Exosuit helps stroke patients re-gain their gait Monday, 31 July 2017

Teams from the University of Harvard and Boston University have developed a lightweight, soft, wearable, ankle-assisting exosuit that can help stroke patients regain their ability to walk normally.

Hemiparesis, or the loss of normal function in one limb, affects about 80 per cent of stroke patients. Patients can recover mobility with rehabilitation, but many end up with abnormalities in their gait hat keep them from participating in many activities, increase their risks of falling and lead to more sedentary lifestyles that cause secondary health problems.

Patients recovering from a stroke develop compensatory walking strategies to deal with the inability to clear the ground with their affected limb and to 'push off' at the ankle during forward movement.

Usually, rigid plastic ankle braces are prescribed to help with walking, but they do not help correct the abnormal gait patterns in about 85 per cent of post-stroke patients.

Researchers at the University of Harvard’s Wyss Institute for Biologically Inspired Engineering, the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), and Boston University’s College of Health and Rehabilitation Services have developed the wearable exosuit aimed at reinforcing normal gaits in hemiparesis patients.

The exosuit is a development of a technology that was earlier demonstrated to help wearers walk and jog, and produced marked reductions in energy costs. Now, with the demonstration that the exosuits could also be used to improve walking after a stroke, the researchers are taking a critical step in de-risking exosuit technology for real-world use.

“Current approaches to rehabilitation fall short and do not restore the mobility that is required for normal life,” said Terry Ellis, director of the Center for Neurorehabilitation at Sargent College and an assistant professor at Boston University.

Exosuits are anchored to the affected limb of a hemiparetic patient via functional apparel, and apply gait-restoring forces to the ankle joint by transferring mechanical power via cable-based transmission from battery-powered actuators that are integrated into a hip belt or an off-board cart placed next to a treadmill.

The researchers found that in treadmill experiments, the powered exosuit improved the walking performance of seven post-stroke patients, helping them clear the ground and push off at the ankle, generating more forward propulsion.

Because walking mechanics and dynamics are different on a treadmill and in the home or communal environment, the team then assessed the exosuit’s benefits in an overground walking experiment.

They found that the untethered exosuit was able to facilitate more normal walking behaviour during overground walking, meaning the technology could be used as rehabilitation devices for patients to use outside of the clinic and in their normal lives.

For the next steps, the team wants to personalise the assistance rendered by the exosuits to specific gait abnormalities, investigate if exosuits can help with other joints such as the hip and knee, and assess the longer term therapeutic effects of the technology.