Microgrooved Surface Topography Does Not Influence Fretting Corrosion of Tapers in Total Hip Arthroplasty: Classification and Retrieval Analysis

摘要

Surface topography has been suggested as a factor in fretting corrosion. The purpose of this study was to develop a method to characterize a broad range of machined smooth stems and intentionally microgrooved stems. As part of a multicenter, institutional review board-approved retrieval program, 398 stems paired with cobalt-chromium (CoCr; ASTM F75 or ASTM F90) alloy heads were collected. Stems were fabricated from CoCr or titanium-6aluminum-4vanadium (Ti-6Al-4V) alloys and were used in a metal-on-polyethylene bearing total hip device. A roundness machine (Talyrond 585, Taylor Hobson, United Kingdom) was used to quantify surface topography. Linear profiles were measured with a diamond-tip stylus capturing a 10-mm line trace. Commercial software (Ultra, Taylor Hobson, United Kingdom) was used to analyze a 1-mm representative as-manufactured region. Three parameters were calculated from the profiles: average surface roughness, amplitude, and wavelength of microgrooves (if any). Surface observations led to a classification system in which a surface had to contain a periodic pattern, a wavelength ＞100μm and an amplitude of ＞4μm to be considered microgrooved. Fifty percent (199/398) of the femoral stem taper surfaces were classified as smooth tapered stems. The remaining 50 % (199/398) femoral stem taper surfaces were classified as microgrooved tapered stems. Using multivariate analysis of covariance, implantation time (p＜ 0.0001), apparent engagement length (p＜ 0.0001), flexural rigidity (p = 0.009), and head size (p = 0.02) were significant factors in fretting corrosion head damage scores. Surface topography (i.e., smooth or microgrooved, p = 0.86), surface wavelength (p = 0.94), surface amplitude (p = 0.49), and head offset (p = 0.028) were not associated with the femoral head fretting corrosion damage score. Overall, the results of this study do not support trunnion surface morphology as a contributing factor to fretting and corrosion damage at the modular head-neck interface.