title: Taper junction failure in large-diameter metal-on-metal bearings.
abstract: OBJECTIVE
  An ongoing prospective study to investigate failing metal-on-metal hip prostheses was commenced at our centre in 2008. We report on the results of the analysis of the first consecutive 126 failed mated total hip prostheses from a single manufacturer.
  
  
  METHODS
  Analysis was carried out using highly accurate coordinate measuring to calculate volumetric and linear rates of the articular bearing surfaces and also the surfaces of the taper junctions. The relationship between taper wear rates and a number of variables, including bearing diameter and orientation of the acetabular component, was investigated.
  
  
  RESULTS
  The measured rates of wear and distribution of material loss from the taper surfaces appeared to show that the primary factor leading to taper failure is the increased lever arm acting on this junction in contemporary large-diameter metal-on-metal hip replacements.
  
  
  CONCLUSIONS
  Our analysis suggests that varus stems, laterally engaging taper systems and larger head diameters all contribute to taper failure.
authors.affiliation: University Hospital of North Tees, Hardwick Road, Stockton TS19 8PE, UK.
authors.forename: D J
authors.initials: DJ
authors.lastname: Langton
authors.forename: R
authors.initials: R
authors.lastname: Sidaginamale
authors.forename: J K
authors.initials: JK
authors.lastname: Lord
authors.forename: A V F
authors.initials: AV
authors.lastname: Nargol
authors.forename: T J
authors.initials: TJ
authors.lastname: Joyce
keywords: Adverse reaction to metal debris; Arthroplasty; Hip; Large diameter; Metal-on-metal; Taper