Compartment syndrome

The hallmark presentation is pain that is out of proportion to injury or findings.
Patients will describe the pain as “deep”, “burning,” and “unrelenting” with difficulty in localization.
Pain with passive stretching of the muscle groups or tightness of the compartment is also common.
Compartment syndrome can occur when the compartment is seemingly open, such as open fractures and stab wounds.
In trauma, the anterior compartment of the leg is the most common location of compartment syndrome; however, it is possible for it to occur in any extremity compartment.
Symptoms commonly arise within 2 hours of injury but can also present up to 6 days later.

The additional findings of paresthesias, anesthesia, paralysis, poikilothermia, and pulselessness are very late findings and should not be relied upon in the initial evaluation.
It is estimated that muscles and nerves can tolerate ischemia for 4–6 hours without significant sequelae. After this there is risk of permanent nerve damage, myonecrosis and muscle contractures.
After 8 hours, necrosis of tissue is certain and a nonfunctional limb is likely.
Rarely, rhabdomyolysis, renal failure, and disseminated intravascular coagulation (DIC) can result from tissue necrosis secondary to the failure to relieve compartmental pressure.
Delay in diagnosis correlates directly with worse outcomes.

Physical examination is paramount as the physician must rely on clinical judgment for diagnosis. See the table below for lower leg compartment syndrome findings.

Lower leg compartment syndrome findings
General findings • Pain out of proportion to injury • Analgesia use out of proportion to injury
Anterior compartment • Weakness of toe extension • Pain on passive toe flexion • Diminished sensation in the first web space
Deep posterior compartment • Weakness of ankle inversion and toe flexion • Pain on passive toe extension referred to the posterior leg • Diminished sensation over medial sole of foot