Response of able-bodied persons to changes in shoe rocker radius during walking: Changes in ankle kinematics to maintain a consistent roll-over shape

Abstract

Recent studies have determined a seemingly consistent feature of able-bodied level ground walking termed the roll-over shape, which is the effective rocker (cam) shape that the lower limb system conforms to between heel contact and contralateral heel contact during walking (first half of the gait cycle). The roll-over shape has been found to be largely unaffected by changes in walking speed, load carriage, and shoe heel height. However, it is unclear from previous studies whether persons are controlling their lower limb systems to maintain a consistent roll-over shape or whether this finding is a byproduct of their attempt to keep ankle kinematic patterns similar during the first half of the gait cycle. We measured the ankle-foot roll-over shapes and ankle kinematics of eleven able-bodied subjects while walking on rocker shoes of different radii. We hypothesized that the ankle flexion patterns during single support would change to maintain a similar roll-over shape. We also hypothesized that with decreasing rocker shoe radii, the difference in ankle flexion between the end and beginning of single support would decrease. Our results supported these hypotheses. Ankle kinematics were changed significantly during walking with the different rocker shoe radii (p < 0.001), while ankle-foot roll-over shape radii (p = 0.146) and fore-aft position (p = 0.132) were not significantly affected. The results of this study have direct implications for designers of ankle-foot prostheses, orthoses, walking casts/boots, and rocker shoes. The results may also be relevant to researchers studying control of human movements.

Differentiation between solid-ankle cushioned heel and energy storage and return prosthetic foot based on step-to-step transition cost

“…For each subject and foot type, roll-over shapes were determined by transforming the COP data from a laboratory-based reference frame to the three-dimensional shank-based coordinate system [21]. Because the COP data progress forward from heel to toe during stance, while the shank is rotated over the foot, the roll-over shapes can be modeled as the lower half of a circle in the shank's plane of progression.…”

Posture Analysis of Various Types of Crutch Gait of Healthy Volunteers

“…Similarly, the present study found no significant differences between the male and female subjects. In a study that analyzed the gaits of persons who were wearing gait assisters with flat shoe soles and those who were wearing gait assisters with slightly bent shoe soles, signifi- cant differences were reported in the dorsal flexion of the ankle and gait velocity which were related to the degrees of flatness and bend of the shoe soles 25) . Gait velocity would increase if the shoe soles of crutch walkers had bent heels to facilitate heel strikes during four-point crutch gait, which is slow but the safest for persons using crutches.…”

Segmental contributions to the ground reaction force in the single support phase of gait

“…Their experimental studies found that the AFROS remains the same irrespective of changes in walking speed , heel height and load carriage (Hansen and Childress, 2005). They also found that a person controls the ankle kinematics to maintain a consistent ROS (Wang and Hansen, 2010) and that in the case of a trans-tibial prosthesis user, an alignment for better walking performance for a given type of prosthetic foot can be determined using this ROS (Hansen et al, 2000). Srinivasan et al (2009) used Hansen's ROS in a forward dynamics model for the gait of trans-tibial prosthesis users.…”