[Intermediate term outcome of of a hip prosthesis revision system]

The Zweymüller shaft for uncemented total hip arthroplasty was developed in the early 1970s. Encouraged by the clinical results with this stem, which was mainly used in primary arthroplasty, longer fitting stems were added to the line to accommodate bony defects and to allow for an optimal load transfer from proximal to distal. The principal of the design is to allow an optimal distal fixation while allowing the bone to remodel in the proximal part. This study reports on 89 patients who underwent revision surgery of the hip for mostly aseptic loosening. The results after a median follow-up of 36 months show an increase of the modified Harris hip score from 52 points pre- to 82 points postoperatively. Radiographic subsidence was found in nine cases, with eight having progressed for more then 3 mm. Postoperative complications occurred in 11.2%, with seven dislocations. Open revision became necessary in two cases. The stem reviewed here seems to achieve predictable results in cases where a proximal cone is still present to facilitate load transfer, while at the same time the quadrangular stem provides solid distal fixation and ensures rotary stability.