Questions and Answers About Sprains and Strains

This fact sheet contains general information about sprains and strains, which are both very common injuries. Individual sections describe what sprains and strains are, where they usually occur, what their signs and symptoms are, how they are treated, and how they can be prevented. At the end is a list of key words to help you understand the terms used in the fact sheet. If you have further questions, you may wish to discuss them with your doctor.

What is the difference between a sprain and a strain?

A sprain is an injury to a ligament--a stretching or a tearing. One or more ligaments can be injured during a sprain. The severity of the injury will depend on the extent of injury to a single ligament (whether the tear is partial or complete) and the number of ligaments involved.

A strain is an injury to either a muscle or a tendon. Depending on the severity of the injury, a strain may be a simple overstretch of the muscle or tendon, or it can result in a partial or complete tear.

What causes a sprain?

A sprain can result from a fall, a sudden twist, or a blow to the body that forces a joint out of its normal position. This results in an overstretch or tear of the ligament supporting that joint. Typically, sprains occur when people fall and land on an outstretched arm, slide into base, land on the side of their foot, or twist a knee with the foot planted firmly on the ground.

Where do sprains usually occur?

Although sprains can occur in both the upper and lower parts of the body, the most common site is the ankle. Ankle sprains are the most common injury in the United States and often occur during sports or recreational activities. Approximately 1 million ankle injuries occur each year, and 85 percent of them are sprains.

The talus bone and the ends of two of the lower leg bones (tibia and fibula) form the ankle joint (see fig. 1). This joint is supported by several lateral (outside) ligaments and medial (inside) ligaments. Most ankle sprains happen when the foot turns inward as a person runs, turns, falls, or lands on the ankle after a jump. This type of sprain is called an inversion injury. One or more of the lateral ligaments are injured, usually the anterior talofibular ligament. The calcaneofibular ligament is the second most frequently torn ligament.

The knee is another common site for a sprain. A blow to the knee or a fall is often the cause; sudden twisting can also result in a sprain (see fig. 2).

Sprains frequently occur at the wrist, typically when people fall and land on an outstretched hand.

Figures 1 and 2

Feet and Fitness: Sprain Feet and Fitness: Sprain