[The destabilization of the 1st carpo-metacarpal joint in musicians' cramp].

Destabilisation of the first carpometacarpal joint in musicians and in occupational cramps constitutes a functional dystonia. Joint laxity predisposes to these conditions as well as the musician's technique or the working position. This destabilisation can cause a lesion of the anterior oblique ligament of the trapezo-metacarpal joint progressing towards osteoarthritis in the long term. Rehabilitation attempts to act on the functional dystonia and on the hand by maintaining carpo-metacarpal structures and reinforcing the musculature of the hand.