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Similar polyethylene wear between cemented and cementless Oxford medial UKA: a 5-year follow-up randomized controlled trial on 79 patients using radiostereometry

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  • Kristian Horsager
  • Frank Madsen
  • Anders Odgaard
  • Claus Fink Jepsen
  • Lone Rømer
  • Per Wagner Kristensen
  • Bart L Kaptein
  • Kjeld Søballe
  • Maiken Stilling
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Background and purpose - Hydroxyapatite (HA)-coated implants have been associated with high polyethylene wear in hip arthroplasties. HA coating as a promoter of wear in knee arthroplasties has not been investigated. We compared the wear-rate of the polyethylene bearing for cemented and cementless HA-coated Oxford medial unicondylar knee arthroplasties (UKA). Secondarily, we investigated whether wear-rates were influenced by overhang or impingement of the bearing. Patients and methods - 80 patients (mean age 64 years), treatment-blinded, were randomized to 1 of 3 Oxford medial UKA versions: cemented with double-pegged or single-pegged femoral component or cementless HA-coated with double-pegged femoral component (ratios 1:1:1). We compared wear between the cemented (n = 55) and cementless group (n = 25) (ratio 2:1). Wear, impingement, and overhang were quantified between surgery and 5-year follow-up using radiostereometry. Clinical outcome was evaluated with the Oxford Knee Score. Results - The mean wear-rate for patients without bearing overhang was 0.04 mm/year (95% CI 0.02-0.07) for the cemented group and 0.05 mm/year (CI 0.02-0.08) for the cementless group. The mean difference in wear was 0.008 mm/year (CI -0.04 to 0.03). No impingement was identified. Half of the patients had medial bearing overhang, mean 2.5 mm (1-5). Wear increased by 0.014 mm/year for each mm increment in overhang. The mean Oxford Knee Score was 39 for the cementless group and 38 for the cemented group at the 5-year follow-up. Interpretation - The wear-rates were similar for the 2 fixation methods, which supports further use of the cementless Oxford medial UKA. However, a caveat is a relatively large 95% CI of the mean difference in wear-rate. Component size and position is important as half of the patients presented with an additional increase in wear-rate due to medial bearing overhang.

Original languageEnglish
JournalActa Orthopaedica
Volume90
Issue number1
Pages (from-to)67-73
Number of pages7
ISSN1745-3674
DOIs
Publication statusPublished - Feb 2019

    Research areas

  • Arthroplasty, Replacement, Knee/adverse effects, Bone Cements/therapeutic use, Cementation/methods, Coated Materials, Biocompatible/therapeutic use, Female, Follow-Up Studies, Humans, Knee Prosthesis/adverse effects, Male, Middle Aged, Osteoarthritis, Knee/surgery, Polyethylene/therapeutic use, Prosthesis Design, Prosthesis Failure, Radiostereometric Analysis, Treatment Outcome

ID: 59200893