title: International comparative evaluation of knee replacement with fixed or mobile non-posterior-stabilized implants.
abstract: BACKGROUND
  Mobile-bearing total knee prostheses were designed to reduce wear and improve implant survivorship following total knee arthroplasty. However, the benefit of mobile-bearing total knee arthroplasty remains unproven. Both mobile-bearing and fixed-bearing total knee arthroplasty implants are available in posterior-stabilized and non-posterior-stabilized designs. With the latter, the implant does not recreate the function of the posterior cruciate ligament (PCL) with a posterior-stabilizing cam mechanism. The purpose of the present study was to compare mobile-bearing, non-posterior-stabilized devices with fixed-bearing, non-posterior-stabilized devices used in total knee arthroplasty through a novel multinational study design.
  
  
  METHODS
  Through the use of a distributed health data network, primary total knee arthroplasties performed for osteoarthritis from 2001 to 2010 were identified from six national and regional total joint arthroplasty registries. Multivariate meta-analysis was performed with use of linear mixed models, with the primary outcome of interest being revision for any reason. Survival probabilities and their standard errors were extracted from each registry for each unique combination of the covariates.
  
  
  RESULTS
  A total of 319,616 patients (60% female) underwent non-posterior-stabilized total knee arthroplasty. A fixed-bearing, non-posterior-stabilized design was used in 258,190 (81%) of the knees and a mobile-bearing, non-posterior-stabilized design in 61,426 (19%) of the knees. Sixty-nine percent of the patients who received a fixed-bearing implant were over sixty-five years of age, compared with 63% of those who received a mobile-bearing implant. Mobile-bearing designs had a higher risk of revision, with a hazard ratio of 1.43 (95% confidence interval, 1.36 to 1.51; p < 0.001).
  
  
  CONCLUSIONS
  Previous comparisons of mobile-bearing and fixed-bearing total knee arthroplasty outcomes have been inconclusive. The current study utilized an advanced, harmonized distributed analysis of six national and regional joint-replacement registries. To our knowledge, it is the largest analysis of mobile-bearing total knee arthroplasty to date. Mobile-bearing, non-posterior-stabilized designs presented a greater risk of failure than was found for fixed-bearing, non-posterior-stabilized designs. Caution should be used in the selection of the mobile-bearing non-posterior-stabilized design for total knee replacement.
authors.affiliation: 6670 Alton Parkway, Irvine CA 92618.
authors.forename: Robert
authors.initials: R
authors.lastname: Namba
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: The Swedish Knee Arthroplasty Register, Department of Orthopedics, Clinical Sciences, SUS/Lund University Hospital, 221 85 Lund, Sweden.
authors.forename: Otto
authors.initials: O
authors.lastname: Robertsson
authors.affiliation: The Norwegian Arthroplasty Register, Department of Orthopaedic Surgery, Haukeland University Hospital, Mollendalsbakken 11, N-5021 Bergen, Norway.
authors.forename: Ove
authors.initials: O
authors.lastname: Furnes
authors.affiliation: Register of the Orthopaedic Prosthetic Implants (RIPO), c/o Medical Technology Laboratory, Istituto Ortopedico Rizzoli, Via di Barbiano 1/10, 40136 Bologna, Italy.
authors.forename: Susanna
authors.initials: S
authors.lastname: Stea
authors.affiliation: Department of Orthopedic Surgery and Traumatology, Hospital del Mar, Parc de Salud MAR, Passeig Maritim 25-27, 08003 Barcelona, Spain.
authors.forename: Lluis
authors.initials: L
authors.lastname: Puig-Verdié
authors.affiliation: Summit Orthopedics, 2090 Woodwinds Drive, St. Paul, MN 55125.
authors.forename: Daniel
authors.initials: D
authors.lastname: Hoeffel
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
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: Weill Cornell Medical College, 402 East 67th Street, New York, NY 10065.
authors.forename: Art
authors.initials: A
authors.lastname: Sedrakyan
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000601:surgery*; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery*; D011474:Prosthesis Design; D016059:Range of Motion, Articular; D012042:Registries