Comparison of bone transport and bone graft methods in the experimental treatment of bone defects

Large segmental bone defects due to trauma, infection or tumor resection are difficult to treat. To compare the effects of a bone transport technique with various bone graft methods in treating this problem, an animal model with a designed mini external fixator to accomplish the bone transport was established. New Zealand white rabbits weighing 3 kg were divided into five groups. A 2 cm bone defect was created in the left hind tibia of each rabbit, then stabilized with an external fixator. In the control group, no treatment was given. In the autograft group, an autogenous bone segment was repositioned after removal of the periosteum. In the double osteotomy group, the tibial shaft was doubly osteotomized at the upper and lower level with preservation of vascular supply to the middle segment. In the allograft group, a deep-frozen allograft was put into the defect and in the bone transport group, the middle segment of the tibia was transported downward gradually beginning 1 week after the osteotomy. The rabbits had weekly radiographic examinations and were killed 3 months postoperatively. Rabbits with fractures, severe infection, incomplete osteotomy or that died were excluded from analysis. There were 12 rabbits remaining in each group. Results were evaluated by radiographic and torsion tests. Rabbits in the double osteotomy group had the best results, followed by the autograft bone transport, allograft and control groups. Fractures at the distal pin-bone interface occurred more often in control and bone transport groups than other groups. Incomplete osteotomy and problems at the docking site were specific to the bone transport group. The results of this study suggest that the bone transport technique may be used to treat large bone defects, but is associated with significant morbidity.