Effects of calcitonin and alendronate on distraction osteogenesis.

In this experimental animal study the effects of calcitonin and alendronate on distraction osteogenesis are investigated. Forty-five mature female New Zealand type rabbits were used. Rabbits were randomized into three groups, each consisting of 15 animals. Under optimal operating conditions a pre-reconstructed circular external fixator was applied to the right tibia of rabbits, and osteotomy was performed with a Gigli saw just below the tibial tuberosity. During the ten days of distraction, a placebo was administered for group I (control group), group II received 10 U of calcitonin, and group III was treated with alendronate (0.5 mg/kg/day) gavages. Rabbits were examined histologically (at the third and eighth weeks, according to Huddlestone et al.), radiologically (at the third, sixth, and eighth weeks, according to Lane and Sandhu), and mechanically (at the eighth week, as torsional loading). During the first three weeks, the groups did not differ much with regard to radiological parameters. However, in the calcitonin and alendronate groups improved histological scores were detected compared with the control group. Radiological images obtained at the end of six weeks demonstrated improved consolidation in the calcitonin and alendronate groups compared with the control group. At the end of eight weeks postoperatively, radiological and histological parameters did not differ among the groups, while torsional failure load was found to be much improved in the calcitonin group (p=0.006). During the distraction osteogenesis period, calcitonin and alendronate affected the quality of regenerate favourably. This effect is sustained until the end of the consolidation period. However, this finding needs to be supported by experimental and human studies.