Thumb ulnar collateral ligament injury is an acute sprain or tear of the ulnar collateral ligament on the ulnar side of the metacarpal-phalangeal joint of the thumb. This condition is also commonly known as skier’s thumb. It is related to the condition known as gamekeeper’s thumb, which is a chronic injury that develops as a result of repeated stretching of the ulnar collateral ligament. Injuries occur when the extended thumb is bent away from the hand at the metacarpal-phalangeal joint.
Common causes of injury typically include falling while holding ski poles, falling onto an outstretched hand, and gripping the steering wheel during a car accident. Symptoms may include pain when using the arm in an overhead position, soreness on the inside of the elbow, minor swelling along the inside of the arm, numbness and tingling in the arm, and instability at the elbow joint. Pinching and gripping with the thumb may be difficult and range of motion may be limited.
UCL injuries are diagnosed by bending the thumb metacarpal-phalangeal joint away from the hand. If mild or partial tears are present, the joint will be stable; however, pain will be present. If the UCL is completely torn, the joint will be unstable. In extreme cases, the joint capsule or volar plate may also be damaged. An X-ray will be required to check for fractures or bone avulsions. An MRI may also be required to diagnose a displaced ligament.
Treatment options for partial tears and nondisplaced fractures are treated with immobilization and placing the thumb in a cast for 4 to 6 weeks. Ruptures, tears and displaced fractures usually require surgical repair.