title: The clinical implications of metal debris release from the taper junctions and bearing surfaces of metal-on-metal hip arthroplasty: joint fluid and blood metal ion concentrations.
abstract: OBJECTIVE
  We wished to investigate the influence of metal debris exposure on the subsequent immune response and resulting soft-tissue injury following metal-on-metal (MoM) hip arthroplasty. Some reports have suggested that debris generated from the head-neck taper junction is more destructive than equivalent doses from metal bearing surfaces.
  
  
  METHODS
  We investigated the influence of the source and volume of metal debris on chromium (Cr) and cobalt (Co) concentrations in corresponding blood and hip synovial fluid samples and the observed agglomerated particle sizes in excised tissues using multiple regression analysis of prospectively collected data. A total of 199 explanted MoM hips (177 patients; 132 hips female) were analysed to determine rates of volumetric wear at the bearing surfaces and taper junctions.
  
  
  RESULTS
  The statistical modelling suggested that a greater source contribution of metal debris from the taper junction was associated with smaller aggregated particle sizes in the local tissues and a relative reduction of Cr ion concentrations in the corresponding synovial fluid and blood samples. Metal debris generated from taper junctions appears to be of a different morphology, composition and therefore, potentially, immunogenicity to that generated from bearing surfaces.
  
  
  CONCLUSIONS
  The differences in debris arising from the taper and the articulating surfaces may provide some understanding of the increased incidence of soft-tissue reactions reported in patients implanted with MoM total hip arthroplasties compared with patients with hip resurfacings. Cite this article: Bone Joint J 2016;98-B:925-33.
authors.affiliation: Newcastle University, Stephenson Building, NE1 7RU, UK.
authors.forename: R P
authors.initials: RP
authors.lastname: Sidaginamale
authors.affiliation: Newcastle University, Stephenson Building, NE1 7RU, UK.
authors.forename: T J
authors.initials: TJ
authors.lastname: Joyce
authors.affiliation: Food and Drugs Administration, 0903 New Hampshire Avenue, Silver Spring, Maryland 20993-0002, USA.
authors.forename: J G
authors.initials: JG
authors.lastname: Bowsher
authors.affiliation: Virginia Tech, Blacksburg, VA 24061, USA.
authors.forename: J K
authors.initials: JK
authors.lastname: Lord
authors.affiliation: Newcastle University, Stephenson Building, NE1 7RU, UK.
authors.forename: P J
authors.initials: PJ
authors.lastname: Avery
authors.affiliation: University Hospital of North Tees, TS19 8PE, UK.
authors.forename: S
authors.initials: S
authors.lastname: Natu
authors.affiliation: University Hospital of North Tees, Farndale House, TS19 8PE, UK.
authors.forename: A V F
authors.initials: AV
authors.lastname: Nargol
authors.affiliation: Freeman Hospital, NE7 7DN, UK.
authors.forename: D J
authors.initials: DJ
authors.lastname: Langton
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip; D002857:Chromium / Q000032:analysis*; D003035:Cobalt / Q000032:analysis*; D005260:Female; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D061825:Metal-on-Metal Joint Prostheses; D008875:Middle Aged; D010316:Particle Size; D011446:Prospective Studies; D011474:Prosthesis Design; D013582:Synovial Fluid / Q000737:chemistry*; D055815:Young Adult
chemical_list: D002857:Chromium; D003035:Cobalt
keywords: ARMD; Arthroplasty; Explant analysis; Hip; Metal-on-metal; Taper