Calf Serum Type Affects Protein Degradation, Bacterial Growth and Polyethylene Wear in Knee Simultor Testing

IN KNEE SIMULTOR TESTING Brandt, J.-M.; Charron, K.D.; Zhao, L.; MacDonald, S.J.; Koval, S., Medley, J.B. Department of Mechanical Engineering, University of Waterloo, ON, Canada, e-mail: [email protected] Department of Orthopaedic Surgery, University of Western Ontario, ON, Canada Department of Biochemistry, University of Western Ontario, ON, Canada Department of Microbiology and Immunology, University of Western Ontario, ON, Canada Introduction The generation of inflammatory polyethylene (PE) wear-particles in modular total knee replacements (MTKR) can lead to osteolysis and eventual implant failure. Thus, there is a great interest in evaluating MTKR in-vitro, gaining some indication on the possible clinical performance. Thus, guidelines for displacement-controlled wear simulator testing have been standardized [1]. However, the according standard recommends the use “calf serum”, without giving ranges on the specific protein constituents, such as albumin and different types of globulin. There has been significant attempt on identifying influential protein related-factors on PE wear of total hip joints [2, 3], but not for MTKR. In addition, antimicrobial agent such as sodium azide (SA) may also be added [1], but has shown to be ineffective in pin-on-disc wear testing [4]. In this study, three types of frequently used calf serum with various protein constituents were used. We attempted to identify protein compounds that perhaps serve as effective boundary lubricants and may affect PE wear rates and evaluated the effectiveness of SA.