Risk of revision for fixed versus mobile-bearing primary total knee replacements

Robert S Namba, Maria C S Inacio, Elizabeth W Paxton, Christopher F Ake, Cunlin Wang, Thomas P Gross, Danica Marinac-Dabic, Art Sedrakyan

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32 Citations (Scopus)

Abstract

BACKGROUND: Mobile-bearing total knee arthroplasty prostheses were developed to reduce wear and revision rates; however, these benefits remain unproven. The purposes of this study were to compare the short-term survivorship and to determine risk factors for revision of mobile-bearing and fixed-bearing total knee replacements.

METHODS: A prospective cohort study of primary total knee arthroplasties performed from 2001 to 2009 was conducted with use of a community total joint replacement registry. Patient characteristics and procedure details were identified. Cox regression models were used. Bearing type was investigated as a risk factor for revision while adjusted for other risk factors such as age, American Society of Anesthesiologists (ASA) score, body mass index, sex, race, diagnosis, bilateral procedures, cruciate-retaining versus posterior-stabilized components, surgical approach, fixation, patellar resurfacing, hospital and surgeon volumes, and fellowship training.

RESULTS: The study cohort consisted of 47,339 total knee arthroplasties, with 62.6% of the procedures in women. Fixed bearings were used in 41,908 knees (88.5%) and mobile bearings in 4830 (10.2%). Rotating-platform designs were used in all mobile-bearing total knee arthroplasties (3112 had a Rotating-Platform Press-Fit Condylar posterior-stabilized design; 1053, a Low Contact Stress [LCS] design; and 665, a Rotating-Platform Press-Fit Condylar cruciate-retaining design). Patients who received fixed-bearing total knee arthroplasty systems were older (mean age, 68.1 years) than those who received mobile-bearing total knee arthroplasty systems (mean age, 62.2 years); the difference was significant (p < 0.001). Overall, 515 knees (1.1%) were revised for reasons other than infection. The survival rate was 97.8% (95% confidence interval [CI], 97.4% to 98.0%) at 6.7 years. The adjusted risk of aseptic revision for the LCS total knee replacements was 2.01 times (95% CI, 1.41 to 2.86) higher than that for fixed-bearing total knee replacements (p < 0.001).There was no significant revision risk for the other mobile-bearing total knee arthroplasty systems. There was no association with surgeon and hospital case volumes and the risk of revision total knee arthroplasty.

CONCLUSIONS: Our study suggests the benefit of potential long-term wear reduction with the LCS implant may not be realized in a community-based setting, where a variety of surgical skills, surgical experience, and diverse patient demographic factors may affect early outcomes.

LEVEL OF EVIDENCE: Therapeutic Level II.

Original languageEnglish
Pages (from-to)1929-35
Number of pages7
JournalJournal of Bone and Joint Surgery - American Volume
Volume94
Issue number21
DOIs
Publication statusPublished or Issued - 7 Nov 2012

Keywords

  • Aged
  • Arthroplasty, Replacement, Knee
  • Female
  • Humans
  • Knee Prosthesis
  • Male
  • Middle Aged
  • Osteoarthritis, Knee
  • Proportional Hazards Models
  • Prospective Studies
  • Registries
  • Reoperation
  • Risk Factors
  • Comparative Study
  • Journal Article
  • Research Support, U.S. Gov't, P.H.S.

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