title: Predictors of Subjective Outcome After Medial Unicompartmental Knee Arthroplasty.
abstract: Unexplainable pain after medial unicompartmental knee arthroplasty (UKA) remains a leading cause for revision surgery. Therefore, the aim of this study is to identify the patient-specific variables that may influence subjective outcomes after medial UKA to optimize results.
  
  
  
  Retrospectively, we analyzed 104 consecutive medial UKA patients. The evaluated parameters consisted of age, body mass index, gender, preoperative radiographic severity of the various knee compartments, and preoperative and postoperative mechanical axis alignments.
  
  
  
  At an average of 2.3-year follow-up, our data demonstrate that body mass index, gender, and preoperative severity among the various knee compartments do not influence Western Ontario and McMaster Universities Arthritis Index (WOMAC) results. Preoperatively, patients aged <65 years had inferior WOMAC stiffness (4.6 vs 2.9, P = .001), pain (9.7 vs 7.6, P = .041), and total (37.2 vs 47.6, P = .028) scores vs patients aged ≥65 years. Postoperatively, only the difference on the WOMAC stiffness subscale remained significant between both age groups, in favor of patients aged ≥65 years (1.0 vs 1.5, P = .035). A postoperative varus mechanical axis alignment of 1°-4° correlated to significantly superior WOMAC pain (P = .03), function (P = .04), and total (P = .04) scores compared to a varus of ≤1° or ≥4°.
  
  
  
  Our data suggest that greater pain relief can be expected in patients aged <65 years and that a postoperative lower limb alignment of 1°-4° varus should be pursued. Taking these factors into consideration will help to maximize clinical outcomes, fulfill patient expectations after medial UKA, and subsequently minimize revision rates.
authors.affiliation: Department of Orthopaedic Surgery, Computer Assisted Surgery Center, Hospital for Special Surgery, Weill Cornell Medical College, New York, New York.
authors.forename: Hendrik A
authors.initials: HA
authors.lastname: Zuiderbaan
authors.affiliation: Department of Orthopaedic Surgery, Computer Assisted Surgery Center, Hospital for Special Surgery, Weill Cornell Medical College, New York, New York.
authors.forename: Jelle P
authors.initials: JP
authors.lastname: van der List
authors.affiliation: Department of Orthopaedic Surgery, Computer Assisted Surgery Center, Hospital for Special Surgery, Weill Cornell Medical College, New York, New York.
authors.forename: Harshvardhan
authors.initials: H
authors.lastname: Chawla
authors.affiliation: Department of Orthopaedic Surgery, Computer Assisted Surgery Center, Hospital for Special Surgery, Weill Cornell Medical College, New York, New York.
authors.forename: Saker
authors.initials: S
authors.lastname: Khamaisy
authors.affiliation: Department of Orthopaedic Surgery, Computer Assisted Surgery Center, Hospital for Special Surgery, Weill Cornell Medical College, New York, New York.
authors.forename: Ran
authors.initials: R
authors.lastname: Thein
authors.affiliation: Department of Orthopaedic Surgery, Computer Assisted Surgery Center, Hospital for Special Surgery, Weill Cornell Medical College, New York, New York.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Pearle
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001168:Arthritis / Q000503:physiopathology; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D015992:Body Mass Index; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D010146:Pain; D011184:Postoperative Period; D011446:Prospective Studies; D012086:Reoperation; D012189:Retrospective Studies; D012720:Severity of Illness Index; D016896:Treatment Outcome
keywords: WOMAC; alignment; functional outcome; predictors; unicompartmental knee arthroplasty