title: The association between submaximal quadriceps force steadiness and the knee adduction moment during walking in patients with knee osteoarthritis.
abstract: METHODS
  Cross-sectional study.
  
  
  OBJECTIVE
  To investigate the relationship between quadriceps force steadiness and knee adduction moment during walking in patients with knee osteoarthritis (OA).
  
  
  BACKGROUND
  Studies have shown that quadriceps force steadiness is impaired in patients with knee OA. Furthermore, patients with knee OA, compared to healthy controls, have also demonstrated a significantly higher external knee adduction moment during walking. However, no studies have examined the relationship between quadriceps force steadiness and the peak knee adduction moment during walking in this population.
  
  
  METHODS
  Forty-one patients with knee OA (34 females and 7 males) were included in the study. Submaximal isometric quadriceps force steadiness was measured during a force target-tracking task. Peak knee adduction moments during ambulation were measured using a 3-dimensional gait analysis system, and knee pain was assessed using the Knee Injury and Osteoarthritis Outcome Score (KOOS) pain subscale and a visual analog scale.
  
  
  RESULTS
  Regression analyses showed that quadriceps force steadiness did not predict the peak knee adduction moment (adjusted R2 = 0.05, P = .41). Inclusion of covariates did not change the outcome.
  
  
  CONCLUSIONS
  No statistically significant association between submaximal isometric quadriceps force steadiness and peak knee external adduction moments during walking was found. It could be speculated that submaximal isometric quadriceps muscle force steadiness and knee joint loads during walking represent 2 distinctive pathways and may have independent influences on knee OA pathogenesis.
authors.affiliation: Clinical Motor Function Laboratory, The Parker Institute, Frederiksberg Hospital, Frederiksberg, Denmark.
authors.forename: Tina Juul
authors.initials: TJ
authors.lastname: Sørensen
authors.forename: Henning
authors.initials: H
authors.lastname: Langberg
authors.forename: Jens
authors.initials: J
authors.lastname: Aaboe
authors.forename: Thomas
authors.initials: T
authors.lastname: Bandholm
authors.forename: Henning
authors.initials: H
authors.lastname: Bliddal
authors.forename: Marius
authors.initials: M
authors.lastname: Henriksen
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000503:physiopathology*; D052097:Quadriceps Muscle / Q000503:physiopathology*; D016138:Walking / Q000502:physiology*