Friction properties at the bone-metal interface: Comparison of four different porous metal surfaces

Abstract

Detailed friction load-displacement response of four distinct metallic surfaces [one beaded porous metal (CTR) and three cast Co-Cr alloy ingrowth mesh surfaces, nonplanar mesh (INX), cast mesh 1 (CM1), and cast mesh 2 (CM2)] on poly-urethane and cancellous bone specimens of six tibiae were measured under different normal stresses (0.1, 0.15, or 0.025 MPa). Bone cubes were obtained from different proximal regions of resurfaced 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 the magnitude of normal stress and the bone excision site (medial, lateral, anterior, posterior, and central). The CM2 surface showed significantly greater resistance with friction coefficients of more than 0.9 for the bone and 0.8 for the polyurethane. The INX surface yielded the second largest resistance followed by CM1 and CTR surfaces. NO significant difference was found between these latter two surfaces. Fatigue tests of up to 4000 loading-unloading cycles showed about 10% reduction in friction coefficient for CTR and INX surfaces, while negligible reduction was found for CM1 and CM2 surfaces.

Friction coefficient and effective interference at the implant-bone interface

“…Friction coefficients between implant surfaces and trabecular bone have been determined in a number of studies, with tangential motion applied uni-or biaxially to the interface, and with a constant normal force (Biemond et al, 2011;Dammak et al, 1997a;Grant et al, 2007;Hashemi et al, 1996;Shirazi-Adl et al, 1993;Zhang et al, 1999). The interface pressures applied in these studies (0.1-1.0 MPa) were mostly lower than the peak magnitudes achieved in the current study (5.6-11.7 MPa) and lie within the range of strengths published for trabecular bone (Goldstein, 1987).…”

“…Friction coefficients have been reported for various constant interface pressure magnitudes and also in biaxial tangential force directions (Biemond et al, 2011;Dammak et al, 1997a;Grant et al, 2007;Hashemi et al, 1996;Shirazi-Adl et al, 1993;Zhang et al, 1999). They have been used to model press-fit implant behaviour to assess relative motion at the bone interface and stress distributions in the bone (Abdul-Kadir et al, 2008;Ramamurti et al, 1997).…”

On the optimal shape of hip implants

“…In the computational model, the distinction between porous coating surface and polished surface is done using different friction coefficients. The friction between porous coating and bone is assumed high with a value for the friction coefficient of 0.6 (Dammak et al, 1997). For uncoated surfaces the friction is much lower.…”

Shape Optimization of a Cementless Hip Stem for a Minimum of Interface Stress and Displacement

“…It was assumed contact without friction where the stem is uncoated and contact with friction for coated surfaces. The value for the friction coefficient is 0.6, suggested by Dammak et al [3]. When multiple loads were used, it was assumed equal weight for each load case, i.e.…”

“…The importance of the initial stem stability has been referred in recent research works. For instance, for Dammak et al [3], the initial stability of a porous cementless stem depends on friction properties, and it is essential to promote bone ingrowth and long-term fixation. Bernakiewicz et al [4] relates the stability with parameters such as the stem shape, surgery techniques and biological response to metallic implants.…”