A torn ligament in the thumb usually affects the ulnar collateral ligament, which is used to pinch and grasp. The ulnar collateral ligament also stabilizes the thumb so it doesn't hyper-extend, or bend too far. An ulnar collateral ligament tear is often called a skier's thumb or a gamekeeper's thumb; skier's thumb describes an acute injury and gamekeeper's thumb a chronic injury, but the terms are used interchangeably.
Cause
Ulnar collateral ligament injuries are usually the result of a sudden force, called a valgus force, bending the thumb backwards, away from the hand. The ulnar collateral ligament normally connects two bones, the metacarpal bone and the first, or proximal, phalanx of the thumb, the physician-driven site Joint Pain Info explains. The space between the two is called the metacarophalangeal (MCP) joint. The sudden force on the thumb tears the ligament either partially or completely. An acute injury such as a fall on the outstretched thumb or a repetitive motion injury from overuse can tear the ligament.
Symptoms
Pain occurs at the time of the injury. Afterward, the thumb is unstable; it's difficult to grasp objects tightly between the thumb and index finger. Bruising and swelling may develop at the base of the thumb. If the ligament has completely torn away from one of the bones, the end may fold under and form a bump that can be felt at the base of the thumb, according to Orthogate, a website of the Internet Society of Orthopaedic Surgery and Trauma. This bump is called a Stener lesion.
Diagnosis
Medical personnel assess the degree of injury by stress testing, which involves bending the thumb and measuring how far the thumb can be moved away from the hand, compared to the uninjured thumb. Ability to move the thumb less than 30 degrees, or 15 degrees more than the uninjured thumb, indicates a partial tear. If the thumb can move more than 30 degrees from the hand or more than 15 degrees than the uninjured thumb, diagnosis is likely to be a complete tear, Dr. Bruce Anderson, reports on Up to Date, a worldwide clinical information site. X-rays are done to check for fractures; sometimes a small piece of bone, called an avulsion fracture, is pulled away from the thumb at the time of injury.
Treatment
If the ligament isn't completely torn, a cast may be used for around six weeks to stabilize the joint and allow the ligament to heal. Ice packs help decrease pain and swelling. If the ligament is completely torn, surgery to repair the ligament is necessary. A cast is normally worn for six to eight weeks after surgery to repair a torn ligament in the thumb.
Considerations
Even with surgery, complications can occur. Nerves in the thumb can be damaged, resulting in numbness. Stiffness, tenderness and discomfort persist after surgery, but are usually reversible with physical therapy and usually subside within a year, the American Association for Hand Surgery states.
