A sprain is a common injury that occurs when a band or bands of connective tissue attached to two bones in a joint are overstretched, pulled or torn. Common causes are falls, sudden changes in direction resulting in the twisting of a joint and blows to a joint. Everyone is susceptible to sprains, according to the American Academy of Orthopaedic Surgeons, because the risk exists in all sports and exercises, including walking.
Sprains Explained
Bones that work together at joints such as your ankle, knee and wrist are connected by at least two, and in many cases more, bands of elastic tissue. These bands, which consist of tough, fibrous tissue, are called ligaments. When a ligament is pulled or stretched too far, or when it is torn, the resulting injury is called a sprain. Sometimes just one ligament is damaged. In other cases, more than one ligament in the same joint may be damaged. The greater the damage to the ligament, the more severe the sprain. For example, a completely torn ligament is more serious than a partially torn ligament.
Ankle Sprains
Every day in the U.S., more than 25,000 people sprain an ankle, according to The National Institute of Arthritis and Musculoskeletal and Skin Diseases. The bones in the ankle are bound by ligaments located both inside and outside the joint. Ankle sprains are common when someone in motion lands on the side of his or her foot, which turns inward. This type of sprain, which doctors call an inversion injury, can occur when a person runs, turns or falls. The injury typically involves a twisting of the joint.
Knee Sprains
Falls are one common cause of sprains, but you don't have to fall to the ground to damage a ligament. If, for example, you change direction suddenly and twist your leg without moving your foot, you can sprain a ligament or ligaments in your knee. Knee ligaments also can be damaged if something or somebody strikes your knee. A roundhouse karate kick delivered to the inside or outside of the knee, for example, could easily damage one or more knee ligaments.
Other Sprains
Although the majority of sprains involve the ankle or the knee, sprains also can occur above waist. Landing on a hand extended to break a fall frequently results in a sprained wrist. The ligaments that bond the bones in the hand can also be damaged. The thumb is a common site of such injuries. Often, the affected ligament is located at the base of the thumb and binds the middle bone of the thumb to the larger bone closer to the wrist.
