Endoprosthetic replacement of the trapezium for arthrosis in the carpometacarpal joint of the thumb.

One hundred silicone endoprosthetic replacements of the trapezium for arthrosis of the carpometacarpal joint of the thumb (CMC-1 joint) were reviewed in 79 patients with a follow-up time from one to 5 years in 67 women and 12 men. Pre- and postoperatively, pain, range of abduction of the CMC-1 joint, grip and pinch strength were recorded. Pain was relieved in 95 hands and abduction was improved in 85 hands. Dislocation of the endoprosthesis was found in the 15 hands with unimproved abduction. Grip strength was improved in 82 hands and pinch strength in 72 hands. Hyperextension of the metacarpophalangeal joint treated by fusion when more than 20 degrees before operation gave better function than when not fused. Complications were dislocation of the endoprosthesis in 19 hands, one infection, and two fractures of the metacarpal shaft. No fracture of the endoprosthesis itself was observed.