title: Alteration in multijoint dynamics in patients with bilateral knee osteoarthritis.
abstract: OBJECTIVE
  To document the alterations of joint motion and torque in patients with bilateral knee osteoarthritis (OA), using a well-defined functional maneuver, the sit-to-stand (STS) task.
  
  
  METHODS
  Twelve patients with bilateral knee OA and 12 age-, sex-, and height-matched control subjects performed the STS maneuver from a stool of a standard height at their natural speeds. A motion analysis system and 2 force platforms were employed to determine the dynamic joint motion and the resultant joint torques at the ankle, knee, and hip joints.
  
  
  RESULTS
  The results showed that OA patients exhibited substantially reduced knee extension torques, accompanied by other alterations in initial sitting posture (more extended knee and more plantar-flexed ankle), movement duration (increased), dynamic range of motion at the knee (reduced), and extension torques at the hip (increased).
  
  
  CONCLUSIONS
  The alterations in joint dynamics among patients with knee OA may have revealed an adaptive motor behavior characterized by redistributing the load from impaired to less-impaired or nonimpaired joints through multijoint dynamics. Two major potential pitfalls of such a movement strategy have subsequently been postulated.
authors.affiliation: Programs in Physical Therapy, Northwestern University Medical School, Chicago, IL 60611.
authors.forename: Y C
authors.initials: YC
authors.lastname: Pai
authors.forename: H J
authors.initials: HJ
authors.lastname: Chang
authors.forename: R W
authors.initials: RW
authors.lastname: Chang
authors.forename: J M
authors.initials: JM
authors.lastname: Sinacore
authors.forename: J L
authors.initials: JL
authors.lastname: Lewis
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D007596:Joints / Q000503:physiopathology*; D007719:Knee Joint; D008297:Male; D008875:Middle Aged; D009038:Motion; D010003:Osteoarthritis / Q000503:physiopathology*; D011187:Posture; D012016:Reference Values; D013997:Time Factors