iStride(TM) Device Used for Stroke Rehabilitation
Condition: Stroke
MeSH terms: Stroke
Study type: Interventional

Summary: 
      The objective of this research is to test a passive shoe to correct gait in individuals with
      asymmetric walking patterns. This will be done in a clinic. 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 iStride, formerly known as 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.
    

Detailed description: 
      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. 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 previous studies suggest that the iStride device that has
      been developed in our laboratory can be used as an alternative gait training device for
      people with stroke. The iStride device 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. The iStride device 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 iStride
      device are similar to the split belt treadmill, and the iStride device generates a similar
      aftereffect, the efficacy of this shoe in modifying the gait of an individual with stroke is
      not yet verified.

      In this study, we will test the efficacy of the iStride device on individuals with stroke in
      the clinic. 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 iStride device
      will result in changes to interlimb coordination of gait that could be a safe and effective
      device to be used in ones' home.

      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. Another measure of temporal asymmetry - double support duration - is similarly
      correlated with walking speed. In addition, spatial (e.g. step length) asymmetry is
      associated with decreased propulsive force on the paretic leg, which limits forward motion of
      the body and reduces gait efficiency. 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. 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. 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 iStride device is designed to cause changes in both
      spatial and temporal gait symmetry. We predict that the iStride device would cause the steps
      on the side with the iStride device 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.

      Although the original idea of the iStride device is derived from the motion of the
      split-belt-treadmill, there are distinct differences between walking on the device and
      walking on a split-belt treadmill with asymmetric belt velocities. While the body's velocity
      relative to ground is zero on a split-belt treadmill, the relative velocity of the iStride
      device is non-zero and forward. The device 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 iStride device, the relative velocity between both feet is
      similar and the backward-moving iStride device takes the place of the faster tread.

      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. 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. 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 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. 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 iStride device 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 iStride device (referred to as
      GEMS at the time) has been published 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 device 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 iStride device produces similar motion to the
      previous version, but it weighs less (under 1 kg) and is shorter (~4.4 cm). We will test the
      efficacy of wearing the current iStride device on gait coordination during walking over
      ground on individuals with stroke in the clinic. All walking will be performed while subjects
      are closely guarded by an experienced physical therapist to prevent falling. The effects of
      the iStride device 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 iStride device 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 iStride device 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 iStride device 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.
    

Intervention name(s): wearing the iStride device
Intervention type(s): Device
Intervention description(s): The device 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 device 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. This research aims to test the iStride on individuals with stroke in their own home in order to determine if the related effects that we saw in the clinic, can also benefit patients at home.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Treatment