title: Cushion bearings versus large diameter head metal-on-metal bearings in total hip arthroplasty: a short-term metal ion study.
abstract: BACKGROUND
  Metal-on-metal total hip arthroplasty (MOM THA) has the advantage of replicating the femoral head size, but the postoperative elevation of serum metal ion levels is a cause for concern. Metal-on-polycarbonate-urethane is a new cushion bearing featuring a large diameter metal head coupled with a polycarbonate-urethane liner.
  
  
  OBJECTIVE
  The aim of this study was to assess and compare serum cobalt (Co) and chromium (Cr) levels in a group of 15 patients treated with a cushion bearing THA system (Group A) and a group of 15 patients treated with a MOM THA system (Group B) at short-term. At a mean follow-up of 27.3 months (18-35 months), in Group A the median Cr and Co serum levels were significantly lower than in Group B, measuring 0.24 μg/L (0.1-2.1 μg/L) and 0.6 μg/L (0.29-2.3 μg/L) compared to 1.3 μg/L (0.1-9 μg/L, p < 0.001) and 2.9 μg/L (0.85-13.8 μg/L, p < 0.001) respectively.
  
  
  RESULTS
  All patients demonstrated an excellent clinical result, as shown by the Harris and Oxford hip scores. The cushion bearing THA studied in this paper showed clinical outcomes similar to the MOM THA bearing, with the advantage of no significant metal ion elevation in the serum.
  
  
  CONCLUSIONS
  These findings warrant the continued clinical study of compliant bearing options.
authors.affiliation: School of Sports Science, University of Bologna, Bologna, Italy. a.moroni@ior.it
authors.forename: Antonio
authors.initials: A
authors.lastname: Moroni
authors.forename: Emanuele
authors.initials: E
authors.lastname: Nocco
authors.forename: Martha
authors.initials: M
authors.lastname: Hoque
authors.forename: Elena
authors.initials: E
authors.lastname: Diremigio
authors.forename: Dario
authors.initials: D
authors.lastname: Buffoli
authors.forename: Francesco
authors.initials: F
authors.lastname: Cantù
authors.forename: Simona
authors.initials: S
authors.lastname: Catalani
authors.forename: Pietro
authors.initials: P
authors.lastname: Apostoli
mesh_terms: D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D002857:Chromium / Q000097:blood*; D003035:Cobalt / Q000097:blood*; D005260:Female; D005500:Follow-Up Studies; D006618:Hip Dislocation, Congenital / Q000601:surgery; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery; D011076:Polycarboxylate Cement; D011446:Prospective Studies; D011474:Prosthesis Design; D012086:Reoperation; D016896:Treatment Outcome
chemical_list: D011076:Polycarboxylate Cement; D002857:Chromium; C005506:polycarbonate; D003035:Cobalt