title: Is isolated insert exchange a valuable choice for polyethylene wear in metal-backed unicompartmental knee arthroplasty?
abstract: OBJECTIVE
  The aim of this study was to evaluate the clinical outcome and survival rate after isolated liner exchange for polyethylene (PE) wear in well-fixed metal-backed fixed-bearing unicompartmental knee arthroplasty (UKA).
  
  
  METHODS
  Twenty medial UKAs in 19 patients [mean age 68.7 years ± 8.7 (range 48.5-81.5 years)] operated on for a direct PE liner exchange after isolated PE wear between 1996 and 2010 in two institutions were retrospectively reviewed. The mean delay between the index operation and revision was 8.2 years ± 2.6 (range 4.8-12.8 years). A four-level satisfaction questionnaire was used, and clinical outcomes were assessed using Knee Society scores (KSS) and range of motion (ROM) evaluation. Radiological evaluation analysed the position of the implants and progression of the disease. Survival rate of the implants was evaluated using Kaplan-Meier analysis with two different end-points.
  
  
  RESULTS
  At the last follow-up [mean 6.8 years ± 5.2 (range 1.1-15.9 years)], 15 patients (79 %) were enthusiastic or satisfied. KSS improved from 73.4 to 86.4 points (p = 0.01) and function from 58.9 to 89.2 points (p < 0.001). ROM at last FU was 126.5° ± 10.3°. The survival rate at 12 years considering "revision for any reason" as the end-point was 71.3 ± 15.3 %, and the survival rate at 12 years considering "revision of UKA to TKA" as the end-point was 93.3 ± 6.4 %.
  
  
  CONCLUSIONS
  Isolated liner exchange for PE wear in well-fixed metal-backed fixed-bearing UKA represents a valuable treatment option in selective patients with durable improvement of clinical outcomes without compromising any future revision.
  
  
  METHODS
  Retrospective therapeutic study, Level IV.
authors.affiliation: Department of Orthopedic Surgery APHM, Institute for Locomotion (IML), Sainte Marguerite Hospital, 13009, Marseille, France.|ISM UMR 7287, Aix-Marseille University, CNRS, 13284, Marseille, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Lunebourg
authors.affiliation: Department of Orthopedic Surgery APHM, Institute for Locomotion (IML), Sainte Marguerite Hospital, 13009, Marseille, France. sebastien@parratte.fr.|ISM UMR 7287, Aix-Marseille University, CNRS, 13284, Marseille, France. sebastien@parratte.fr.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Parratte
authors.affiliation: Department of Orthopedic Surgery APHM, Institute for Locomotion (IML), Sainte Marguerite Hospital, 13009, Marseille, France.|ISM UMR 7287, Aix-Marseille University, CNRS, 13284, Marseille, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Galland
authors.affiliation: Department of Orthopedic Surgery, Hôpital Renée Sabran, Giens, 83406, Hyeres, France.
authors.forename: François
authors.initials: F
authors.lastname: Lecuire
authors.affiliation: Department of Orthopedic Surgery APHM, Institute for Locomotion (IML), Sainte Marguerite Hospital, 13009, Marseille, France.|ISM UMR 7287, Aix-Marseille University, CNRS, 13284, Marseille, France.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Ollivier
authors.affiliation: Department of Orthopedic Surgery APHM, Institute for Locomotion (IML), Sainte Marguerite Hospital, 13009, Marseille, France.|ISM UMR 7287, Aix-Marseille University, CNRS, 13284, Marseille, France.
authors.forename: Jean-Noël
authors.initials: JN
authors.lastname: Argenson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation* / Q000379:methods*; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D007720:Knee Prosthesis; D008297:Male; D008670:Metals; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery; D020959:Polyethylene; D011474:Prosthesis Design; D011475:Prosthesis Failure; D016059:Range of Motion, Articular; D012086:Reoperation; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D008670:Metals; D020959:Polyethylene
keywords: Clinical outcome; Implant survival rate; Isolated replacement of polyethylene; Polyethylene wear; Unicompartmental knee arthroplasty