A UCL injury of the thumb, also known as “skier’s thumb” and “gamekeeper’s thumb,” is a common hand injury in sports.

Mechanism of injury

The ulnar collateral ligament on the inside of the thumb (the side closest to the other four fingers) is torn off the thumb after being subjected to a valgus force that pulls the thumb away from the other four fingers. Some of the ways that this stress to the thumb can occur include falling on the outstretched hand and having the thumb pulled away from the other four fingers or a ball hitting the player on the tip of the thumb, forcing it away from the other four fingers.

Signs and symptoms

It is a painful injury to an athlete, and he or she will usually pinpoint the pain to the base of the thumb on the ulnar side (the side closest to the other four fingers). Often he or she will complain of difficulty gripping a ball or racquet. A sports medicine physician or hand surgeon can evaluate the injury and often make the diagnosis by physical exam. The athlete will usually have a fair amount of swelling at the location of injury. Stressing the ligament to see if the thumb opens up more at that location can confirm the diagnosis. The physician can try to pull the thumb away from the other four fingers. If the joint at the base of the thumb opens up more than it does on the thumb of the opposite hand, this increased opening can be diagnostic of an injury to the ligament. X-rays are often ordered to rule out the possibility that part of the bone has been pulled off the base of the thumb.

UCL injury of the thumb
The physician will note swelling and increased opening of the thumb to valgus stress (orange arrow).

Treatment of a UCL injury of the thumb

The treatment depends on the extent of the injury. If the ligament has pulled off the base of the thumb and has flipped outside of one of the tendons of the thumb, this type of injury does not heal on its own. In this case, surgery to put the ligament back in the proper position and repair it to the bone is necessary. Complete tears of the ligament or injuries in which the ligament pulls a small piece of bone off the base of the thumb are also often treated with surgical repair. Sprains or partial tears of the ligament can sometimes be treated by putting the athlete in a thumb spica cast which immobilizes the thumb up to its tip.

Recovery and return to sports

With or without surgery, the injury can take 6 to 8 weeks or more to heal. Depending on the sport or activity that the athlete performs, he or she might be able to play in a cast to protect the healing ligament. In a sports such as football, the cast can be padded to protect other players. If the athlete plays a throwing sport, however, it is usually very difficult to play in a cast.

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