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Carpometacarpal Joint Injuries

The biconcave shape of the carpometacarpal (CMC) joint of the thumb (the joint of the extension of the thumb to the wrist) makes it anatomically different from the other hand joints. This saddle joint permits the special function of opposition of the thumb to the little finger. The volar oblique ligament is the most important structure in maintaining stability. Complete dislocations of the CMC joint without associated fracture are relatively rare. The most common mechanism of injury is a fall on the outstretched hand.


– Pain occurs together with tenderness and impaired function.
– Deformity of the joint outline can be seen.


The doctor may:
– reduce the joint back to its normal position;
– immobilize the joint for 4–6 weeks in a cast or splint;
– recommend surgery when the stability of the joint is in doubt, surgically inserting a wire through the joint to hold it in position.

Healing and complications

In cases of chronic instability, surgical reconstruction of the volar ligament may be indicated. In cases of recurrent laxity following reconstruction, or where joint changes are present, removal or fusion of the CMC joint may be the ultimate treatment.

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