title: Surface and Subsurface Analyses of Metal-on-Polyethylene Total Hip Replacement Retrievals.
abstract: Metal-on-polyethylene (MoP) articulations are one of the most reliable implanted hip prostheses. Unfortunately, long-term failure remains an obstacle to the service life. There is a lack of higher resolution research investigating the metallic surface component of MoP hip implants. This study investigates the surface and subsurface features of metallic cobalt chromium molybdenum alloy (CoCrMo) femoral head components from failed MoP retrievals. Unused prostheses were used for comparison to differentiate between wear-induced defects and imperfections incurred during implant manufacturing. The predominant scratch morphology observed on the non-implanted references was shallow and linear, whereas the scratches on the retrievals consisted of largely nonlinear, irregular scratches of varying depth (up to 150 nm in retrievals and up to 60 nm in reference samples). Characteristic hard phases were observed on the surface and subsurface material of the cast samples. Across all samples, a 100-400 nm thick nanocrystalline layer was visible in the immediate subsurface microstructure. Although observation of the nanocrystalline layer has been reported in metal-on-metal articulations, its presence in MoP retrievals and unimplanted prostheses has not been extensively examined. The results suggest that manufacturing-induced surface and subsurface microstructural features are present in MoP hip prostheses prior to implantation and naturally, these imperfections may influence the in vivo wear processes after implantation.
authors.affiliation: Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada.
authors.forename: Vicky
authors.initials: V
authors.lastname: Vuong
authors.affiliation: Division of Applied Materials Science, Department of Engineering Sciences, Uppsala University, Uppsala, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Pettersson
authors.affiliation: Division of Applied Materials Science, Department of Engineering Sciences, Uppsala University, Uppsala, Sweden.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Persson
authors.affiliation: Department of Surgical Sciences-Orthopaedics, Uppsala University Hospital, Uppsala, Sweden.
authors.forename: Sune
authors.initials: S
authors.lastname: Larsson
authors.affiliation: Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada. kgrandfield@mcmaster.ca.
authors.forename: Kathryn
authors.initials: K
authors.lastname: Grandfield
authors.affiliation: Division of Applied Materials Science, Department of Engineering Sciences, Uppsala University, Uppsala, Sweden.
authors.forename: Håkan
authors.initials: H
authors.lastname: Engqvist
mesh_terms: D000497:Alloys; D019644:Arthroplasty, Replacement, Hip; D002857:Chromium; D003035:Cobalt; D005260:Female; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008982:Molybdenum; D020959:Polyethylene; D011475:Prosthesis Failure; D013499:Surface Properties
chemical_list: D000497:Alloys; D002857:Chromium; D003035:Cobalt; D008982:Molybdenum; D020959:Polyethylene
keywords: Biotribology; Cobalt chromium; Electron microscopy; Hip implant retrievals; Metal-on-polymer; Transmission electron microscopy