Neo-osseous flaps using demineralized allogeneic bone in a rat model.

Abstract

Surgical reconstruction with revascularized bone grafts can be compromised by donor tissue limitations and may be refined by prefabrication of compound neoflaps using bone substitutes. The principal suitability of demineralized allogeneic bone (DALB) slabs in fabricating neo-osseous flaps based on the inferior epigastric vascular system was studied and compared with neoflaps with autologous bone (AUB). In 45 rats, the histological pattern of bone formation in response to angiogenesis induced by vessel implantation was assessed, and characteristics of vascularization of the neoflap were studied microangiographically at 2, 4, 6, and 8 weeks. Histological techniques included decalcified and nondecalcified sections, as well as intravital polyfluorochrome labeling. Blood flow of the neoflap was also assessed quantitatively using 15-microm microspheres labeled with technetium 99-methylene diphosphate (99-MDP) 8 weeks after flap fabrication. Although the DALB neoflaps showed consistent bone formation and neovascularization, the bone regeneration process was delayed distinctly in comparison with AUB. Microangiographically, however, no differences between the two types of grafts became apparent during all time periods tested. Furthermore, the radioactivity of the DALB neoflap, which means bone blood flow per dry weight, was significantly higher than in AUB grafts and even more than that of intact iliac bone (p = 0.001). The exact meaning of elevated blood flow in DALB and similar degrees of vascularization corresponding to native AUB grafts remains to be determined, but may be a sign of ongoing bone formation resulting in a suitable DALB-containing neo-osseous flap in the long term. The authors findings support that allogeneic bone could be a potential substitute for AUB in creating a prefabricated neo-osseous flap.