title: Evidence-Based Indications for Mobile-Bearing Unicompartmental Knee Arthroplasty in a Consecutive Cohort of Thousand Knees.
abstract: The indications for unicompartmental knee arthroplasty remain controversial. Previously recommended contraindications include the following: age under 60 years, weight 180 lb (82 kg) or over, patients undertaking heavy labor, chondrocalcinosis, and exposed bone in the patellofemoral joint. This study explores whether these contraindications are valid in mobile-bearing unicompartmental knee arthroplasty.
  
  
  
  Using a prospective series of 1000 consecutive medial unicompartmental knee arthroplasties in which the reported contraindications were not applied, the functional outcome and survival in patients with or without contraindications were compared.
  
  
  
  Of the 1000 consecutive unicompartmental knee arthroplasties (818 patients), 68% (678 knees) would be considered contraindicated based on published contraindications. At a mean follow-up of 10 years (5-17), there was no difference in American Knee Society (AKS) Objective Scores (P = .05) or Oxford Knee Score (P = .08) between groups. However, knees with contraindications had significantly (P = .02) fewer poor outcomes and significantly better AKS Functional Scores (P < .001) and Tegner Activity Scores (P < .001). At 15 years, no difference in implant survival (P = .33) was observed. The 3% of unicompartmental knee arthroplasties performed in young men (age <60) weighing 180 lb or over with high activity levels, who have been reported to have poor outcomes after fixed-bearing unicompartmental knee arthroplasty, had significantly better AKS Functional Scores (P < .001), Oxford Knee Score (P = .01), and Tegner Activity Score (P < .001) at 10 years. No difference in AKS Objective Scores (P = .54) at 10 years or implant survival at 15 years (P = .75) was seen.
  
  
  
  This large case series provides evidence that patients with the previously reported contraindications do as well as, or even better than, those without contraindications. Therefore these contraindications should not apply to mobile-bearing unicompartmental knee arthroplasty.
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Botnar Research Centre, Oxford, UK.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Hamilton
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Botnar Research Centre, Oxford, UK; Nuffield Orthopaedic Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, UK.
authors.forename: Hemant G
authors.initials: HG
authors.lastname: Pandit
authors.affiliation: Nuffield Orthopaedic Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, UK.
authors.forename: Cathy
authors.initials: C
authors.lastname: Jenkins
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Botnar Research Centre, Oxford, UK.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Mellon
authors.affiliation: Nuffield Orthopaedic Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, UK.
authors.forename: Christopher A F
authors.initials: CAF
authors.lastname: Dodd
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Botnar Research Centre, Oxford, UK; Nuffield Orthopaedic Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, UK.
authors.forename: David W
authors.initials: DW
authors.lastname: Murray
mesh_terms: D000328:Adult; D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data; D002805:Chondrocalcinosis; D015331:Cohort Studies; D000075204:Contraindications, Procedure; D005260:Female; D006801:Humans; D007717:Knee / Q000601:surgery; D007719:Knee Joint / Q000601:surgery; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery; D057071:Patellofemoral Joint / Q000601:surgery; D011446:Prospective Studies; D012086:Reoperation; D016896:Treatment Outcome
keywords: clinical outcomes; implant survival; mobile-bearing; patient selection; unicompartmental knee arthroplasty