A study of the influence of hip OA related gait impairments on the efficiency of gait and a possible rehabilitation strategy was carried out using a proof-of-concept approach. Gait analysis and oxygen consumption testing during walking on the treadmill was conducted with 24 women with unilateral hip OA. Additionally, split-belt treadmill training was conducted with 10 women with unilateral hip OA. Information on demographics, kinematics, kinetics, and metabolic cost were collected in both studies.

The purpose of Aim 1 study was to evaluate whether reduced sagittal plane hip ROM and peak ankle plantar flexor moment are associated with increased step length asymmetry in hip OA patients. The participants with hip OA who demonstrated a greater step length asymmetry presented with lower sagittal plane hip ROM during gait. Additionally, sagittal plane hip ROM during gait predicted step length asymmetry when self-selected walking speed was not in the model. This indicated that sagittal plane hip ROM during gait might contribute to the step length asymmetry.

The objective of the Aim 2 study was to evaluate the consequences of step length asymmetry on COM and the energy cost of walking. Increased step length asymmetry was associated with lower mechanical energy exchange in people with hip OA. In addition, more mechanical energy exchange was associated with lower O2 cost during gait. These findings suggest that modifying step length asymmetry could enhance metabolic gait efficiency indirectly by improving mechanical energy exchange in women with hip OA.

The purpose of Aim 3 study was to determine whether modifying step length through split-belt treadmill training improved gait efficiency in people with hip OA. At the end of adaptation period of split-belt treadmill training, step length asymmetry and O2 rate significantly decreased, while mechanical energy exchange increased from the baseline to the end of the adaptation period. Moreover, reduction of step length asymmetry was significantly associated with reduction of O2 rate. These findings suggest that modifying step length asymmetry by split-belt treadmill could be a potential rehabilitation strategy to improve gait efficiency in people with hip OA.

Step length asymmetry is a modifiable factor associated with gait inefficiency and kinematic deviation in older adults with hip OA. Modifying step length asymmetry by splitbelt treadmill training could be a rehabilitation strategy to improve gait efficiency. This is the first time, linked OA-associated gait impairments to the efficiency of gait and explore a possible rehabilitation strategy. Improving gait efficiency could potentially facilitate better physical activity level in people with hip OA.