Dual energy X-ray absorptiometry analysis of peri-prosthetic stress shielding in the Birmingham resurfacing hip replacement.

INTRODUCTION

Numerous reports in the literature refer to the femoral neck fracture rate in hip resurfacing. The aim of this study was to determine the bone mineral density and evidence of stress shielding around the femoral component of the Birmingham resurfacing prosthesis.

MATERIAL AND METHODS

Twenty-eight patients with primary unilateral osteoarthritis had a Birmingham resurfacing prosthesis. DEXA analysis of the proximal femur and femoral neck was performed and compared with the opposite unaffected side.

RESULTS

Total periprosthetic bone mineral density was 0.49% greater than the control, but this did not achieve statistical significance. Although the BMD of the femoral neck was slightly increased on the prosthetic side (1.002 g/cm2) as opposed to the control side, this difference did not reach statistical significance.

CONCLUSION

The Birmingham resurfacing prosthesis does not appear to reduce femoral neck bone mineral density in comparison to the normal femoral neck bone density. We conclude that femoral neck fractures are unlikely to be due to stress shielding related to the prosthesis.