gms | German Medical Science

Objectives/Interrogation: Indications for total trapeziometacarpal (TTM) arthroplasty in the management of thumb basal joint arthritis are becoming more and more common. The trapezium in particular is exposed to complications such as aseptic loosening or fracture. Loosening of TTM prosthesis generally leads to simple trapeziectomy. The aim of this study was to present our experience of revision of a failed TM prosthesis by replacing it with a new prosthetic implant.

Methods: Our study involved 8 cases of revision of Elektra metal-metal prosthesis with a 6.5mm impacted cup. Between 2012 and 2018, 8 patients (1 male, 7 female) with a mean age of 63 years (58-72) were operated on by the same surgeon for aseptic loosening of the prosthetic cup including 2 cases of trauma. The mean delay between the initial surgery and revision was 31.8 months (11-87). In all cases the bone scan showed a loosening of the trapezium implant. We found no fractures of the trapezium on the preoperative CT-scan. All cups were surgically revised with implantation of 1 cemented cup, 2 double mobility impacted cups with bone graft and 5 double mobility screwed cups (9 or 10mm) without bone graft. Complications consisted of 1 case of intra-operative fissuring of the trapezium which, however, did not prevent the implantation of a cup, and 1 early mobilization of an impacted cup, although this did not require surgical revision.

Results and Conclusions: At a mean follow-up of 37.3 months (9-73) no patients required reoperation. Residual pain on the VAS was 0.71 with a Quick-Dash score of 21.2. Mean pinch strength was 3.5 kg and the key-grip was 4.25 kg. Five patients "forgot" their prosthesis and these represented our best results. Radiographic evaluation showed signs of loosening of the cemented cup, but the clinical result remained excellent. No radiologic modifications were noted for the other implants.

The particularity of this series was the revision of a small trapezium cup and the absence of preoperative fracture of the trapezium which conditioned preserving this bone. The surgical technique without a bone graft currently represents the preferred procedure during revision surgery of a total TM prosthesis with a conservable trapezium. Preoperative CT-scanning is important to measure the dimension of the loosening cavity of the trapezium which must not go beyond 10mm of diameter.

In selected clinical cases, loosening of a total TM prosthesis can be revised by replacing it with another prosthesis leading to stable results at medium-term follow-up.