title: Comparative effectiveness of ceramic-on-ceramic implants in stemmed hip replacement: a multinational study of six national and regional registries.
abstract: BACKGROUND
  The rapid decline in use of conventional total hip replacement with a large femoral head size and a metal-on-metal bearing surface might lead to increased popularity of ceramic-on-ceramic bearings as another hard-on-hard alternative that allows implantation of a larger head. We sought to address comparative effectiveness of ceramic-on-ceramic and metal-on-HXLPE (highly cross-linked polyethylene) implants by utilizing the distributed health data network of the ICOR (International Consortium of Orthopaedic Registries), an unprecedented collaboration of national and regional registries and the U.S. FDA (Food and Drug Administration).
  
  
  METHODS
  A distributed health data network was developed by the ICOR and used in this study. The data from each registry are standardized and provided at a level of aggregation most suitable for the detailed analysis of interest. The data are combined across registries for comprehensive assessments. The ICOR coordinating center and study steering committee defined the inclusion criteria for this study as total hip arthroplasty performed without cement from 2001 to 2010 in patients forty-five to sixty-four years of age with osteoarthritis. Six national and regional registries (Kaiser Permanente and HealthEast in the U.S., Emilia-Romagna region in Italy, Catalan region in Spain, Norway, and Australia) participated in this study. Multivariate meta-analysis was performed with use of linear mixed models, with survival probability as the unit of analysis. We present the results of the fixed-effects model and include the results of the random-effects model in an appendix. SAS version 9.2 was used for all analyses. We first compared femoral head sizes of >28 mm and ≤28 mm within ceramic-on-ceramic implants and then compared ceramic-on-ceramic with metal-on-HXLPE.
  
  
  RESULTS
  A total of 34,985 patients were included; 52% were female. We found a lower risk of revision associated with use of ceramic-on-ceramic implants when a larger head size was used (HR [hazard ratio] = 0.73, 95% CI [confidence interval] = 0.60 to 0.88, p = 0.001). Use of smaller-head-size ceramic-on-ceramic bearings was associated with a higher risk of failure compared with metal-on-HXLPE bearings (HR = 1.36, 95% CI = 1.09 to 1.68, p = 0.006). Use of large-head-size ceramic-on-ceramic bearings was associated with a small protective effect relative to metal-on-HXLPE bearings (not subdivided by head size) in years zero to two, but this difference dissipated over the longer term.
  
  
  CONCLUSIONS
  Our multinational study based on a harmonized, distributed network showed that use of ceramic-on-ceramic implants with a smaller head size in total hip arthroplasty without cement was associated with a higher risk of revision compared with metal-on-HXLPE and >28-mm ceramic-on-ceramic implants. These findings warrant careful reflection by regulatory and clinical communities and wide dissemination to patients for informed decision-making regarding such surgery.
authors.affiliation: Weill Cornell Medical College, 402 East 67th Street, New York, NY 10065.
authors.forename: Art
authors.initials: A
authors.lastname: Sedrakyan
authors.affiliation: Australian Orthopaedic Association National Joint Replacement Registry, Discipline of Public Health, MDP DX 650 511, University of Adelaide, Adelaide, SA 5005, Australia.
authors.forename: Stephen
authors.initials: S
authors.lastname: Graves
authors.affiliation: Register of Orthopaedic Implants (RIPO), c/o Medical Technology Laboratory, Istituto Ortopedico Rizzoli, via de Barbiano 1/10, 40136 Bologna, Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Bordini
authors.affiliation: Hip and Knee Replacement Unit, Orthopaedic Surgery Department, Hospital Sant Rafael, Paseo Vall d'Hebrón 107-117, Barcelona 08035, Spain.
authors.forename: Miquel
authors.initials: M
authors.lastname: Pons
authors.affiliation: The Norwegian Arthroplasty Register, Department of Orthopaedic Surgery, Haukeland University Hospital, Mollendalsbakken 11, N-5021 Bergen, Norway.
authors.forename: Leif
authors.initials: L
authors.lastname: Havelin
authors.affiliation: HealthEast Joint Registry (HEJR), 1690 University Avenue West, Data Science, Suite 400, Minneapolis, MN 55104.
authors.forename: Susan
authors.initials: S
authors.lastname: Mehle
authors.affiliation: Surgical Outcomes & Analysis Department, Kaiser Permanente, 8954 Rio San Diego Drive, Suite 406, San Diego, CA 92108.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Paxton
authors.affiliation: Department of Orthopedic Surgery, Kaiser Permanente, 280 West MacArthur Boulevard, Oakland, CA 94611.
authors.forename: Thomas
authors.initials: T
authors.lastname: Barber
authors.affiliation: Surgical Outcomes & Analysis Department, Kaiser Permanente, 8954 Rio San Diego Drive, Suite 406, San Diego, CA 92108.
authors.forename: Guy
authors.initials: G
authors.lastname: Cafri
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects* / Q000379:methods; D002516:Ceramics; D005260:Female; D005270:Femur Head / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery*; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012042:Registries; D012086:Reoperation