A strain is a stretched or torn muscle or tendon. A sprain is a stretched or torn ligament.
Sprains occur most often in ankles, knees or fingers, although any joint can be sprained.
Sprained joints can function, but only with pain. Swelling of the affected joint. Redness or bruising in the area of injury, either immediately or several hours after injury. Loss of normal mobility in the injured joint. The ankle is injured most often because of its anatomical weakness, its exposed position and the stress it sustains in athletic and recreational activities.