Surgical management of basal joint arthritis of the thumb. Part I. Long-term results of silicone implant arthroplasty.

Seventy-two procedures in 53 patients with advanced basal joint arthritis are retrospectively evaluated with follow-up ranging from 12 months to 8 years. Follow-up of a subset of 32 silicone implant arthroplasties in osteoarthritic thumbs averaged 3.9 years with a 25% failure rate. Despite providing early symptomatic relief, silicone implants lost nearly 50% of vertical height at the ulnar margin secondary to cold flow and wear and subluxed 35% of the width of the prosthesis during the study period. Dynamic tendon transfers did not prevent implant subluxation and had no effect on the magnitude or pattern of implant wear. Ligamentous reconstruction reduced implant instability, but was accompanied by an increase in silicone wear and cold flow. Reactive giant cell synovitis with silicone particulates and adjacent bone resorption was seen in some cases of implant arthroplasty failure. Forces across the osteoarthritic basal joint would seem to preclude a stable silicone implant arthroplasty in the absence of eventual wear and symptomatic foreign body synovitis. Because of this unresolved conflict between implant stability and wear, at the present time we seldom use silicone in the osteoarthritic basal joint, but continue to utilize the silicone hemitrapezium or the cannulated trapezium replacement with satisfactory results in the low-demand rheumatoid thumb.