Process of osteointegration of heat-treated bone graft

1998 Fiscal Year Final Research Report Summary

• Project/Area Number: 08671651
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Orthopaedic surgery
• Research Institution: Aichi Medical University (1997-1998); Nagoya University (1996)
• Principal Investigator: SATO Keiji Aichi Medical University, Professor, 医学部, 教授 (20178726)
• Co-Investigator(Kenkyū-buntansha): 片桐 浩久 名古屋大学, 医学部, 医員 ; 伊藤 隆安 名古屋大学, 医学部, 医員
• Project Period (FY): 1996 – 1998
• Keywords: MRI / compression strength / Remodelling of bone / Osteointergration / Heat-treated bone

Research Abstract

In vivo experiment: Periodical maging modalities such as MRI and Radiogram could not reveal any differences in osteointegrating process between 70℃-treated bone graft and fresh bone graft, especially bone union and marrow changes. Histology disclosed that degree of vascular invasion and osteoblast invasion were less obvious in heat-treated bone graft, Sample of fresh bone graft obviously decreased in its mineral content than that of heat-treated bone graft with significant difference since 2 months after grafting. Compression strength of the sample of fresh bone graft gradually decreased after grafting and reached bottom around 6 month, and recovered to normal strength until 1 year after grafting. On the other hand, that of heat-treated bone had kept its strength until 1 year after grafting and then reached lowest level around 1 year and half. After that point, strength of heat-treated bone recovered until 2 years, This means remodeling of the heat-treated bone is more slow than that o f fresh bone graft, In vitro experiment: Quantification of type 1 collagen and osteocalcin in culture medium at 3, 5 and 7th day of culture, produced by osteoblast like cells cultured on the pulverized bone powder of 70℃-treated bone, 120℃-treated bone and fresh bone were done. Quantity of type 1 collagen and osteocalcin produced by cells cultured on l20℃treated bone were markedly increased than that of cells on 70℃-treated bone and fresh bone (osteocalcin p<0.0001, type 1 collagen p<0.0002) with significant differences. Osteocalcin level produced by cells cultured on the l20℃-treated bone decreased gradually. On the other hand, type 1 collagen level increased This means osteoblast, like cells cultured on unfamiliar atmosphere such as l20℃-treated bone were forced to be differentiated and high level of osteocalcin and type 1 collagen should be produced. However, 70℃-treated bone and fresh bone provided natural condition to osteoblast-like cells and these cells could grow with low level of production of osteocalcin and type 1 collagen.