Biomechanical adaptation to compensate balance recovery in people with knee osteoarthritis.

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Older adults with knee osteoarthritis are twice as likely to fall compared to healthy counterparts. Furthermore, in healthy older adults, greater trunk flexion is associated with increased falling. While spatio-temporal and strength measures have been connected to balance dysfunction in osteoarthritis, to date no studies have investigated compensation of both upper and lower body kinematics on balance recovery in this population. Forty-eight older people with knee osteoarthritis (age 71.02±6.76years, 54% females, BMI 29.10±4.58) and 15 asymptomatic controls (age 72.47±4.81, 27% females, BMI 26.17±3.06) completed balance recovery during a simulated forwards fall. Ankle, knee, hip, trunk and head kinematics were collected and analysed using three trial types (no additional, cognitive dual-task and physical dual-task). Two-way MANCOVA were conducted to identify group differences in ankle, knee, hip, and trunk angle, and head position (control and knee osteoarthritis), trial differences (no additional, cognitive and physical dual-task) and group by trial differences. Postural differences in older adults with knee osteoarthritis included greater knee flexion (p=.02) and lower hip and trunk flexion (p<.01). Following a simulated fall, older adults with knee osteoarthritis showed greater knee flexion at first contact which might suggest inability to resist forwards motion of the body.The more extended hip in this group and the resulting compensation of the upper body posture may lead to no difference in number of steps taken when compared to controls.