title: Postoperative Anteroposterior Laxity Influences Subjective Outcome After Total Knee Arthroplasty.
abstract: We hypothesized that postoperative anteroposterior (AP) stability of the knee correlates with patient-reported clinical outcome and knee function after total knee arthroplasty (TKA).
  
  
  
  This study enrolled 110 knees in 81 patients after TKA. AP laxity was measured with a KS Measure Arthrometer at 30°, 60°, and 90° flexion, which was confirmed with a goniometer. We assessed knee pain and function by using the Knee Society Function Score (KSS) and Knee Injury and Osteoarthritis Outcome Score (KOOS). Correlations among AP translation values and KOOS subscale scores (pain symptom, activities of daily living, and knee-related quality of life), KSS, and range of motion (ROM) were analyzed.
  
  
  
  The mean follow-up period for the assessment of the KOOS was 4.4 ± 2.2 years (range, 1.1-11.5 years). Twenty-five knees had posterior-stabilized fixed-bearing TKA, and 85 knees had posterior-stabilized mobile-bearing TKA. The mean KSS functional score and mean ROM were 96.3 ± 5.7 (range, 75-100) and 121.6° ± 14.4° (range, 90°-145°), respectively. The mean AP laxity was 4.5 ± 2.2 mm, 3.6 ± 1.9 mm, and 3.0 ± 1.9 mm at 30°, 60°, and 90° knee flexion, respectively. A significant inverse association was observed between AP laxity at 60° knee flexion and KOOS pain (P = .02∗, R2= 0.05), but no significant association was found between AP laxity and other KOOS subscale score, KSS, and ROM.
  
  
  
  We found that the AP laxity at 60° knee flexion in this study significantly correlated with patient-reported pain. The observed AP laxity can be considered as a register of normal AP translations after arthroplasty.
authors.affiliation: Department of Orthopedic Surgery, Gifu University Graduate School of Medicine, Gifu, Japan.
authors.forename: Kazu
authors.initials: K
authors.lastname: Matsumoto
authors.affiliation: Department of Orthopedic Surgery, Gifu University Graduate School of Medicine, Gifu, Japan.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Ogawa
authors.affiliation: Department of Orthopedic Surgery, Gifu University Graduate School of Medicine, Gifu, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Yoshioka
authors.affiliation: Department of Orthopedic Surgery, Gifu University Graduate School of Medicine, Gifu, Japan.
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Akiyama
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D053587:Arthrometry, Articular / Q000706:statistics & numerical data*; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects* / Q000523:psychology; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000209:etiology* / Q000523:psychology; D007719:Knee Joint / Q000502:physiology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery; D000071066:Patient Reported Outcome Measures; D011184:Postoperative Period; D011788:Quality of Life; D016059:Range of Motion, Articular
keywords: KOOS; anteroposterior laxity; patient satisfaction; stability; total knee arthroplasty