title: Biomechanical and neuromuscular adaptations during the landing phase of a stepping-down task in patients with early or established knee osteoarthritis.
abstract: BACKGROUND
  To compare the knee joint kinematics, kinetics and EMG activity patterns during a stepping-down task in patients with knee osteoarthritis (OA) with control subjects.
  
  
  METHODS
  33 women with knee OA (early OA, n=14; established OA n=19) and 14 female control subjects performed a stepping-down task from a 20cm step. Knee joint kinematics, kinetics and EMG activity were recorded on the stepping-down leg during the loading phase.
  
  
  RESULTS
  During the stepping-down task patients with established knee OA showed greater normalized medial hamstrings activity (p=0.034) and greater vastus lateralis-medial hamstrings co-contraction (p=0.012) than controls. Greater vastus medialis-medial hamstrings co-contraction was found in patients with established OA compared to control subjects (p=0.040) and to patients with early OA (p=0.023). Self-reported knee instability was reported in 7% and 32% of the patients with early and established OA, respectively.
  
  
  CONCLUSIONS
  The greater EMG co-activity found in established OA might suggest a less efficient use of knee muscles or an attempt to compensate for greater knee laxity usually present in patients with established OA. In the early stage of the disease, the biomechanical and neuromuscular control of stepping-down is not altered compared to healthy controls.
authors.affiliation: Injury Prevention Centre, School of Public Health, University of Alberta, Canada.
authors.forename: Diana C
authors.initials: DC
authors.lastname: Sanchez-Ramirez
authors.affiliation: Musculoskeletal Rehabilitation Research Group, Department of Rehabilitation Sciences, Faculty of Kinesiology and Rehabilitation Sciences, KU Leuven, Belgium.
authors.forename: Bart
authors.initials: B
authors.lastname: Malfait
authors.affiliation: Musculoskeletal Rehabilitation Research Group, Department of Rehabilitation Sciences, Faculty of Kinesiology and Rehabilitation Sciences, KU Leuven, Belgium; Department of Rehabilitation Sciences and Physiotherapy, Faculty of Medicine and Health Sciences, University of Antwerp, Belgium; Pain in Motion Research Group (www.paininmotion.be), Belgium.
authors.forename: Isabel
authors.initials: I
authors.lastname: Baert
authors.affiliation: Amsterdam Rehabilitation Research Centre Reade, Amsterdam, The Netherlands.
authors.forename: Marike
authors.initials: M
authors.lastname: van der Leeden
authors.affiliation: MOVE Research Institute Amsterdam, Faculty of Human Movement Sciences, VU University Amsterdam, The Netherlands.
authors.forename: Jaap
authors.initials: J
authors.lastname: van Dieën
authors.affiliation: VU University Medical Center, Department of Rheumatology, Amsterdam, The Netherlands.
authors.forename: Willem F
authors.initials: WF
authors.lastname: Lems
authors.affiliation: VU University Medical Center, Department of Rehabilitation Medicine, Amsterdam, The Netherlands.
authors.forename: Joost
authors.initials: J
authors.lastname: Dekker
authors.affiliation: Skeletal Biology & Engineering Research Center, Faculty of Medicine, KU Leuven, Belgium.
authors.forename: Frank P
authors.initials: FP
authors.lastname: Luyten
authors.affiliation: Musculoskeletal Rehabilitation Research Group, Department of Rehabilitation Sciences, Faculty of Kinesiology and Rehabilitation Sciences, KU Leuven, Belgium. Electronic address: sabine.verschueren@faber.kuleuven.be.
authors.forename: Sabine
authors.initials: S
authors.lastname: Verschueren
mesh_terms: D000222:Adaptation, Physiological; D000368:Aged; D001696:Biomechanical Phenomena; D004576:Electromyography; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D007719:Knee Joint / Q000503:physiopathology*; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology*; D020370:Osteoarthritis, Knee / Q000503:physiopathology*; D013647:Task Performance and Analysis
keywords: Biomechanics; Knee instability; Muscle strength; Osteoarthritis; Stepping-down