic setting, additional soft tissue coverage procedures may be warranted because the traumatized/scarred soft tissues can become thin and atretic during the distraction process, resulting in an unstable scar that can lead to open/infected wounds. An Ilizarov external fixation frame has the secondary benefit of immobilizing the ankle and suspending the foot in midair, eliminating the possibility of developing pressure sores in the lower leg.

●Masquelet technique – The Masquelet technique is a length-independent technique that is used for large segmental bone defects and consists of two steps [81,94-96]. Following debridement, a polymethylmethacrylate (PMMA) bone cement spacer is introduced in the bone defect and soft tissue reconstruction is performed. The spacer induces a foreign body reaction with the formation of a well-vascularized membrane. Six to eight weeks later, the spacer is removed in a second step, and the defect is filled with bone graft.

JOINT RECONSTRUCTION — The goal of joint reconstruction is mobility and stability with a smooth articular surface to reduce pain and improve function. In addition, the reconstructed joint requires soft tissue coverage to promote healing [7]. Joint reconstruction procedures are categorized into replacement/arthroplasty, arthrodesis (ie, fusion), and replacement of the defective soft tissue. Unlike the upper extremity, joint transplantation is not standard of care or commonly performed/reported for the lower extremity. Arthroplasty is preferred over arthrodesis when possible since the latter eliminates motion in the joint.

Arthroplasty — Prosthetic joint replacement is performed mainly on large joints, such as the hip, knee, and ankle. (See "Total hip arthroplasty" and "Total knee arthroplasty".)

Prosthetic arthroplasty in the lower extremity is performed to repair severe joint destruction in arthritis, osteonecrosis, and joint defects from tumor resection. The main objectives of arthroplasty are to replicate range of motion of the joint, resist wear/tear with time, function under weight-bearing, and maintain alignment and stability. As is the case of all prostheses, arthroplasty is not without complications, and exposure, infection, and loosening/malalignment are possible over time. (See "Complications of total hip arthroplasty" and "Complications of total knee arthroplasty".)

Adequate soft tissue coverage is necessary for patients undergoing lower extremity joint arthroplasty and should be performed prophylactically in patients at high risk of complications following knee or ankle arthroplasty [6,8]. In revision total knee arthroplasty, prompt soft-tissue reconstruction improves the likelihood of success, and contamination/protracted surgical courses increase the rate of failure and amputation [7].

Arthrodesis — Arthrodesis refers to the fusion of bones in a joint and involves resection of the cartilage and stabilization, typically with plate and screw constructs. This procedure is performed when stabilization takes precedence over mobility and was once considered standard of care prior to the development of modern arthroplasty techniques. While arthrodesis still has a role in the treatment of severe ankle defects, hip and knee joints are not typically fused because of their necessary range of motion during ambulation.

NERVES, MUSCLES, AND TENDONS

Nerve repair/reconstruction — Following lower extremity injury, the surgeon should assess for nerve injury at the time of surgical exploration. The general principles are similar for managing lower extremity and upper extremity nerve injury; however, nerve/tendon and muscle-tendon transfers are not as commonly used as part of the reconstructive algorithm in the lower extremity (algorithm 3). Sharp nerve transections may be repaired primarily, but if the mechanism is a crush or blast injury, tagging the nerve and delayed repair is preferred [97]. The notion that tibial nerve neuropraxia/injury or absent plantar sensation precludes limb salvage is outdated. Patients may, in fact, recover sensation after salvage [41]. (See 'Lower Extremity Assessment Project (LEAP)' above.)

General principles — Procedures that treat lower extremity nerve disorders include neurolysis and nerve repair with or without nerve grafting. As with nerve repair in the upper extremity, nerve transfers are often thwarted by the short window of opportunity to complete the transfer before the recipient muscle is unable to accept a signal from a donor nerve. Delay of referral to a specialist able to perform the nerve transfer can therefore eliminate this reconstructive option.

●Neurolysis – Neurolysis is a procedure that removes scar tissue from around and/or inside of a nerve to allow more effective signal conduction through the nerve. This can either be external decompression (dissection outside the epineurium) or internal (interfascicular dissection). Some forms of nerve blockage include neoplastic lesions, scars, or adhesions formed by inflammation. In cases of trauma, neurolysis is sometimes performed to release the nerve compressed between bone and soft tissue.

●Nerve repair with or without grafting – If the nerve is transected, suturing with or without a graft is typically performed. However, outcomes following repair of injured motor nerves of the lower extremity in adults are overall poor. Suturing severed nerves is an intricate procedure that is usually done under a microscope or high-powered loupe magnification for delicate examination. A primary repair should be completed in a tension-free manner, as tension inhibits recovery of conduction. It is very rare to be able to perform a tension-free end-to-end primary coaptation of a major peripheral nerve injury in the lower extremity if more than one week has elapsed since the injury.

Unlike in the upper extremity, nerve transfers are not as commonly used in lower extremity reconstruction. Nerve conduits or grafts can be used if there is a gap between the severed ends. When the gap becomes long, there may be a role for vascularized nerve grafts, with the sural nerve being the most common donor. However, vascularized nerve allograft reconstruction is limited to small case reports/series [98,99]. Data on nerve transfers show mixed results from different centers, indicating that nerve transfers in the lower extremity are much less reliable compared with those performed in the upper extremity, possibly stemming from an intrinsic difference in nerve healing/regeneration in the lower extremity. However, there has been some renewed interest in nerve transfers, particularly for treating foot drop using donor motor nerves from the tibial nerve [100-102]. (See "Foot drop: Etiology, diagnosis, and treatment", section on 'Nerve or tendon transfer'.)

Peroneal nerve injury — Treatments for peroneal nerve injury include primary neurorrhaphy, neurolysis, nerve grafts, partial nerve transfer, neuromusculotendinous transfer, tendon transfer, and ankle-foot orthosis and arthrodesis.

●For persistent traumatic paralysis of the common peroneal nerve, tendon transfers are traditionally based off the posterior tibialis muscle, which is commonly transferred from the posterior compartment to the dorsal second or third cuneiform, allowing the tibialis posterior to function as a dorsiflexor to improve gait mechanics [103].

●For traumatic peroneal nerve palsy that persists despite prior repair, neuromusculotendinous transfer, otherwise known as the Ninkovic procedure, has been used for several decades [104]. In this operation, the lateral head of the gastrocnemius muscle and hemi-achilles tendon is transposed to the three anterior compartment tendons (extensor digitorum longus, extensor hallucis longus, tibialis anterior) beneath the anterior retinaculum of the ankle. Simultaneously, the undamaged proximal end of the deep peroneal nerve is transferred to the motor nerve of the gastrocnemius muscle. Importantly, this transfer requires an intact common peroneal nerve proximal to the injury for motor innervation of the transferred gastrocnemius muscle. To ensure adequate motor input, intraoperative frozen sections of the deep peroneal nerve are typically sent to ensure >70 percent axonal viability. If there is inadequate axonal viability of the donor deep peroneal nerve, then a posterior tibialis tendon transfer is done instead. Like other nerve and tendon transfers, the Ninkovic procedure also requires a supple ankle joint across which the transferred muscle can act. If the superficial peroneal is still intact, intraneural dissection must be undertaken intraoperatively to free the deep from superficial peroneal and avoid additional morbidity from injury to the superficial peroneal.

VASCULAR RECONSTRUCTION — Vascular reconstruction (open surgical, endovascular) may be necessary to repair vessels in the setting of trauma to augment flow to the distal extremity in patients with pre-existing vascular disease or replace vessels removed during tumor resection. Surgical procedures used to revascularize the lower extremity are discussed separately. (See "Surgical management of severe lower extremity injury", section on 'Revascularization' and "Endovascular techniques for lower extremity revascularization" and "Lower extremity surgical bypass techniques".)

The extent of arterial injury in crushed limbs or those with traumatic amputation is often more severe than it appears upon first inspection. Reconstructed arteries can have damage that leads to thrombosis after creation of the anastomosis in cases of microsurgical reconstruction. So, while free tissue transfer at the same time as vascular bypass can be successful, it is more often performed in a staged fashion given the perioperative risk of failure of the revascularization. Performing bypass and microsurgical reconstruction in a staged fashion also allows for easier troubleshooting of the flap, should it become compromised, as the bypass as presumably matured enough to be reliable by the time microsurgical reconstruction is undertaken. At the second stage, the flap can be anastomosed to native vessels above the level of the injury, with the use of a vein graft, if necessary, or directly to the open bypass graft. Alternatively, an arterial-to-venous (A-V) loop can be created at the time of bypass and buried near the site of future free flap coverage to provide an easy target for future microvascular anastomosis [105,106].

For lower extremity free flap coverage, the posterior tibial artery is the most commonly selected recipient target, while the anterior tibial artery is preferred when reconstructing the lateral malleolus or dorsum of the foot [107]. We prefer end-to-side anastomosis to prevent disruption of distal perfusion and anastomosis outside of the zone of injury. When the recipient vessel is not in continuity due to trauma, the anastomosis may be performed end-to-end above the level of injury.

Veins at or above the level of the popliteal should be repaired to prevent extremity edema distal to the injury, but most other extremity venous injuries can be ligated [108,109]. The popliteal vein is particularly important to reconstruct if injured, as it forms a natural choke point for venous drainage of the lower extremity that has very little redundancy, particularly if the superficial venous system has been traumatized. Veins should also be reconstructed in degloving injuries to prevent venous congestion in the flap.

The extremity should be monitored for the development of compartment syndrome after arterial reconstruction to the ischemic limb. (See "Acute compartment syndrome of the extremities" and "Lower extremity fasciotomy techniques" and "Patient management following extremity fasciotomy".)

In addition, lymphedema may develop following proximal circumferential soft tissue injuries with resulting disruption of lymphatic and venous outflow. First-line treatment includes compression garments and decompressive therapy, with surgical interventions reserved for advanced/refractory cases. Like many of the surgical interventions previously mentioned, timely intervention is paramount when addressing lower extremity lymphedema. Lymphedema predictably shifts from a primarily fluid-based phenomenon to fibrofatty disease over time. Once this fibrofatty tissue has matured, lymphovenous bypass is no longer a treatment option, leaving only liposuction, vascularized lymph node transfer, or in extreme cases, excisional procedures (ie, Charles procedure). (See "Lower extremity lymphedema" and "Surgical treatment of primary and secondary lymphedema".)

SOFT TISSUE RECONSTRUCTION — The process of soft tissue reconstruction is termed "coverage," which is accomplished using skin grafts or locoregional or free flaps based on the principles of the reconstructive ladder. Regardless of the use of muscle versus fasciocutaneous flaps for coverage, patients report similar improvements in functional scores and improved physical and mental health [110].

●Skin grafting using autologous skin or skin substitutes may provide adequate coverage for limited wounds. (See "Skin autografting" and "Skin substitutes".)

●For more extensive skin and soft tissue loss in the lower extremity, locoregional or free flaps will be required. (See "Flap reconstruction of the lower extremity", section on 'Soft tissue flap reconstruction'.)

POSTOPERATIVE CARE — The reconstructive surgeon should remain vigilant in the postoperative period to ensure the ongoing healing of the repair [111].

Prophylactic systemic anticoagulation is mandatory to reduce the risk for venous thromboembolism (VTE).

If prolonged immobility is a concern postoperatively, the patient may be placed on low molecular weight heparin (LMWH) for 30 days or until ambulation/rehabilitation begins. Prophylactic anticoagulation is for prevention of VTE rather than for flap-related reasons. An oral anticoagulant (eg, apixaban) can be used in place of LMWH in patients with renal insufficiency or for patients who cannot administer or do not wish to have subcutaneous injections. (See "Prevention of venous thromboembolic disease in adult nonorthopedic surgical patients".)

To our knowledge, no prospective studies have evaluated the potential benefit or harm for flap survival for anticoagulation (prophylactic or therapeutic). Management of patients who have undergone flap reconstruction for closure of the wound is discussed separately. (See "Flap reconstruction of the lower extremity", section on 'Flap monitoring and wound care'.)

Postoperative antibiotics should be dictated by the nature of the patient's original injury (eg, wound contamination, infection) and antibiotic sensitivities at the surgeon's institution. Early infectious disease consult should be obtained in complicated cases. The patient's nutritional status should be maximized.

There may be long periods of non-weight-bearing status and leg elevation to allow for fracture and soft-tissue healing, and patient expectations should be set early. An external fixator can be applied to a foot and ankle reconstruction to act as a kickstand to offload pressure, particularly around the Achilles and posterior heel region. Timing of progression to a dependent position of the lower extremity free flap remains an area of significant debate. Due to severed autonomic nerves at the time of flap harvest, free flaps lack internal flow regulation and cannot signal upstream to limit inflow or maximize venous egress through the normal venoarterial response. As a result, flap swelling can occur if dangled too early, with additional related sequelae including potential venous compromise. However, there is a balance to be struck, as some element of venous pooling and permissive ischemia stimulates neovascularization between the flap and surrounding tissue.

It is our practice to wait approximately one to two weeks before beginning a dangling protocol, depending on the specific patient/clinical scenario.

The other component of monitoring patients who have undergone skeletal reconstruction typically includes serial conventional radiographs or computed tomography/magnetic resonance cross-sectional imaging to assess for osseous healing. Plain films are used for follow-up, and cross-sectional imaging is typically reserved for surveillance of these patients who underwent reconstruction after resection of malignancy, or for those patients experiencing an associated complication of their skeletal reconstruction. Bone scans may also have a role for assessing viability of the skeletal construct.

Postoperative rehabilitation — Most patients are immobilized on bed rest after their lower extremity reconstruction, and elevation of the leg is beneficial in preventing dependent fluid accumulation in the soft tissues of the leg. All areas of potential pressure necrosis (eg, back of heel, calf) should be off-loaded.

An interdisciplinary approach for the leg, foot, and ankle is critical, as issues with weight-bearing may be due to bony, ligament, or muscle abnormalities rather than flap choice. Flap debulking should not be regarded as a complication, as it is often necessary to optimize function and form for shoe fitting. Orthotics may be necessary to improve gait, and shoe inserts may help distribute weight. Reconstruction is only part of the treatment algorithm, and it should be followed by meticulous foot care and long-term vigilance. Plantar flaps are prone to breakdown, and therefore we have a strict non-weight-bearing protocol for the first six weeks following reconstruction, and close follow-up cannot be stressed enough.

Patients' weight-bearing status will be, in part, dictated by the healing status of fracture or osseous union, but also by the stability of the soft tissue repair. Although we advocate early ambulation (especially in older adults to prevent deconditioning and joint stiffness), the surgeon should ensure that early movement does not put their reconstruction at risk. Negative pressure wound therapy (NPWT) is an excellent dressing for skin grafts to the leg, and the continuous suction has been shown to help with skin graft take [112,113]. Though the suction power of a NPWT dressing can permit the patient to ambulate minimally (to a bedside commode a few times a day, for example), the danger of graft shear still exists with this dressing, and the patient should be placed on near bedrest for five days.

In our experience, even the youngest and previously most active patients require aggressive rehabilitation after a major traumatic injury to the lower extremity. Data from the Lower Extremity Assessment Project suggest that maximizing the psychosocial function of the patient contributes to better outcome. Poorer outcomes in lower extremity reconstruction were associated with a low level of education, poverty, lack of private health insurance, smoking, and involvement with disability-compensation litigation [25]. Earlier research about post-injury function also showed that outcome is affected by patients' perceptions of self-efficacy and social support [114].

COMPLICATIONS — Complications after lower extremity reconstructive surgery include infection (wound, osteomyelitis), flap necrosis, tendon adhesions, joint contractures, pseudoarthrosis, chronic regional pain syndrome, and sensory disorders. Complications following wound closure are reviewed separately. (See "Flap reconstruction of the lower extremity", section on 'Complications'.)

OUTCOMES — Though by no means a settled issue, the best data show that reconstruction of the acutely traumatized limb is probably most cost-effective and results in equal functional outcome to amputation, though lower extremity trauma itself is quite morbid, despite how it is managed. Given that reconstructed patients have a higher reoperation and rehospitalization rate and the enormous number of different and nearly unquantifiable factors that compose a single patient's injury, the decision to pursue reconstruction versus primary amputation should be highly individualized and patient centered. It is also important to counsel the patient that the majority of lower extremity free tissue reconstruction will ultimately require additional procedures for refinement or definitive wound closure [115]. For patients undergoing reconstruction, aesthetics will play an increasingly larger role in planning and execution as the field of limb salvage evolves with newer approaches, techniques, and technologies [116].

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Extremity compartment syndrome" and "Society guideline links: Lower extremity (excluding hip) fractures in adults".)

SUMMARY AND RECOMMENDATIONS

●Lower extremity reconstruction – Reconstructive surgery may be needed to correct dysfunction and form of the lower extremity caused by trauma, infection, malignancy, degenerative disease, or congenital deformities. Successful reconstruction restores both function and appearance of the affected limb by replacing lost tissue. Surgical reconstruction may need to be staged, and a combination of reconstructive techniques may be required to provide optimal closure of a particular wound. (See 'Indications' above.)

●Limb salvage versus amputation for trauma – Reconstruction of the acutely traumatized limb is probably more cost effective and results in equal functional outcome to amputation. Reconstructive outcomes are optimized with early triage and intervention at a tertiary trauma center. Community centers that lack microvascular expertise, multidisciplinary resources, and psychosocial support services should consider using the Lower Extremity Guide for Salvage (LEGS) when faced with the challenging decision of amputation versus salvage following severe trauma. (See 'Patient triage and Lower Extremity Guide for Salvage (LEGS)' above and "Flap reconstruction of the lower extremity", section on 'Soft tissue flap reconstruction'.)

●Bone stabilization and reconstruction – Bony stabilization constitutes the foundation of extremity reconstruction. To reinforce fracture fixation, bone grafting or bone shortening may be necessary. Bone transport with the Ilizarov technique and Masquelet procedure are options for large bony defects [87]. Osteocutaneous flaps can also be used bone grafting procedures as well as for osseous defects. (See 'Bone stabilization and reconstruction' above and 'Osteocutaneous free flaps' above.)

●Joint reconstruction – The goal of joint reconstruction is mobility and stability with a smooth articular surface to reduce pain and improve function. Joint restoration is accomplished through arthroplasty, arthrodesis, and soft tissue reconstruction. Arthrodesis (fusion of a joint) is performed when stabilization takes precedence over mobility. (See 'Joint reconstruction' above.)

●Nerve muscle and tendon reconstruction – Nerves, muscles, and tendons are approached as an integral neuromusculotendinous unit during the reconstructive process. Procedures to manage damaged nerves include neurolysis and nerve repair with or without nerve grafting. Nerve/tendon and muscle-tendon transfers are not commonly used as part of the reconstructive algorithm in the lower extremity; however, tendon transfer or neuromusculotendinous transfer (Ninkovic procedure) can be used for traumatic peroneal nerve palsy. (See 'Nerves, muscles, and tendons' above.)

●Vascular reconstruction – Early involvement of vascular specialists/surgeons is critical to the success of any lower extremity vascular reconstruction. Vascular reconstruction is generally using primary repair or with interposition grafting or bypass grafting using autogenous vein conduit. Veins are ligated if unable to be repaired easily or if there is uncontrolled bleeding in the setting of patient instability. The ischemic limb is managed with attention to reperfusion and compartment syndrome. (See 'Vascular reconstruction' above and "Flap reconstruction of the lower extremity", section on 'Soft tissue flap reconstruction'.)

●Soft tissue reconstruction – The process of soft tissue reconstruction is termed "coverage," which is the ideal operation, but sometimes it is not possible. Coverage is accomplished using skin grafts or locoregional or free flaps based on the principles of the reconstructive ladder. (See 'Soft tissue reconstruction' above and "Flap reconstruction of the lower extremity" and "Flap reconstruction of the lower extremity", section on 'Reconstruction by location' and "Flap reconstruction of the lower extremity", section on 'Soft tissue flap reconstruction'.)

●Postoperative care – Postoperative care following surgical reconstruction of the lower extremity involves vigilant monitoring of vascular and flap reconstruction using frequent examination and Doppler assessment of pulses, monitoring for the development of compartment syndrome, and intermittent radiography to assess bone healing. Most patients are immobilized on bed rest after their lower extremity reconstruction, and measures to prevent venous thromboembolism are important and elevation of the leg is beneficial for preventing dependent fluid accumulation in the soft tissues of the leg. (See 'Postoperative care' above and "Flap reconstruction of the lower extremity", section on 'Postoperative care'.)

●Complications – Complications after lower extremity reconstructive surgery include infection (wound, osteomyelitis), flap necrosis, tendon adhesions, joint contractures, pseudoarthrosis, chronic regional pain syndrome, and sensory disorders. (See 'Complications' above and "Flap reconstruction of the lower extremity", section on 'Complications'.)

ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges Raymond Dunn, MD, who contributed to an earlier version of this topic review.