Abstract
The focus of this chapter is compartment syndrome of the leg. The evaluation, diagnosis, and treatment of acute and chronic compartment syndrome are described. The updated use of technologies such as ultrasound for treatment is discussed.
Keywords
compartment pressure, compartment syndrome, fascial fenestration, fasciotomy, functional manual therapy, leg pain
| Synonyms | |
| |
| ICD-10 Codes | |
| M62.9 | Disorder of muscle, unspecified |
| T79.A0 | Compartment syndrome, unspecified |
| T79.A2 | Compartment syndrome (deep) (posterior) (traumatic), of the lower extremity |
| T79.A29 | Traumatic compartment syndrome of unspecified lower extremity |
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. 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. ACS can occur in as many as 17% of tibial fractures. The anterior compartment is most commonly affected, although multiple compartments can be involved.
Non-traumatic causes of ACS are more rare. These include hemorrhage into a compartment, as can occur in anticoagulated patients, and compartment syndrome after diabetic muscle infarction. 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.
Another non-traumatic cause of compartment syndrome is ischemia leading to hyperperfusion, often caused by prolonged surgery in the lithotomy position. This is 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.
Chronic Exertional Compartment Syndrome
Chronic compartment syndrome 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. This has been coined chronic exertional compartment syndrome (CECS) and results from repetitive movements common in endurance sports. An increase in compartmental pressure interferes with blood flow, leading to ischemia and pain when the metabolic demands cannot be met. The risk of CECS is increased by anabolic steroids, which can induce muscle hypertrophy, thereby causing an increase in intracompartmental pressure and decreasing fascial elasticity. CECS is most commonly seen in runners, cyclists, and 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 without seeking out a healthcare professional. With normal physical activity, muscle volume can increase up to 20%. The anterior compartment is most commonly involved, followed by the deep posterior compartment, then the lateral and superficial posterior leg compartments.
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 involved nerve. 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.
Chronic Exertional Compartment Syndrome
In CECS, 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.
As symptoms progress, a dull aching pain may persist. Pain may be localized to a particular compartment, although multiple compartments are often involved. Numbness and tingling may occur in the nerves that travel within the involved lower limb compartment. CECS can also 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.
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.
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. Pulses and capillary refills are generally normal, as these are involved only with extremely high pressures.
Chronic Exertional Compartment Syndrome
In CECS, 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 auto-release. 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 in anterior or posterior compartment syndrome. 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. In severe cases, sensory testing will show numbness in the area supplied by the nerve involved, but this is usually normal at rest. 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 heel 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.
Functional Limitations
Acute Compartment Syndrome
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.
Chronic Exertional Compartment Syndrome
With CECS, 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 ). Newer devices, such as the transducer-tipped probe ( Fig. 67.3 ), are now gaining popularity. Ultrasound-guided transducer placement is especially helpful in patients receiving anticoagulation, patients with a large body habitus, and patients with distorted anatomy, such as after surgery or trauma.
Acute Compartment Syndrome
Normal compartment pressure is less than 10 mm Hg. Traditionally, absolute tissue pressure above 30 mm Hg was considered the cutoff value for fasciotomy to be performed. However, it is likely that many unnecessary fasciotomies were performed by use of this measure alone. Currently, continuous monitoring of compartment pressures is used in high-risk cases, such as leg trauma with tibial fractures. The differential pressure, calculated as the intramuscular pressure subtracted from the diastolic blood pressure, determines the treatment course. If the differential pressure is less than 30 mm Hg, fasciotomy is indicated. Studies have shown that if this differential pressure remains consistently above 30 mm Hg, even with markedly elevated tissue pressures, patients have excellent clinical outcomes and fasciotomy is not necessary.
Because of the invasive nature of compartmental pressure measurements, other diagnostic tools have been sought. Magnetic resonance imaging may be helpful in making the diagnosis. Magnetic resonance imaging findings may include loss of normal muscle architecture on T1-weighted images, edema within the compartment, and strong enhancement of the affected compartment with the contrast agent gadolinium-DTPA.
Chronic Exertional Compartment Syndrome
For CECS, absolute pressure measurements obtained at rest, during exercise, and after exercise are used to make the diagnosis. Interestingly, there does not seem to be a particular threshold compartmental pressure at which symptoms occur, and patients with higher pressures do not necessarily have worse symptoms than those with lower pressures. The average time from the onset of symptoms to the time that the diagnosis is made is 22 months.
The following is one set of values commonly used to diagnose anterior compartment syndrome:
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Pre-exercise pressure > 15 mm Hg
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1 minute after exercise > 30 mm Hg
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5 minutes after exercise > 20 mm Hg
A large systematic review found that pre-exercise, means values ranged from 7.4 to 50.7 mm Hg for CECS patients and 5.7 to 12 mm Hg for controls; 1-minute post exercise timing interval showed values ranging from 34 to 55.4 mm Hg and 9 to 19 mm Hg in CECS patients and controls, respectively. The authors concluded that levels above the highest reported value for controls (27.5 mm Hg) along with a good history should be regarded as highly suggestive of CECS.
It is important that the patient’s symptoms correlate with the compartment in which there is elevated pressure. Pressure should increase in the symptomatic compartment with exercise and remain elevated for an abnormal time. Values for posterior compartments are more controversial. Normal resting pressures are less than 10 mm Hg, and values should return to resting levels after 1 to 2 minutes of exercise.
Drawbacks to measurement of pressures include the following:
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They are invasive and can be complicated by bleeding or infection.
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Because of the anatomy, it is difficult to test the deep posterior compartment.
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Pressures are dependent on the position of the leg and the technique used, so strict standards should be followed.
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It is time-consuming because each compartment must be tested separately, and all compartments should be tested because multiple areas are often involved.
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It is often difficult for patients to exercise with the catheter in place.
Because of these drawbacks, alternative tests to confirm the diagnosis are sometimes used. Magnetic resonance imaging done before and after exercise can show increased signal intensity throughout the affected compartment in the T2-weighted images after exercise in patients with compartment syndrome. Alternatively, near-infrared spectroscopy has been used as well. This method measures the hemoglobin saturation of tissues. In cases of CECS, there is de-oxygenation of muscle during exercise and delayed re-oxygenation after exercise. Failure of the compartment to return to baseline within 25 minutes after exercise is diagnostic of CECS. Although near-infrared spectroscopy seems to be helpful in patients with anterior compartment syndrome, light absorption may be altered in deeper compartments, and therefore it is more difficult to monitor the pressure in these deeper compartments. Other methods include thallium stress testing and nuclear magnetic resonance spectroscopy, which may also be helpful in the diagnosis of CECS. Triple-phase bone scan and single-photon emission computed tomography scans can be used to rule out other conditions in the differential diagnosis, such as medial tibial stress syndrome or stress fractures.
More recently, ultrasound has been studied as a point of care diagnostic tool used to diagnose CECS. One pilot study showed that the mean anterior compartment thickness (ACT) in patients with CECS versus control subjects significantly increased after exertion at 0.5 minutes, 2.5 minutes, and 4.5 minutes. The authors concluded that ultrasonography reveals a significant increase in ACT in patients with CECS of the anterior leg compartment ( Fig 67.4 ).
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