Symptoms of acute compartment syndrome (ACS) can include severe pain, poor pulses, decreased ability to move, numbness, or a pale color of the affected limb. It is most commonly due to physical trauma such as a bone fracture (up to 75% of cases) or crush injury, but it can also be cause by acute exertion during sport. It can also occur after blood flow returns following a period of poor blood flow. Diagnosis is generally based upon a person's symptoms and may be supported by measurement of intracomparmental pressure before, during, and after activity. Normal compartment pressure should be within 12-18 mmHg, anything out of that range would be considered abnormal and would need treatment. Treatment is by surgery to open the compartment, completed in a timely manner. If not treated within six hours, permanent muscle or nerve damage can result.