A sprain is damage to or tearing of ligaments or a joint capsule. A strain refers to damage to or tearing of a muscle.
When excessive force is applied to a joint, the ligaments that hold the bones together may be torn or damaged. This action results in a sprain, and its seriousness depends on how badly the ligaments are torn. Any joint can be sprained, but the most frequently injured joints are the ankle, knee, and finger.
Strains are tears in the muscle. Sometimes called pulled muscles, they usually occur because of overexertion or improper lifting techniques. Straining the muscles of the back is common.
Sprains and strains are common. Anyone can have them. Children under age eight are less likely to have sprains than are older people. Children's ligaments are tighter, and their bones are more apt to break before a ligament tears. People who are active in sports suffer more strains and sprains than less active people. However, being overweight and generally inactive also increases the chance of developing a strain or sprain. Repeated sprains in the same joint make the joint less stable and more prone to future sprains.
Causes and symptoms
Any unfamiliar activity that stresses a muscle or joint may cause a strain or sprain. Heavy lifting, falls, and playing a sport without warming up or conditioning are common causes. There are three grades of sprains.
Grade I sprains are mild injuries in which there is no tearing of the ligament and no joint function is lost, although there may be tenderness and slight swelling. Grade II sprains are caused by a partial tear in the ligament. These sprains are characterized by obvious swelling, extensive bruising, pain, difficulty bearing weight, and reduced function of the joint. Grade III, or third degree, sprains are caused by complete tearing of the ligament where there is severe pain, loss of joint function, widespread swelling and bruising, and the inability to bear weight. These symptoms are similar to those of bone fractures.
Strains can range from mild muscle stiffness to great soreness. Strains result from overuse of muscles, improper use of the muscles, or as the result of injury in another part of the body when the body compensates for pain by altering the way it moves.