Design and Pilot Study of a Gait Enhancing Mobile Shoe

Abstract

Hemiparesis is a frequent and disabling consequence of stroke and can lead to asymmetric and inefficient walking patterns. Training on a split-belt treadmill, which has two separate treads driving each leg at a different speed, can correct such asymmetries post-stroke. However, the effects of split-belt treadmill training only partially transfer to everyday walking over ground and extended training sessions are required to achieve long-lasting effects. Our aim is to develop an alternative device, the Gait Enhancing Mobile Shoe (GEMS), that mimics the actions of the split-belt treadmill, but can be used during overground walking and in one's own home, thus enabling long-term training. The GEMS does not require any external power and is completely passive; all necessary forces are redirected from the natural forces present during walking. Three healthy subjects walked on the shoes for twenty minutes during which one GEMS generated a backward motion and the other GEMS generated a forward motion. Our preliminary experiments suggest that wearing the GEMS did cause subjects to modify coordination between the legs and these changes persisted when subjects returned to normal over-ground walking. The largest effects were observed in measures of temporal coordination (e.g., duration of double-support). These results suggest that the GEMS is capable of altering overground walking coordination in healthy controls and could potentially be used to correct gait asymmetries post-stroke.

Keywords: adaptation; asymmetric gait; hemiparesis; learning; locomotion; rehabilitation; shoe.

Figures

Figure 1

The Gait Enhancing Mobile Shoe is designed to generate a motion relative to ground. The shoe pictured here generates a forward motion during the stance phase. A similar shoe with the wheels facing the opposite direction can generate a backward motion.

Figure 2

The four phases of walking relevant to the Gait Enhancing Mobile Shoe design are shown above for a typical walking pattern (top) and when walking on the backward moving GEMS (bottom). Although not shown here, the shoe can be constructed to generate a forward motion.

Figure 3

The horizontal (fore-aft) and vertical forces change throughout the gait cycle. Our GEMS uses these changing forces to generate the necessary motions for altering gait patterns. The shaded regions represent the standard deviation of seven steps.

Figure 4

GEMS wheel shape (A) The shape of the wheel is defined as an Archimedean spiral. This shape redirects the downward force to generate a forward or backward motion. (B) Parameters: R is the instantaneous radius and L is the distance from ground contact to wheel center.

Figure 4

GEMS wheel shape (A) The shape of the wheel is defined as an Archimedean spiral. This shape redirects the downward force to generate a forward or backward motion. (B) Parameters: R is the instantaneous radius and L is the distance from ground contact to wheel center.

Figure 5

Forward moving GEMS top view schematic of Unidirectional Damper and Reset Mechanism. (1) Unidirectional Damper, (2) Steel Chain, (3) Reset Spring, (4) Reset Pulley, and (5) GEMS Wheel.

Figure 6

Experimental paradigm. Solid lines show periods that were recorded. The dashed line (adaptation) was not recorded. Subjects wore the GEMS during the red periods, and walked in normal sneakers for the black periods (Baseline and Post-Adaptation). All of the recorded periods consisted of ten trials. A trial was equivalent to 1 pass across the over ground walking path, which took 8–12 steps. The unrecorded adaptation period (dashed line) lasted 10 min, which was equivalent to 309.3 ± 56.5 steps (mean ± SD).

Figure 7

(A) Step length is defined as the distance between malleolus (ankle) markers at the instant of heel strike, as shown in the stick figure, and was defined as right (red) or left (black) depending on which leg was leading. Note that the forward-rolling GEMS was on the right foot, and the backward-rolling GEMS on the left. (B) Double support duration during stride cycle. Stance and swing phases are represented by solid and dashed lines, respectively (red = right; black = left). Double support occurs when both feet are contacting the ground (shown by shaded boxes), and is termed “right” or “left” by the limb stance which it follows. (C) Single-subject data showing the average difference in step length (right-left; ± standard deviation), during baseline (BL), early adaptation (EA), late adaptation (LA), and post-adaptation (PA). (D) Single-subject differences in double support duration, as shown in C. Double support difference was calculated by subtracting the duration of right double support (expressed as a percent of stride cycle) from the duration of left double support. (E) Summary of single-subject and group-averaged differences in step length between baseline (blue diamonds) and post-adaptation (red squares). Error bars show 1 standard deviation (F) Summary of single-subject and group-averaged differences in double support time between baseline and post-adaptation, as shown in E.