Radiological subsidence and acetabular erosion after tapered uncemented hemiarthroplasty in femoral neck fractures a 10- to 13- year follow-up study.

BACKGROUND

Contemporary uncemented hemiarthroplasties are being used after displaced femoral neck fractures, however, their functional and radiological results remain controversial. The aim of this study was to evaluate the clinical and radiological results of a tapered uncemented stem combined with a uni- or bipolar hemiarthroplasty after a minimum follow-up of ten years.

PATIENTS AND METHODS

135 patients underwent uncemented hip hemiarthroplasty after a displaced femoral neck fracture between 2004 and 2007. Their mean age was 81.5 years old (range, 70 to 90). 38 patients were evaluated with a minimum follow-up of ten years. We analysed the complications and the postoperative clinical result according to the Merle D´Aubigné and Postel scale. Radiological femoral type according to Dorr et al., femoral canal filling and the appearance of stem loosening, subsidence and acetabular erosion according to Baker et al., were also assessed.

RESULTS

There were two early periprosthetic femoral fractures. The mean clinical score was 15.8 (range, 9 to 17). Six hips were converted to a total hip arthroplasty due to acetabular erosion, and three stems were revised due to an infection, a late periprosthetic fracture and one aseptic loosening. The survival rate for any cause was 85.4% (Confidence interval (CI) 76 - 92.4%). The survival rate for revision surgery on the acetabular side at 10 years was 92.6% (CI 85 - 100%) and on the femoral side was 97.6% (CI 94.4 - 100%). 14 hips showed non-progressive radiological subsidence and 9 acetabular erosion. Stem subsidence was related to a femoral canal filling < 80% (p = 0.035) and acetabular erosion to a cylindrical femur (p = 0.024).

CONCLUSION

Bone fixation can be obtained with a contemporary uncemented stem in hemiarthroplasty for patients over 70 years old with a femoral neck fracture. Acetabular erosion was frequent after ten years, however, the rate of revision surgery was low.