[Failure of total uncemented trapeziometacarpal prosthesis. A multicenter study]

The total trapeziometacarpal prosthesis that we have designed has been used clinically for five years. We thought it would be useful to revise failures of these prostheses in a multicentre study in order to identify the causes of the problems and to provide necessary modifications for improvement of the results. Eleven surgeons participated in this study, allowing the review of 24 failures out of a total of 188 implanted prosthesis (12.7%). One case of sepsis and three prosthesis dislocations were observed. In ten cases, we found that the cup was not correctly oriented, leading to a progressive loosening of the cup. In five cases, the shaft had sunk into the metacarpal which was associated with modification of the axis of the shaft in relation to the metacarpal in two cases. In three of these cases, the size of the shaft was too small. Twenty-three failures were reoperated. Metallosis of periprosthetic tissues was observed in 6 cases. This disadvantage has disappeared since treating the heads with ionic nitrogen implantation. A larger size of the same type of prosthesis was able to be implanted in 5 cases. A silicone prosthesis was used in 2 cases and a trapezectomy with or without ligamentoplasty was performed in 16 cases. The high failure rate related to a poor orientation of the cup has led us to increase the range of motion of the prosthesis in order to compensate for the possibly poor orientation of the cup during implantation.