Soft robotic ankle support improves walking in stroke patients: study

US researchers have created a lightweight, soft robotic ankle support that could help stroke patients walk more easily, according to a study published Wednesday.

"In about 80 percent of patients post-stroke, it is typical that one limb loses its ability to function normally -- a clinical phenomenon called hemiparesis," said the study published in the US journal Science Translational Medicine.

"And even patients who recover walking mobility during rehabilitation retain abnormalities in their gait that hinder them from participating in many activities, pose risks of falls, and, because they impose a more sedentary lifestyle, can lead to secondary health problems," it said.

To help stroke patients regain their walking abilities, various robotics groups from industry and academia are developing powered wearable devices known as exoskeletons, but most of which are rigid, bulky products that are impractical for people to wear during everyday activities.

In search of a better alternative, researchers at Harvard University's Wyss Institute for Biologically Inspired Engineering and Boston University's College of Health & Rehabilitation Sciences developed a soft robotic ankle-support system weighing 0.9 kg, roughly twice as heavy as a soccer ball, to be worn on one side of the body.

Their system consists of a close-fitting waist belt and leg straps connected to a calf sleeve where small robotic actuators exerted force on a shoe insole to provide forward propulsion and correct problems with ankle dorsiflexion, commonly referred to as "drop foot," which affects roughly 20 percent of stroke survivors.

Over two days of testing, nine subjects ranging from 30 to 67 years old who were undergoing rehabilitation after strokes all showed more efficient and less asymmetrical strides when wearing the device, both when walking on a treadmill in the lab and over ground in a real-world environment.

What's more, the researchers observed the most pronounced improvements among the individuals who had the slowest unassisted walking speeds.

The team was now looking to further personalize its system to specific gait abnormalities, investigate assistance at other joints such as the hip and knee, and assess longer-term therapeutic effects of their technology.

"This study provides a glimpse of a new future where much of patient care will be carried out at home with the help of human-friendly robots, which look nothing like the robots we see in television and movies," Wyss Institute Founding Director Donald Ingber, who was not involved in the study, said in a statement.

"This exosuit looks more like sports clothing than R2D2, yet it is equally programmable and carries out tasks on command; however, the exosuit is lightweight, flexible, virtually invisible to others, and individualizes itself for each patient. We hope that it will soon enter clinical use where it undoubtedly could transform the lives of stroke patients for the better," Ingber said.