Effect of Hydroxyapatite Coated Implant on Long Bone

• Main Authors: Kwo-Fong Lu, 呂國峰
• Other Authors: Guan-Liang Chang
• Format: Others
• Language: zh-TW
• Published: 1993
• Online Access: http://ndltd.ncl.edu.tw/handle/25559937954672473036

碩士 === 國立成功大學 === 醫學工程學系 === 81 === In this study, we adopted hydroxyapatite(HA) to provide fixation of implant and bone, that HA have advantage in offering reproducible skeletal attachment in total joint replacement by bone ingrowth and bone ongrowth. The purposes are to analyze the effect of HA-coated implant on strain distribution of long bone and to compare interfacial shear strength of different HA coating thickness. A plasma-sprayed HA coatings (about 50 micro,50μ) was applied to the Ti-6Al-4V and Co-Cr-Mo rods, and were implanted intramedullarly in the distal femur of mongrel dog. The implants were harvested after twelve weeks and prepared to evaluate distribution of strain and shear strength. Another test was to investigate the biological reaction and shear strength of the long bone with intramedullary nail of without or with different HA coatings at twelve and twenty-four weeks. As bone ongrowth on implant surface after 12 weeks, femoral bending rigidity increases, the mechanical axis strain reduces, and the top of rod increase especially for Co-Cr-Mo stem. Shear strength and shear stiffness indicated by push-out test that Co-Cr-Mo stem have well-fixed rigidity than Ti-6Al-4V. According to this phenomenon, there would sereously have stress shielding with time on Co-Cr-Mo stem than Ti-6Al-4V. Histologically, after period of 12 and 24 weeks implantation, there are no extensive direct apposition or lining of the ongrowth to the uncoated Ti-6 Al-4V surface, but the HA coating support mineralization directly onto its surface. The HA/bone interface osteointegration increase with time for HA coating, and the bone ongrowth of 200μ HA coating have well apposition than that of 50μ. Direct comparison of shear strength values reveal that the 200μ have good strength than 50μ at 12 weeks postimplantation. The specimen of 200μ significantly failure at HA/implant interface by push-out test.