title: The role of knee joint moments and knee impairments on self-reported knee pain during gait in patients with knee osteoarthritis.
abstract: BACKGROUND
  The association between high mechanical knee joint loading during gait with onset and progression of knee osteoarthritis has been extensively studied. However, less attention has been given to risk factors related to increased pain during gait. The purpose of this study was to evaluate knee joint moments and clinical characteristics that may be associated with gait-related knee pain in patients with knee osteoarthritis.
  
  
  METHODS
  Sixty-seven participants with knee osteoarthritis were stratified into three groups of no pain (n=18), mild pain (n=27), or moderate/severe pain (n=22) based on their self-reported symptoms during gait. All participants underwent three-dimensional gait analysis. Quadriceps strength, knee extension range of motion, radiographic knee alignment and self-reported measures of global pain and function were also quantified.
  
  
  RESULTS
  The moderate/severe pain group demonstrated worse global pain (P<0.01) and physical function scores (P<0.01) compared to the no pain and the mild pain groups. The moderate/severe pain group also walked with greater knee flexion moments during the midstance phase of gait compared to the no pain group (P=0.02). Additionally, the moderate/severe pain group demonstrated greater varus knee malalignment (P=0.009), which was associated with higher weight acceptance peak knee adduction moments (P=0.003) and worse global pain (P=0.003) and physical function scores (P=0.006).
  
  
  CONCLUSIONS
  Greater knee flexion moment is present during the midstance phase of gait in patients with knee osteoarthritis and moderate/severe pain during gait. Additionally, greater varus malalignment may be a sign of increased global knee joint dysfunction that can influence many activities of daily living beyond gait.
authors.affiliation: Solutions Physical Therapy & Sports Medicine, Alexandria, VA, USA.
authors.forename: Megan
authors.initials: M
authors.lastname: O'Connell
authors.affiliation: Human Movement Research Laboratory, University of Pittsburgh, Pittsburgh, PA, USA; Departments of Physical Therapy and Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA. Electronic address: Farrokhi@pitt.edu.
authors.forename: Shawn
authors.initials: S
authors.lastname: Farrokhi
authors.affiliation: Department of Physical Therapy, University of Pittsburgh, Pittsburgh, PA, USA; Physical Therapy and Clinical and Translational Research Center, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: G Kelley
authors.initials: GK
authors.lastname: Fitzgerald
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D018450:Disease Progression; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000503:physiopathology*; D010146:Pain / Q000503:physiopathology*; D052097:Quadriceps Muscle / Q000503:physiopathology; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology; D016138:Walking / Q000502:physiology; D016474:Weight-Bearing / Q000502:physiology
keywords: Biomechanics; Knee joint moment; Knee pain; Osteoarthritis; Three-dimensional gait