ReStore: A Solution For Propulsion Asymmetry

Stroke is currently the leading cause of acquired disability in the U.S. and internationally, with more than 795,000 strokes per year. This includes 610,000 new strokes and 185,000 recurrent episodes. With the increasingly younger age of patients disabled by stroke and the overall aging population, effective rehabilitation treatments are an ever-present need. 

After a stroke, patients may suffer from hemiparesis, or significant weakness on one side of the body. This causes severe reduction in stamina, limited mobility, and a decrease in the overall quality of life of the patient. Physical Therapy is the conventional treatment whereby a patient works to regain function on the paretic side of the body. 

Mechanics Of Gait Training

One main area of focus for post-stroke rehabilitation is gait training. Rehabilitation requires vigorous and extensive sessions where a patient walks for set periods of time and/or set distances to gauge individual starting points and progress. Normal gait mechanics involve three phases: 

  1. Stance support
  2. Propulsion
  3. Limb advancement

For stance support training and function, there are currently many tools that assist the patient to stand upright and remain supported while moving. Unfortunately many of these devices sacrifice mobility at the foot and ankle to regain this initial stability, and this can result in gait compensations such as circumducting and hip hiking on the paretic limb in order to achieve limb advancement.

Due to weakness from the hemiparesis as well as the decreased available natural motion that comes from utilizing things like common ankle foot orthoses (AFOs), there is often a significant degree of asymmetry in the propulsion force produced between the two limbs. 

What is Propulsion Asymmetry?

In order to move forward while walking, ankle plantarflexion motion is required. This is what allows the human body to propel itself forward in an on-going manner, with ideal gait mechanics and the least amount of energy expenditure.

The plantarflexion motion comes from a group of muscles that cross the ankle joint and produce the push off motion created by the lower part of the leg and the foot. These muscles permit the tapping of the toe while seated and if standing, these muscles allow you to raise up on the balls of your feet by pressing against the ground. 

When walking, that same force against the ground when one leg is behind the body, propels you forward. When these muscles are affected on one side of the body, such as with hemiparesis after stroke, this is known as propulsion asymmetry. Propulsion asymmetry has historically been somewhat overlooked during stroke rehabilitation, with the gait compensations mentioned above becoming necessary evils to achieve functional gains.

Once these compensatory patterns are ingrained however, many negative consequences ensue including: increased cost of walking, lower walking speed, decreased ability to reintegrate into work and the community, as well as increased risk for injury and falls.

ReStore Assists in Post-Stroke Rehabilitation and Recovery

The ReStore Exo-suit is a robotic technology designed to work responsively in concert with a patient’s motion and the therapists’ treatment style. ReStore does this through the use of soft, comfortable textile components, cables, motion sensors, and an easy to use app based software interface with three modes of action: Assist, Brace, Slack

ReStore Assist Mode

When working in Assist mode, the posterior cable provides plantarflexion assistance during forward propulsion. This allows the foot to once again press against the earth propelling the body forward. The anterior cable provides dorsiflexion assistance during the swing phase when the limb advances forward – in other words, this allows the ankle to flex while the leg is brought forward which provides ground clearance and prevents trips and falls. 

Assist mode is the primary mode in which Restore will be utilized during physical therapy sessions to achieve the exciting results of improved walking symmetry, speed and endurance. Walking in Assist mode has also been shown to help train patients out of utilizing the previously discussed compensatory patterns for advancing the paretic leg forward.

ReStore Brace Mode

In Brace mode, the cables are locked in position to provide continuous, static ankle support in the same manner as conventional methods used during post-stroke rehabilitation. Brace mode allows clinicians to continue with the normal flow of their session, but with augmented support provided by ReStore in Assist mode as indicated.

ReStore Slack Mode

In Slack mode, the cables are released to allow the ankle to move freely. Clinicians can use this mode to challenge patients during on:off intervals and also to track response to training over time. 

More About The ReStore Exo-Suit

The ReStore Exo-suit provides a solution to a significant problem when it comes to post-stroke rehabilitation and recovery. It utilizes robotics technology to assist in gait training by correcting propulsion asymmetry in patients during post-stroke rehabilitation and recovery. It utilizes anterior and posterior cables to provide dorsiflexion and plantarflexion motion, respectively, which assist in ground clearance and forward propulsion training. 

ReStore is meant to be utilized during rehabilitation to facilitate proper movements with increased energy efficiency which allow for patients to participate in more intense physical therapy sessions to achieve a faster and more complete recovery. 

For more information, contact us here to set up a demo to see if ReStore is right for your patients and clinical practice. 

Reference for the ‘post stroke gait’ photo:

Mohan, Dhanya & Khandoker, Ahsan & Wasti, Sabahat & Alali, Sarah & Jelinek, Herbert & Khalaf, Kinda. (2021). Assessment Methods of Post-stroke Gait: A Scoping Review of Technology-Driven Approaches to Gait Characterization and Analysis. Frontiers in Neurology. 12. 10.3389/fneur.2021.650024.

Additional ReWalk Propulsion Resources:

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