Acute Compartment Syndrome

Etiology

Compartment syndrome is the end result of many different injury patterns. While fracture is the number one cause of compartment syndrome, many types of soft tissue injuries can also lead to compartment syndrome. Nonfracture etiologies of compartment syndrome are relatively uncommon, and as such can lead to a delay in diagnosis.

Fracture

Almost 70% of all cases of compartment syndrome are due to fracture.¹ Fractures of the tibia, distal radius, and ulna are the most common injuries that lead to acute compartment syndrome. Interestingly, acute compartment syndrome is caused by an equal distribution of high-energy and low-energy mechanisms of injuries.¹ Because the increase in compartment pressure is highest at the fracture site,⁹ it is imperative to measure pressures at the site of the fracture. Contrary to traditional teaching, an open fracture does not reduce the risk of compartment syndrome. McQueen and Court-Brown⁶ found there was no difference in the intracompartment pressure between open and closed fractures.

Fracture reduction and manipulation can actually increase the risk of compartment syndrome. In one case series, fracture manipulation increased compartment pressure by reducing the total volume in a stretched compartment.¹⁰ Dresing et al¹⁰ found the average pressure increased by 21 mm Hg during wrist reduction, warranting close observation after fracture reduction and close observation of the patient’s pain and neurovascular status.

McQueen et al¹¹ evaluated the risk factors for the development of acute compartment syndrome from tibial diaphyseal fractures and found that younger patients were at the highest risk. Patients between ages 10 to 19 years old had an odds ratio (OR) of 12.09; 20 to 29 years old had an OR of 9.84; and patients older than age 40 years had an OR of 1.¹¹ As previously stated, younger patients have larger muscle volumes compared to their older counterparts and therefore have less space for edema after the primary muscle injury.

Soft Tissue Injury

Direct soft tissue injury can lead to a rise in compartment pressures due to trauma, infections, and burns even in the absence of fractures. Unfortunately, under these circumstances, patients with direct soft tissue injury are at high risk for a delay in diagnosis.¹² The primary injury can be worsened by underlying coagulopathies.¹ A circumferential constrictive eschar from burns can also cause external compression to a compartment¹³ as well as edema, which decreases the compliance of the fascia, leading to a rise in compartment pressure.

Vascular Injuries and Unusual Causes

Arterial Vessel Damage. Injuries to single arterial vessels can also lend to the development of acute compartment syndrome. Arterial damage from high-energy trauma causes acute compartment syndromes due to the rapid development of a hematoma and pressure in affected compartments. Loss of the arterial blood flow from the traumatized artery also causes cell necrosis and edema to the muscle bed, further increasing the compartment pressure. The result of these injuries is the development of acute compartment syndrome in uncommon locations such as the thigh^{14 and foot.15}

Arterial damage from relatively low-energy ankle-inversion injuries have also been implicated in development of acute compartment syndrome of the foot.¹⁵ Conversely, damage to branches of an artery may cause symptoms in the compartments of the proximal extremity, but spare the blood flow and pulsations to the distal portion.¹³ This atypical mechanism of injury requires the physician to maintain a high index of suspicion and consider arteriography and direct pressure management in diagnosis and treatment of this condition.

Deep Vein Thrombosis. Deep vein thrombosis (DVT) can also be associated with acute compartment syndrome. A large clot burden, such as that observed in phlegmasia cerulea dolens, can lead to reduced venous flow and increased pressure, resulting in decreased arteriovenous gradient and tissue perfusion. Acute compartment syndrome caused by extensive DVT is often treated with anticoagulation therapy, thrombolysis or thrombectomy, but fasciotomy also has a role as an adjunct treatment to reduce compartment pressure sufficiently to return blood flow.¹⁶

Medication-Induced Compartment Syndrome

Injections of medications or illicit drugs can lead to increased compartment pressure through several independent mechanisms (Table).¹⁷ Local tissue vasotoxicity from direct injection of a caustic agent can cause direct muscle necrosis and edema. In addition, prolonged external compression while lying in a coma-like state induced by alcohol intoxication or central nervous system suppressant drugs, or a state of unconsciousness from any cause, can produce direct injury to the compartment (Table).

Diagnosis

Signs and Symptoms

Diagnosis of acute compartment syndrome is primarily clinical, using compartment pressure measurement as an adjunct in evaluation. Because the features of early acute compartment syndrome are nonspecific, a high clinical suspicion must be maintained for all at-risk populations.