The compartment syndrome is a condition in which accumulating fluid creates high pressure within a closed fascial space reducing perfusion surrounding tissues below the level necessary for viability. The four compartments of the leg and forearm are involved most frequently. Permanent loss of function and limb contraction may occur if pressure remains sufficiently high for several hours. Prompt diagnosis is essential followed by immediate decompression. Decompression allows the muscles to increase in volume and reduces pressure in the fascial enclosure.
Volkmann’s Contracture is the residual limb deformity that is the last stage of muscle and nerve necrosis after an acute compartment syndrome. Clawing of the toes after tibial fractures suggests deep posterior compartment ischemia. The superficial posterior is the least involved compartment.
The most important symptom of impending compartment syndrome is pain greater than expected from the primary problem. The pain is usually described as a deep throbbing feeling of unrelenting pressure.
The earliest and only objective finding of a compartment syndrome is a swollen, palpable tense compartment that is a direct manifestation of increased intra-compartmental pressure. Subcutaneous edema can mask the underlying swelling and increase pressure in the compartment. Palpation of the compartment is a crude indicator of increased pressure and is very difficult to quantify.
The leading causes of compartment syndrome are fracture, soft tissue injury, arterial injury, and others.
Pain on stretch of the involved muscles is a common finding. Pain is subjective and depends on the reliability of the patient and the patient's threshold of pain. All patients have pain after fractures or contusions and differentiating this from ischemia to muscle can be quite difficult. Pain on stretch may be absent later in the course of the syndrome because of the anesthesia secondary to nerve ischemia. Paresis or weakness is likewise difficult because it may arise secondary to nerve involvement.
There is usually a sensory deficit (paresthesia). Careful sensory examination is extremely helpful provided the patient is conscious and can cooperate. Careful examination can help confirm the compartment involved. Any sensory deficit after an injury must be explained.
With delay in treatment, hypoesthesia progressing to anesthesia is inevitable. Peripheral pulses are palpable and capillary refill occurs routinely in a patient with CS. The physician must be aware of this and not have a false sense of security by palpating the pulse and deciding all is well.
The differential diagnosis for patients with limb injuries and neurovascular deficit is limited to compartment syndromes, arterial injuries, and nerve injuries. An arterial injury requires immediate surgical restoration. A nerve injury associated with a fracture is most commonly a neurapraxia and the treatment is observation. The arterial injury usually results in absent pulses, poor skin color and decreased skin temperature. In contrast, compartment syndrome routinely presents with intact peripheral circulation. Nerve injuries usually give little pain and the diagnosis is often made by exclusion of the other two entities. Doppler measurement, arteriography and pressure measurement are frequently required to aid in the differential diagnosis of these three conditions. Small portable pressure monitoring systems have been developed. One is the Stryker pressure monitor system.
Measurement of compartment pressure is particularly valuable for uncooperative or unreliable patients. This includes adults in which alcohol or other drugs may make interpretation of clinical signs difficult or impossible. Pressure should be measured in patients whose injuries put them at risk for development of compartment syndrome and whenever clinical signs and symptoms are absent or confusing. The time between injury and the onset of compartment syndrome may vary from hours to days because ischemia does not take place until the pressure rises to more than 30 mm. hg.
Compartment Syndromes, in Operative Orthopedics, Scott Mubarak (Michael Chapman Editor, 2nd Edition, 1993)