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, 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 moving normally. In severe cases, the sprained joint can become unstable and loose, bones can move out of alignment and the joint may extend beyond its normal range of motion.
Although ligaments can be sprained in a variety of ways, the actual ligament damage is usually caused by at least one of the following:
Any unusual force across a joint can cause a sprain. Among athletes, more than any other group, sprains are common. Knee sprains and shoulder sprains are common 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 skiing, football, basketball, baseball, roller hockey, boxing, basketball, volleyball and weightlifting. The specific joint that tends to be sprained during a particular sport is usually related to the kinds of joint movements that the sport requires or to the types of impact or collision 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.
Off the playing field, sprains often occur because of high-impact accidents — for example, striking the knee on the dashboard during a car crash or slipping on a patch of ice and landing on a wrist or shoulder. Sprains are also common in the workplace.
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