Causes / typical injury mechanism: Chronic exertional compartment syndrome (CECS) is a condition characterized by reversible ischemia to muscles within a particular compartment.

CECS should be differentiated from acute compartment syndrome, which is most commonly caused by trauma and crush injuries. The presentation of acute compartment syndrome is much more critical, with persistent pain unrelated to activity, and requires emergency surgical intervention.

Classic history and presentation: CECS most commonly affects the anterior compartment of the lower leg (70% of cases), but it has also been reported in the other lower leg compartments (10% of cases involve the anterior and lateral lower leg compartments), as well as the forearms, thighs, feet, and hands. It is most commonly seen in runners and military service personnel. It often presents bilaterally.

The condition typically presents as aching or burning pain and an objective and/or subjective sensation of swelling in the lower leg during physical exertion. Paresthesias may also be present over the dorsum of the foot. The symptoms are relieved by rest. Patients are usually able to identify the duration of exercise until they experience pain and how long the pain will last after they have ceased exercise.

Prevalence: It is relatively rare.

• Age – Most commonly seen in the third decade of life.
• Sex / gender – Equal incidence in adult men and women (in the pediatric population, it is more common in girls).

Risk factors: Risk factors include running, sports involving jumping or skating, cycling, and military service. Specific risk factors for CECS involving the upper extremities are athletic activities that involve frequent gripping such as rowing, gymnastics, and cycling.

Pathophysiology: The pathophysiology of CECS is not well understood and is most likely multifactorial. The ultimate cause of pain in CECS involves reversible ischemia within the specific compartment as a result of increased pressure. In normal muscle, muscular volume increases by up to 20% during exercise (due to increases in blood flow and tissue swelling) and is reflected by an increase in intracompartmental pressure. Tissue swelling is thought to occur via a combination of fluid extravasation and the buildup of metabolic waste products that are not removed / metabolized quickly enough. In individuals with CECS, this increase in intracompartmental pressure leads to a cascade of impaired venous outflow narrowing the arteriovenous gradient. At a certain pressure, interstitial (tissue) pressure rises above perfusion pressure. This results in impaired capillary blood flow, decreased tissue oxygenation, and subsequent ischemia, resulting in the symptoms of CECS.