The twenty-year survivorship of two CDH stems with different design features.

UNLABELLED: Previous studies have shown that anatomical abnormalities of the femur in dislocated hips require the application of special CDH prosthesis for the reconstruction of the proximal femur in total hip arthroplasty (THA). We have retrospectively examined the clinical records and radiographs of 50 patients (67 hips) with low and high dislocations treated with THA in our institution, between January 1987 and December 1994. For the reconstruction of the femur, the stainless steel Charnley CDH stem, with polished surface, monoblock and collarless, was used in 32 hips; the Harris CDH stem, made of CoCr, precoated at the proximal part, modular and with collar was used in 35 hips. At the time of the latest follow-up, 11 Charnley and 6 Harris CDH stems had been revised for aseptic loosening at an average of 14 years (range 6-20) and 13 years (range 2-19), respectively. The survival rate at 20 years, with failure for aseptic loosening as the end point, was 63% for the Charnley and 78% for the Harris CDH stems. These results provide a basis for evaluation of newer techniques and designs. LEVEL OF EVIDENCE: Therapeutic study, Level IV.