TOTAL HIP REPLACEMENT IN PATIENTS WITH FEMORAL DYSPLASIA USING STRAIGTH CONICAL WAGNER-TYPE STEMS

Abstract

Aim: The evaluation of the middle term behaviour of the Wagner-type stems in dysplastic femurs and the presentation of the technical and surgical differences with the implantation of a Wagner stem.

Materials and Methods: Between 1997 and 2008 we implanted 64 Wagner stems in 58 patients. Average age at the time of implantation was 64 years. 52 patients was operated because of DDH, and 12 had had previous osteotomy. All patients were prospectively evaluated radiographically and clinically at annual intervals. Functional outcome was assessed with Harris Hip Score and Oxford Score.

Results: Mean follow-up of these series was 4 years (11-1)One stem was revised because of fracture of the lesser trochander and two more patients were re-operated for open reduction. With the re-operation as end-point and 95% Confidence Interval survivorship rate was 98, 5%. There were no progressive radiolucent lines. Stem migration was at an average 2mm (1–6) during the first two years and remained stable thereafter. There was no deep infection in these series. After the second year a dense zone is evident in all Gruen zones at the implant –bone interface with a width of 2–3 mm.

Discussion: Dysplasia of the proximal femur may pose significant technical problems during THA due to the distortion of the geometry and the narrowing of the femoral canal. The sort, conical Wagner type stems can offer a very good alternative is such patients. They allow control of the anteversion and they are able get a good press-fit despite the metaphyseal/diaphyseal mismatch and the femoral bowing.

Conclusions: Wagner type stems are a reliable alternative when performing THA in patients with dysplastic femurs