title: Factors Associated With Trunnionosis in the Metal-on-Metal Pinnacle Hip.
abstract: Trunnionosis of the tapered head-stem junction of total hip arthroplasties, either through corrosion or mechanical wear, has been implicated in early implant failure. Retrieval analysis of large numbers of failed implants can help us better understand the factors that influence damage at this interface.
  
  
  
  In this study, we examined 120 retrieved total hip arthroplasties of one bearing design, the 36-mm diameter metal-on-metal, DePuy Pinnacle, that had been paired with 3 different stems. We measured material loss of the bearing and head-trunnion taper surfaces and collected clinical and component data for each case. We then used multiple linear regression analysis to determine which factors influenced the rate of taper material loss.
  
  
  
  We found 4 significant variables: (1) longer time to revision (P = .004), (2) the use of a 12/14 taper for the head-trunnion junction (P < .001), (3) decreased bearing surface wear (P = .003), and (4) vertical femoral offset (P = .05). These together explained 29% of the variability in taper material loss.
  
  
  
  Our most important finding is the effect of trunnion design. Of the 3 types studied, we found that S-ROM design was the most successful at minimizing trunnionosis.
authors.affiliation: Institute of Orthopaedics and Musculoskeletal Science, University College London and the Royal National Orthopaedic Hospital, Stanmore, United Kingdom.
authors.forename: Harry S
authors.initials: HS
authors.lastname: Hothi
authors.affiliation: The Coxa Hospital for Joint Replacement, Tampere, Finland.
authors.forename: Antti P
authors.initials: AP
authors.lastname: Eskelinen
authors.affiliation: Institute of Orthopaedics and Musculoskeletal Science, University College London and the Royal National Orthopaedic Hospital, Stanmore, United Kingdom.
authors.forename: Reshid
authors.initials: R
authors.lastname: Berber
authors.affiliation: The Coxa Hospital for Joint Replacement, Tampere, Finland.
authors.forename: Olli S
authors.initials: OS
authors.lastname: Lainiala
authors.affiliation: The Coxa Hospital for Joint Replacement, Tampere, Finland.
authors.forename: Teemu P S
authors.initials: TP
authors.lastname: Moilanen
authors.affiliation: Institute of Orthopaedics and Musculoskeletal Science, University College London and the Royal National Orthopaedic Hospital, Stanmore, United Kingdom.
authors.forename: John A
authors.initials: JA
authors.lastname: Skinner
authors.affiliation: Institute of Orthopaedics and Musculoskeletal Science, University College London and the Royal National Orthopaedic Hospital, Stanmore, United Kingdom.
authors.forename: Alister J
authors.initials: AJ
authors.lastname: Hart
mesh_terms: D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D003343:Corrosion; D020878:Device Removal; D005260:Female; D005269:Femur / Q000601:surgery; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D008297:Male; D061825:Metal-on-Metal Joint Prostheses / Q000009:adverse effects*; D008670:Metals / Q000009:adverse effects; D008875:Middle Aged; D011474:Prosthesis Design; D011475:Prosthesis Failure
chemical_list: D008670:Metals
keywords: corrosion; material loss; metal-on-metal; retrieval; taper