The vascularized allotransplant– successful alternative for massive bone defects

Abstract

Introduction. The massive bone defects after trauma, in congenital anomaly, tumors, infections or nonunions is a real dilemma for reconstructive surgery of the locomotor system. Contemporary methods that are usually used for reconstruction of the bone structure are: bone transplant, cryopreserved allografts, autograft or prosthesis, having high levels of morbidity and complication rates. Their common features are bad blood circulation and unviability, resulting in mechanical instability and poor bone consolidation (periprosthetic fractures, stress fractures, pseudoarthrosis, sepsis). Aim of the study. To determine what are the different methods used in reconstruction of massive bone defects. Materials and methods. Scientific papers and research results regarding bone defects reconstruction methods were reviewed. Review. A vascularized bone graft, reclosed microsurgicaly in the circuit, has a good potential for regeneration, plasticity, and a post-graft mechanical stiffness. The vascular bone autograft, with all biological and mechanical characteristics is considered the "gold standard" in the treatment of small bone defects. However, it becomes insufficient in size, shape and cellular repair capacities in the case of massive bone defects due to the increased circulatory needs of the injured segment. Maintaining the osteoplastic properties of the vascularized autograft and combining them with the orthotopic characteristics of an allogene bone or bone segment would be a successful alternative for the reconstructive surgery of the locomotor. The dilemma imposed by vascularized composite allotransplantation (VCA), is immunosuppression (IS) and immunomodulation for life, which is not justified in case of vital organs (heart, liver, kidneys) transplants, because of adverse effects risk (systemic complications, sepsis, neoplasms). Without an IS, the immune cascade will cause vascular endothelial cell lysis, compromise microcirculation with necrosis of the graft. The last studies, describe the surgical neoangiogenesis typical of the host in VCA with a short-term IS - 14 days, as an effective one, with results that allow consolidation and mechanical stability. Studies are performed preclinically on rats, rabbits and pigs. Other studies present decelularization methods of the vassel while preserving vascular stiffness. Conclusions. A perfect alternative in treatment of the massive bone defects is using a vascular allograft, without associated immunosuppression.