A Study of the Lower Limbs Movement of Elderly Adults by Vibratory Somatosensory Stimulation Applied to the Ankle Tendon

Normal walking on staircases is a very important ordinary activity. It is a complicated motion that requires a big muscular strength and moment, and a big joint exercise scope. Due to such characteristics, staircase walking may be an obstacle to those with weakened lower limb muscle strength, and actually, fall injury accidents occur. Existing studies focus on dynamic changes in staircase walking. However, this study aimed to analyze staircase-walking characteristics evidenced when applying vibratory somatosensory stimulus to the ankle joint in a bid to reduce the risk of fall injuries associated with staircase walking. Five elderly male subjects, who had no disease related to the musculoskeletal system, participated in experiments. Experiments were held in a motion analysis laboratory equipped with 3-D motion analysis systems, force platforms, etc. In order to gather motion data, subjects wore markers and vibratory stimulation devices designed to apply somatosensory stimulus to ankle joints, and climbed down a staircase with the height adjusted appropriately. Using motion data gathered from staircase-walking, the ankle joint, knee joint and hip joint angles were obtained, and thus each joint's contribution to the motion was calculated. In the case of vibratory somatosensory stimuli being applied to the Achilles's tendon, the ankle joint contributed more to the motion of climbing down a staircase than the knee joint and the hip joint did. On the other hand, in the case of vibratory somatosensory stimulus being applied to the anterior tibialis, the ankle joint contribution was lowered, and to make up for it, the knee joint and the hip joint contribution increased. This outcome revealed that the effect of the vibratory somatosensory stimulation applied to the ankle joint can appear in not only the ankle joint, but also in the whole lower limbs due to chain reaction.

Hip Contact Stress during Normal and Staircase Walking: The Influence of Acetabular Anteversion Angle and Lateral Coverage of the Acetabulum

Hip contact stress is considered to be an important biomechanical factor related to development of coxarthrosis. The effect of the lateral coverage of the acetabulum on the hip contact stress has been demonstrated in several studies of hip dysplasia, whereas the effect of the anterior anteversion remains unclear. Therefore, the joint hip contact stress during normal level walking and staircase walking, in normal and dysplastic hips, for small and large acetabular anteversion angle was computed. For small acetabular anteversion angle, the hip contact stress is slightly increased (less than 15%) in staircase walking when compared with normal walking. In hips with large angle of acetabular anteversion, walking downstairs significantly increases the maximal peak contact stress (70% in normal hips and 115% in dysplastic hips) whereas walking upstairs decreases the peak contact stress (4% in normal hips and 34% in dysplastic hips) in comparison to normal walking. Based on the presented results, we suggest that the acetabular anteversion should be considered in biomechanical evaluation of the hips, especially when the lateral coverage of the acetabulum is small.