Compartment syndrome is a dangerous condition caused by increased pressure within the closed muscle compartments of the body. It can result from fractures, surgery, or severe bruising. Symptoms include severe pain disproportionate to the injury that is not relieved by pain medication, tight muscles, numbness, and loss of pulse. An early diagnosis within 24 hours of onset through tests like the Whiteside maneuver and direct pressure measurement allows for fasciotomy surgery to release the pressure and prevent permanent nerve and muscle damage. Compartment syndrome requires prompt treatment to avoid complications.