INTRAVENOUS ZOLEDRONIC ACID IMPROVES THE AMOUNT AND STRENGTH OF NEW BONE FORMATION DURING DISTRACTION OSTEOGENESIS IN IMMATURE RABBITS

Aim: To examine the effect of the bisphosphonate zoledronic acid in doses of 0.1mg/kg on new bone formation and stress shielding in a distraction-osteogenesis model in New Zealand white rabbits. Method: Thirty male rabbits underwent a right tibial osteotomy at eight weeks of age. Distraction of the osteotomy by 0.75mm/day was performed for two weeks followed by four weeks for consolidation. Group I was given saline infusions, Group II zoledronic acid at surgery, and Group III received zoledronic acid at surgery and again at two weeks. DXA scans evaluated BMC and BMD. Quantitative computerised tomography measured the cross-sectional areas. Four-point bend testing of both distracted and non-operated tibiae was performed in a standardised fashion. Results: Bone mineral accretion between two and four weeks was significantly higher in treated versus saline groups, and was better maintained at six weeks (P Conclusions: Zoledronic acid administration significantly increased the rate and amount of new bone formation and its mineralisation. The increases in bone formation and retention translated to a significant, dose-dependent increase in strength. Further research into the role of zoledronic acid in orthopaedic surgery is indicated.