Blood Supply of Vascularized Bone Graft Contributes to Superior Survival of Bone Cells

Vascularized bone graft (VBG) is a form of vascularized bone marrow transplant in which the bone marrow is surgically grafted with its microenvironment intact. Due to the preservation of cellular viability, VBG have significant advantages over non-vascularized bone grafts. Free vascularized fibula grafts have superior material properties and tolerate infection. Bone healing can be accomplished in a shorter period, even in an irradiated bed. In addition to these properties, VBG has other biological advantages that are not always familiar to oncological surgeons. Hypertrophic change can be divided into reactive and adaptive hypertrophy. Early hypertrophy is associated with donor-derived cells, whereas later remodeling is associated with recipient-derived cells. VBG has significant advantages in enhancing neo-revascularization of necrotic bone. We reviewed VBG from a novel viewpoint that stems from our basic research. Reconstruction of massive skeletal deficiencies following tumor resection remains a challenging problem for musculoskeletal oncologists. Recent advances in vascularized bone grafts (VBG) have dramatically expanded the possibilities for reconstruction of massive extremity bone defects. For long-bone defects, the most appropriate donor source of VBG is undoubtedly the fibula. In 1973, the first free vascularized fibula graft (FVFG) was carried out for a patient with cancer by Ueba and Fujikawa (1). These workers used FVFG to correct a deficiency comprising one-third of the ulna in an 11-year-old boy following resection of a neurofibroma. Subsequently in 1975, Taylor et al. reported the first two cases of reconstruction for trauma cases (2). Several articles have reviewed the advantages of VBG for oncological reconstruction (3-5). A long-bone defect of between 6 to 10 cm is generally considered justification for a FVFG by surgeons (6). Due to preservation of cellular viability, VBGs have significant advantages over nonvascularized bone grafts. Moreover, FVFGs have superior material properties, including strength, toughness and elasticity that is twoto four-times greater than nonvascularized fibula grafts (7). Bone healing can be accomplished in a shorter period, even in a difficult environment such as a scarred or irradiated bed. FVFG can tolerate infection and also has the potential for longitudinal growth in children (3). In addition to these properties, VBG has other biological advantages that are not always familiar to oncological surgeons. In the present review, we consider VBG from a novel viewpoint that stems from our basic research. Blood Supply of Vascularized Bone Graft Contributes to Superior Survival of Bone Cells The major biological advantage of VBG is maintenance of a blood supply to the bone through anastomosis of the vascular pedicle. The fibula receives two sources of blood via the periosteal and nutrient vessels (5, 8). The predominant blood supply is from a nutrient artery which enters the medullary canal from the posterior surface just proximal to the midshaft to anastomose with the endosteal artery. The endosteal vascular system supplies the vast majority of bone tissue. The periosteum receives its blood supply by way of adjacent muscle, although this source appears to provide only a minority of the total bone nutrition (9-11). However, using a canine vascularized rib graft model, Berggren et al. concluded that a bone transplant with re-vascularization of only the periosteal vessels could still supply enough vascularity to the entire bone (12, 13). 2701 This article is freely accessible online. Correspondence to: Keiichi Muramatsu, MD, Department of Orthopedic Surgery, Yamaguchi University School of Medicine, 11-1 Minami-Kogushi, Ube, Yamaguchi 755-8505, Japan. Tel: +81 836222268, Fax: +81 836222267, e-mail: [email protected]