Bone growth after osteotomy and internal fixation in young rabbits.

The factors leading to overgrowth following fixation of long-bone fractures in children have never been clearly understood. The amount of trauma and the type of fixation may play a role. A rabbit model was used to investigate the influence of a femoral osteotomy and plate fixation on subsequent growth. Unilateral midshaft femoral osteotomy was performed 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 length or with a segment removed. Bone length measurements at the end of growth revealed no significant difference in growth between the control femur and the femur that had undergone osteotomy and plate fixation. Shortened plated femora also showed no tendency to grow longer or faster than full-length fixed femora or controls. Interestingly, in the ipsilateral tibia a small but statistically significant length increase, equivalent to about 2% increase in additional growth, was observed, whereas technetium-99 methylene diphosphonate uptake was reduced in the tibial physes. In the context of the rabbit experimental model chosen, these results suggest that significant femoral over-growth does not occur following femoral osteotomy and plate fixation.