RESUMO
PURPOSE: To investigate the causes of structural degradation in Ti-6A1-4V alloy. MATERIALS AND METHODS: We prepared 20 metal specimens by cutting the fringe of 4 screw holes of tibial components taken from 5 cases of MG TKS(unused: 1, 3 years used: 2, 6 years used: 2). The structure and composition of specimens were analyzed by Scanning electron microscope(SEM), Energy dispersive spectrometer(EDS), and hardness tester. RESULTS: In soft tissue, titanium contained giant cells were observed by H-E stain, and Ti and Va peaks were detected by EDS. SEM showed that the unused specimens had normal metal fiber mesh texture, and the texture began to disappear from the surface of specimens after 3 years later. There were no metal fiber mesh, but black deposits were detected in specimens of 6 years. EDS revealed that Ti, Va, and Al peaks were appeared in the unused specimens, whereas 0 and C peaks in specimens of 3 years a#od 0, C, P, S, Ca and Cl peaks in specimens of 6 years were obtained. The hardness was decreased with the used period. CONCLUSION: It seemed that various molecular components of human body including carbon, hydrogen and oxygen influenced the metal elements of alloy to degrade in their structure.