Balance. Dynamic standing balance was assessed with the step test, a reliable and valid measure in older people (ICC .9)29 that is sensitive enough to discriminate between those with knee OA and those without knee OA.30 Participants stood barefoot on the osteoarthritic limb in front of a 7.5-cm step and were instructed to move the opposite foot on and off the step as many times as
possible over 15 seconds. This test does not require the participant to move body weight over the step but simply to perform a potentially destabilizing foot placement activity.
The number of times the participant could place the foot on the step and return it to the floor was recorded, with higher scores indicating better balance.