title: Better quality of life after medial versus lateral unicondylar knee arthroplasty.
abstract: BACKGROUND
  The number of unicompartmental knee arthroplasties (UKAs) is growing worldwide. Because lateral UKAs are performed much less frequently than medial UKAs, the limited information leaves unclear whether UKAs have comparable survival and health-related quality of life (HRQoL) of the lateral UKA to medial UKAs.
  
  
  OBJECTIVE
  We therefore compared the (1) survivorship and (2) HRQoL after lateral versus medial cemented mobile-bearing UKAs and (3) determined whether there is an association of survival to modifications of surgical technique in one of three phases.
  
  
  METHODS
  We retrospectively reviewed 558 patients who underwent mobile-bearing UKAs from 2002 to 2009. From the records we determined revision of the joint for any reason and revision for aseptic loosening. Patients reported their physical function, pain, and stiffness as measured by the WOMAC, SF-36 physical-component summary (PCS), and Lequesne knee score. Information regarding implant survival was collected for 93% of the patients. We analyzed the patients separately by three phases based on surgical changes associated with each phase (1: initial technique; 2: improved cementing; 3: additional bone resection to ensure backward sliding of the inlay without impingement). The minimum followup was 2.1 years (mean, 6 years; range, 2.1-9.8 years).
  
  
  RESULTS
  Implant survival was 88% at 9 years. We found similar implant survival rates for medial (90%) and lateral UKAs (83%). In all HRQoL measures, patients receiving a medial UKA had better mean scores compared with patients who had a lateral UKA: WOMAC physical function (23 versus 34, respectively) and pain (21 versus 34) and SF-36 PCS (41 versus 38). There were no survival differences by surgical phase.
  
  
  CONCLUSIONS
  Our observations suggest a medial UKA is associated with superior HRQoL when compared with a lateral UKA, although implant survival is similar.
authors.affiliation: Department of Orthopaedic Surgery, University of Schleswig-Holstein Medical Center, Kiel Campus, Michaelisstr 1, 24105, Kiel, Germany. liebs@liebs.eu
authors.forename: Thoralf R
authors.initials: TR
authors.lastname: Liebs
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Herzberg
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D001696:Biomechanical Phenomena; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D007719:Knee Joint / Q000503:physiopathology / Q000601:surgery*; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010147:Pain Measurement; D010149:Postoperative Pain / Q000175:diagnosis / Q000523:psychology / Q000601:surgery; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D011475:Prosthesis Failure; D011788:Quality of Life; D020127:Recovery of Function; D012086:Reoperation; D012189:Retrospective Studies; D011795:Surveys and Questionnaires; D013997:Time Factors; D016896:Treatment Outcome