Surgical management of severe lower extremity injury

INTRODUCTION — Trauma to the extremities is one of the most common injury patterns seen in emergency medical and surgical practice. Optimal outcomes for these patients require a multidisciplinary approach with oversight by the general or trauma surgeon and care from other specialists including orthopedic, vascular, and plastic surgeons and rehabilitation specialists. In most instances, a course of limb salvage can be attempted even if the patient has a mangled extremity; however, occasionally, the lower extremity injury is so severe that primary amputation at the initial operation is required to save the patient's life. Complications of surgical treatment for lower severe extremity injury are common; early recognition and treatment are important to minimize morbidity and mortality.

The surgical management of severe lower extremity injuries will be reviewed here. The initial management of severe extremity injury is discussed elsewhere. (See "Severe lower extremity injury in the adult patient" and "Surgical reconstruction of the lower extremity".)

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

EXTREMITY EVALUATION — The evaluation of the lower extremity should include all four functional components of the extremity (nerves, vessels, bones, soft tissues). Injury to three of these four elements constitutes a "mangled extremity." The evaluation and radiologic evaluation of the severely injured extremity is discussed in detail separately. (See "Severe lower extremity injury in the adult patient", section on 'Initial evaluation and management' and "Severe lower extremity injury in the adult patient", section on 'Lower extremity evaluation'.)

LOWER EXTREMITY ANATOMY — Knowledge of lower extremity anatomy and functional physiology is important for proper preoperative and postoperative extremity assessment.

The bony structures of the lower extremity include the femur, tibia, and fibula. The musculature is contained within defined compartments including the anterior, posterior, and medial compartments of the thigh (figure 1) and the anterior, lateral, posterior, and deep posterior compartments of the leg (figure 2).

The nerves of the lower extremity are derived from the lumbar plexus (figure 3) and include the sciatic, femoral, saphenous, tibial, and peroneal (fibular) nerves (figure 4). The femoral nerve (L2 through L4) (figure 5) is lateral to the common femoral artery (figure 6). The femoral nerve provides motor branches to the hip and knee extensors and sensation to the anterior thigh, femur, knee joint, and medial leg. The saphenous nerve is the extension of the femoral nerve and is purely sensory.

The sciatic nerve (L4 through S3) (figure 7) runs posteriorly down the thigh, continuing below the knee after dividing into the tibial and common fibular nerves. It supplies the hip flexors, motor function of the lower leg, and nearly all the sensory function of the lower extremity (figure 8). The superficial and deep peroneal (fibular) nerves are derived from the common fibular nerve. The deep peroneal (fibular) nerve passes distally with the anterior tibial artery while the tibial nerve accompanies the posterior tibial artery.

The lower extremity is perfused by the common femoral artery (figure 6). The common femoral artery branches into the superficial and deep femoral (ie, profunda femoris) vessels. The superficial femoral artery (figure 9) runs anteriorly down the thigh between the adductor and quadriceps muscles within the anterior compartment. In the distal third of the femur, the superficial femoral artery is in close proximity to the femur and passes through the adductor canal to become the popliteal artery (picture 1), which divides at the level of the tibial tuberosity into the anterior tibial artery and tibioperoneal trunk (figure 10A-B), which further divides into the posterior tibial and peroneal arteries. The anterior tibial artery accompanies the deep peroneal (fibular) nerve along the posterior margin of the tibia. The peroneal artery passes adjacent the medial margin of the fibula throughout its course distally. The posterior tibial artery is accompanied by the tibial nerve within the deep posterior compartment.

The collateral circulation in the lower extremity is derived from the deep femoral artery (profunda femoris) (figure 9). Collaterals are poorly developed in younger patients who tend to develop severe acute ischemia with arterial disruption.

LIMB SALVAGE VERSUS AMPUTATION — The decision to salvage a limb or proceed with primary amputation is difficult. A management algorithm from the Western Trauma Association illustrates the complexity of this decision as well as the lack of high-quality evidence to guide it (algorithm 1) [1]. Machine learning models show some promise in predicting failed limb salvage; however, these prognostic tools should not replace clinical judgement and shared decision making [2].

If limb salvage can be accomplished at the index operation without threatening the patient's life, we suggest making the effort even if the patient has multiple risk factors for limb loss. This strategy allows time for the patient and family or other caregivers to accept amputation if it becomes necessary. Provided there is some chance for functional recovery of the limb, initial limb salvage is cost effective [3]. The downsides of attempting limb salvage include a higher risk of acute kidney injury and possible longer length of stay, although mortality rates are similar [4].

Patients with a severely crushed extremity, traumatic amputation or near-amputation who have destruction of the tissues distal to the injury, mangled stump, excess intervening tissue loss, or in whom the amputated extremity is missing, should undergo a formalized amputation when stable. (See "Lower extremity amputation" and "Techniques for lower extremity amputation".)

If there is a fracture in the same extremity proximal to the amputation, stabilizing the fracture preserves residual limb length, which may improve the ability to ambulate [5]. Other generally accepted principles of open fracture management should be followed. (See 'Fracture management' below.)

SURGICAL MANAGEMENT — The goal of surgical management is salvaging the limb in a manner that results in optimal function (figure 11). Patients with life-threatening injuries should undergo a damage control approach, and a small number of patients with devastating injuries will require amputation. (See 'Limb salvage versus amputation' above.)

Damage control surgery — When emergency surgery is indicated to control life-threatening bleeding in the abdomen or chest, lower extremity fractures should be quickly reduced and stabilized with splinting or in-line traction. Damage control chest or abdominal surgery takes priority as long as sites of extremity bleeding remain controlled. Tourniquets and dressings may need to remain in place on the extremity until life-threatening hemorrhage is controlled. (See "Overview of damage control surgery and resuscitation in patients sustaining severe injury".)

After life-threatening torso injuries are addressed, the extremity injury can be reassessed. Priorities include definitive control of bleeding sites with vascular ligation or placement of a vascular shunt, debridement of devitalized or grossly contaminated tissue, and quick stabilization of fractures, if possible. Following these measures, soft tissue wounds can be managed with temporary closure using gauze dressings or negative pressure wound dressings. Once the patient has been stabilized in the intensive care unit, plans are made for definitive management.

Vascular ligation — In general, ligation (arterial or venous) is best tolerated with distal or minor vascular injuries. There is some degree of redundancy of circulation in the lower leg. Ligation of any one of the three vessels (anterior tibial, peroneal, posterior tibial) is a damage control option provided alternative in-line flow to the foot is present.

Whenever possible, we prefer vascular shunting over arterial ligation as a damage control technique for managing injuries to more proximal arterial structures. Arterial ligation of major vessels should be undertaken with caution only after options for reconstruction have been carefully considered since ligation risks the development of limb-threatening ischemia. If the vascular injury needs to be ligated, the patient should be closely monitored in the postoperative period for evidence of progressive ischemia that may indicate a need for revascularization or amputation depending upon the patient's other injuries and clinical status.

Similarly, ligation of major veins can cause venous hypertension. This can increase the rate of arterial graft failure in the acute setting and can also increase the incidence of long-term complications such as limb swelling and skin breakdown from venous stasis.

Vascular shunting — A less morbid damage control approach (compared with ligation) for patients with extremity vascular injury is vascular shunting, a technique that has been used for over 50 years [6]. A vascular shunt is a synthetic tube that is inserted into the vessel and secured proximally and distally to allow temporary vascular flow past the area of injury.

Vascular shunts are typically used for proximal arteries and veins (eg, femoral, popliteal) [7-11]. Ischemia in proximal vessels is associated with increased morbidity due to a greater burden of tissue ischemia compared with more distal vessels. Traditionally, an ischemic threshold of six hours was standard, but evidence suggests that in the setting of shock the time to ischemia may be as soon as one hour [12,13]. In these cases, shunting can expedite reperfusion and improve nerve and muscle recovery. Vascular shunting may also be more crucial for injuries in which collateral circulation has been disrupted, such as sizable soft tissue wounds.

The effectiveness of temporary vascular shunting in patients with severe extremity injury has been demonstrated in studies of combat casualties and in high-volume civilian practices [7-9,14]. In one retrospective review, the use of temporary intravascular shunts in 786 patients treated over a 10-year period was reviewed [14]. Shunts were placed in the context of damage control to allow stabilization of Gustilo IIIc fractures (table 1) or limb replantation. In this series of patients at high risk for limb loss, the limb salvage rate was 82 percent. In a later multicenter study using the PROspective Vascular Injury Treatment (PROOVIT) registry, shunts expedited limb perfusion and lowered amputation rates during the early phase of care [15].

Temporary vascular shunting is preferred in the following clinical circumstances:

●Life-threatening non-extremity injuries

●Hemodynamic instability, coagulopathy, acidosis, hypothermia

●Unstable skeleton

●Major wound contamination/infection or wound deficits that preclude soft tissue coverage

●Vascular injury requiring a complicated repair

●Resource-limited environment

Definitive vascular reconstruction should be performed as soon as the patient is sufficiently stable to undergo the procedure. Systemic anticoagulation is not typically used to maintain shunt patency due to the potential for bleeding from other injuries. (See 'Revascularization' below.)

Infection control

Antibiotics — The risk of infection increases with injury severity (see 'Wound complications' below). Early use (within six hours) of antimicrobial agents for open fractures is well established to decrease the incidence of osteomyelitis. The choice of antibiotic depends on Gustilo-Anderson grade of the fracture (table 1 and table 2) and associated contamination. The duration of therapy depends on fracture grade and timing of soft tissue coverage. (See "Osteomyelitis associated with open fractures in adults", section on 'Prevention'.)

For isolated soft tissue injury, recommendations for antibiotic usage are less clear. Guidelines for combat-related extremity injuries include cefazolin given within three hours of injury and continued for one to three days [16]. Antibiotic selection should be as narrow as possible. A review of antibiotic use in military trauma patients with soft tissue injuries compared narrow antibiotic use (cefazolin or clindamycin) with narrow and expanded gram-negative coverage, based on provider judgement [17]. There was no benefit to expanded coverage, and the proportion of resistant gram-negative organisms increased in those who received expanded coverage.

Antibiotics should be redosed after large-volume blood resuscitation (more than 1.5 to 2 L) is given. A tetanus booster should be given to patients with contaminated wounds who are more than five years out from their last dose, and tetanus immune globulin should be given to unimmunized patients [17].

Debridement and irrigation — At initial operation, devitalized tissue and foreign material are surgically debrided from the wound. The location and extent of any soft tissue injury and its communication with the skeletal injury are evaluated. Serial debridement of extensive soft tissue injury is often necessary, especially with high-energy injury mechanisms where tissue viability may not be clinically apparent on initial debridement.

Wounds should be copiously irrigated. The FLOW trial (Fluid Lavage of Open Wounds) demonstrated that saline was superior to a soap solution, and low-pressure was superior to high-pressure lavage in outcomes for open fracture wounds [18]. High-pressure irrigation such as pulse lavage should be avoided, as it may displace bacteria deeper into the soft tissues.

Low-pressure saline irrigation is an acceptable, low-cost strategy for the irrigation of open fractures and extensive soft tissue injuries. A bulb syringe can be used, and for extensive wounds, cystoscopy irrigation systems are efficient methods for delivering large volumes of irrigation.

Antibiotic-impregnated local wound adjuncts — Meticulous debridement remains the mainstay of infection control for traumatic wounds, and no antibiotic regimen or antimicrobial adjunct can replace clinical judgement.

Nevertheless, there is ongoing interest in local delivery of antibiotics to wounds via implanted substances. Polymethyl methacrylate (PMMA) bone cement, mixed with antibiotic powder, can be formed into a chain of beads and left in the wound bed. However, these are most often used as adjuncts to systemic antibiotic therapy. A randomized trial comparing systemic antibiotics alone with antibiotic PMMA beads alone showed no significant difference in infection rates [19]. Formulations of biodegradable material, such as calcium sulfate, can also be impregnated with antibiotics and will dissolve over time, but high-quality evidence on their efficacy is lacking [20]. A retrospective study showed that intrawound antibiotic powder can reduce deep infection in the residual limbs of combat-wounded patients, particularly those undergoing revision (16 percent absolute risk reduction) and with previously infected limbs (25 percent absolute risk reduction) [21].

Surgeons should be aware of adverse effects from locally implanted antibiotic adjuncts, such as mechanical issues from permanent PMMA beads, antibiotic toxicity, and hypercalcemia from calcium sulfate beads [20].

Fracture management — Once a fracture is identified, it is reduced as much as possible and splinted. If an open fracture is suspected, the patient should be taken to the operating room to debride and stabilize the fracture (usually with external fixation) either after life-threatening injuries have been managed or concurrently while urgent but not life-threatening chest, abdominal, or head injuries are being addressed [22]. Open fractures should then be graded using the Gustilo-Anderson grading system (table 1) [22]. The timing of definitive stabilization of fractures depends upon the nature and severity of the fracture and the presence of significant vascular or soft tissue injury.

Primary fracture management — External fixation is often the initial stabilization procedure of choice, as it can be accomplished with limited resources, few complications, and rarely needs to be modified [23]. Initial internal fixation is preferred when extensive soft tissue destruction, associated vascular injury, and significant contamination of an open fracture wound are not present. (See 'Definitive fracture fixation' below.)

External fixation or splinting of the skeleton is used until the wound is clean enough to perform definitive internal stabilization (algorithm 2). The soft tissue defect is evaluated every 24 to 96 hours in the operating room depending upon the appearance of the wound at the last assessment.

If vascular and orthopedic injuries are both present, multidisciplinary discussion is needed to determine the sequence and timing of treatment. In general, achieving bony stabilization greatly facilitates the vascular reconstruction. External fixation is usually performed quickly; however, if any problems are foreseen, a vascular shunt can be placed prior to external fixation to limit warm ischemia time to the distal limb. (See 'Vascular shunting' above.)

Once the limb has been brought out to length and stabilized, vascular reconstruction can then proceed without concern for disrupting the anastomosis during subsequent bone manipulation. (See 'Revascularization' below.)

Definitive fracture fixation — Definitive stabilization of complex open orthopedic injuries depends upon the degree of bone lost, the extent of soft tissue injury, and the nature and severity of associated injuries (algorithm 2). Definitive fracture fixation is not performed until the patient is hemodynamically stable and other life-threatening injuries have been managed. Patients with isolated extremity injuries and patients with minimal associated non-extremity injuries can undergo definitive fracture stabilization without delay.

Early stabilization of fractures improves pain control, protects the surrounding soft tissues, and facilitates mobilization of the patient. If the patient is well resuscitated with a mild-to-moderate disease burden and has a low-grade open fracture, intramedullary (IM) nailing of long bone fractures is the preferred approach.

For patients who are initially managed with external fixation, conversion to IM nailing within 28 days of external fixation results in a lower incidence of infection (3.7 versus 22 percent) [24]. Some clinicians prefer to allow fixation sites to heal during a "safety interval" by casting the patient prior to definitive IM nailing. Others employ this technique only when pin site infections have occurred but otherwise convert directly from external fixation to IM nailing once the patient is stable and soft tissue coverage of open fractures has been achieved [25].

Several studies have suggested that reamed IM nailing is safe and beneficial in patients with low-grade open fractures [26-28]. A multicenter trial randomly assigned 1319 patients to reamed IM nailing versus unreamed IM nail stabilization [26]. Patients undergoing reamed IM nailing of closed fractures were significantly less likely to undergo reoperation (relative risk [RR] 0.67, 95% CI 0.47-0.96), less likely to undergo fasciotomy for intraoperative compartment syndrome (RR 0.15, 95% CI 0.02-1.25), and less likely to experience fracture dynamization from a broken or bent screw (RR 0.42, 95% CI 0.22-0.80). These benefits were not observed in the open fracture group.

The adjunctive use of bone morphogenetic protein (BMP) added to the fracture bed during definitive stabilization has been evaluated to improve bony union. A systematic review and meta-analysis of 11 trials found no significant difference in healing rates with BMP [29]. However, fewer secondary procedures were required in patients treated with BMP (RR 0.65, 95% CI 0.50-0.83, three studies). Because of considerable industry involvement in these studies, these findings should be viewed with caution.

Revascularization — Ischemia due to vascular injury is a major risk factor for amputation. The neuromuscular ischemic threshold is traditionally quoted as six hours, however data show it can be even less. A study from the National Trauma Database (NTDB) examining the impact of time to revascularization showed that optimal limb salvage is achieved when the opportunity for revascularization (arrival to the operating room) occurs within one hour of extremity vascular injury [13]. Findings from that study were corroborated by a study from the United States and United Kingdom military trauma registries showing that the opportunity for limb salvage following severe injury is reduced by 10 percent for every hour of extremity ischemia [30]. This same study demonstrated that the presence of hemorrhagic shock worsens this time-dependent limb salvage curve, further shortening the ischemic threshold of the extremity. The authors from both studies suggested that to improve survival and limb salvage after extremity arterial injury, efforts should be focused on strategies to expedite reperfusion in some manner within one to three hours following injury.

Bony stabilization of orthopedic fractures prior to vascular reconstruction facilitates the creation of an appropriate length of interposition graft and limits motion, thereby reducing the potential for anastomotic disruption [31]. If external fixation will result in an excess duration of ischemic time, a vascular shunt should be placed prior to fixation. (See 'Vascular shunting' above and 'Debridement and irrigation' above.)

Injuries to the tibial vessels may not require repair depending upon the degree of perfusion to the foot. If the anterior or posterior tibial artery remains intact and the foot is warm, immediate vascular reconstruction may not be needed. However, if the peroneal artery is the only intact vessel, perfusion of the foot through collaterals may be inadequate and distal bypass to the anterior or posterior tibial artery should be performed if the foot is in jeopardy. One study confirmed this selective approach, emphasizing the importance of Doppler examination in deciding which distal vascular injuries could be safely ligated and which required reconstruction [32]. In this study, the need for immediate vascular reconstruction increased significantly as the number of involved tibial vessels increased.

Techniques — Specific considerations for revascularization in the setting of trauma are reviewed below. Specific techniques for open lower extremity revascularization are reviewed separately. (See "Lower extremity surgical bypass techniques".)

For stabilized patients following initial shunt placement for damage control or patients with few other injuries, we suggest the following approach at the index operation for definitive vascular reconstruction:

●The patient should be systemically anticoagulated unless the risk of bleeding from coexisting brain, torso, or soft tissue injuries prohibit the use of intravenous heparin in the operating room. An analysis from the American Association for the Surgery of Trauma (AAST) PROspective Vascular Injury Treatment (PROOVIT) registry demonstrated that graft patency and limb salvage rates were not improved with the use of systemic anticoagulation in this setting [33]. Systemic anticoagulation was associated with prolonged hospital stay and increased blood product use. In a later analysis, neither anticoagulation or antiplatelet therapy impacted the complication rate after arterial repair with autologous vein [34]. Trauma patients can be treated with or without antithrombotic therapy per discretion of the operative surgeon(s).

●Once the injured vessel has been identified, the devitalized vessel wall should be debrided back to healthy, uninjured artery or vein.

●All thrombus should be removed from within the proximal and distal vascular segments using a Fogarty embolectomy catheter, forceps, or a small clamp or within the vessel lumen to withdraw any remaining clot. This maneuver is critical and may require several passes of the Fogarty catheter (proximal and distal) until unabated inflow to and outflow from the segment undergoing repair is confirmed.

●Regardless of the ability to systemically anticoagulate the patient with vascular injury, heparinized saline (1 to 10 units heparin per mL 0.9% normal saline) should be used liberally to remove thrombus and platelet aggregates from the vascular repair site from the inflow and outflow vessels following thrombectomy. In these instances, at least 60 to 120 cc of "regional heparin" should be injected or flushed into the proximal and distal arterial segments after all clot is removed and onto the surfaces of the healthy vessel and conduit used for repair.

●A primary anastomosis, when possible without tension, is preferred. More typically, reconstruction with an interposition or bypass graft is needed due to the extent or length of the injury.

●The ideal conduit is reversed autologous great saphenous vein from an uninjured leg. If both lower extremities are injured, the saphenous vein from the least injured extremity can be used, or arm vein can be considered. Prosthetic graft material (eg, polytetrafluoroethylene [PTFE]) is an option for the extremities, if no autologous conduit is available [35,36]. In a small retrospective review of combat vascular injuries reconstructed with PTFE compared with matched injuries reconstructed with autologous vein, PTFE had good long-term patency and freedom in the proximal upper extremity, but long-term outcomes for common femoral and superficial femoral reconstruction were suboptimal [35].

●At the conclusion of the reconstruction, we confirm the adequacy of arterial repair using Doppler, repeat ankle-brachial index (ABI), or completion arteriogram depending upon available time and resources.

●Whenever possible, we repair proximal venous injuries, particularly if the adjacent paired vein is also injured [37,38]. Venous ligation is appropriate for distal veins and proximal injuries associated with other life-threatening injuries. Severely injured extremities often have enough soft tissue injury that interrupts collateral venous flow, and although the patency rates of venous reconstruction are lower than those of arterial reconstruction, vein repair provides outflow and limits extremity swelling in the short term. Preserving venous outflow also decreases the likelihood of early arterial graft failure, especially with injuries to the popliteal vessels [37-39], which may ultimately decrease the incidence of secondary amputation as compared with venous ligation [40].

Extremity fasciotomy — Prophylactic fasciotomy should be performed in all high-risk extremities, which can include patients with significant crush injury and those patients with an ischemic time greater than six hours, which includes prehospital and operative time. Fasciotomy should also be considered in all patients who will undergo a significant evacuation period or other circumstance in which continuous evaluation and rapid treatment for compartment syndrome are not available. The diagnosis and treatment of acute compartment syndrome are discussed in detail elsewhere. (See "Pathophysiology, classification, and causes of acute extremity compartment syndrome" and "Acute compartment syndrome of the extremities".)

In the lower extremity, the standard approach is a two-incision, four-compartment release through medial and lateral lower leg incisions. Thigh compartment syndrome is rare but is similarly managed by opening the anterior and posterior fascia of the thigh. (See "Lower extremity fasciotomy techniques".)

Complications related to the need for fasciotomy, including rhabdomyolysis and wound-related issues, are discussed in detail elsewhere. (See "Patient management following extremity fasciotomy".)

Role of endovascular repair — The use of endovascular techniques in vascular trauma is increasing, especially for thoracic, abdominal, and cerebrovascular injuries. For junctional injuries, improved survival is seen with the use of endovascular treatment. For extremity vascular injury, open surgery remains the mainstay of treatment given that most are readily accessible [41].

Nerve repair — Peripheral nerve repair in the lower extremity is much less common compared with the upper extremity given differences in reconstruction thresholds to meet functional requirements. At the index operation, providing the patient's condition permits, the ends of transected nerves can be identified and marked with fine suture for later repair. Definitive management options include nerve decompression, repair, or nerve transfer, the choice of which depends upon the nature of the nerve injury.

Although repair can be performed at the index operation, nerve repair is often delayed to allow for debridement of contaminated wounds and resolution of other concomitant injuries (algorithm 3). Repair of peripheral acute nerve injuries can be delayed, if needed. If the nerve was transected, direct epineural repair with fine monofilament sutures can be performed. If a tension-free repair is not possible, an artificial or autologous nerve conduit (eg, the sural nerve) can be used.

Wound care and coverage

Wound care — Open wounds can initially be packed using moist dressings, but following debridement, negative pressure wound dressings can be used to provide interim coverage between operations (picture 2).

Negative pressure wound therapy has the advantages of reducing wound edema, maintaining skin integrity, and limiting bedside wound manipulation [42-44]. The basic principles and use of negative pressure wound devices are discussed in detail elsewhere. (See "Negative pressure wound therapy".)

Timing of definitive coverage — Definitive coverage of a wound is achieved by skin grafts and tissue flaps. The presence of an increased volume of exudate, suppuration, redness, and swelling of surrounding tissues may be signs of infection indicating the need for additional debridement.

Some fasciotomy wounds and small soft tissue defects can be managed with delayed primary closure as soft tissue edema decreases. Elevation of the extremity, gentle compression, and diuresis when able can assist in this process.

Larger skin defects and fasciotomy wounds that are unable to be closed primarily may require skin grafting or the use of skin substitutes (eg, dermal regeneration templates). Skin substitutes can assist in coverage of exposed bone or tendon, restore contour defects, and provide additional soft tissue coverage for residual limbs prior to skin grafting [45]. This may reduce the need for soft tissue flap coverage. (See "Skin autografting" and "Skin substitutes".)

Extensive wounds, particularly open wounds overlying a vascular repair or graft, may require rotational or free flaps [46,47]. The functional outcomes of these various techniques are the subject of ongoing research [48]. (See "Flap reconstruction of the lower extremity".)

The timing of closure of any residual tissue defect depends upon the availability of donor tissues and the level of contamination within the wound. It is generally accepted that immediate coverage can be performed for uncontaminated wounds when good-quality soft tissue is available to cover the defect [49,50].

For wounds that do not meet these criteria, the timing of coverage is controversial.

●One study found an increased incidence in infection for soft tissue coverage (1.5 versus 17.5 percent) and free flap failure (0.75 versus 12 percent) for wounds that were managed after 72 hours compared with beforehand [51].

●In a retrospective review, the incidence of infection was lower if soft tissue coverage was provided <10 days (18 versus 69 percent) compared with >10 days [52]. Wounds that were allowed to heal by secondary intention had a 53 percent incidence of infection.

●The authors' experience using local rotational or free flap at a mean of 20 days following the initial operation resulted in infection in 5 to 18 percent of patients [47].

Degloving injuries — Rotational injuries to the lower extremity can avulse the skin and subcutaneous fat from the underlying tissues. These free-floating segments of skin and soft tissue can become ischemic and slough completely, resulting in large areas of soft tissue loss. These injuries are often treated in a similar fashion as burn injuries.

Once a degloving injury has been identified, systemic antibiotics should be administered to cover skin flora (eg, cefazolin) to minimize the development of infection, which significantly increases the patient's morbidity and mortality.

If the patient has no underlying fractures or vascular injuries, the patient can be taken to the operating room and the soft tissue managed first by debriding obviously devitalized tissue. The free-floating subcutaneous tissues can then be tacked down to the underlying fascia and closed suction drains or a negative pressure dressing placed to evacuate serous fluid.

A bulky overlying dressing and a splint should be applied to immobilize the extremity. The injury should then be reassessed in the operating room in 24 to 48 hours to identify any additional devitalized tissue. Use of a skin substitute (eg, dermal regeneration template) followed by skin grafting can be used in areas where skin needs to be debrided.

POSTOPERATIVE CARE AND FOLLOW-UP — The postoperative course for patients with lower extremity injury is highly variable depending on the nature and severity of extremity injury, associated injuries, and the patient's comorbidities. General issues related to inpatient management of injured patients are discussed elsewhere. (See "Overview of inpatient management of the adult trauma patient".)

Activity and rehabilitation — To limit lower extremity swelling, the revascularized extremity should be elevated when the patient is not ambulating. Early mobilization should be achieved as soon as is feasible in patients with multiple injuries. Generally, patient activity will be limited more by the orthopedic and soft tissue injuries and reconstruction than by vascular reconstruction.

Patients with extremity fractures benefit from physical therapy once or twice daily beginning in the intensive care unit. The goals of therapy should be graduated and tailored to the patient's pre-injured physical activity status. However, patients with badly comminuted fractures, even after internal fixation, will need to limit weight-bearing activity for a period that ranges from weeks to months, but they should participate in physical therapy to the extent they are able. (See "Surgical reconstruction of the lower extremity", section on 'Postoperative rehabilitation'.)

Antithrombotic therapy

VTE prophylaxis — Patients with severe lower extremity injury are at high risk for venous thromboembolism (VTE). (See 'Venous thromboembolism' below.)

Patients should receive both mechanical and pharmacologic prophylaxis for VTE as soon as is feasible. With rare exception, anticoagulation should be continued perioperatively during subsequent procedures given the high risk of thromboembolic complications in this population. Pharmacologic agents and dosing regimens for VTE prophylaxis are discussed in detail elsewhere. (See "Venous thromboembolism risk and prevention in the severely injured trauma patient".)

The risk of VTE rises sharply if treatment is delayed beyond 72 to 96 hours [53]. If pharmacologic therapy is contraindicated for a period that will extend beyond this time frame, a prophylactic inferior vena cava filter may be indicated [54]. For patients who receive a temporary inferior vena cava filter, the trauma team should ensure that a protocol is in place to arrange follow-up for its retrieval [55]. (See "Placement of vena cava filters and their complications", section on 'Retrievable filters'.)

Antiplatelet therapy — Following revascularization procedures, patients with vascular injuries should be maintained on an antiplatelet medication (eg, aspirin, 80 or 325 mg orally once daily) for at least 6 to 12 weeks until the intima heals at the anastomotic sites. In an analysis of the PROspective Vascular Injury Treatment (PROOVIT) registry, anticoagulation or antiplatelet therapy did not impact the complication rate after arterial repair with autologous vein [34]. Recommendations for at least a temporary course of antiplatelet therapy following repair of vascular injury is based on the mechanisms of action of these medications and extrapolation from similar regimens in patients having undergone vascular procedures for age-related vascular disease.

Systemic anticoagulation may be used transiently in the postoperative period if there is concern for residual distal thrombus. Dextran has been used in the setting of venous reconstruction, although the benefits of this approach have not been rigorously studied [56].

Surveillance of the vascular repair — As with any vascular reconstruction, routine clinical surveillance, which includes evaluation for symptoms, vascular examination, and, possibly, duplex ultrasonography of the vascular reconstruction, should be performed postoperatively and at regular intervals. (See "Lower extremity surgical bypass techniques", section on 'Graft surveillance' and "Endovascular techniques for lower extremity revascularization", section on 'Surveillance after endovascular interventions'.)

COMPLICATIONS — Patients with severe lower extremity injuries have a high incidence of complications, including wound complications (infection, necrosis, nonunion, osteomyelitis), venous thromboembolism, rhabdomyolysis, and late complications including amputation and heterotopic ossification in residual limbs. Most of these complications require or prolong hospitalization or require additional operative treatment [57].

Amputation as a primary treatment or secondary to failed revascularization or infection is discussed separately. (See 'Amputation and functional outcomes' below.)

Wound complications — Wound problems, due to ischemia or infection, are the most common complications of severe extremity injury and can result in wound breakdown, exposure of bone or vascular grafts, and secondary infection.

The incidence of infection correlates with increasing injury severity as defined by the Gustilo-Anderson grade (table 1) [58]. Representative infection rates (wound infection and/or osteomyelitis) are as follows [58-62]:

●Infection rates (percent):

•Grade I: 0 to 2

•Grade II: 2 to 5

•Grade IIIA: 5 to 10

•Grade IIIB: 10 to 50

•Grade IIIC: 25 to 50

The presence of infection affects the type and timing of soft tissue wound closure and the progress of bony union, and increases the risk for late amputation [63]. Established infections are treated with antibiotics based upon antibiotic sensitivities and ongoing debridement of devitalized soft tissue and bone, as needed. (See "Osteomyelitis associated with open fractures in adults", section on 'Prevention'.)

Venous thromboembolism — Deep venous thrombosis (DVT) and pulmonary embolism (PE) occur in up to 40 and 20 percent of injured patients, respectively [64-66]. The most important risk factors are likely related directly to the extremity injury and immobilization. Up to one half of documented deep vein thromboses affect the proximal lower extremity veins. Venous repair does not appear to increase the incidence of venous thromboembolic complications based on a review of 103 venous injuries [37]. In this study, DVT occurred at 10 sites remote from the vascular injury site in 82 total patients. There were three vein thromboses in 34 repairs.

The evaluation and treatment of venous thromboembolism are discussed in detail elsewhere. (See "Overview of the treatment of proximal and distal lower extremity deep vein thrombosis (DVT)" and "Treatment, prognosis, and follow-up of acute pulmonary embolism in adults".)

Rhabdomyolysis and myoglobinuria — Muscle cell death (rhabdomyolysis) and myoglobinuria can result from severe extremity trauma, crush injury, compartment syndrome, and revascularization. Rhabdomyolysis presents with elevated serum muscle enzymes (including creatine kinase), red to brown urine due to myoglobinuria if there is persistent renal function, and electrolyte abnormalities. Peak serum creatine kinase levels depend upon the volume of muscle breakdown and the muscle mass of the patient. (See "Severe crush injury in adults" and "Crush-related acute kidney injury" and "Rhabdomyolysis: Clinical manifestations and diagnosis".)

Patients with severe lower extremity injury and risk factors for rhabdomyolysis should have serial serum creatine kinase (CK) levels measured twice daily until decreasing levels are observed.

Aggressive saline hydration is the primary initial therapy of myoglobinuria, lowering the risk of induction of acute kidney injury. The prevention and general management of heme pigment-induced acute kidney injury is discussed in detail elsewhere. (See "Prevention and treatment of heme pigment-induced acute kidney injury (including rhabdomyolysis)".)

Heterotopic ossification — Bone healing can be complicated by the formation of ectopic bone within skeletal soft tissues (image 1) in patients with severe extremity injuries. Rates of heterotopic ossification (HO) increase with severity of injury. Civilian trauma-related amputations develop HO at rates of 10 to 30 percent, while military trauma injuries develop HO in 60 to nearly 100 percent of patients. Other risk factors for HO include neurologic injury (brain, spinal cord, or peripheral nerves), tissue ischemia, and high bioburden of contamination [67].

Prophylaxis against HO includes radiation therapy, which is often used in civilian trauma patients, to whom it can be administered early (first 72 hours after injury). The bisphosphonate etidronate is approved by the US Food and Drug Administration for HO prophylaxis; however, HO often progresses after treatment is stopped. Nonsteroidal anti-inflammatory drugs can reduce rates of HO formation, and cyclooxygenase-2 inhibitors are often used for both pain control and HO prophylaxis. Topically applied indomethacin in wounds has been studied in vitro and seems promising for HO prophylaxis.

Many patients with HO remain asymptomatic; however, symptoms in others include pain, skin breakdown, prosthetic fit issues, or other mechanical effects of ectopic bone. If nonoperative management of HO fails, surgery is indicated. Excision of HO should be done in a delayed fashion (at least six months postinjury), to permit maturation of the cortex and reduce the risk of recurrence [67].

AMPUTATION AND FUNCTIONAL OUTCOMES — The presence of extremity injury is a significant determinant in the patient's long-term functional recovery after major trauma [68]. In one longitudinal study of patients with severe lower extremity trauma, 50 percent had persistent severe disability over the seven-year study period [69]. Patient characteristics associated with poorer outcomes include older age, female sex, lower education level, living in a poor household, current or previous smoking, and poor health status before the injury [69]. In a retrospective review of popliteal injuries, preoperative factors associated with a higher risk of amputation included shock, associated orthopedic injury, and lack of preoperative Doppler signals; postoperative factors included a lack of Doppler signals postoperatively, no antiplatelet therapy, and loss of primary patency [70]. Functional recovery depends greatly on the social and economic resources available to the patient, which can be more of a factor than the severity of the initial injury [71-73].

Blunt extremity injuries are associated with a higher rate of amputation [74-76]. In one review, the amputation rate was 18 percent [74], compared with 3 percent in another review of mostly penetrating femoral artery injuries [75]. Popliteal artery injuries have a 10 to 15 percent rate of limb loss, the highest of any lower extremity vascular injury location. In an outcomes study of lower extremity arterial trauma from the United States and United Kingdom trauma registries, most injuries sustained during the Iraq and Afghanistan Wars were from explosive mechanisms that negatively affected the tibial vasculature [77]. At a mean follow-up of more than five years, long-term limb salvage was worse following blast injury compared with firearm or gunshot wounding. The mortality associated with limb salvage attempts was low and delayed secondary amputations occurred in the weeks and months after injury allowing the patient to be involved in the recovering and amputation decision process.

In below-knee arterial injuries, the number and location of affected vessels impact the likelihood of amputation. In a registry review, amputation rates were higher for blunt compared with penetrating injury (26.8 percent versus 7.5 percent), but the amputation rate was not associated with Injury Severity Score (ISS), sex, or age [76]. The amputation rate increased with the number of tibial vessels injured. For all three tibial vessels injured, the amputation rate was 50 percent; for two vessels, it was 29 percent, and for one vessel, it was 17.6 percent. Injury to the anterior tibial artery was associated with the highest amputation rate at 35.3 percent. A similar review showed amputation rates increased with number of tibial arteries injured [78].

Functional recovery is more likely with an isolated amputation. In a review of 395 patients, 59 percent had isolated lower extremity amputations. Following amputation, 17 percent returned to military duty, the majority of whom had a single extremity amputation [79].

Comparing outcomes for different levels of lower extremity amputation, a systematic review evaluated 3105 patients and found significantly lower physical component scores for progressively shorter residual limb lengths (below-knee, through-knee, and above-knee amputation) [80]. A significantly greater proportion of patients with a below-knee (72 versus 55 percent) or through-knee amputation (78 versus 55 percent) were able to walk 500 meters compared with an above-knee amputation or bilateral amputations (72 and 78 versus 50 percent, respectively). However, patients with a through-knee amputation wore their prosthesis less and had significantly more pain (85 versus 58 percent) compared with those with an above-knee amputation.

There is no single risk factor that increases the likelihood of delayed amputation [40], but the combination of complex pain symptoms and neurologic dysfunction appears to increase the risk, particularly if the initial injury was a severe hindfoot injury or distal tibial fracture [81]. In civilian studies, long-term functional outcomes for severe extremity injuries are not significantly different in patients with limb salvage versus amputation, although most patients prefer limb salvage initially.

●A retrospective review of 93 civilian patients with open lower extremity fractures from blunt trauma from 1994 to 2012 included seven patients who underwent primary amputation and four patients who expired within one month of injury [82]. Of the remaining 82 patients, 10 (12 percent) underwent secondary amputation after a median follow-up of 22 months. Factors that were significantly different between the limb salvage group and the secondary amputation group were Gustilo-Anderson fracture grade, high-energy injury mechanism, mangled extremity severity score, AO fracture classification, vascular injury, and fasciotomy.

●A retrospective comparison of 850 civilian and 115 military open tibia fractures found a higher overall injury severity and limb injury severity in combat casualties [83]. There were 45 amputations in the civilian group (5.3 percent) and 24 amputations in 21 military patients (18.3 percent). There was no difference in the civilian versus military amputation rate for Gustilo-Anderson grade I through IIIA fractures (1.2 versus 0 percent) or Gustilo-Anderson grade IIIB fractures (6.9 versus 10 percent). However, amputation rates were significantly higher in the military population (28.8 percent versus 69 percent). In both groups, limb ischemia was predictive of failed limb salvage, although many patients with ischemia on initial evaluation had successful limb salvage. In this study, follow-up was limited to the index hospital stay for the civilian group and up to 60 days in the military group.

●In a detailed review of 104 distal combat-related lower extremity injuries, 80 percent of patients did not require revascularization [32]. The overall amputation rate (primary and secondary) was similar (23 versus 19 percent) between revascularized and nonrevascularized patients. There was a trend toward less chronic pain in the bypass group (10 versus 30 percent).

●In an outcomes assessment that evaluated 569 patients after limb salvage (n = 384) or primary/early secondary (within three months) amputation (n = 161) [84]. Limb salvage and amputation had similar degrees of disability. Of 330 limb salvage patients with 24 months of follow-up, 4 percent underwent late secondary amputation (after three months).

Ultimately, limb salvage commits the patient to a prolonged recovery with an increased risk of complications and, potentially, additional surgery. The patient and his/her social supports often experience significant stress, which may lead the patient who initially preferred limb salvage to opt for amputation [85].

MORTALITY — In blunt civilian extremity injury, mortality ranges from 5 to 10 percent and is greater with blunt compared with penetrating injuries [74,86]. Mortality is a reflection of the severity of extremity injury, overall injury severity, and the development of complications (eg, venous thromboembolism). Mortality correlates to the volume of blood lost as a result of the extremity injury, which can be significant with junctional vascular injuries [87]. Isolated extremity injuries have lower rates of mortality.

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: Acute extremity ischemia" and "Society guideline links: Severe blunt or penetrating extremity trauma" and "Society guideline links: Extremity compartment syndrome".)

SUMMARY AND RECOMMENDATIONS

●Severe lower extremity injury – Trauma to the lower extremities represents one of the most common injury patterns seen in emergency medical and surgical practice. For patients with severe lower extremity injury, a brief lower extremity examination is performed during the initial trauma assessment but should be repeated in detail once life-threatening injuries have been addressed. Injury to three of the four functional elements (nerves, vessels, bones, soft tissues) constitutes a "mangled extremity" (calculator 1). (See 'Extremity evaluation' above and "Severe lower extremity injury in the adult patient", section on 'Initial evaluation and management' and "Severe lower extremity injury in the adult patient", section on 'Lower extremity evaluation'.)

●Damage control – Damage control techniques are used to manage patients with concomitant life-threatening torso or head injuries. Damage control torso surgery takes priority over the extremity injury as long as sites of extremity bleeding remain controlled. Fractures are managed with traction, splinting, or external fixation; vascular injuries with shunting of larger injured vessels or ligation of smaller vessels; injured nerves are rapidly identified and tagged if time permits; and soft tissues are irrigated and debrided to remove gross contamination, foreign material, and devitalized soft tissues. (See 'Damage control surgery' above.)

●Surgical reconstruction – Achieving an optimal outcome in patients with severe lower extremity injuries requires a multidisciplinary approach with oversight by the general or trauma surgeon and commitment from other specialist surgeons. Definitive treatment includes internal fixation with intramedullary nailing of long bones, arterial and venous reconstruction with autologous vein interposition graft(s), decompression or repair of peripheral nerves, and immediate or interval coverage of soft tissues. (See 'Fracture management' above and 'Revascularization' above and 'Nerve repair' above and 'Wound care and coverage' above.)

●Perioperative care – The postoperative course for patients with lower extremity injury is highly variable depending on the nature and severity of the injury, associated injuries, and the patient's comorbidities. Patients should receive mechanical and pharmacologic prophylaxis for venous thromboembolism as soon as is feasible given the high risk for deep venous thrombosis (DVT) and pulmonary embolism (PE) in this population. The risk of thromboembolic complications rises sharply if pharmacologic prophylaxis is delayed beyond three days. (See 'VTE prophylaxis' above and 'Venous thromboembolism' above.)

●Complications – Complications from severe lower extremity injury are common and can be life- or limb-threatening, and, thus, early recognition and treatment are important to minimize morbidity and mortality. Complications include wound complications (wound breakdown, infection), venous thromboembolism, rhabdomyolysis and myoglobinuria (crush injury, ischemia-reperfusion, extremity compartment syndrome), and heterotopic ossification. The threshold for performing extremity fasciotomy is low in patients with severe extremity injury. (See 'Complications' above and 'Extremity fasciotomy' above.)

●Functional outcomes – In civilian studies, functional outcomes for severe lower extremity injuries are not significantly different for patients who have undergone limb salvage compared with amputation, although most patients prefer limb salvage initially. Long-term functionality depends more on patient social factors than the severity of the injury. Mortality for civilian extremity injury ranges from 5 to 10 percent. (See 'Amputation and functional outcomes' above and 'Mortality' above.)

ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges Jeremy W Cannon, MD, FACS, who contributed to an earlier version of this topic review.