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).
Conclusion: 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.