title: Uneven damage on head and liner contact surfaces of a retrieved Co-Cr-based metal-on-metal hip joint bearing: An important reason for the high failure rate.
abstract: Detailed metallurgical investigations have been performed on a used Co-Cr-based metal-on-metal (MoM) hip joint bearing containing a type of liner that is commonly used in such joints. The damage on the metal-liner sliding surface was considerably more severe than that on the metal head counterpart, in terms of wear-scar density and width and microcrack frequency. Cross-sectional transmission electron microscopy revealed that a thick (>3 μm) nanocrystalline layer formed on the sliding surface of the head, whereas the liner had coarse carbides embedded in it and nanocrystals were formed in a very limited region no deeper than 1 μm. Comparative investigation of an unused head and a liner of identical type showed that although the chemical compositions of the liner and head were nearly identical, their microstructures were significantly different. Specifically, the grain size in the liner was larger than that in the head on average, and the grain boundaries of the liner were decorated with coarse carbides. Moreover, X-ray diffraction analysis revealed a large tensile residual stress only in the liner. These differences are possibly responsible for the wear damage on the liner being more serious than that on the head.
authors.affiliation: Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan. Electronic address: koizumi@imr.tohoku.ac.jp.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Koizumi
authors.affiliation: Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan.
authors.forename: Yan
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan.
authors.forename: Yunping
authors.initials: Y
authors.lastname: Li
authors.affiliation: Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Yamanaka
authors.affiliation: Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Chiba
authors.affiliation: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan.
authors.forename: Shun-Ichiro
authors.initials: S
authors.lastname: Tanaka
authors.affiliation: Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Hagiwara
mesh_terms: D019644:Arthroplasty, Replacement, Hip; D019645:Arthroplasty, Replacement, Knee; D002857:Chromium / Q000737:chemistry*; D002858:Chromium Alloys / Q000737:chemistry; D003035:Cobalt / Q000737:chemistry*; D006801:Humans; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry; D056951:Photoelectron Spectroscopy; D013499:Surface Properties; D013718:Tensile Strength; D014961:X-Ray Diffraction
chemical_list: D002858:Chromium Alloys; D002857:Chromium; D003035:Cobalt
keywords: Chemical composition; Co–Cr alloy; Hip prosthesis; Surface analysis