Bone formation and remodeling after symmetric and asymmetric physeal distraction.

Bone formation after symmetric and asymmetric physeal distraction was studied in growing sheep. After gradual distraction by external fixation, separation of the growth plate occurred. Fluorescence microscopy, microradiography, and histomorphometric methods were used to study neometaphysis formation. The bone was formed from the inner layer of the periosteum to encircle the distraction area, where the osteogenesis occurred according to the collagen bundles. At consolidation, the distraction area was composed of lamellar trabecular and partly woven bone. The bone trabeculae in the distraction area were thicker than in the control radius. After asymmetric physeal distraction, spontaneous correction of the formed angulation occurred through remodeling and asymmetric physeal growth. Although local physeal changes were noted histologically, enchondral growth usually continued after distraction.