Overview
Acute compartment syndrome is an emergency in which pressure builds inside a closed muscle compartment in the lower leg, reducing blood flow to the tissues and nerves that help the foot and ankle move. It most often occurs after an injury, but it can also happen after bleeding or swelling from other causes. When pressure rises, pain can become intense and nerves may start to malfunction, leading to numbness, weakness, and loss of motion. Because tissue damage can progress quickly, prompt diagnosis and treatment are critical.
Symptoms
Patients usually notice severe pain in the lower leg or around the foot/ankle that seems out of proportion to the injury or the level of swelling. The pain often worsens when the muscles are stretched, and the area may feel tight, firm, or swollen. Over time, numbness or tingling can develop in the foot and toes, and weakness can make it difficult to lift the foot or move the ankle normally. In advanced cases, the foot may feel cold and pulses may be reduced, but pulse changes are often late.
Causes
Acute compartment syndrome develops when increased pressure inside a muscle compartment blocks normal blood flow. Common triggers include fractures, crush injuries, or bleeding after trauma, as well as tight bandages, casts, or other external compression. Inflammation and fluid buildup after certain injuries or medical events can also raise compartment pressure. The resulting lack of circulation can injure nerves and muscle.
Risk Factors
Risk is higher after high-energy trauma, such as fractures or crush injuries to the lower leg, and after procedures or accidents that cause bleeding or significant swelling. Wearing or applying tight circumferential dressings, casts, splints, or inflatable devices increases risk if they become too tight. People with bleeding disorders, patients on blood thinners, and those who develop significant swelling after vigorous exercise or prolonged compression are also at increased risk.
Prevention
After injuries to the lower leg, monitor pain and swelling closely and avoid tightening casts, wraps, or splints beyond what is needed. If a dressing or splint feels increasingly tight, seek reassessment promptly rather than waiting. For people at risk of swelling with activity, gradually increase training intensity, stay well hydrated, and stop activity if pain becomes severe or progressive. If you have a known bleeding risk, coordinate injury care and follow clinician guidance for wound care and monitoring.
How the Diagnosis Is Evaluated
Clinicians start with a focused history of a recent injury, cast or splint placement, or other cause of swelling or bleeding. The exam looks for pain out of proportion, a tense or firm compartment, and pain with passive stretch, along with neurologic findings such as decreased sensation or weakness. Compartment pressure measurement may be used to confirm the diagnosis when findings are unclear. Imaging is typically not the key test for diagnosis, but X-rays may help identify fractures or other causes of the symptoms.
Nonsurgical Treatment Options
Immediate non-surgical steps focus on stopping the pressure and preserving blood flow while definitive care is arranged. This includes removing or loosening any tight bandages, casts, or splints, and correcting external compression that may be contributing to swelling. Clinicians also provide urgent pain control and close neurologic checks to monitor progression. Activity is stopped and the limb is positioned appropriately to support circulation (often not excessively elevated). In practice, conservative steps are usually temporary measures; many patients require urgent decompression to prevent permanent nerve and muscle damage.
When to Seek Medical Attention
Seek emergency care immediately if you have severe, worsening leg or foot pain after an injury, especially if it is out of proportion or pain increases with passive stretching. Get urgent evaluation if you develop numbness, tingling, weakness, trouble moving the foot/ankle, a rapidly increasing tight swelling, or any color or temperature change in the foot. After a cast, splint, or tight wrap, do not wait if symptoms are worsening or the limb feels increasingly tight. Call emergency services if symptoms progress quickly or you cannot bear weight due to intense pain.
Frequently Asked Questions
It usually causes severe pain in the lower leg that feels out of proportion to the injury and often gets worse when the muscles are stretched.
Yes, if a wrap or circumferential device becomes too tight due to swelling, it can raise compartment pressure.
Next Steps
If you suspect acute compartment syndrome, seek emergency evaluation now rather than monitoring at home. If symptoms started after an injury or after a cast/splint was applied, tell the clinician exactly when symptoms began and whether the tightness changed. Prompt assessment can help prevent permanent nerve and muscle damage.