Physical therapists have long been supporting stroke survivors during their recovery period. Now they are walking with them.
Scientists at Northwestern University and the Shirley Ryan Ability Lab have developed a first-of-its-kind rehabilitation system that virtually connects therapists and patients via a robotic exoskeleton. Real-time connectivity allows therapists to react to patient movements and continuously adapt support and assistance as patient performance evolves.
After training with the new system, patients had increased range of motion in their joints, took longer and higher steps, and activated their muscles at the same levels seen with traditional treatment.
The study is scheduled to be published in the journal Wednesday (June 17) science robotics.
“Therapist-directed rehabilitation remains the cornerstone of recovery for many patients, and this study shows its potential to complement this standard of care,” said Jose L. Pons, who conceived, led and supervised the research program.
Pons is Professor of Science in the Shirley Ryan Ability Lab, Professor of Physical Medicine and Rehabilitation at Northwestern University Feinberg School of Medicine, and Professor of Mechanical Engineering (courtesy) at Northwestern University’s McCormick School of Engineering. Other Northwestern co-authors include Daniel Ludwig, research scientist in the Shirley Ryan Ability Lab and research assistant professor at McCormick College; Levi Hargrove, Regenstein Foundation Biomedical Center Scientific Chair in the Shirley Ryan Ability Lab, Professor of Physical Medicine and Rehabilitation at Feinberg College, and Professor of Biomedical Engineering at McCormick College (courtesy). Kevin Lynch, professor of mechanical engineering at McCormick College and director of the Center for Robotics and Biosystems at Northwestern University.
According to the Centers for Disease Control and Prevention, nearly 800,000 Americans survive a stroke each year. For many people, the road to recovery includes relearning one of life’s most basic activities: walking. Muscle weakness, impaired coordination, and loss of leg control can make simple movements difficult. Recovery often requires months of intensive rehabilitation as patients work with physical therapists to regain mobility, independence, and confidence.
In traditional physical therapy, therapists provide hands-on support and corrective guidance as patients walk. Because only a limited number of movements can be physically supported at once, therapists often focus on one aspect of gait. More complex full-body workouts may require multiple therapists. On the other hand, while rehabilitation exoskeletons increase training intensity and help patients practice walking for extended periods of time, many rely on fixed movement patterns that do not fully adapt to patient performance in real time, limiting therapists’ ability to provide personalized care.
To address these gaps, the Northwestern and Shirley Ryan Ability Lab team developed a new intervention called Therapist-Exoskeleton-Patient Interaction (TEPI). With TEPI, the therapist and stroke survivor each wear a lower limb exoskeleton that is virtually connected at the hip and knee. The virtual connection acts like a combination of springs and shock absorbers, allowing therapists and patients to influence each other’s movements in real time. This study demonstrated that therapists can effectively utilize TEPI to create a more personalized rehabilitation experience and support patients as they work towards their recovery goals.
Combining the hands-on adaptability of physical therapy with the scalability and precision of robotic systems enables more comprehensive full-body gait training without the need for multiple therapists, while also introducing real-time responsiveness to patient performance, allowing support, resistance, and feedback to be dynamically adjusted. ”
Lorenzo Vianello, postdoctoral fellow in the Shirley Ryan Ability Lab and co-first author of the paper
In an evaluation of eight stroke survivors, TEPI outperformed traditional therapist-led treadmill training on several measures of gait performance. Participants showed greater range of motion of their joints and took longer and higher seconds while maintaining similar muscle activation. They also reported high levels of motivation and enjoyment.
“By allowing therapists to guide patient movements through their own leg movements, TEPI can effectively complement traditional gait training for stroke rehabilitation and reduce therapist fatigue and injury-causing physical effort during hands-on therapy,” said study co-lead author Emek Baruš Küçütabak, who completed the study as a graduate research assistant at Northwestern University and the Shirley Ryan Ability Lab.
Next, the researchers plan to investigate how this framework can be applied to other functionally relevant activities, such as overground walking, stair climbing, and sit-to-stand transitions over multiple training sessions.
“Future research will also explore more accessible and scalable systems that can extend therapist-led rehabilitation into the home and support remote care,” said study co-lead author Matthew R. Short, a postdoctoral fellow at the University of Delaware.
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Reference magazines:
Küçütabak, E.B.; others. (2026). Therapist, exoskeleton, and patient interaction for ambulatory therapy. scientific robotics. DOI: 10.1126/scirobotics.adz9628. https://www.science.org/doi/10.1126/scirobotics.adz9628
