what is a sprained knee
By Mayo Clinic Staff. Your ligaments are tough, elastic-like bands that connect bone to bone and hold your joints in place. A sprain is an injury to a ligament caused by tearing of the fibers of the ligament. The ligament can have a partial tear, or it can be completely torn apart. Of all sprains, ankle and knee sprains occur most often. Sprained ligaments often swell rapidly and are painful. Generally, the greater the pain and swelling, the more severe the injury is. For most minor sprains, you probably can start initial injury treatment yourself. Rest the injured limb.