title: No superior performance of hydroxyapatite-coated acetabular cups over porous-coated cups.
abstract: OBJECTIVE
  Hydroxyapatite (HA) coating is believed to improve bone-implant ingrowth and long-term survival of prostheses. Recent studies, however, have challenged this view. Furthermore, HA particles may produce third-body wear and initiate aseptic loosening of implants. We report the performance of HA- and porous-coated acetabular cups in a prospective randomized trial.
  
  
  METHODS
  This was an 8-year follow-up study of our previously published prospective randomized study to compare clinical outcomes, survival, periprosthetic bone mineral density, migration, and wear rates of HA- and porous-coated acetabular cups. Dual X-ray absorptiometry (DXA) and Ein Bild Roentgen Analyse (EBRA) measurements were used. 100 patients who underwent unilateral cementless total hip arthroplasty were randomized to either porous-coated cups or HA-coated cups. Patients were examined preoperatively and at 3, 6, and 9 months, and also 1, 3, and 8 years after surgery. 81 patients were available for 8-year follow-up, 40 with porous-coated cups and 41 with HA-coated cups.
  
  
  RESULTS
  Age, sex, bone mineral density, and clinical results (Harris hip score) were similar in the 2 groups. The survival, wear, and migration patterns of the cups were also similar in both groups. The results of periprosthetic bone mineral density scans in region of interest 2 was in favor of the porous-coated cups, but there were no differences between the 2 groups in all the remaining regions of interest.
  
  
  CONCLUSIONS
  HA coating had no statistically significant effect on clinical results, survival, wear, or migration at the 8-year follow-up.
authors.affiliation: Farsoe Clinic of Hip and Knee Arthroplasty , Department of Orthopaedic Surgery, Aalborg University Hospital, Aalborg.
authors.forename: Kestutis
authors.initials: K
authors.lastname: Valancius
authors.forename: Kjeld
authors.initials: K
authors.lastname: Søballe
authors.forename: Poul T
authors.initials: PT
authors.lastname: Nielsen
authors.forename: Mogens B
authors.initials: MB
authors.lastname: Laursen
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000077:Acetabulum / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation / Q000379:methods; D015519:Bone Density / Q000187:drug effects / Q000502:physiology; D020099:Coated Materials, Biocompatible / Q000494:pharmacology*; D017886:Durapatite / Q000494:pharmacology*; D005260:Female; D005500:Follow-Up Studies; D006622:Hip Prosthesis; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D016062:Porosity; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012086:Reoperation; D016896:Treatment Outcome
chemical_list: D020099:Coated Materials, Biocompatible; D017886:Durapatite