title: Femoral diameter and stem type are independent risk factors for ARMD in the large-headed ASR THR group.
abstract: BACKGROUND
  Adverse soft-tissue reaction to metal debris (ARMD) continues to be major source of concern in metal-on-metal (MoM) hip replacements. In our earlier study we were able to establish several risk factors for ARMD in patients who had received a small-diameter (<50 mm) Articular Surface Replacement (ASR, DePuy, Warsaw, IN, USA). The aims of the present study were to analyze whether these previously established risk factors also apply to patients who have received a large-headed (>50 mm) ASR™ XL THR.
  
  
  METHODS
  Large-headed ASR total hip replacements were used in 225 operations (196 patients) at our institution. 176 patients (203 hips) attended a screening programme, consisting of a clinical evaluation, whole blood cobalt and chromium measurements, and cross-sectional imaging.
  
  
  RESULTS
  Revision surgery was performed on 84 hips (37%) in 75 patients. ARMD was diagnosed in the majority (n = 73 [87%]) of these revisions. Cumulative 8-year survivorship was 52%. The previously established risk factors for ARMD were not applicable. Interestingly, increasing femoral diameter and stem type were identified as independent risk factors for ARMD but reduced cup coverage had no significant association with ARMD.
  
  
  CONCLUSIONS
  Stem type and increasing femoral size as independent risk factors for ARMD in the cohort of ASR XL THR patients, support the importance of taper failure in the development of ARMD. The present results suggest that the degree of taper failure may be variable and dependent on the taper design.
authors.affiliation: Coxa Hospital for Joint Replacement, Biokatu 6b, 33520, Tampere, Finland. Aleksi.reito@fimnet.fi.
authors.forename: Aleksi
authors.initials: A
authors.lastname: Reito
authors.affiliation: Coxa Hospital for Joint Replacement, Biokatu 6b, 33520, Tampere, Finland. petra.elo@fimnet.fi.
authors.forename: Petra
authors.initials: P
authors.lastname: Elo
authors.affiliation: Coxa Hospital for Joint Replacement, Biokatu 6b, 33520, Tampere, Finland. timo.puolakka@coxa.fi.
authors.forename: Timo
authors.initials: T
authors.lastname: Puolakka
authors.affiliation: Coxa Hospital for Joint Replacement, Biokatu 6b, 33520, Tampere, Finland. j.pajamaki@coxa.fi.
authors.forename: Jorma
authors.initials: J
authors.lastname: Pajamäki
authors.affiliation: Coxa Hospital for Joint Replacement, Biokatu 6b, 33520, Tampere, Finland. antti.eskelinen@fimnet.fi.
authors.forename: Antti
authors.initials: A
authors.lastname: Eskelinen
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects; D005260:Female; D005549:Foreign-Body Reaction / Q000209:etiology*; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008670:Metals / Q000009:adverse effects; D008875:Middle Aged; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012044:Regression Analysis; D012086:Reoperation; D012307:Risk Factors
chemical_list: D008670:Metals