Distraction osteogenesis of free interpositional membranous bone: experimental design.

The purpose of this study is to explore the possibility of bone formation in distraction osteogenesis of the free interpositional membranous bone. Three canine dogs were used as subjects. Two mandibular osteotomies were made in the mandibular body. The oral soft tissue and periosteum of the segment between the two osteotomies were freed from periosteum and the surrounding soft tissue as a free interpositional bone graft 2 cm wide was created. The free interpositional bone was fixed to the proximal mandibular body with a miniplate. The external fixation device was applied to the proximal mandibular body and the distal mandibular body. Mandibular distractions were performed postoperatively at a rate of 1 mm/day for a total of 10-mm distraction for 10 days. The latency period was 1 week in Dog 1, 2 weeks in Dog 2, and 3 weeks in Dog 3. Three dogs were killed 6 weeks after distraction, and interpositional bone specimens were obtained. In Dogs 1 and 2, the free interpositional bone showed severe resorption and had no new bone formation at the distracted area. However, in Dog 3, new bone developed along the distracted gap. Our study demonstrated the possibility of distraction osteogenesis in the free interpositional membranous bone and suggested that free interpositional membranous bone be allowed, under rigid fixation device, to have enough revascularization from surrounding tissue to have osteogenesis for at least 3 weeks or even more.