Hydroxyapatite-coated titanium fiber metal implant for spine fusion

Research Project

Project/Area Number	04670893
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	Orthopaedic surgery
Research Institution	Kochi Medical School
Principal Investigator	YAMAMOTO Hiroshi Kochi Medical School, Professor, 医学部, 教授 (90035709)
Co-Investigator(Kenkyū-buntansha)	HOSHIJIMA Kazuo Kochi Medical School, Assistant, 医学部, 助手 (40243836) KAMIOKA Yoshihiko Kochi Medical School, Instructor, 医学部, 講師 (60185981) 谷俊一高知医科大学, 医学部・整形外科学, 助教授 (90136250)
Project Period (FY)	1992 – 1993
Project Status	Completed (Fiscal Year 1993)
Budget Amount *help	¥1,500,000 (Direct Cost: ¥1,500,000) Fiscal Year 1993: ¥800,000 (Direct Cost: ¥800,000) Fiscal Year 1992: ¥700,000 (Direct Cost: ¥700,000)
Keywords	hydroxyapatite / titanium fiber metal / biomaterial / spine fusion / animal study / bone ingrowth / mechanical characteristics / 機械的特性 / ハイドロキシアパタイト / チタン線繊金属
Research Abstract	For uses the titanium fiber metal implant (TFMI) as spine fusion material, we have researched in details of mechanical characteristics and implant attitude to bone ingrowth. We found several findings about material compression test. The manufacturing method of TFMI was improved with loading "pre-load" after sintering the implant. Amount of pre-load was about 12 MPa, and after pre-loading, the failure load of TFMI was similar to the amount of pre-load. There was little decrease of implant porosity and the elastic modulus were not so compromised with the pre-loading. To add "pre-load, " we found the way to control the stable and long-standing mechanical characters of the TFMI. In the other research program, plasma spray hydroxyapatite (HAp) coated TFMI was evaluated pore size and bone ingrowth with implantation to adult mongrel dogs. We compared the effect of three different thicknesses of coatings, 20mum, 50mum, and 100mum. The mean pore sizes were decreased in 50mum coating. In 100mum coating, however, the small Pores on the TFMI surface were obstructed and mean pore sizes were same as of non-coated implants. Up to 20 weeks of implantation to iliac crest to the dogs, HAp-coated implant was shown preferable bone apposition and bone ingrowth. In the other hand, implantation to lumbar interbody fusion of 50mum coated implants were failed to show no union to the vertebrae. The possible cause of failure was supposed there was narrowing of optimal Pore size with HAp coating and micromotion between the implant and bone, which were combined to interfere bone ingrowth into the implant.