The anatomically difficult primary total hip replacement - Medium-to long-term results using a cementless modular stem

This prospective study presents the ten-year ( 5 to 16) clinical and radiological results of 55 primary total hip replacements ( THR) using a cementless modular femoral component ( S-ROM). All patients had a significant anatomical abnormality which rendered the primary THR difficult. The mean Harris hip score was 36 ( 12 to 72) pre-operatively, 83 ( 44 to 100) at five years, and 85 ( 45 to 99) at ten years. The Western Ontario and McMaster Universities osteoarthritis index ( WOMAC) and short-form ( SF)-12 scores were recorded from the year 2000. The mean SF-12 score at five years after surgery was 45.24 ( 22.74 to 56.58) for the physical component and 54.14 ( 29.20 to 66.61) for the mental component. By ten years the SF-12 scores were 42.86 ( 21.59 to 58.95) and 51.03 ( 33.78 to 61.40), respectively. The mean WOMAC score at five years post-operatively was 25 ( 0 to 59), and at ten years was 27 ( 2 to 70). No femoral components were radiologically loose, although five had osteolysis in Gruen zone 1, three had osteolysis in zone 7, and two showed osteolysis in both zones 1 and 7. No osteolysis was observed around or distal to the prosthetic sleeve. No femoral components were revised, although three hips underwent an acetabular revision and two required a liner exchange. At a mean of ten years' follow-up the S-ROM femoral component implanted for an anatomically difficult primary THR has excellent clinical and radiological results.