Sprain (Overview)

What Is It?

A sprain is a tear of ligaments, the tough bands of fibrous tissue that connect bones to one another at a joint. Normally, ligaments stabilize a joint and keep the joint tight. They also help to keep the joint's bones aligned and limit the motion of a joint to the normal range. When a joint is sprained, its torn or stretched ligaments can lose part or all of their ability to reinforce the joint and to keep it operating normally. In severe cases, the sprained joint can become unstable and loose, bones can move out of alignment and the joint may move outside the normal range of motion.

Although ligaments can be sprained in a variety of ways, the actual ligament damage usually is caused by at least one of the following patterns of injury:

• Flexing (bending), extending (stretching out) or twisting a joint beyond its normal range of motion - This injury pattern is a common cause of wrist sprains in skiers. If the skier falls with a ski pole still strapped to the wrist, the attached pole can twist the wrist beyond its normal limits and cause a sprain.

• Suddenly increasing the tension (strain or pull) on a ligament to the point that it snaps in two - This type of injury can happen in the knee joint when a running athlete suddenly stops short. The extreme tension of the braking force actually tears one of the knee ligaments in two, causing a pop inside the knee when the ligament snaps.

• Hitting the joint directly, or hitting one of the bones near the joint - This type of sprain often happens in contact sports, especially when a shoulder or knee joint takes the full impact of a collision between two athletes.

Any unusual force across a joint can cause a sprain. For athletes, more than any other group, sprains are common. Knee sprains and shoulder sprains are common injuries among those who participate in football, basketball, soccer, rugby, wrestling, gymnastics and skiing. Foot sprains are a danger for ballet dancers, snowboarders, windsurfers, equestrians and competitive divers. Wrist sprains are common in football, basketball, baseball, roller hockey, boxing, basketball, volleyball and weightlifting. The specific joint that tends to be sprained during a particular sport usually is related to the kinds of joint movements that the sport requires, or to the types of impacts or collisions that can happen. For example, many knee sprains in football players are caused by the extreme knee stress of cutting moves and sharp turns. Others are caused by the direct impact of tackles.