A sprain is an injury to a ligament. Ligaments connect bone to bone, and help stabilize a joint. Injuries commonly occur due to a fall on an outstretched hand, or during sports activities, such as skiing. Symptoms typically include pain, swelling and stiffness. A thorough medical evaluation is necessary to assess the severity of the injury and joint instability. Treatment is often conservative if there is a partial injury using a cast or splint/orthosis. If there is a complete tear, surgery may be necessary.