An investigation of the contribution of the extraosseous tissues to the diaphyseal fracture callus using a rabbit tibial fracture model.

The contribution of the extraosseous tissues to diaphyseal fracture healing was investigated using a new fracture model. A transverse osteotomy of the tibial diaphysis of 18 New Zealand White rabbits was reamed and nailed, and a 2-cm length of the periosteum was excised from either side of the osteotomy. Healing was studied by radiography and by haematoxylin/eosin histology at intervals over 2 weeks. None of the osteotomies had united at the end of the observation period. Within days, cellular activity was observed in the remnant of the periosteum, which subsequently resulted in cartilage and bone formation. The repair tissue derived from the periosteum advanced in the direction of the osteotomy site. The extraosseous tissues did not appear to contribute significantly to the fracture callus.