Severe lower extremity injury in the adult patient

INTRODUCTION — Trauma to the extremities represents one of the most common injury patterns seen in emergency medical and surgical practice. As extremity injuries are evaluated, each of four functional components (nerves, vessels, bones, and soft tissues) must be considered individually and together. If three of these four elements are injured, the patient has a "mangled extremity" [1,2]. Achieving the best outcome in patients with severe lower extremity injuries requires a multidisciplinary approach with oversight by the general or trauma surgeon and commitment from other specialists including orthopedic, vascular, and plastic surgeons as well as rehabilitation specialists. In most instances, limb salvage (ie, saving a limb that would be lost without intervention) can be attempted even if the patient has a mangled extremity. However, at times, the injury to the lower extremity is so severe that primary amputation at the initial operation is required to save the patient's life.

The initial management of severe lower extremity injury will be reviewed here. The management of severe upper extremity injury is reviewed separately. (See "Severe upper extremity injury in the adult patient".)

The management of minor lower extremity injuries, including isolated fracture management, is discussed elsewhere. (See "General principles of fracture management: Bone healing and fracture description" and "General principles of fracture management: Early and late complications" and "General principles of acute fracture management" and "General principles of definitive fracture management".)

ETIOLOGY — The etiology of extremity injuries ranges widely from falls and motor vehicle collisions to blast and fragmentation injuries. The nature and severity of lower extremity injuries differs between the military and civilian settings. Military extremity injuries are primarily due to penetrating or combined mechanisms, which are associated with high rates of open fracture and vascular injury [3]. In contrast, most severe extremity injuries in civilians are due to blunt trauma, but approximately 12 percent of civilian extremity injures occur because of penetrating or combined mechanisms.

Civilian — Civilian extremity injuries occur most often due to falls (representing 50 to 60 percent of lower extremity injuries), industrial or work-related accidents, and motor vehicle crashes [4]. In civilians with nonfatal trauma, lower extremity injuries are the most common reason for hospitalization, with more than one third of those hospitalized having serious or limb-threatening injuries [4-6]. Gunshot injury and civilian blast injury can affect the lower extremities and are associated with concomitant long bone fractures and a higher rate of vascular injury [7-11]. In a systematic review of 3187 lower extremity injuries requiring vascular repairs, the overall secondary amputation rate was 10 percent [12].

Military — Approximately 50 percent of the injuries recorded in the Joint Theater Trauma Registry involve the extremities [13,14]. Many soldiers with extremity injuries also have other serious life-threatening injuries that complicate limb salvage [15]. In one series, 25 percent had an extremity injury associated with another serious non-extremity injury [3].

Most extremity wounds during combat have a penetrating component, typically resulting from explosions (81 percent) or gunshot wounds (17 percent). Only 2 percent of extremity injuries during combat are due to isolated blunt trauma [13]. Because of the predominantly penetrating mechanism and war environment, many of these injuries involve multiple functional components (bone, nerve, vessel and soft-tissue damage), resulting in a high rate of mangled extremities.

INCIDENCE — In 2012, 278,100 lower extremity injuries were entered into the civilian National Trauma Data Bank (NTDB) [5]. Traumatic injury in civilians results in an estimated 3700 major amputations annually [4,16]. The contemporary incidence of extremity injuries during combat is lower than in previous recorded conflicts, representing approximately 50 percent of injuries, compared with approximately 59 percent during World War II, 60.2 percent during the Korean War, and 61.1 percent in the Vietnam War [14,17].

The presence of an open fracture significantly increases the risk of osteomyelitis and, ultimately, limb loss depending upon the severity of injury to the associated soft tissues. Open fractures occur in approximately 3 percent of long bone fractures for an annual incidence of between 11.5 and 13 per 100,000 [18,19]. The long bone that is most commonly involved in open fracture is the tibia. In one study, 24 percent of tibial fractures were open [20]. High-energy motor vehicle collisions were responsible for 58 percent of these injuries [19].

While the tibia is also the most frequently injured bone following combat-related trauma, in a review of 2996 injured service members, the highest rates of delayed amputation were in patients with navicular (36.2 percent), talus (30.0 percent), or calcaneus (28.1 percent) fractures [21].

Motor vehicle crash (MVC) is a common cause of civilian lower extremity trauma, and compared with other lower extremity fractures, ankle fractures have been associated with higher rates of delayed amputation. Understanding the risk factors and fracture patterns associated with MVC-associated foot and ankle fractures is useful. Ankle fractures account for 24 to 56 percent of MVC-associated fractures below the knee, occurring in 0.2 to 0.4 percent of all frontal crashes [22]. In a frontal crash, drivers are twice as likely to have an ankle fracture compared with passengers [23]. Increased age and body mass index are additional risk factors for MVC-associated ankle fracture [22]. Due to axial loading, pronation, or forced dorsiflexion associated with braking [24,25], the right lower extremity is most commonly affected, and fractures most commonly involve the malleoli [22]. Use of seat belt restraints and airbags have not reduced the risk of MVA-associated ankle fracture [23].

Associated vascular injuries occur in <1 percent of all civilian fractures (0.4 percent in one series) [26]. The risk of vascular injury increases with increasing injury severity. In retrospective reviews, the incidence of vascular injury was cited at 5 percent for severe fractures [18] and 6.6 percent for penetrating extremity injuries [27]. Among patients with arterial injury, bony injuries were present in 43 percent of patients, in a five-year retrospective review [28]. Venous injuries occurred in 20 percent of the patients studied.

In contemporary combat reviews, the lower extremity is the most common site of vascular injury [29,30]. In one review, among 3900 service members, 17.6 percent had vascular injuries [30]. Of these, 45 percent involved the lower extremity. The overall rate of vascular injury in modern combat has also increased; rates of vascular injury in prior conflicts ranged from 1 percent in World War II to 2 to 3 percent in Korea and Vietnam.

EXTREMITY ANATOMY — Knowledge of extremity anatomy and functional physiology is important for proper preoperative and postoperative extremity assessment. The anatomy of the lower extremity is reviewed elsewhere. (See "Surgical management of severe lower extremity injury", section on 'Lower extremity anatomy'.)

INITIAL EVALUATION AND MANAGEMENT — We perform initial resuscitation, diagnostic evaluation, and management of the trauma patient with blunt or penetrating trauma based upon protocols from the Advanced Trauma Life Support (ATLS) program, established by the American College of Surgeons Committee on Trauma [31,32]. The initial resuscitation and evaluation of the patient with blunt or penetrating head, thoracic, or abdominal trauma is discussed in detail elsewhere. Resuscitation and management of these life-threatening injuries takes precedence over the extremity injury. (See "Initial management of trauma in adults".)

Control of hemorrhage — External bleeding from the extremity, and particularly bleeding from the junctional segment of the extremity vasculature (ie, common femoral artery), is life-threatening and should be controlled as soon as possible [33]. (See "Control of external hemorrhage in trauma patients".)

Bleeding from lower extremity vascular injury can usually be controlled using direct pressure. However, because prolonged application of direct pressure is often not practical during transport in the prehospital or tactical environment, other approaches have been used including topical agents, external compression clamps, and endovascular occlusion devices [33]. These methods are not widely accepted in mainstream civilian clinical practice but have been endorsed by the American College of Surgeons in the prehospital setting [33].

Bleeding can also be controlled using a tourniquet [34,35] or direct clamping of visible vessels. Clamping vessels that cannot be clearly identified should not be performed. Pneumatic tourniquets are commonly used to lessen bleeding during extremity surgery. There is renewed interest in the civilian community in the use of tourniquets for control of extremity hemorrhage [36]. ATLS endorses the judicious use of a tourniquet for major extremity arterial hemorrhage, and several civilian guidelines now include tourniquet application as a temporary adjunct to control extremity hemorrhage when direct pressure is unsuccessful [32,37,38] or during tactical civilian events, which are situations where ballistic or explosive wounds are possible (eg, an active shooter standoff) [39].

A variety of tourniquets have been developed to manage combat-related extremity hemorrhage with a low risk of ischemia and neurologic complications [40,41]. The Combat Application Tourniquet (CAT), Emergency and Medical Tourniquet (EMT), and Special Operations Forces Tactical Tourniquet (SOFTT) meet the effectiveness standard of the United States military and occlude distal flow in >80 percent of subjects [40,41]. The relative effectiveness of these tourniquets has been evaluated in human volunteers with each shown to attenuate the distal arterial pulse in the extremities [42]. The benefits of tourniquet application are illustrated in the following studies in combat casualty populations:

●In a study that evaluated 165 patients, 67 of whom had a prehospital tourniquet applied, control of bleeding was significantly improved with tourniquet application versus no tourniquet (83.3 versus 60.7 percent), and there were no differences in secondary amputation rates [40].

●A prospective study of 232 combat casualties found a significantly improved survival rate (77 versus 0 percent) when using a tourniquet (prehospital or emergency department) versus no tourniquet [41]. In this study, no amputations were required due to tourniquet use, but four transient nerve palsies were reported.

Similar results have been demonstrated in civilian patients with both pre-hospital and in-hospital tourniquet application [43-45]. In an AAST multicenter prospective analysis of prehospital tourniquet use for extremity civilian trauma, prehospital tourniquet application was being widely and safely adopted and was associated with decreased incidence of arrival in shock without increasing limb complications [46,47].

Extremity radiography — Patients with any of the following findings on primary trauma survey should undergo plain radiographs. Radiographic assessment should focus on the area of abnormality to include a joint above and below the potential injury, and the study should be performed with two projections (eg, anterior-posterior and lateral).

●Extremity deformity

●Point tenderness

●Ecchymosis

●Laceration deep to the muscle fascia

●Laceration in proximity to a joint

●Joint laxity

Bony injuries, particularly comminuted fractures, increase the risk of concomitant arterial injury (table 1) and include fractures of the mid-femur (image 1) and mid- or distal tibia-fibula fractures (image 2). The presence of these fractures on radiographic survey should prompt full vascular assessment. (See 'Vascular assessment' below.)

Antibiotics — Systemic antibiotics should be started at the time of the diagnosis of open fracture (table 2). The open fracture site should be cleaned of any foreign debris and dressed with a moist sterile dressing. (See "Surgical management of severe lower extremity injury", section on 'Infection control'.)

Tetanus prophylaxis — Tetanus prophylaxis should be given according to the Centers for Disease Control (CDC) guidelines [48]. (See "Tetanus-diphtheria toxoid vaccination in adults", section on 'Immunization for patients with injuries'.)

Special situations — Two clinical scenarios involving extremity injury require specific management: traumatic amputation and electrical injury.

Traumatic amputation — Traumatic amputation refers to limb loss that occurs in the field at the time of the initial trauma and is a special form of the mangled extremity. It is distinguished from primary amputation, which is removal of the limb during initial operative management, and secondary amputation, which is removal of the limb following attempted limb salvage. (See "Surgical management of severe lower extremity injury", section on 'Limb salvage versus amputation' and "Lower extremity amputation".)

Replantation is performed most commonly for traumatic upper extremity traumatic amputations. (See "Surgical management of severe lower extremity injury", section on 'Limb salvage versus amputation'.)

In the lower extremity, a prosthesis provides a good functional outcome that, in some cases, may be superior to that achieved with replantation [49]. Lower limb replantation may be possible if the distal detached extremity is relatively uninjured.

Warm ischemia time should be limited by wrapping the amputated body part in saline-soaked gauze or by indirect cooling (placing the body part in a container and then placing the container on ice) [50]. The extremity should not be exposed directly to ice. Lower extremity replantation is generally not recommended if warm ischemia time is more than six to eight hours for major traumatic amputation.

A multidisciplinary decision for replantation is made at the receiving facility with input from the trauma surgeon overseeing the patient's care, taking into consideration the patient's other injuries, and with input from subspecialists in orthopedic, plastic, and vascular surgery regarding feasibility of replantation and likely projected outcomes. Even if replantation is deemed inadvisable, careful preservation of the amputated segment may provide tissue that can be repurposed to provide soft tissue coverage or aid in nerve reconstruction [51].

Extremity electrical injury — Electrical injuries, which can result in significant soft tissue damage, are less common in the lower extremity. Injuries are stratified into two groups based upon the voltage involved: low voltage (ie, <1000 volts) and high voltage (≥1000 volts). The epidemiology, diagnosis, and general issues of the treatment of electrical injuries are discussed in detail elsewhere. (See "Electrical injuries and lightning strikes: Evaluation and management".)

Soft tissue damage occurring between the entrance and exit wounds can be substantial with high-voltage injuries. Amputation is necessary in up to 40 percent of these cases, which is not surprising given the large volume of soft tissue loss [52]. The involved soft tissues should be closely monitored for necrosis and vascular thrombosis. Reconstruction can be undertaken once the full extent of soft tissue injury has manifested.

Compartment syndrome should be anticipated with high-voltage injuries, and early fasciotomy should be performed as indicated. (See "Acute compartment syndrome of the extremities" and "Lower extremity fasciotomy techniques" and "Patient management following extremity fasciotomy".)

LOWER EXTREMITY EVALUATION — A brief extremity exam is performed during the initial trauma assessment (primary survey) but should be repeated in more detail once life-threatening injuries have been addressed and any active external bleeding is controlled. The extremity evaluation should proceed in an orderly fashion using the four functional elements of the extremity as a framework, which includes assessment of the nerves, vessels, bones, and soft tissues.

Peripheral nerve assessment — The neurologic exam in alert, cooperative patients should easily identify associated motor or sensory deficits. In the unconscious or uncooperative patient, gross deficits should be noted, such as a lack of movement in all or part of an extremity, or asymmetric movements. Detailed ongoing extremity evaluation should be performed as the patient's neurologic status improves to identify specific deficits referable to peripheral nerve injury.

In the lower extremity, function of the femoral, sciatic, tibial, and peroneal nerves should be assessed since these nerves are more likely to be directly injured or affected by ischemia.

●Injury to the femoral nerve results in decreased sensation on the anterior thigh and weakness of hip flexion and knee extension.

●Injury to the sciatic nerve causes decreased sensation in the lateral leg and the lateral, dorsal, and plantar aspects of the foot; weakness of knee flexion; and loss of motor function of the leg and foot.

●Deep peroneal nerve injury causes foot drop. Sensation in the first webspace commonly has a tibial contribution that can mask or confuse deep peroneal nerve injury.

●Injury to the tibial nerve results in loss of sensation to the heel, inability to plantar flex the foot, and cavus deformity of the foot.

Although lack of plantar sensation has historically been taught as a useful indicator of an unsalvageable extremity, subsequent data have found that this is not a reliable physical finding. Some patients with an insensate foot on initial exam can subsequently regain function [53].

Vascular assessment — A detailed vascular assessment of the injured extremity begins with a complete pulse examination (common femoral, popliteal, dorsalis pedis and posterior tibial arteries, axillary, brachial, radial, ulnar arteries) to identify asymmetry of pulses or the absence of palpable pulses. Auscultation over the injury site may reveal a bruit that may be indicative of a partially thrombosed or compressed vessel or the presence of an arteriovenous fistula.

In the setting of a shock or the presence of joint dislocation or angulated fracture, the pulse assessment should be repeated after resuscitation and/or reduction of the abnormality. In a study of combat injuries, 74 percent of patients who had no pulses on initial examination had reestablished blood flow to the foot following resuscitation and limb stabilization [54].

Hard signs of arterial injury — Hard signs of vascular injury include the following [5]:

●Active/pulsatile hemorrhage

●Expanding or pulsatile hematoma

●Bruit or thrill over wound

●Absent distal pulses

●Extremity ischemia (pain, pallor, paralysis, cool to touch)

In a large observational study of penetrating extremity trauma, the presence of a hard sign of arterial injury was nearly 100 percent predictive of a vascular injury warranting surgical repair [27]. These patients should be taken directly to the operating room where the injury can be surgically explored. If arteriography is needed to clarify arterial anatomy, it can be performed intraoperatively.

With blunt trauma, hard signs are less reliable and false positives are common. Repeat physical examination after resuscitation, warming, and reduction of any orthopedic injuries should be performed. If a diminished pulse or other signs of vascular injury persist in the hemodynamically stable patient with blunt extremity injury, either conventional angiography or computed tomographic (CT) angiography should be performed to further delineate the location and nature of the injury. (See 'Arteriography' below.)

Injured extremity index — The injured extremity index (IEI) or arterial pressure index (API) is analogous to the ankle-brachial index (ABI) and should be performed in any patient who does not have hard signs of vascular injury. The term "injured extremity index" is a trauma-specific term that is broader and can be applied to any extremity. (See "Noninvasive diagnosis of upper and lower extremity arterial disease", section on 'Ankle-brachial index'.)

The IEI is the ratio of the highest systolic occlusion pressure in the injured extremity at the level of the dorsalis pedis/posterior tibial (or radial/ulnar arteries) divided by the systolic pressure in a proximal vessel in an uninjured extremity (most often the brachial artery).

●A normal IEI (ie, >0.9) has a high negative predictive value for vascular injury, allowing the patient to be observed or managed without immediate vascular imaging [55,56].

●An IEI that is abnormal (ie, ≤0.9) may indicate an occult vascular injury. For patients who are hypothermic or hypotensive during the initial assessment, the IEI should be repeated 10 to 15 minutes after resuscitation and warming. An IEI that is persistently below 0.9 is predictive of vascular injury that requires additional vascular evaluation [55,56].

The diagnostic approach for patients with an IEI ≤0.9 should be within the context of the patient's overall clinical status and other associated injuries. In patients with multiple injuries who require head, torso, and abdominal CT, adding extremity CT angiography is a rational choice. The information obtained with respect to the extremity (positive or negative) assists the trauma surgeon in determining which injuries to manage first.

For isolated extremity injuries or injuries with less complex associated injuries, the approach should be more individualized. Some patients may benefit from immediate surgical exploration and others from digital subtraction arteriography (DSA) rather than CT angiography. Every effort should be made to avoid an algorithm that exposes the patient to excessive radiation and intravenous contrast load such as CT angiography followed by DSA, which usually occurs in the context of seeking to better define subtle irregularities [57]. Consultation with a vascular surgeon can help aid with decision making.

Arteriography — Arteriography, which can be accomplished using CT or conventional DSA, may be necessary to exclude vascular injury in hemodynamically stable patients with clinical signs consistent with potential vascular injury, such as an equivocal pulse examination, persistently diminished IEI in spite of resuscitation, and posterior knee dislocation. (See 'Injured extremity index' above.)

The need for vascular repair (open or endovascular) should be determined in the context of clinical findings in conjunction with an arteriographic study that shows a vascular injury. The clinical findings also establish the timing or urgency of the operation. In the context of a clinical examination, the following findings on arteriography (CT or DSA) strongly indicate the need for exploration and vascular repair. (See "Surgical management of severe lower extremity injury", section on 'Revascularization'.)

●Extravasation of contrast or pseudoaneurysm.

●Arteriovenous fistula.

●Flow-limiting intimal flap (flow limiting based upon clinical exam). If the injured extremity index is normal, any observed flap is not considered to be flow limiting.

●Occlusion of axial extremity arteries.

●Distal embolism (may occur even in the presence of a relatively minor proximal injury).

The high sensitivity and speed of modern CT makes it attractive as a noninvasive study to identify and characterize suspected vascular injury [58]. To obtain optimal images, contrast injection should be performed remote from the extremity of interest. The sensitivity of helical CT angiography with three-dimensional reconstruction ranges from 90 to 100 percent, with specificities >99 percent [59-61]. Interobserver agreement is approximately 90 percent. Newer-generation multidetector scanners (16 or 64 slice) have sensitivity and specificity approaching 100 percent for clinically significant injuries [62,63]. In one study, multidetector CT angiography adequately imaged the extremity vasculature in spite of the artifact caused by orthopedic hardware and retained fragments [64]. Three-dimensional reconstruction is not an absolute requirement with higher-slice scanners. We use a 64 slice scanner without reconstruction but consider it ideal to have the trauma or vascular surgeon review the cross-sectional images together with the radiologist.

CT angiography is often preferred in patients with multiple trauma because it is less invasive than conventional arteriography and can be performed at the same time as head, chest, or abdominal CT, which are frequently needed in trauma patients. As a single study, CT angiography is less expensive than conventional arteriography [63]. However, the cost of additional studies to sort out nondiagnostic findings on CT angiography and the cost of unnecessary surgical explorations or other interventions based upon the results of CT angiography need to be taken into account. As an example, in a study of 132 patients with penetrating trauma, 59 patients underwent CT angiography, of which 28 were performed as a completion of a head/chest/abdominal series and 31 were for isolated extremity injury [57]. Ten percent of the studies were indeterminate with two of patients requiring exploration. There was no difference in the rate of indeterminate studies between whole body studies and those done for isolated extremity injury.

Conventional DSA may be preferred initially in some patients and can be performed in a dedicated interventional suite or in the operating room. Arteriography in the operating room has the advantage of eliminating unnecessary patient transport. A hybrid operating room (operating suite with interventional capabilities) is ideal but not necessary. Intraoperative arteriography can be performed using a portable power injector and portable digital subtraction arteriography, which are generally available in the operating room at civilian and military hospitals [65].

Soft tissue and bone assessment — The soft tissue envelope of muscle, subcutaneous fat, and skin should be evaluated for signs that indicate a potential underlying fracture and to assess the severity of soft tissue damage, which is important for determining the potential risk of limb loss.

The soft tissue injury should identify areas of missile entry and exit, soft tissue avulsion, skin or muscle flap formation, and evidence of contamination. In penetrating injuries, such as high-velocity gunshot wounds or fragmentation injuries, the external wound may be relatively small; however, underlying soft tissue destruction can be significant.

Rotational (shearing) injuries to the extremities can avulse the skin and subcutaneous fat off the underlying tissues, which are termed degloving injuries [66]. These can be classified as pure degloving injuries involving the skin only (open or closed), those that involve the deep soft tissues, and those associated with long-bone fracture [67]. Traumatic separation of the skin and subcutaneous tissues from the underlying fascia without a break in the skin constitutes a closed degloving injury (Morel-Lavallee, post-traumatic seroma) [68]. Closed degloving occurs most frequently overlying the hip and in the proximal thigh. Free-floating segments of skin and soft tissue can become ischemic and slough completely, resulting in large areas of soft tissue loss that must then be skin grafted. (See "Surgical management of severe lower extremity injury", section on 'Degloving injuries'.)

Severe or extensive muscle tissue damage can lead to rhabdomyolysis, independent of other risk factors such as ischemia-reperfusion or acute compartment syndrome. The diagnosis and management of rhabdomyolysis is reviewed elsewhere. (See "Rhabdomyolysis: Clinical manifestations and diagnosis".)

Lacerations should be assessed for proximity to fracture sites and joint spaces. Extremity injuries with suspected joint space involvement (traumatic arthrotomy) can be further evaluated by injecting the joint with saline (ie, saline load test). However, using CT may be preferred unless it is not available or not practical. In one study of 62 patients, the sensitivity and specificity of CT for detecting a traumatic open arthrotomy at the knee was significantly higher compared with the saline load test (100 versus 92 percent) [69]. An additional advantage of CT is the ability to detect open periarticular knee fracture. In one study, CT altered the fracture classification in 48 percent of patients [70]. When a saline load test is used, the joint should be assessed to identify any distension and the associated wound or laceration evaluated for fluid extravasation. Available studies indicate that as much as 194 mL of saline may need to be injected to achieve 95 percent sensitivity for identifying traumatic arthrotomy of the knee [71-73]. In a retrospective study of the saline load test used in 50 trauma patients at risk for a traumatic arthrotomy of the knee, the at-risk joint was loaded until fluid was noted to extravasate from the wound or to the maximum volume tolerated by the patient [73]. This technique resulted in a sensitivity of 94 percent and a negative predictive value of 97 percent with injected volumes ranging from 40 to 180 mL.

The muscle compartments of the affected extremity should also be evaluated on initial exam. Soft tissue injury and swelling can result in compartment syndrome. The lower extremity is more prone to compartment syndrome compared with the upper extremity because of its greater muscle mass and possibly because of its dependent position. The diagnosis and management of compartment syndrome are discussed elsewhere. (See "Acute compartment syndrome of the extremities" and "Patient management following extremity fasciotomy" and "Lower extremity fasciotomy techniques".)

Extremity deformity, point tenderness, ecchymosis, laceration deep to the muscle fascia, laceration near a joint, and joint laxity are signs of a potential fracture. Plain radiography should be performed to establish a diagnosis. (See 'Extremity radiography' above.)

Detailed discussions of specific fractures are found in separate topic reviews:

●Hip and thigh – (See "Overview of common hip fractures in adults" and "Midshaft femur fractures in adults".)

●Leg and ankle – (See "Proximal tibial fractures in adults" and "Tibial shaft fractures in adults" and "Ankle fractures in adults".)

An open fracture is defined as a bony fracture and soft tissue laceration that are in communication with each other (picture 1). In civilian series, open fractures occur in up to 24 percent of tibia fractures [19,20]. In a review of 1281 soldiers with extremity injuries, 915 fractures were identified, of which 82 percent were open [74]. Open fracture significantly increases the risk of osteomyelitis and, ultimately, limb loss depending upon the severity of the associated soft tissue injury. (See 'Open fracture grading' below and "Surgical management of severe lower extremity injury", section on 'Wound complications'.)

Following the initial assessment, the affected bone(s) should be aligned as well as possible and stabilized with a splint or traction to minimize soft tissue injury and to optimize distal perfusion. Open wounds should be irrigated with saline to eliminate gross contamination prior to the application of temporary gauze dressings. The patient can then undergo further diagnostic workup for associated injuries. Techniques for splinting musculoskeletal injuries are discussed elsewhere. (See "Basic techniques for splinting of musculoskeletal injuries".)

Posterior knee dislocation is associated with popliteal artery injury, and a careful vascular examination should be performed when this injury is identified. Following reduction of the dislocation, the vascular examination should be repeated, and, if normal, the patient should continue to be observed. If the pulses remain abnormal, vascular imaging is indicated (arteriography), and management depends upon the findings (algorithm 1). (See "Knee (tibiofemoral) dislocation and reduction".)

INJURY SEVERITY SCORING — Following examination of the extremity, overall injury severity should be assessed to determine whether a primary amputation should be performed or if the limb is potentially salvageable. The utility of using injury severity scores in predicting the success of limb salvage is discussed elsewhere. (See 'Predicting limb loss' below.)

Various extremity injury severity scores are described, including the Mangled Extremity Severity Score (MESS); the Limb Salvage Index (LSI); the Predictive Salvage Index (PSI); the Mangled Extremity Syndrome Index, the Nerve Injury, Ischemia, Soft-Tissue Injury, Skeletal Injury, Shock, and Age of Patient Score (NISSSA); the Hannover Fracture Scale-97 (HFS-97); and the Gustilo-Anderson open fracture grading system [1,75-80].

The American Association for the Surgery of Trauma (AAST) has also introduced the peripheral vascular organ injury scale as a means to grade the severity of peripheral vascular injury in those with extremity trauma (table 3).

MESS — The Mangled Extremity Severity Score (MESS) is the most widely applied scoring system to categorize the degree of extremity injury [1]. The term "mangled" refers to a limb in which at least three of the four functional components (bone, vessels, nerves, and soft tissue) are injured.

The MESS is calculated by scoring each of the areas listed below (calculator 1). Component scores are then added to yield the MESS, which ranges from 2 to 14. "Severity and duration of ischemia" scores are doubled if perfusion has not been restored within six hours of injury. Patients with a truly mangled extremity will typically have MESS scores of 4 or greater.

●Severity of skeletal and/or soft tissue injury

●Severity and duration of limb ischemia

●Severity of shock

●Patient age

Open fracture grading — Open fractures should be graded using the Gustilo-Anderson system (table 4), which is usually performed intraoperatively; however, the severity of the orthopedic injury can generally be estimated during the initial extremity evaluation. An increasing grade of open fracture has been correlated to an increased risk of infection and rate of amputation [75,76]. A disadvantage of this scoring system is the low interobserver agreement of 60 percent [77,78].

The Orthopaedic Trauma Association has recently proposed a framework for developing a new classification scheme for open fractures [79]. Over time, this descriptive framework may replace the Gustilo-Anderson system, but it has yet to be validated and correlated with complications and outcomes.

Predicting limb loss — The likelihood that extremity injury will result in limb loss can be estimated based upon clinical findings with the aid of scoring systems. However, no injury severity scoring system has been found to be sufficiently sensitive for determining whether efforts at limb salvage will fail. Primary amputation may be considered in those with a combination of uncontrollable hemodynamic instability; extensive and concurrent soft tissue, bone, vascular, and/or nerve injuries; prolonged limb ischemia; and blunt arterial trauma or crush injury; these may be helpful when counseling the patient or family members or other caretakers about options for treatment and may guide a decision for primary amputation [81]. (See "Surgical management of severe lower extremity injury", section on 'Limb salvage versus amputation'.)

Clinical predictors — Some injuries are associated with high amputation rates in spite of best efforts at limb salvage. The risk of limb loss is the greatest for injuries with combined bony instability, vascular injury (particularly combined arterial and venous injury), and soft tissue injury. An example is blunt injury to the popliteal region, which can injure the popliteal artery and vein [82,83]. High-energy and penetrating injuries can also lead to combined bony, vascular, and soft tissue injury [29].

Guidelines for the management of complex extremity injuries prepared by the American College of Surgeons Committee on Trauma ad hoc Committee on Outcomes [84], supplemented by the Eastern Association for the Surgery of Trauma (EAST) [85], cite the following as factors that increase the risk for limb loss:

●Delay in revascularization

●Blunt trauma

●High-velocity penetrating trauma

●Lower extremity vascular involvement (especially popliteal artery)

●Associated injuries

●Older age and older physiologic health

●Shock and obvious limb ischemia

●Forward combat zone

●Resource-limited environment

●Multi-casualty event

A study of the National Trauma Data Bank in the United States noted that high-energy trauma mechanisms, crush injury at or above the knee, systolic blood pressure <90 mmHg in the Emergency Department, and severe head injury independently predicted amputation within the first hospital day [2].

Lower extremity injuries requiring vascular repair have a high rate of amputation. Amputation rates are higher for blunt compared with penetrating injury. For below-the-knee arterial injuries, the need for amputation correlates with the number of vessels injured [86,87]. In a systematic review, other factors that increase the risk of amputation include major soft tissue injury (26 versus 8 percent for no soft tissue injury), associated fracture (14 versus 2 percent), and mechanism of injury (blast: 19 percent, blunt: 16 percent, penetrating: 5 percent). In this review, shock and nerve or venous injuries were not significant prognostic factors for secondary amputation [12]. However, while not an independent risk factor for delayed amputation, in one review, nerve injury significantly increased the risk for delayed amputation when it occurred in combination with an open calcaneal fracture (odds ratio 41.74, 95% CI 14.7-118.6) [21]. Nerve injury is also frequently a significant source of pain or limited function in both salvaged and amputated extremities. (See "Surgical management of severe lower extremity injury", section on 'Amputation and functional outcomes'.)

Efficacy of scoring systems — Injury severity scoring systems are widely applied but are not highly sensitive for predicting the need for amputation following extremity injury. (See 'Injury severity scoring' above.)

The MESS (calculator 1) is a commonly cited tool that provides a frame of reference for comparing extremity injuries; however, it is limited in its ability to predict need for amputation. The MESS is best used alongside clinical exam and patient comorbidities to help in the decision for or against limb salvage. A low score suggests limb salvage potential; however, a high score does not reliably predict the need for eventual amputation.

The Lower Extremity Assessment Program (LEAP) investigators evaluated 556 patients with lower extremity injuries using five injury severity scoring systems, including MESS [88]. Each of the scoring systems were highly specific (0.84 to 0.98) but not sensitive (0.37 to 0.67) for predicting limb loss. Specifically, regarding the MESS, these authors found that an MESS of 7 had a sensitivity of 0.45 but a specificity of 0.93 for predicting amputation.

MANAGEMENT APPROACH — Once a severe extremity injury has been identified, a management plan should be developed taking into consideration the patient's other injuries. In multiply injured trauma patients, the management plan should be made by one lead surgeon in collaboration with the orthopedic, vascular, and neurosurgery services, as needed. The priority of, timing to, and approach to each injury should be determined in advance. Optimal limb salvage is achieved when revascularization of lower extremity injury can be accomplished within one hour of injury [58,89].

Hemodynamically unstable — Based upon Advanced Trauma Life Support (ATLS) principles, the hemodynamically unstable trauma patient with indications for surgery (eg, positive Focused Assessment with Sonography for Trauma [FAST], hard signs of vascular injury) should be taken to the operating room to identify and control bleeding. Life-threatening injuries to the head, neck, chest, or abdomen take precedence over the extremity injury. A damage control or staged approach to the injured extremity is warranted once external bleeding from the extremity is controlled. In some cases, the severity of the extremity injury or time constraints due to the need to manage life-threatening injuries will preclude meaningful attempts at limb salvage, and primary amputation may be the best option. If the extremity is the primary (or only) injury, a more definitive approach to repair can be taken at the outset. (See 'Hard signs of arterial injury' above and "Surgical management of severe lower extremity injury", section on 'Damage control surgery'.)

Hemodynamically stable with vascular injury — For hemodynamically stable patients, the timing of the management of extremity injury when vascular injury is present depends upon the degree and duration of ischemia. Patients with hard signs of vascular injury should be taken immediately to the operating room for evaluation and management. Patients with clinical signs of arterial injury, including an injured extremity index (IEI) <0.9, should be evaluated using computed tomographic (CT) angiography or conventional arteriography depending upon institutional resources. In the presence of bony instability, arterial revascularization is fraught with difficulties. Under these circumstances, arterial shunting, if needed, and fracture stabilization followed by definitive vascular repair once the bones have been stabilized may be the most appropriate sequence of care. (See "Surgical management of severe lower extremity injury", section on 'Revascularization' and "Surgical management of severe lower extremity injury", section on 'Fracture management'.)

Hemodynamically stable without vascular injury — The timing and management of extremity injury when no vascular injury is present depends upon the severity of fracture and the degree of soft tissue loss. Open fracture debridement and fracture stabilization should be performed as soon as is feasible depending upon the nature and extent of nonextremity injuries. Multiple debridement procedures are frequently required before definitive fracture fixation and soft tissue coverage can be achieved. (See "Surgical management of severe lower extremity injury", section on 'Wound care and coverage' and "Surgical management of severe lower extremity injury", section on 'Fracture management'.)

MORBIDITY AND MORTALITY — Patients with severe lower extremity injuries have a high incidence of complication, 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 result in prolonged hospitalization, and many require additional operative treatment [90]. These complications are discussed elsewhere. (See "Surgical management of severe lower extremity injury", section on 'Complications'.)

In blunt civilian extremity injury, mortality ranges from 5 to 10 percent and is greater with blunt compared with penetrating injuries [28,91]. Mortality correlates to the volume of blood lost as a result of the extremity injury, which can be significant with injuries involving the junctional vasculature [34]. Higher mortality rates reflect more severe extremity injury, coexistent injury, and development of complications (eg, venous thromboembolism). Mortality rates are lowest for isolated extremity injuries.

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" and "Society guideline links: Severe blunt or penetrating extremity trauma".)

SUMMARY AND RECOMMENDATIONS

●Lower extremity trauma – Trauma to the lower extremities represents one of the most common injury patterns seen in emergency practice. Civilian lower extremity injuries are most commonly due to blunt mechanisms, whereas combat injuries are predominantly due to penetrating or mixed mechanisms. In combat, extremity injuries are present in one half of all casualties. (See 'Introduction' above and 'Incidence' above and 'Etiology' above.)

●Initial extremity evaluation – A brief lower extremity exam is performed during the initial trauma assessment (primary survey) but should be repeated once life-threatening injuries have been addressed. The lower extremity evaluation should be structured to assess the four functional components of the extremity (nerves, vessels, bones, soft tissues). Injury to three of these four elements constitutes a "mangled extremity." Patients with extremity deformity, point tenderness, ecchymosis, deep laceration, laceration near a joint, or joint laxity should undergo plain radiographs to evaluate for extremity fracture. (See 'Initial evaluation and management' above.)

●Management of unstable patients – Patients with hard signs of a vascular injury (eg, pulsatile bleeding, an expanding hematoma, distal ischemia) should be taken to the operating room for further examination and management.

•Direct pressure – Direct pressure is usually effective in controlling extremity hemorrhage.

•Extremity tourniquet – For extremity hemorrhage that is not adequately controlled with direct pressure, we suggest placement of a tourniquet (Grade 2C). Military and civilian experience with prehospital and emergency department tourniquet application has shown that tourniquets save lives with a low rate of complications. (See 'Control of hemorrhage' above and "Control of external hemorrhage in trauma patients".)

●Vascular assessment and imaging for stable patients – For patients without hard signs of vascular injury, an injured extremity index (IEI) should be performed, which is analogous to the ankle-brachial index (ABI). An abnormal IEI (<0.9) suggests the presence of a vascular injury. Hemodynamically stable patients with an abnormal IEI should undergo further imaging to exclude vascular injury. (See 'Injured extremity index' above and 'Arteriography' above.)

•Computed tomographic (CT) angiography – CT angiography is often selected as the initial vascular imaging study because it is less invasive than conventional arteriography; has high sensitivity and specificity; and can be performed at the same time as head, chest, or abdominal CT, which are frequently needed.

•Catheter-based arteriography – Where an appropriately sensitive CT scanner is not immediately available, conventional arteriography can be performed to exclude vascular injury either in a dedicated interventional suite or in the operating room.

●Attempt limb salvage – Every effort should be made to salvage the lower extremity if there is no clear indication for primary amputation. (See 'MESS' above and 'Predicting limb loss' above.)

•Mangled extremity – An attempt to salvage a mangled extremity is reasonable in most instances; however, in a patient with severe multisystem injuries and a mangled extremity, a primary amputation may be indicated to save the patient's life. Although clinical scoring systems can indicate when limb salvage is likely to be successful, these are not accurate for determining the need for emergent primary amputation.

•Reevaluation – Following every initial limb salvage attempt, the extremity should be reevaluated in the short term for signs of sensorimotor function and tissue viability. Factors that increase the risk of limb loss include lower extremity vascular injury, delayed revascularization, blunt or high-velocity mechanism, multiple additional injuries, advanced age and multiple comorbidities, shock and obvious limb ischemia, and a severe extremity injury sustained in a resource-limited environment or during a mass casualty event.

ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges Jeremy W Cannon, MD, FACS, and Jason M Souza, MD, FACS, CDR, USN, MC, who contributed to an earlier version of this topic review.