Abstract: PURPOSE: Double-barrel vascularized fibula graft is one of the most common surgical techniques to augment or maintain the height of the neo-mandible. The purpose of this study was to investigate whether the gap completely disappeared and gap ossification ultimately achieved between the double barrels. METHODS: Six rabbits were used in the study. Each animal's tibia was vertically osteotomized at its midpoint, folded onto each other and fixed by mini-titanium plate, thus an animal model of “double barrel” was established. Specimens were obtained at 3 months and 6 months postoperatively, then the gap ossification between the double barrels was evaluated by radiography and histomorphology. Measurements of the gap width between the two tibial struts on X-ray films were performed 3 months after the operation at three sites: distal, middle and proximal site. Measurements were compared with those obtained immediately after operation using SPSS 19.0 software package. RESULTS: Three months after operation, radiography demonstrated that the gap between the double barrels gradually became vague. Histological study showed that irregular new woven bone formed in the gap between the two struts. There was significant difference in mean gap width at the distal and proximal site (P<0.05), but there was no significant difference at the middle site(P=0.552). Radiological and histological study showed cortical bone resorption in the contact area and two thin tubular bones fused into a thicker one 6 months postoperatively. CONCLUSIONS: The double-barrel tibia fixed with titanium microplate can fuse into a large, unique, continuous bone barrel.

Key words: Double- barrel technique, Gap ossification, Tibia, Rabbit