Definition

Compartment syndrome can be either an acute or chronic condition caused by increased tissue pressure within an enclosed fascial space. The focus of this chapter is compartment syndrome of the leg, although it can also affect the thighs or upper extremities.

Acute Compartment Syndrome

Acute compartment syndrome (ACS) is a serious condition caused by a rapid rise in pressure in an enclosed space, which can lead to necrosis of the muscles and nerves in the involved compartment. Untreated, ACS can progress to contractures, paralysis, infection, and gangrene in the limb as well as systemic problems, such as myoglobinuria and kidney failure [1]. ACS, most commonly occurring in males younger than 35 years, is most often caused by trauma such as fractures, crush injuries, muscle rupture, direct blow to a muscle, and circumferential burns. Direct pressure from a cast or antishock garment can increase the risk for compartment syndrome [2]. ACS can occur in as many as 17% of tibial fractures [3]. The anterior compartment is most commonly affected, although multiple compartments are often involved.

Nontraumatic causes of ACS are more rare. These include hemorrhage into a compartment, as can occur in anticoagulated patients [2], and compartment syndrome after diabetic muscle infarction [4]. In patients with decreased mental status with prolonged limb compression, such as with alcohol or drug abuse, ACS can also develop from soft tissue injury and swelling [5].

Another nontraumatic cause of compartment syndrome is ischemia and then hyperperfusion caused by prolonged surgery in the lithotomy position. This is also known as well leg compartment syndrome and is most often seen after pelvic and perineal surgery. Risk factors include the length of the procedure, the amount of leg elevation, the amount of perioperative blood loss, and the presence of peripheral vascular disease and obesity. The overall incidence in complex pelvic surgeries may be as high as 1 in 500 [6].

Chronic Compartment Syndrome

Chronic compartment syndrome (CCS) occurs when the fascia in the lower leg does not accommodate to the increase in blood flow and fluid shifts that may occur with heavy exercise [7]. An increase in compartmental pressure then interferes with blood flow, leading to ischemia and pain when the metabolic demands cannot be met [8]. The risk of CCS is increased by anabolic steroids, which can induce muscle hypertrophy, thereby causing an increase in intracompartmental pressure and decreasing fascial elasticity [9]. CCS is most commonly seen in runners [10], cyclists, and other athletes in sports that demand running, jumping, and cutting, such as basketball and soccer. The true incidence is unknown as most people suffering from early symptoms will decrease or modify their activity [11]. With normal physical activity, muscle volume can increase up to 20% [12]. The anterior compartment is most commonly involved, followed by the deep posterior compartment [11].

Symptoms

The area in which symptoms occur and the type of complaints depend on which compartment is involved.

Acute Compartment Syndrome

Patients may present with pain out of proportion to the injury and swelling or tenseness in the area. Other symptoms include severe pain with passive movement of the muscles within the compartment, loss of voluntary movement of the muscles involved, and sensory changes and paresthesias in the area supplied by the nerve involved [3,7]. The classic findings associated with arterial insufficiency are often described as signs of ACS, but this is incorrect. Of the five classic signs (pain, pallor, pulselessness, paresthesias, paralysis), only pain is commonly associated with compartment syndrome, particularly in its early stages [12].

Chronic Compartment Syndrome

In CCS, pain has a gradual onset that usually coincides with an increase in exercise training load or training on hard surfaces. It is described as aching, burning, or cramping and occurs with repetitive movements in a specific muscle region. The pain usually occurs around the same time each time the patient participates in the activity (e.g., after 15 minutes of running) and increases or stays constant if the activity continues. The pain disappears or dramatically lessens after a few minutes of rest. Symptoms can occur bilaterally [8].

As symptoms progress, a dull aching pain may persist. Pain may be localized to a particular compartment, although multiple compartments can often be involved. Numbness and tingling may occur in the nerves that travel within the involved lower limb compartment. CCS can be seen with other overuse syndromes (e.g., concurrent with tibial stress fractures).

Physical Examination

The examination is focused on the following four compartments of the leg (Fig. 67.1).

Anterior compartment contains the tibialis anterior, which dorsiflexes the ankle; the long toe extensors, which dorsiflex the toes; the anterior tibial artery; and the deep peroneal nerve, which supplies sensation to the first web space.

Lateral compartment contains the peroneus longus and brevis, which evert the foot, and the superficial peroneal nerve, which supplies sensation to the dorsum of the foot.

Superficial posterior compartment contains the gastrocnemius and soleus muscles, which plantar flex the foot, and part of the sural nerve, which supplies sensation to the lateral foot and distal calf [1,8,12].

Deep posterior compartment contains the tibialis posterior, which plantar flexes and inverts the foot; the long toe flexors, which plantar flex the toes; the peroneal artery; and the tibial nerve, which supplies sensation to the plantar surface of the foot. This compartment may contain several subcompartments [13].

Acute Compartment Syndrome

In ACS, inspection reveals a swollen, tense limb. Motor testing reveals weakness or paralysis of the muscles involved in the affected compartment. Sensory testing may show numbness in the area supplied by the nerve involved in the affected compartment. Two-point discrimination is a better diagnostic test for compartment syndrome than pinprick [13]. Pulses and capillary refills are generally normal as these are involved only with extremely high pressures [3,7,14,15].

Chronic Compartment Syndrome

In CCS, inspection is usually unremarkable, but fascial defects have been observed in up to 40% of individuals. These defects may represent the body’s attempt to accomplish an autorelease [11]. Palpation of the affected area will reveal a firm compartment and tender muscle group. There may also be tenderness along the posteromedial surface of the tibia [16]. In approximately 40% of cases, muscle herniation in the compartment can be palpated, especially in the anterior and lateral compartments where the superficial peroneal nerve pierces the fascia [6]. In severe cases, sensory testing will show numbness in the area supplied by the nerve involved, but this is usually normal at rest [7]. Motor testing may reveal weakness, depending on the compartment involved: dorsiflexion weakness if the anterior compartment is involved, foot eversion weakness if the lateral compartment is involved, and plantar flexion weakness if one of the posterior compartments is involved. Pain is reproduced by repetitive activity, such as toe raises, or running in place. Compartment syndrome occurs more commonly in patients who pronate during running; thus, pronation is a common finding on physical examination [1,7,17].

The sequelae of ACS may be nerve and muscle injury with resulting footdrop, severe muscle weakness, and contractures. This can lead to an abnormal gait and all the limitations that this can cause, including difficulties with stairs, sports participation, and activities of daily living. In addition, it can lead to muscle necrosis, thereby causing long-term disability [18].

Chronic Compartment Syndrome

With CCS, functional limitations usually occur around the same point each time during exercise, at that individual’s ischemic threshold. For example, symptoms may start to develop each time a runner reaches the half-mile mark or each time a cyclist climbs a large hill. This may significantly limit sports participation and occasionally even interferes with activities of daily living, such as prolonged walking.

Diagnostic Studies

Compartmental tissue pressure measurement is the “gold standard” for diagnosis. The devices most commonly used to measure intracompartmental pressures were traditionally the slit and wick catheters (Fig. 67.2