Skier’s Thumb:

Skiers Thumb: What it is and how to avoid it

Skier’s thumb is a common injury to the ulnar collateral ligament (UCL) of the thumb. This ligament is important for holding the thumb close to the hand, and not letting it deviate outwards. It is located on the inside of the base of the thumb. You can test the integrity of the thumb UCL by giving yourself a thumbs up and then pulling the thumb to the outside away from the hand. In a normal thumb, there will not be significant amounts of deviation to the outside. In a thumb with a ruptured UCL, it will move an unsettling amount towards the outside. 

Ortho testing of a UCL rupture from many years ago. This athlete has been able to rehabilitate their thumb and now only has pain and discomfort after certain...

This injury is classically called a gamekeeper's thumb. Many peoples first instincts nowadays is to relate this to excessive amounts of video game play. However, this nomenclature has been around since long before the first xbox or playstation. It is actually a term coined when describing this injury in game keepers at rooster fights. They would injure their UCL’s when taking the unfortunate losing rooster by the neck, and swinging their body around to put their suffering to an end. 

In skiers, this injury is often caused by improperly looping the ski straps around the base of the thumb. If the skier falls or the poles catch, they can violently pull the thumb to the outside, causing a rupture to the UCL. Initially the athlete feels significant amounts of pain at the base of the thumb, with exquisite tenderness on the inside where the UCL resides. They will also have pain with thumb adduction and pinching the thumb towards the hand. Swelling and discoloration (buising) may also occur in the thumb, wrist and hand. 

Dr. John explaining how what skiers thumb is and how it commonly occurs. He also shows how to prevent it with a simply change in how the ski straps are put on.

There are multiple grades ranging from a partial tear to complete rupture of the ligament. This injury typically doesn’t require surgery, but can predispose individuals to arthritis at the base of the thumb. One instance that requires surgery is if the athlete develops a stener lesion. A stener lesion occurs when the UCL completely ruptures, and the remaining flap of connective tissue becomes displaced on top of one of the muscles of the thumb (the adductor pollicis for you anatomy nerds out there) causing continued damage and displacement. Another high grade injury that can result from this mechanism is an avulsion fracture. In this case the ligament pulls so hard that the bone it is attached to breaks as opposed to the ligament. This injury requires much more rest and immobilization in order to heal properly. This injury can be assessed and graded with either an MRI or high frequency ultrasound like we have in the office. In many cases high level ultrasound can be the modality of choice because we can perform a dynamic assessment. This means that we can move the thumb, testing the ligament while looking at it in real time with the ultrasound. MRI can only take a still image, and is much more expensive. If and avulsion fracture is suspected, then x-rays may also be done on the thumb and wrist. 

Tape depicting the location and approximate structure of the UCL of the thumb

Conservative management involves initially splinting the thumb in a brace that does not allow the thumb to move outwards, and resting until the discoloration and/or swelling go down. Then, individuals can start working on moving the thumb around in different directions in order to increase the range of motion, and allow the brain to reconfigure how it moves the thumb without placing too much stress where the ligament once was. Once pain diminishes with simple movements, then we begin to reincorporate pinching. This can be done by pulling against a rubber band in the action of adduction, or moving the thumb towards the index finger. This can also be done by pinching against an object such as a water bottle. These exercises should only be performed to a slight increase in discomfort (only increasing 1-2 points of 10 on the pain scale) and should be stopped if there is lingering pain after the exercise, or significant increases occur in pain or tenderness during the exercise. If the thumb does not respond to rehab after a few weeks, then it is important to have it looked at by a healthcare professional because it could be a sign of an avulsion fracture, or a higher level of injury not only to the UCL, but other parts of the thumb as well.