The WEKO prosthesis was developed between 1989 and 1993 in order to restore stability and function of destroyed metacarpophalangeal joints in rheumatoid arthritis. The prosthesis is a hinged one and is fixed to the bone cementlessly by special osseointegrated sleeves in which the stem of the implant is fastened by a cone. Forty-eight patients with 74 prosthesis have been operated on in 1993. In a follow-up study in 2003, 43 of them (89.5 %) with 65 prostheses (87.8 %) could be re-examined clinically and radiographically. In seven patients (16.2 %) implant arthroplasty failed comprising loosening of the prosthesis within their sleeves, loosening of the sleeves in the bone and implant breakage. Twelve implants (16.2 %) had to be removed. The range of motion at follow-up was 0/10/70 degrees in comparison to 0/0/90 degrees postoperatively. Patients satisfaction over the first three to four years was higher than later due to deterioration of the rheumatoid disease. Thus, classical handscores to assess the outcome could not be applied. A second generation of the WEKO prosthesis was developed to improve rotational stability and osseointegration paying attention to reports concerning failures which were seen also by other authors. The stem of the implant was changed to a cylindrical one with star shaped cross-section which allows some pistoning in order to reduce the stressload of the sleeves.