Identification of movement strategies during the sit-to-walk movement in patients with knee osteoarthritis

Patients with osteoarthritis of the knee commonly alter their movement to compensate for lower limb weakness and alleviate joint pain. Movement alterations may lead to weight-bearing asymmetries, and potentially to the progression of the disease. This study presents a novel numerical procedure for the identification of sit-to-walk strategies and differences in movement habits between control adults and persons with knee osteoarthritis. Ten control and 12 participants with osteoarthritis performed the sit-to-walk task in a motion capture laboratory. Participants sat on a stool with the height adjusted to 100% of their knee height, then stood and walked to pick up an object from a table in front of them. Different movement strategies were identified by means of hierarchical clustering. Trials were also classified as to whether the left and right extremities used a bilateral or an asymmetrical strategy. Participants with osteoarthritis used significantly more asymmetrical arm strategies (P = .03) while adopting the pushing through the chair strategy more often than the control subjects (P = .02). The results demonstrated that the 2 groups favor different sit-to-walk strategies. Asymmetrical arm behavior possibly indicates a compensation for the weakness of the affected leg. The proposed procedure may be useful to rapidly assess postoperative outcomes and developing rehabilitation strategies.