Fixation failure with musculo-skeletal system rises with fluctuations of stress-strain relation at the implant/tissue interface. Varied materials' responses differ in keeping their bearing capabilities. Micro-motion at the fixed interface is unavoidable, relative friction causes mobility between adhesive components and gradual increase of plastic strain, and eventually brings about macro-scale dislocation between implant and surrounding tissues. Using micro-motion tester simulates the occurrence of implant displacement at the inserted interface. The range of micro-motion was assigned as ±40 μ m per cycle with constant speed of 0.0014 mm/s, moving forward for 10,000 cycles each, and under a bearing load of 100 N. Experimental result demonstrated that boundary friction caused micro-imbalance and thus reduced contact area; a localized edge effect was occurred. Further SEM observations and roughness tests provided that the fretting wear debris was generated in sequence: 316L stainless steel, Ti-based metal and Co-based metal. Along partial edge of Ti-base pin, small amount of PMMA particles were adhered. The roughness tests were corresponded to friction-to-wear mechanics: on both X and Y-axis among the post-tested bone cement did not differ obviously (p>0.05); however, the roughness of the surfaces was increased in sequence: Ti-based metal, Co-based mutal and 316L stainless steel. It is thus not excluded that the inserted stem lost mechanical interlocks with bone cement; a gradual slip at the interface would decrease their adherence. The released species might facilitate and accelerate their detachment and diminish the elastic range and create loosening or shrinking effect to the inserted stem.
|Number of pages||8|
|Journal||Journal of Medical and Biological Engineering|
|Publication status||Published - 2001 Dec 1|
All Science Journal Classification (ASJC) codes
- Biomedical Engineering