Unraveling the UCL Injury of Thumb
Injury: Ulnar Collateral Ligament Sprain/Tear, Skier's Thumb
Mechanism OF INJURY
A ulnar collateral ligament (UCL) of the thumb typically occurs when the thumb is forcibly pushed outward and extended away from the hand. The specific injury occurs between the metacarpal bone as well as the phalanx bone. The joint is referred to as the metacarpal-phalangeal joint. The direction of the force of the injury causes the thumb to bend outward causing the ulnar collateral ligament (UCL) to stretch or tear. Athletes commonly feel a pop at the time of the injury.
Examination of the Thumb
Most individuals will have pain directly over the metacarpal-phalangeal joint. Swelling may also be seen directly over the ulnar collateral ligament. Other symptoms may include the decreased ability to grasp an object between the thumb and the 4th finger in a pinching fashion. An evaluation should be done to assess if the metacarpal-phalangeal joint is stable. By recreating the force of the injury one can see if the joint "opens up" or stretches further than the unaffected side. If the joint is felt to be stable ,then non-operative treatment can be considered. On the other hand, if the joint is found to be unstable there may be a complete tear indicating surgery may be necessary. In either instance, it is recommended to get an x-ray to determine if the injury is due to a fracture of the bone rather than a ligamentous injury.
When a complete tear is suspected, an MRI can be obtained to determine if a Stener lesion has developed. A Stener lesion occurs when the ulnar collateral ligament is completely torn and the fibrous tissue of the thumb blocks the two halves of the ligament from healing together. If a Stener lesion is not treated, the ulnar collateral ligament will not heal. Improper healing will lead to instability of the joint as well as weakness and possible pain with a pinching grip.
For a significant sprain or tear, non-operative treatment typically consists of a thumb spica cast or brace that immobilizes the thumb. Generally, the period of immobilization is approximately 4-6 weeks, with the slightly shorter period for children. Surgical treatment is initiated if there is a fracture that is out of place or there is a complete tear of the UCL with a Stener lesion. After surgical treatment the patient is usually placed in a thumb spica cast for 4-6 weeks. However, opinions regarding surgery may differ if the patient has a complete tear with no Stener lesion seen on MRI.
Return to Play
Return to play after a UCL sprain or tear depends on the sport the athlete is returning to as well as if the injury is to the dominant hand. If there is a possibility of re-injury a thumb brace can be used for protection in sport. For example, a soccer player may be able to return with thumb protection, more quickly than a basketball player or football player.