ALTERATION IN MULTIJOINT DYNAMICS IN PATIENTS WITH BILATERAL KNEE OSTEOARTHRITIS

Objective. To document the alterations of joint motion and torque in p atients with bilateral knee osteoarthritis (OA), using a well-defined functional maneuver, the sit-to-stand (STS) task. Methods. Twelve pati ents with bilateral knee OA and 12 age-, sex-, and height-matched cont rol subjects performed the STS maneuver from a stool of a standard hei ght at their natural speeds. A motion analysis system and 2 force plat forms were employed to determine the dynamic joint motion and the resu ltant joint torques at the ankle, knee, and hip joints. Results. The r esults showed that OA patients exhibited substantially reduced knee ex tension torques, accompanied by other alterations in initial sitting p osture (more extended knee and more plantar-flexed ankle), movement du ration (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 ad aptive motor behavior characterized by redistributing the load from im paired to less-impaired or nonimpaired joints through multijoint dynam ics. Two major potential pitfalls of such a movement strategy have sub sequently been postulated.