Sprains and strains occur commonly, and most result in minor injuries.
- Sprains. A sprain occurs when you overextend or tear a ligament while severely stressing a joint. Ligaments are tough bands of fibrous tissue that connect one bone to another. They help to stabilize joints, preventing excessive movement. You may sprain your knee or ankle when walking or exercising on an uneven surface. A sprain also may occur when you land awkwardly, either at the end of a jump or while pivoting during an athletic activity.
- Strains. A muscle becomes strained or pulled — or may even tear — when it stretches unusually far or abruptly. This type of injury — an acute strain — often occurs when muscles suddenly and powerfully contract. A muscle strain may occur when you slip on ice, run, jump, throw, lift a heavy object or lift in an awkward position. A chronic strain results from prolonged, repetitive movement of a muscle.