title: Difference in knee rotation between total and unicompartmental knee arthroplasties during stair climbing.
abstract: OBJECTIVE
  The purpose of this study was to compare knee kinematics during stair walking in patients with simultaneous total knee arthroplasty (TKA) and unicompartmental knee arthroplasties (UKA). It was hypothesized that UKA would reproduce more normalized knee kinematics than TKA during stair ascent and descent.
  
  
  METHODS
  Six patients who received UKA in one knee and TKA in the other knee were included in the study. For this study, a four-step staircase was assembled with two force platforms being positioned at the centre of the second and third steps. Each patient was attached with 16 reflective markers at both lower extremities and was asked to perform five roundtrip trials of stair climbing. Kinematic parameters including stance duration, knee angle, vertical ground reaction force (GRF), joint reaction force, and moments were obtained and analysed using a10-camera motion system (VICON, Oxford, UK). Nonparametric Friedman test was used to compare the results between two arthroplasty methods and between stair ascent and descent.
  
  
  RESULTS
  Compared to TKA, UKA knees exhibited significantly greater degree of rotation in transverse planes (5.0 degrees during ascent and 6.0 degrees during descent on average), but showed no difference in terms of the other parameters. When comparing the results during stair ascent with descent, overall greater knee angle, vertical GRF, joint reaction force, and moment were observed during stair descent.
  
  
  CONCLUSIONS
  Both UKA and TKA knees have shown overall similar knee kinematics, though UKA knee may allow greater degree of rotation freedom, which resembles normal knee kinematics during stair walking.
authors.affiliation: Department of Industrial Engineering, Ajou University College of Engineering, Suwon, South Korea.
authors.forename: Myung-Chul
authors.initials: MC
authors.lastname: Jung
authors.forename: Jun Young
authors.initials: JY
authors.lastname: Chung
authors.forename: Kwang-Hyun
authors.initials: KH
authors.lastname: Son
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.forename: Jaejin
authors.initials: J
authors.lastname: Hwang
authors.forename: Jay Joong
authors.initials: JJ
authors.lastname: Kim
authors.forename: Joon Ho
authors.initials: JH
authors.lastname: Kim
authors.forename: Byoung-Hyun
authors.initials: BH
authors.lastname: Min
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D001696:Biomechanical Phenomena; D005260:Female; D005684:Gait / Q000502:physiology; D006801:Humans; D007717:Knee / Q000503:physiopathology / Q000601:surgery; D007719:Knee Joint / Q000503:physiopathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000503:physiopathology* / Q000601:surgery; D016059:Range of Motion, Articular; D012399:Rotation; D016138:Walking / Q000502:physiology