Trapezium implant arthroplasty: evaluation of a semiconstrained implant.

Twenty-five patients who presented with symptoms of disabling pain secondary to arthritis at the base of thumb had 29 arthroplasties with silicone rubber trapezium implants. Stabilization was achieved with tenodesis using a strip of abductor pollicis longus as described by Eaton. All patients had relief of pain after surgery. We examined 23 hands in 19 patients for follow-up. Average follow-up was 31 months. Assessment of functional status and measurements of prehensile capabilities showed that all patients had improved after surgery. Range of motion of the thumb was measured (radial abduction averaged 40 degrees; 80% had full opposition). Average key pinch was 8 pounds. Stability of the implant was assessed with standard posteroanterior, lateral, and stress views of the trapeziometacarpal joint. Comparisons were made with previously reported results for Eaton and Swanson trapezium implants. The tenodesis effect may provide a more stable, although possibly less mobile, CMC joint of the thumb.