Zoledronic acid improves the mechanical properties of normal and healing bone

Objective. To determine the effects of the bisphosphonate zoledronic acid on the mechanical properties of normal and regenerating bone in a rabbit model of distraction osteogenesis. Background. Bisphosphonate therapy is used for treating osteoporosis and, more recently, to enhance bone healing and reduce stress-shielding osteoporosis in distraction osteogenesis. Methods. Thirty eight rabbits underwent 14 days of distraction osteogenesis on the right rear limb. They received either zero, one or two doses of intravenous zoledronic acid. Four point bending tests were performed to collect mechanical data. Results. The peak load capacity of the regenerating bone was significantly increased by bisphosphonate therapy, but a similar trend in normal bone was not significant. The energy absorbed to failure did not vary significantly in either group. Conclusions. These data suggest that bisphosphonate therapy has a beneficial effect on the load capacity of regenerating bone, without increasing the brittleness of either new or existing bone.