title: Contact mechanics of modular metal-on-polyethylene total hip replacement under adverse edge loading conditions.
abstract: Edge loading can negatively impact the biomechanics and long-term performance of hip replacements. Although edge loading has been widely investigated for hard-on-hard articulations, limited work has been conducted for hard-on-soft combinations. The aim of the present study was to investigate edge loading and its effect on the contact mechanics of a modular metal-on-polyethylene (MoP) total hip replacement (THR). A three-dimensional finite element model was developed based on a modular MoP bearing. Different cup inclination angles and head lateral microseparation were modelled and their effect on the contact mechanics of the modular MoP hip replacement were examined. The results showed that lateral microseparation caused loading of the head on the rim of the cup, which produced substantial increases in the maximum von Mises stress in the polyethylene liner and the maximum contact pressure on both the articulating surface and backside surface of the liner. Plastic deformation of the liner was observed under both standard conditions and microseparation conditions, however, the maximum equivalent plastic strain in the liner under microseparation conditions of 2000 µm was predicted to be approximately six times that under standard conditions. The study has indicated that correct positioning the components to avoid edge loading is likely to be important clinically even for hard-on-soft bearings for THR.
authors.affiliation: Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK. Electronic address: xijinhua@outlook.com.
authors.forename: Xijin
authors.initials: X
authors.lastname: Hua
authors.affiliation: Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK.
authors.forename: Junyan
authors.initials: J
authors.lastname: Li
authors.affiliation: State Key Laboratory for Manufacturing System Engineering, Xi'an Jiaotong University, Xi'an, Shanxi, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Wang
authors.affiliation: Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK; State Key Laboratory for Manufacturing System Engineering, Xi'an Jiaotong University, Xi'an, Shanxi, China.
authors.forename: Zhongmin
authors.initials: Z
authors.lastname: Jin
authors.affiliation: Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK.
authors.forename: Ruth
authors.initials: R
authors.lastname: Wilcox
authors.affiliation: Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK.
authors.forename: John
authors.initials: J
authors.lastname: Fisher
mesh_terms: D019644:Arthroplasty, Replacement, Hip; D020342:Finite Element Analysis; D008422:Materials Testing; D055595:Mechanical Phenomena; D008670:Metals; D020959:Polyethylene; D011474:Prosthesis Design; D012399:Rotation; D013499:Surface Properties; D016474:Weight-Bearing
chemical_list: D008670:Metals; D020959:Polyethylene
keywords: Contact mechanics; Edge loading; Metal-on-polyethylene; Microseparation; Total hip replacement