Osteoinduction and Osteoconduction with Porous Beta-Tricalcium Phosphate Implanted after Fibular Resection in Humans

Abstract

Osteoinductive properties of β-TCP remain unknown in humans. It is important to improve the bone grafts which have been the standard treatment for bone defect due to their biocompatibility and bone-healing properties. The purpose of this study was to radiologically clarify the bone forming property of β-TCP by evaluating the replacement of β-TCP by newly formed bone in the defect after fibular resection and to examine the histological features of a β-TCP specimen three months after grafting. Radiographs of 17 patients who underwent β-TCP grafting were evaluated. Osteoinductive and osteoconductive properties were assessed by examining bone formation from the remnant fibula, periosteum, and β-TCP alone. In one case, β-TCP was removed later because of postoperative complications and was evaluated histologically. Twenty two of 34 sites between the remnant fibula and β-TCP had achieved good bone regeneration. Five of 14 sites between the periosteum and β-TCP had achieved good bone regeneration. We found immature but evident bone formation in three cases with no osseous and periosteal sites. Histological analysis revealed bone formation on the outer macropore surface of β-TCP. Some blood vessels formed in the macropores expressed CD31 and CD34, while a few lymphatic vessels expressed CD34 and podoplanin. Thus, the osteoinductive ability of β-TCP alone was demonstrated in humans radiographically for the first time. The histological morphology of β-TCP was demonstrated at an early stage after grafting in humans.