Femoral neck remodelling after hip resurfacing surgery: a radiological study.

Background: Narrowing of the femoral neck under the femoral component of the hip resurfacing has been noted previously and has raised concern. In this study we examined the X-rays of patients following Birmingham hip resurfacing surgery at 6-years follow-up.

Methods: Bony changes proximally and distally were measured. Fifty-two patients were available for evaluation.

Results: There were 40 (76.9%) men and 12 (23.1%) women, with a mean age of 52 years (25-64). The unoperated contralateral femoral neck was measured as a control. We found femoral neck narrowing proximally in 82.7% of patients and distally in 26.9% and on the contralateral side in 54.5%. The average narrowing was 3.6%. Widening was observed proximally in 17.3% and distally in 73.1% and on the contralateral side in 45.5%. The average widening was 3.9%. Four of the 52 patients had proximal narrowing exceeding 10% of the femoral neck diameter, and one of the 52 patients had inferior narrowing exceeding 10%.

Conclusion: Gender, body mass index, component size and age did not affect remodelling. We conclude that the observed findings are likely to be a manifestation of a generalized remodelling response in the femoral neck rather than a localized and isolated narrowing at the junction of the component and the femoral neck.