BONE-GROWTH AFTER OSTEOTOMY AND INTERNAL-FIXATION IN YOUNG-RABBITS

The factors leading to overgrowth following fixation of long-bone frac tures in children have never been clearly understood. The amount of tr auma and the type of fixation may play a role. A rabbit model was used to investigate the influence of a femoral osteotomy and plate fixatio n on subsequent growth. Unilateral midshaft femoral osteotomy was perf ormed in 6-week-old rabbits, and the bone was fixed internally with a plate and screws. End-to-end reduction was performed either at full le ngth or with a segment removed. Bone length measurements at the end of growth revealed no significant difference in growth between the contr ol femur and the femur that had undergone osteotomy and plate fixation . Shortened plated femora also showed no tendency to grow longer or fa ster than full-length fixed femora or controls. Interestingly, in the ipsilateral tibia a small but statistically significant length increas e, equivalent to about 2% increase in additional growth, was observed, whereas technetium-99 methylene diphosphonate uptake was reduced in t he tibial physes. In the context of the rabbit experimental model chos en, these results suggest that significant femoral overgrowth does not occur following femoral osteotomy and plate fixation.