Effect of Lubricant Composition on the Fatique Properties of Ultra High Molecular Weight Polyethylene (UHMWPE) for Knee Simulator Testing- Investigating Team: Department of Bioengineering, Clemson University Clemson University
Abstract: Fatigue failure of ultra high molecular weight polyethylene (UHMWPE) has been cited as the prevalent surface failure mechanism. Hence, it becomes imperative to simulate in-vivo conditions in in-vitro simulations. In this study. the hypothesis that the physiological environment influences the fatigue properties of the polymer was explored. The present study examined the effect of adding hyaluronic acid in varying clinical concentrations on the fatigue crack growth response of UHMWPE. A fracture mechanics approach was adopted to relate the fatigue properties of the polymer determined using the ASTM E 647, to the physiological environment. The fractured surfaces were characterized using scanning electron microscopy to evaluate the effect of lubricant viscosity on the fatigue failure mechanisms. The serum protein adsorption on the surface of the specimens was studied by Fourier Transform Infrared Spectroscopy. Rheological analysis indicated that the viscosity of the lubricants with the three concentrations of hyaluronic acid -2.22 g/l, 0.55 g/l and 1.5 g/l were representative of those found. Respectively HA was found to significantly affect lubricant viscosity and wettability. These are environmental factors, which are theorized to directly affect the fatigue properties of the polymer, and can be directly related to the clinical environment as well. Results showed that the presence of HA in the bovine serum not only affects the crack initiation of the polymer, but also causes a significant shift of the linear crack growth regime compared to 50% bovine serum alone (t-test, a = 0.05). Key words: fatigue, FTIR, Hyaluronic acid, UHMWPE from Clemson University to Hyalogic specifically asking to use Synthovial Seven® because of the high molecular weight of our product.
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