Introduction and Aims: This study evaluated the proximal femoral remodelling associated with three uncemented femoral prostheses of different designs and surface treatments. We hypothesised that less bone loss will occur over time with a titanium implant designed for proximal stress transfer compared to a more rigid stem that produces diaphyseal loading.

Method: During total hip arthroplasty (THA), patients were implanted with either: AML cobalt-chrome alloy porous-coated stem (11 patients), Osteonics titanium alloy hydroxyapatite-coated stem (13 patients), or Sulzer titanium alloy hydroxyapatite-coated stem (eight patients). All patients followed the same surgical and post-surgical protocol for THA. Dual energy x-ray absorptiometry (DEXA) scans of the operated proximal femur were performed on all patients pre-operatively, three to seven days post-operatively, and then six weeks, six months, and annually up to five years post-operatively. Longitudinal changes in bone mineral density (BMD) were compared within and between the two groups.

Results: Using the first post-op DEXA scan as baseline, the percent change in BMD (g/cm²) at one year was −17.06% in patients implanted with the AML stem. The percent change in BMD at one year was −3.06% in the Osteonics group and in the Sulzer group, the percent change in BMD at one year was −4.11%. The greater bone loss observed with the AML stem was found to be statistically different than the bone loss observed with the other two stems. These findings continued at three and five years post-operatively.

Conclusion: There was a trend toward less bone atrophy and preservation of bone stock in patients implanted with both the HA and Sulzer stems. Extensively coated, diaphyseal-fitting, CoCr stems (AML) definitely caused greater bone loss, both proximally and in the diaphysis.

Introduction and Aims: This study evaluates the effect of risedronate (Actonel) on proximal femoral bone loss after total hip arthroplasty (THA). Studies have shown that alendronate (Fosamax) reduces periprosthetic bone loss after primary THA. We hypothesise that patients who take risedronate, post-THA, will have less bone loss than patients not taking risedronate.

Method: All patients in this prospective study undergo uncemented THA and follow the same post-operative protocol. Patients in the study group take five mg of risedronate daily, beginning five to seven days pre-operatively, and continuing for 24 months after surgery. Patients randomised to the control group do not receive risedronate. Dual energy x-ray absorptiometry (DEXA) scans of the operated proximal femur are performed on all patients pre-operatively, three to seven days post-operatively, and then six weeks, six months, one year and two years post-operatively. Longitudinal changes in bone mineral density (BMD) are compared within and between the two groups.

Results: Analysis of data for female subjects showed the percent change in BMD (g/cm²) for the control group at six months was −9.71% and for the study group −4.55%. Longitudinal changes in BMD between groups were examined using repeated measures analysis within each gender and were found to be significantly different between groups of females (p=.05). A similar trend was observed among the male subjects. One and two-year prospective data will be presented at the meeting.

Conclusion: Bone loss after THA can increase the rate of failure of THA and cause revision surgery to be more complex and have compromised outcomes. Short-term data reveal significantly decreased bone loss after uncemented THA among patients taking risedronate.