Individual joint contributions to forward propulsion during treadmill walking in women with hip osteoarthritis

As we age, reliance on the ankle musculature for push-off during walking reduces and increased reliance on the hip musculature is observed. It is unclear how joint pathology like osteoarthritis may affect this distal-to-proximal redistribution of propulsion. Here, we revisited a proof-of-concept study to study the effect of split-belt treadmill training, designed to reduce step length asymmetry, on forward propulsion during walking. Eleven women with hip osteoarthritis and five age-matched control participants walked on an instrumented split-belt treadmill at their preferred speed (hip osteoarthritis: 0.73 ± 0.11 m/s; controls: 0.59 ± 0.26 m/s). Women with hip osteoarthritis had less ankle power and propulsive force than controls, and greater hip contributions to forward propulsion on their involved limb. Following split-belt treadmill training, propulsive force increased on the involved limb. Five of 11 participants experienced a change in redistribution ratio that was greater than the minimal clinically meaningful difference. These "responders" had greater variability in pre-training redistribution ratio compared to non-responders. Women with hip osteoarthritis had poorer propulsive gait mechanics than controls yet split-belt treadmill training improved propulsive force. Redistribution ratio also changed in participants with high baseline variability. Our results suggest that split-belt treadmill training may be beneficial to people with hip osteoarthritis who have high variability in walking parameters. Further, the age-related shift to increased hip contributions to propulsion across populations of older adults may be due to increased variability during walking.