Filling of a bone defect during experimental osteotaxis distraction

Gradual distraction of a tibiofibular bone osteotomy in 14 rabbits was compared with a neutral osteotomy in 14 control rabbits using an osteotaxis device as fixation. The osteotomy was distracted for a period of 8 weeks at a rate of 1 mm/week. The control osteotomies united in 5 to 6 weeks with minimal external callus formation. In the distraction group, the periosteum and endosteum participated in the filling of the distraction gap. The most vigorous osteoblastic activity was observed in the middle of the osteotomy gap (growth zone) where calcification was delayed. In the distraction group the bone united in 6 to 7 weeks, not significantly later than in the controls. Two instances of non-union (2/14) were observed in the distraction group.