title: International comparative evaluation of knee replacement with fixed or mobile-bearing posterior-stabilized prostheses.
abstract: BACKGROUND
  Posterior-stabilized total knee prostheses were introduced to address instability secondary to loss of posterior cruciate ligament function, and they have either fixed or mobile bearings. Mobile bearings were developed to improve the function and longevity of total knee prostheses. In this study, the International Consortium of Orthopaedic Registries used a distributed health data network to study a large cohort of posterior-stabilized prostheses to determine if the outcome of a posterior-stabilized total knee prosthesis differs depending on whether it has a fixed or mobile-bearing design.
  
  
  METHODS
  Aggregated registry data were collected with a distributed health data network that was developed by the International Consortium of Orthopaedic Registries to reduce barriers to participation (e.g., security, proprietary, legal, and privacy issues) that have the potential to occur with the alternate centralized data warehouse approach. A distributed health data network is a decentralized model that allows secure storage and analysis of data from different registries. Each registry provided data on mobile and fixed-bearing posterior-stabilized prostheses implanted between 2001 and 2010. Only prostheses associated with primary total knee arthroplasties performed for the treatment of osteoarthritis were included. Prostheses with all types of fixation were included except for those with the rarely used reverse hybrid (cementless tibial and cemented femoral components) fixation. The use of patellar resurfacing was reported. The outcome of interest was time to first revision (for any reason). Multivariate meta-analysis was performed with linear mixed models with survival probability as the unit of analysis.
  
  
  RESULTS
  This study includes 137,616 posterior-stabilized knee prostheses; 62% were in female patients, and 17.6% had a mobile bearing. The results of the fixed-effects model indicate that in the first year the mobile-bearing posterior-stabilized prostheses had a significantly higher hazard ratio (1.86) than did the fixed-bearing posterior-stabilized prostheses (95% confidence interval, 1.28 to 2.7; p = 0.001). For all other time intervals, the mobile-bearing posterior-stabilized prostheses had higher hazard ratios; however, these differences were not significant.
  
  
  CONCLUSIONS
  Mobile-bearing posterior-stabilized prostheses had an increased rate of revision compared with fixed-bearing posterior-stabilized prostheses. This difference was evident in the first year.
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: Weill Cornell Medical College, 402 East 67th Street, New York, NY 10065.
authors.forename: Art
authors.initials: A
authors.lastname: Sedrakyan
authors.affiliation: The Norwegian Arthroplasty Register, Department of Orthopaedic Surgery, Haukeland University Hospital, Mollendalsbakken 11, N-5021 Bergen, Norway.
authors.forename: Valborg
authors.initials: V
authors.lastname: Baste
authors.affiliation: Department of Orthopaedic Surgery, Section 112E, Minneapolis VAMC, 1 Veterans Drive, Minneapolis, MN 55417.
authors.forename: Terence J
authors.initials: TJ
authors.lastname: Gioe
authors.affiliation: 6670 Alton Parkway, Irvine, CA 92618.
authors.forename: Robert
authors.initials: R
authors.lastname: Namba
authors.affiliation: Àmbit d'Avaluació, Agència de Qualitat i Avaluació Sanitàries de Catalunya (AQuAS), Departament de Salut - Generalitat de Catalunya, Carrer de Roc Boronat, 81-95 (edifice Salvany), 08005 Barcelona, Spain.
authors.forename: Olga
authors.initials: O
authors.lastname: Martínez Cruz
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: 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: Samprit
authors.initials: S
authors.lastname: Banerjee
authors.affiliation: Weill Cornell Medical College, 402 East 67th Street, New York, NY 10065.
authors.forename: Abby J
authors.initials: AJ
authors.lastname: Isaacs
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
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