title: Superior long-term survival for fixed bearing compared with mobile bearing in ligament-balanced total knee arthroplasty.
abstract: OBJECTIVE
  Only few long-term data on ligament-balanced cruciate-retaining total knee arthroplasty (CR TKA) are currently available. Either a mobile- or fixed-bearing insert can be chosen, which showed good mid-term outcome and few complications and revisions. This multi-centre retrospective cross-sectional cohort study investigated the 12-year results of primary TKA using a balancing gap technique and compared survival and clinical outcome between fixed and mobile inserts.
  
  
  METHODS
  In this retrospective cross-sectional cohort study, 557 cases of three clinics (2 Swiss, 1 Dutch) operated between 1998 and 2003 with the first series of a TKA implanted with a balanced gap technique (433 (77.7%) fixed, 124 (22.3%) mobile (anterior-posterior gliding (7-9 mm) and rotational (15°) degrees of freedom) inserts) were included for survival analysis (Kaplan-Meier, by insert type). At the 12-year follow-up (FU) examination of 189 cases, range of motion, knee society score (KSS), numeric rating scale (NRS) for pain and satisfaction were determined and radiographs were evaluated by median tests, by insert type.
  
  
  RESULTS
  Of 521 cases available for analysis, 28 (5.4%; 11 fixed, 17 mobile bearing) were revised. Mean cumulative survival after 12.4 years was 97.0% (95% CI 94.7-98.4) for fixed bearings and 85.4% (95% CI 77.5-90.7) after 12.2 years for mobile bearings, p < 0.0001. Patients' mean age at 11.0 years FU (n = 189) was 78.0 (range 54.5-97.3) years. Mean total KSS was 157.8 (24-200) points, and mean passive flexion was 114° (45-150); no clinical score differed significantly between fixed and mobile bearings.
  
  
  CONCLUSIONS
  This study showed a superior survival for fixed bearing compared with mobile bearing in a CR TKA using a ligament-balanced technique after more than 12 years. Clinical outcomes are excellent to good after long-term follow-up, and similar for fixed and mobile bearing.
  
  
  METHODS
  Therapeutic studies-retrospective cohort study, Level III.
authors.affiliation: Sint Maartenskliniek, Nijmegen, The Netherlands. P.heesterbeek@maartenskliniek.nl.
authors.forename: P J C
authors.identifier: http://orcid.org/0000-0003-2873-8907
authors.initials: PJC
authors.lastname: Heesterbeek
authors.affiliation: Sint Maartenskliniek, Nijmegen, The Netherlands.
authors.forename: A H
authors.initials: AH
authors.lastname: van Houten
authors.affiliation: Orthopädische Klinik orthosiloah Bern-Gümligen, Bern, Switzerland.
authors.forename: J S
authors.initials: JS
authors.lastname: Klenk
authors.affiliation: Regionalspital Emmental AG, Burgdorf, Switzerland.
authors.forename: H
authors.initials: H
authors.lastname: Eijer
authors.affiliation: Orthopädische Klinik Bern, Bern, Switzerland.
authors.forename: B
authors.initials: B
authors.lastname: Christen
authors.affiliation: Sint Maartenskliniek, Nijmegen, The Netherlands.
authors.forename: A B
authors.initials: AB
authors.lastname: Wymenga
authors.affiliation: Orthopädische Klinik orthosiloah Bern-Gümligen, Bern, Switzerland.
authors.forename: A J
authors.initials: AJ
authors.lastname: Schuster
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007720:Knee Prosthesis; D008022:Ligaments / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery; D017063:Outcome Assessment, Health Care; D011474:Prosthesis Design; D016059:Range of Motion, Articular; D012189:Retrospective Studies
keywords: Balanced gap technique; Clinical outcome; Dependent gap total knee arthroplasty; Fixed bearing; Ligament balancing; Long-term follow-up; Mobile bearing; Survival; Total knee arthroplasty