Delayed Administration of Risedronate Does Not Restore Bone Loss In Patients Following Total Hip Arthroplasty - A randomized, double blinded clinical study

Background : Periprosthetic bone loss after total hip arthroplasty (THA) increases the risk of serious post-operative complications. Previous studies have reported the beneficial effect of risedronate therapy to improve periprosthetic bone mineral density (BMD) around new implants. The current study is to evaluate the effect of risedronate treatment in enhancing mature well fixed THA implants one year or more after implantation.  Methods and Results : A total of 32 osteoarthritic patients received total hip replacement surgeries and were enrolled from the primary investigator’s clinical practice between February and September 2007. All eligible patients who met the inclusion criteria underwent total hip arthroplasty for reasons other than low traumatic hip fracture due to osteoporosis with normal or osteopenic lumbar spine BMD scores. Subjects received oral risedronate or a placebo with daily calcium plus Vitamin D. DEXA BMD scanning and bone-specific biomarkers, NTx and ALK phosphatase were collected at 6 and 12 months post-surgery. The result showed that risedronate did not increase BMD values of operative femur nor levels in NTx or ALK phosphatase.  Conclusions :  This study suggests that risedronate treatment is not effective in preventing periprosthetic bone loss nor enhancing existing density in well fixed osteointegrated following total hip arthroplasty.  Key words : risedronate, bisphosphonate therapy, total hip arthroplasty