title: The influence of clearance on friction, lubrication and squeaking in large diameter metal-on-metal hip replacements.
abstract: Large diameter metal-on-metal bearings (MOM) are becoming increasingly popular, addressing the needs of young and more active patients. Clinical data has shown excellent short-to-mid-term results, though incidences of transient squeaking have been noted between implantation and up to 2 years post-operative. Geometric design features, such as clearance, have been significant in influencing the performance of the bearings. Sets of MOM bearings with different clearances were investigated in this study using a hip friction simulator to examine the influence of clearance on friction, lubrication and squeaking. The friction factor was found to be highest in the largest clearance bearings under all test conditions. The incidence of squeaking was also highest in the large clearance bearings, with all bearings in this group squeaking throughout the study. A very low incidence of squeaking was observed in the other two clearance groups. The measured lubricating film was found to be lowest in the large clearance bearings. This study suggests that increasing the bearing clearance results in reduced lubricant film thickness, increased friction and an increased incidence of squeaking.
authors.affiliation: Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds LS2 9JT, UK. C.L.brockett@leeds.ac.uk
authors.forename: Claire L
authors.initials: CL
authors.lastname: Brockett
authors.forename: Phil
authors.initials: P
authors.lastname: Harper
authors.forename: Sophie
authors.initials: S
authors.lastname: Williams
authors.forename: Graham H
authors.initials: GH
authors.lastname: Isaac
authors.forename: Rob S
authors.initials: RS
authors.lastname: Dwyer-Joyce
authors.forename: Zhongmin
authors.initials: Z
authors.lastname: Jin
authors.forename: John
authors.initials: J
authors.lastname: Fisher
mesh_terms: D019644:Arthroplasty, Replacement, Hip; D001672:Biocompatible Materials / Q000737:chemistry; D004867:Equipment Design; D019544:Equipment Failure Analysis; D017276:Friction; D006621:Hip Joint; D006622:Hip Prosthesis; D006801:Humans; D008153:Lubrication; D008422:Materials Testing; D008670:Metals / Q000737:chemistry*; D011474:Prosthesis Design; D012212:Rheology; D013499:Surface Properties; D013997:Time Factors
chemical_list: D001672:Biocompatible Materials; D008670:Metals