We present the results of a 5 year prospective follow-up study on the functional outcome after total replacement of the trapeziometacarpal joint with the Ivory prosthesis (Memometal, Stryker Corporate, Kalamazoo, Michigan, USA) in 22 patients. The female to male ratio was 21:1 and the mean age was 66 (range 54-78) years. The mean follow-up period was 67 (range 60-77) months after operation. Patient satisfaction was high. The mobility of the operated thumb was restored to a range of motion comparable to the contralateral thumb. Key pinch and grip strength improved by 13% and 31%, respectively. Overall function, according to Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH) score, improved by 59%. Pain decreased by 85% according to the numerical rating scale. Radiological evaluation revealed no loosening of the implant after 5 years except in one patient who required revision due to polythene wear with secondary joint instability. Another patient had asymptomatic polythene wear that required no revision but remains in follow-up. The 5 year overall survival of the prosthesis was 95%. These medium-term results suggest that the Ivory arthroplasty is a reliable option for treating advanced trapeziometacarpal arthritis, because it appears to give a very good functional outcome and has the potential for long-term survival rates.
Keywords: Ivory prosthesis; Trapeziometacarpal arthroplasty; trapeziometacarpal arthritis.