Immediate effects of unilateral restricted ankle motion on gait kinematics in healthy subjects

Correcting a pathological toe walking gait pattern can be achieved by restricting excessive plantarflexion during the swing phase of gait. A common conservative treatment measure is providing the patient with an ankle-foot-orthosis on the affected lower leg. This study examined the lower body gait kinematics and temporal-spatial parameters of fifteen healthy adults when walking freely and with unilateral restricted ankle motion. The latter was achieved by fitting an ankle-foot-orthosis. Specific hip and knee kinematic parameters and temporal-spatial parameters were investigated. Differences between the two conditions were calculated by paired Student's t-tests and 95% confidence intervals. Unilateral restricted ankle motion influenced kinematics mainly in the swing phase. Hip and knee peak flexion in the swing phase were increased on the restricted side (hip: 49.2° (SD 4.2°), knee: 75.9° (SD 6.1°)) compared to walking freely (hip: 43.3° (SD 4.5°), knee: 66.7° (SD 5.3°)). Peak hip flexion occurred earlier in the swing phase in the restricted condition (85% (SD 2%)) compared to the free-walking condition (96% (SD 5%)). For these parameters, the confidence intervals were different, indicating clinical relevance. Walking with unilateral restricted ankle motion had a negative effect on walking velocity, cadence, step time, and step length. The confidence intervals, however, overlapped. These results might be a reaction to unusual sensory feedback from the feet with the ankle-foot-orthosis or due to increased hip flexor activity compensating for the reduced function of the plantarflexors. The evaluation of the immediate changes in unilateral restricted ankle motion in individuals with healthy gaits can contribute to a more complete understanding on this topic.