The thumb is a complex unit, and we use it so frequently in every day life.  In fact, we take it often for granted until an injury occurs which limits the use of the thumb.  Anatomically, the thumb has three joints. The carpometacarpal joint (CMC joint) which is right at the bottom where the thumb meets the wrist; the metacarpophalangeal joint (MP joint) and the interphalangeal (IP joint) which is the tip joint. The middle joint (the MP joint) can be injured in skiing activity, often, when we fall over with a ski pole in our hands. It can also be commonly injured when the thumb receives a blow to the tip, such as during sporting games or from a fall on an outstretched hand.  So, what happens in this situation?

The MP joint is surrounded by ligaments which provide stability to the joint, making these ligaments super important in giving our thumbs strength.  The ulnar collateral ligament, which is located on the side of the joint closest to the index finger, prevents the joint from moving too far in a radial/lateral direction. The ligament attaches the metacarpal bone to the proximal phalanx bone.  

When the ligament is injured, symptoms include a painful joint, swelling and reduced movement. Because the ulnar collateral ligament provides support the the MP joint, the joint can often become unstable following an injury. This can result in reduced pinch strength and feelings of the joint frequently dislocating or ‘giving way’ during gripping and pinching. The ligament injury can be classified a number of ways. This includes:

  1. A ligament sprain, where the joint stability is not affected
  2. An incomplete or partial tear of the ligament with some mild instability of the joint
  3. A complete tear/rupture of the ligament from either of the bones the ligament attaches to
  4. And an avulsion fracture where portion of the bone from either the metacarpal or proximal phalanx is torn away with the ligament.

We assess the ligament through stress testing the joint. We compare the ligament laxity in comparison to the other thumb through applying a radial deviation force to the proximal phalanx.  This photo shows a complete tear of the ulnar collateral ligament with stress testing. You can see just how far the thumb deviates to the side, which is not normal.


The majority of ulnar collateral ligament injuries are treated in a custom-made thermoplastic thumb splint for a total of 6 weeks. This allows the ligament to heal.  If the joint is very unstable, often the patient will see a surgeon for opinion, as sometimes the ligament will need to be re-attached surgically.  After 6 weeks of splinting, we start patients on thumb movement and eventually strengthening exercises.  The splints we use are moulded to fit and cover only the thumb, so you are free to use the rest of the hand and wrist.


The majority of people who injure their MP joint ulnar collateral ligament make a fantastic recovery and are able to return to sports and heavy tasks at 10-12 weeks post injury. Leaving an ulnar collateral ligament injury to mend itself with no supportive splinting may lead to longer term pain and instability when using the thumb.  It is best to get these looked at sooner rather than later.

Happy skiing!