FRICTION PROPERTIES AT THE BONE-METAL INTERFACE - COMPARISON OF 4 DIFFERENT POROUS METAL-SURFACES

Detailed friction load-displacement response of four distinct metallic surfaces [one beaded porous metal (CTR) and three cast Co-Cr alloy in growth mesh surfaces, nonplanar mesh (INX), cast mesh 1 (CM1), and cas t mesh 2 (CM2)] on polyurethane and cancellous bone specimens of six t ibiae were measured under different normal stresses (0.1, 0.15, or 0.0 25 MPa). Bone cubes were obtained from different proximal regions of r esurfaced cadaveric tibiae. Both monotonic and cyclic fatigue loadings of up to 4000 cycles at 1 Hz were considered. Comparison of measured results indicated that the friction coefficient was not affected by th e magnitude of normal stress and the bone excision site (medial, later al, anterior, posterior, and central). The CM2 surface showed signific antly greater resistance with friction coefficients of more than 0.9 f or the bone and 0.8 for the polyurethane. The INX surface yielded the second largest resistance followed by CM1 and CTR surfaces. No signifi cant difference was found between these latter two surfaces. Fatigue t ests of up to 4000 loading-unloading cycles showed about 10% reduction in friction coefficient for CTR and INX surfaces, while negligible re duction was found for CM1 and CM2 surfaces. (C) 1997 John Wiley & Sons , Inc.