Fasciotomy is designed to prevent nerve injury and myonecrosis resulting from compartment syndrome characterized by elevated pressure within a fixed extremity compartment. Compartment syndrome is most often observed after reperfusion of an acutely ischemic extremity or among patients who present after severe limb trauma with associated soft-tissue and orthopedic injuries leading to elevated compartment pressures, compromised venous and arterial circulation, and direct barotrauma. In 1881 Volkmann was the first to describe acute limb compartment syndrome when he noted the development of contracture as a common sequela after application of tight bandages to an extremity. The first reported treatment of compartment syndrome was described by Petersen in 1888, and in 1926 Jepsen was the first to demonstrate an experimental model of ischemic contracture. In 1975 Whitesides and colleagues reported the development of a needle manometer to measure tissue compartment pressures as an adjunctive tool for determining the need for fasciotomy.
Fasciotomy may be performed either prophylactically in an extremity at high risk for compartment syndrome or therapeutically in the presence of an established compartment syndrome. For example, a prophylactic fasciotomy can be performed at the time of a severe crush injury or immediately after restoration of blood flow to a severely ischemic extremity. Prophylactic fasciotomy is most often performed after restoration of blood flow to an extremity that has been ischemic for 3 or more hours, in the presence of concomitant major venous injury, after repair of vascular injury with associated soft-tissue or nerve injury, following reduction and fixation of long bone fractures with severe crush injury, in the setting of an electrical injury, or when the mechanism of injury places a patient at high risk but serial clinical examination cannot be performed because of brain injury, the need for mechanical ventilation, or evacuation to another facility.
A therapeutic fasciotomy is performed after the diagnosis of compartment syndrome is established by clinical findings or through direct measurement of compartment pressures. The clinical diagnosis of compartment syndrome may be noted in the presence of pain out of proportion to examination, paresthesias, pallor, paralysis, and poikilothermia. However, the most reliable indicator is pain, which is commonly aggravated on passive stretch of the affected muscle groups. In the lower extremity, the anterior compartment if often the first compartment to be affected. An early indicator of compartment syndrome is pain on palpation of the anterior compartment, as well as anterior compartment pain elicited on passive dorsiflexion of the ankle. Decreased sensation on the dorsum of the foot over the first web space is also consistent with compartment syndrome because of injury to the deep peroneal nerve, which courses within the anterior compartment. Paresthesias are a relatively late and ominous finding. Palpable pulses may be present in the setting of a compartment syndrome. Compartment pressures greater than 30 mm Hg or greater than 20 mm Hg below diastolic blood pressure are suggestive of compartment syndrome. Nonetheless, normal pressures in the presence of a consistent clinical examination does not reliably exclude compartment syndrome, and fasciotomy should be performed.
History and physical examination. Acute ischemia often occurs as a result of an embolism or thrombosis in patients with multiple existing comorbidities, such as diabetes, renal insufficiency, and heart disease. A thorough history of existing medication, including oral anticoagulants, should be obtained.
Resuscitation. Fluid resuscitation and alkalinization of the urine with intravenous bicarbonate should be initiated to reduce the risk of myoglobinemia-induced renal dysfunction. Patients with extremity trauma may also present with coagulopathy related to shock, anemia, or hypothermia, which should be corrected.
Unrecognized Compartment Syndrome
The time during which nerve and muscle are exposed to elevated compartment pressures correlates with tissue damage and is eventually irreversible. A high index of suspicion or anticipation for the development of compartment syndrome should be maintained with a low threshold to perform fasciotomy. Patterns of injury prone to the development of elevated compartment pressures include venous injury, restoration of perfusion after prolonged ischemia (>3 hours), crush or soft-tissue injury, and large volume resuscitation, all of which increase extremity edema in the postinjury period.
Failure to Release Extremity Compartments
Familiarity with limb anatomy is necessary to ensure all compartments have been adequately opened. The deep posterior and anterior compartments of the lower leg are commonly missed, potentially resulting in neurovascular compromise. The deep posterior compartment contains the posterior tibial, flexor digitorum, and flexor halluces longus muscles, as well as the posterior tibial nerve and artery, which control plantar flexion of foot. The compartment is bound by the posterior tibia, fibula, and interosseous membrane in the proximal two thirds of the leg.
The common peroneal nerve becomes subcutaneous behind the head of the fibula, before penetrating the posterior intermuscular septum, and becomes closely opposed to the periosteum of the proximal fibula, after which it divides into superficial and deep peroneal nerves. Thus the common peroneal nerve is at risk for injury at the superior extent of the lateral fasciotomy incision, which can lead to weakness in ankle dorsiflexion or foot drop. Injury to the posterior tibial artery can occur at the inferior extent of the medial incision as the artery becomes superficial. Injury to the saphenous vein, when conducting the medial incision, can lead to bothersome bleeding in the postoperative period if unrecognized.
In the upper extremity, injury to the median nerve and its branches is most common. The anterior interosseous and palmar cutaneous branches in the arm and the recurrent branch in the hand can be injured as the volar compartment and carpal tunnel are opened. Injury to the median nerve may lead to weak pronation of the forearm, flexion, and radial deviation of wrist, as well as weakness of intrinsic hand muscles, thenar atrophy, and inability to oppose or flex the thumb. Numbness of the radial palm, thumb, index finger, middle finger, and radial aspect of the ring finger may be noted. The median nerve enters the forearm between the two heads of pronator teres, passes superficial to the flexor digitorum profundus and beneath the flexor digitorum superficialis, and runs between and deep to the flexor carpi radialis and palmaris longus into the carpal tunnel.
Inadequate Postoperative Surveillance
Frequent repeat examinations of the extremity are required regardless of whether a fasciotomy has been performed. If a fasciotomy has not been performed, inspection is necessary to monitor for signs of compartment syndrome. Otherwise, the extremity should be examined after fasciotomy to assess for adequacy of perfusion, decompression, and signs of reperfusion injury. Second-look procedures are necessary to assess tissue viability, with debridement as indicated.
Lower Leg Fasciotomy
The lower leg is composed of four compartments that are termed anterior, lateral, superficial posterior, and deep posterior ( Fig. 53-1 ). The deep posterior and the anterior compartments contain the most vital neurovascular structures and are therefore the most important to release during fasciotomy. Although minimally invasive or single-incision fasciotomies have been described, the most reliable technique uses generous medial and lateral incisions.
The anterior and lateral compartments of the lower leg are approached through the same lateral, longitudinal skin incision parallel to the tibia and positioned approximately 6 to 8 cm lateral to the anterior edge of the tibia ( Fig. 53-2 ). The incision extends a distance that is one half to three quarters the distance from the lateral tibial tuberosity to the lateral malleolus. Through this skin incision, the anterior compartment is opened via a longitudinal incision of the fascia 2 cm lateral to the anterior edge of the tibia ( Fig. 53-3 ). It is important during this step to visualize and firmly palpate the tibia under the superior or medial skin flap to verify that the anterior, not the lateral, compartment is released. The skin must be opened for an adequate length to ensure it is not hampering a full compartment release.