Article

Residual hip impairments, such as decreased hip muscle moment and power during
walking, have been reported in patients with total hip arthroplasty (THA).
Meanwhile, greater ankle power has also been reported in these patients. We
investigated the interaction between hip and ankle joints during walking to
determine the effects of different ankle pushoff instructions on hip biomechanics
in patients with THA. Twenty-four women (age, 60.8+/-5.5 years) were randomly
assigned to walking exercise groups with either decreased pushoff or increased
pushoff. Patients in the decreased pushoff group and increased pushoff group were
given the instructions "push less with your foot when you walk" and "push more
with your foot when you walk," respectively. Exercises lasted approximately 10-15
min. A series of gait-related parameters were analyzed during pre-exercise,
exercise, and post-exercise session. In the decreased ankle pushoff group, hip
flexor power absorption and hip/ankle power ratio were higher during
post-exercise than during pre-exercise. An increase in hip power from -9.8% to
32.1% was identified. The effect of increase in the hip power by the decreasing
ankle pushoff was higher in the patients with greater ankle pushoff in their
natural gaits. The patients in the increased ankle pushoff group showed decreased
hip flexion angle and hip muscle moment and power after the walking exercise,
although ankle pushoff was not increased. Walking exercise with decreased ankle
pushoff may help improve the distribution of muscle power between hip flexors and
ankle plantarflexors during walking in patients with THA.
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