NO SUBSIDENCE OF TAPERED WAGNER STEMS BETWEEN ONE AND TEN YEARS AFTER IMPLANTATION. RESULTS OF A COMPLETE 10-YEAR FOLLOW-UP

Abstract

Introduction: The Wagner SL Stem is a well established implant to bridge proximal femoral defects in hip revision surgery. The tapered shape offers the possibility of press-fit anchorage distal to the bone defect. There are missing long term results with absolute follow-up over ten years. The goal of the study was to observe the subsidence and the restoration of the proximal bony stock within ten years.

Patients and Methods: From 1988 until 2005 198 Wagner Stems were implanted in our hospital. 50% of the indications were due to aseptic loosening, 25 % due to septic loosening and 10% due to periprosthetic fracture and 15% other indications. Clinical function was measured with an adapted Harris Hip Score; subsidence was measured in the way that was previously described by Callaghan. The bony restoration was controlled with Böhm’s technique. The length and the thickness of the area of integration were measured in mm on the ap radiographs of the femur.

Results: The over all survival of the 198 Wagner stems after 17 years was 87%, for aseptic loosening. There were 57 implanted stems with ≥10 years follow-up. 31 of the patients died before the ten year control, four stems had to be exchanged because of aseptic loosening, three patients referred the clinical control so that a total number of 19 stems could be followed for at least 10 years. In two of those 19 stems there was significant subsidence (12 and 33mm), the subsidence occurred within the first year after implantation. The area of integration showed no change of length or thickness. The bony restoration was good or excellent in 70%. The adapted Harris Hip Score declined only little from 80 postoperatively to 75 after ten years.

Conclusion: No significant subsidence after Osteointegration occurred. The principle of the tapered stem is as good that the Wagner SL Stem can be widely indicated.