The objective of this research is to test a passive shoe capable of to test the capability of a mobile shoe to enhance gait improvements in individuals with asymmetric walking patterns. Individuals with central nervous system damage, such as stroke, often have irregular walking patterns and have difficulty walking correctly. Recent research has shown that using a split-belt treadmill can create after-effects that temporarily correct the inefficient walking patterns. However, the corrected walking pattern does not efficiently transfer from the treadmill to walking over ground. The Gait Enhancing Mobile Shoe (GEMS) may allow a patient to practice walking in many different locations, such as their own home, which we hypothesize will result in a more permanent transfer of learned gait patterns. To enable long-term use, our proposed shoe design is passive and uses the wearer's natural forces exerted while walking to generate the necessary motions.
Hemiparesis and other impairments are 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 gait asymmetries post-stroke (Reisman et al. 2005, Reisman et al. 2007). 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 (Reisman et al. 2009). Our previous studies suggest that the Gait Enhancing Mobile Shoe (GEMS) that has been developed in our laboratory can be used as an alternative gait training device for people with stroke (Handzic, Reed, and colleagues 2011, 2011, 2012, 2013). The GEMS mimics the actions of the split-belt treadmill, but can be used during over-ground walking and in one's own home, thus enabling long-term training. This GEMS does not require any external power and is completely passive; all necessary forces are redirected from the natural forces present during walking since it utilizes the wearer's weight to generate its movements. While the movements of the GEMS are similar to the split belt treadmill, and the GEMS generates a similar aftereffect, the efficacy of this shoe in modifying the gait of an individual with stroke is not yet verified. This research aims to test the GEMS on individuals with stroke to determine if the related effects that show up on healthy subjects can benefit individuals with stroke.
In this study, we will test the efficacy of the GEMS on individuals with stroke. Efficacy will be evaluated based on the change in gait coordination and also based on subjects' self-reported comfort on the device. We predict that the GEMS will result in changes to interlimb coordination of gait. Note that this is a efficacy study, not an effectiveness or safety study of the device; this distinction is made clear in a paper by Singal et al. (2014).
The asymmetric nature of hemiparetic gait can have a large impact on functional walking ability. For example, swing phase asymmetry is a significant predictor of hemiparetic walking performance because it strongly correlates with stages of motor recovery, walking speed, and falls (Brandstater et al. 1983; Titianova and Tarkka 1995). Another measure of temporal asymmetry - double support duration - is similarly correlated with walking speed (Olney et al. 1994). In addition, spatial (e.g. step length) asymmetry is associated with decreased propulsive force on the paretic leg (Balasubramanian et al. 2007; Bowden et al. 2006), which limits forward motion of the body and reduces gait efficiency (Brouwer et al. 2009; Kahn and Hornby 2009). The importance of gait efficiency should not be understated - the elevated energy demands of hemiparetic gait combined with physical deconditioning post-stroke can greatly limit performance of activities of daily living, contributing to poor cardiovascular fitness and metabolic syndrome. In turn, this can increase the risks of a second stroke or cardiovascular event and is associated with increased morbidity and mortality rates (Ivey et al., 2005). Therefore, improving gait symmetry should be an important goal for therapy, to not only improve functional mobility and reduce injury, but also to enhance general health and well-being post-stroke.
Practicing walking on a split-belt treadmill can correct abnormal interlimb coordination of gait in individuals with hemiparesis following stroke or other central nervous system lesions (Reisman et al. 2005, Reisman et al. 2007). Asymmetric gait can manifest as a spatial asymmetry, in which steps taken on one side are longer than those on the other. It can also manifest as a temporal asymmetry, where the timing is uneven on the paretic and non-paretic sides. Temporal asymmetries are often measured as differences in the duration of double support periods, which are the amount of time both feet are simultaneously contacting the ground and are measured separately for the paretic and non-paretic sides. The GEMS is designed to cause changes in both spatial and temporal gait symmetry. We predict that the GEMS would cause the steps on the side with the GEMS to be larger since individuals would compensate for the backward rolling motion by placing their foot farther forward in stance, thus increasing the distance between the two feet. Similarly, since the stride is longer, it may also shorten the duration of stance relative to the other side. With shortened stance duration, the amount of time spent in double-support at the end of stance would likely decrease as well. An alternative is to have a GEMS that moves the foot forward, which would have the opposite effect, shortening steps and lengthening double-support durations of the foot that it is placed on. Therefore, the same effect could be obtained by using a backward-moving GEMS on the healthy-side foot as would be obtained using a forward-moving GEMS on the paretic-side foot. In this study, we will focus on the backward moving GEMS.
Although the original idea of the GEMS is derived from the motion of the split-belt-treadmill, there are distinct differences between walking on the GEMS and walking on a split-belt treadmill with asymmetric belt velocities (Handzic and Reed, 2013). While the body's velocity relative to ground is zero on a split-belt treadmill, the relative velocity of the GEMS is non-zero and forward. The GEMS forces the wearer's foot forward or backward whereas the treadmill moves both feet backward, but at different speeds. For both the split-belt treadmill and the GEMS, the relative velocity between both feet is similar and the backward-moving GEMS takes the place of the faster tread. Our short-term study will examine how the motion of the shoe affects the change in gait.
We hypothesize that training over ground will lead to a change in the interlimb coordination in individuals with asymmetric gait and allow individuals to develop a more persistent symmetric gait. There are several differences between training on ground and a treadmill, such as visual flow and vestibular information signaling forward movement that likely limit the expression of learning in the over-ground context when trained on a treadmill. Visual cues appear to be particularly important for context awareness (Keamey, 2003). Visual cues, coupled with prior experience, are so powerful that predictive postural responses cause an individual to stumble when stepping onto an escalator that is not moving (Reynolds and Bronstein 2003; Bronstein et al. 2009). The body has learned an internal model that expects an acceleration when stepping onto an escalator, but when that acceleration does not occur, the person stumbles. A recent study of split-belt walking showed that transfer to over-ground walking is enhanced when subjects are blindfolded during training on the treadmill and tested over ground (Torres-Oviedo and Bastian, 2010). Since blindfolding eliminates visual cues about the environment, this also suggests that vision is a key factor in determining the context-dependence of learning. Since it is not realistic to blindfold stroke patients during gait training, we designed the GEMS so that training could occur during over-ground walking, thus visual cues during training and later walking over ground would be the same.
Data from control subjects using an earlier version of the GEMS has been published (Handzic et al. 2011) and a video of this previous version can be found at http://reedlab.eng.usf.edu/publications/handzic2011GEMS.mp4. In this study, we found that this earlier version of the GEMS was capable of changing step length as predicted, however the previous design was too heavy and too tall to be considered practical for testing in stroke populations. The current version of the GEMS produces similar motion to the previous version, but it weighs less (~1 kg) and is shorter (~4.4 cm). We will test the efficacy of wearing the current GEMS on gait coordination during walking over ground on individuals with stroke. All walking will be performed while subjects are wearing a gait belt and are closely guarded by an experienced physical therapist to prevent falling. Subjects may wear a safety harness attached to the SOLO-STEP® System (Solo-Step, Sioux Falls, SD ) if necessary. The effects of the GEMS on gait coordination will be compared to those induced on a split-belt treadmill.
The proposed project represents one of the first attempts to build a device that corrects walking symmetry while walking over ground. Not only would this allow people to experience gait corrections while performing normal movements, but the simplicity and relative low cost of these devices would also open up potential opportunities to train at home (for high-functioning individuals with supervision) and in clinics where a split-belt treadmill is not available. The studies outlined here will establish whether the GEMS is capable of changing interlimb coordination of gait, and whether individuals with stroke can use these devices for rehabilitation purposes. This work will thus build the foundation for future training studies examining the effectiveness of long-term use of the GEMS for improving symmetric walking patterns.
The question that this study targets is the modification of human walking patterns for use in stroke rehabilitation. It is our ultimate objective to show that the GEMS can change a person's temporal and spatial gait asymmetry into a symmetric gait. Our points of reference are results obtained by previous studies with split-belt treadmills. We are also interested in how altering the interface between a foot and the ground influences the adaptation to new walking patterns.
- Wearing the GEMS Device
Intervention Desc: The GEMS mimics the actions of the split-belt treadmill, but can be used during over-ground walking and in one's own home, thus enabling long-term training. This GEMS does not require any external power and is completely passive; all necessary forces are redirected from the natural forces present during walking since it utilizes the wearer's weight to generate its movements. While the movements of the GEMS are similar to the split belt treadmill, and the GEMS generates a similar aftereffect, the efficacy of this shoe in modifying the gait of an individual with stroke is not yet verified. This research aims to test the GEMS on individuals with stroke to determine if the related effects that show up on healthy subjects can benefit individuals with stroke. ARM 1: Kind: Experimental Label: wearing the GEMS Description: The long-term training will consist of four weeks of training with three training sessions performed each week. The training sessions will consist of up to forty minutes of training over up to eight shorter sessions of walking on the GEMS with breaks between walking sessions and as needed if the subject requests an additional break. Subjects will place the GEMS on their foot in which they have the shortest step length, as measured during the pre-training gait analysis. This is typically the healthy side foot. For split-belt treadmill sessions, the format will be exactly the same, but they will walk on a split-belt treadmill instead of the GEMS with the faster tread moving on the same foot that would wear the GEMS in the over-ground walking sessions.
- Masking: Open Label
- Purpose: Treatment
- Intervention: Single Group Assignment
|Type||Measure||Time Frame||Safety Issue|
|Primary||Percentage change in step length asymmetry||Baseline assessment at start and one-month and three-month followups||No|
|Primary||Percentage change in double support asymmetry||Baseline assessment at start and one-month and three-month followups||No|