Each year, nearly 800,000 Americans survive a stroke. For many, the journey to recovery includes relearning one of life's most fundamental activities: walking. Weakness, impaired coordination and reduced control of the legs can make even simple movements challenging, often requiring months of intensive rehabilitation led by physical therapists as patients work to regain mobility, independence and confidence.
A first-of-its kind study utilizing lower-limb exoskeletons to facilitate therapist-patient interaction during functional tasks — published today in Science Robotics — could revolutionize this paradigm.
As part of the study, scientists from Shirley Ryan AbilityLab and Northwestern University introduced a novel intervention they call therapist-exoskeleton-patient interaction (TEPI), in which a therapist and a stroke survivor are each equipped with a lower-limb exoskeleton virtually connected at the hips and knees via spring-damper elements. This connection enables bidirectional physical interaction, allowing the therapist to guide and respond to the patient's movement through the forces generated by the virtual connection.
"Therapist-led rehabilitation remains the foundation of recovery for many patients, and this research shows promise for complementing this standard of care," said José L. Pons, PhD, a scientific chair at the Shirley Ryan AbilityLab and professor at Northwestern University, who conceptualized, led and supervised the research program.
In conventional physical therapy, therapists provide hands-on support and corrective guidance as patients walk. Because they can physically assist a limited number of movements at once, therapy often focuses on a single aspect of gait, while more complex, whole-body training may require multiple therapists. Meanwhile, rehabilitation exoskeletons can increase training intensity and help patients practice walking longer, but many rely on fixed movement patterns that do not fully adapt to a patient's performance in real time, limiting therapists' ability to deliver personalized care.
This research addresses these gaps and demonstrates that therapists can effectively leverage the technology to create more personalized rehabilitation experiences, supporting patients as they work toward their recovery goals
"By combining the hands-on adaptability of physical therapy with the scalability and precision of robotic systems, it can enable more comprehensive, whole-body gait training without requiring multiple therapists, while also introducing real-time responsiveness to patient performance — allowing support, resistance and feedback to be adjusted dynamically," said Lorenzo Vianello, PhD, a postdoctoral researcher at Shirley Ryan AbilityLab and a co-first author of the paper.
As part of the study, the research team evaluated this approach with eight stroke survivors, comparing TEPI training to conventional therapist-guided mobilization during treadmill walking. Results showed that TEPI led to greater joint range of motion, increased step length and height, and similar muscle activation compared to conventional therapy, as well as high self-reported motivation and enjoyment.
"By allowing therapists to guide a patient's movements through their own leg movements, TEPI could provide an impactful complement to conventional gait training for stroke rehabilitation, reducing physical effort that can contribute to fatigue and injury for therapists during hands-on therapy," said Emek Barış Küçüktabak, PhD, a co-first author of the paper, who completed the research while a graduate research assistant at Shirley Ryan AbilityLab and Northwestern University.
As a next step, researchers plan to explore how this framework can be applied to other functionally relevant activities, such as overground walking, stair climbing, and sit-to-stand transitions across multiple sessions of training.
"Future work will also investigate more accessible and scalable systems that can extend therapist-guided rehabilitation into the home and support remote care," said Matthew R. Short, PhD, a co-first author of the paper and postdoctoral researcher at the University of Delaware.
Other authors on the paper, "Therapist-Exoskeleton-Patient Interaction for Gait Therapy," were Daniel Ludvig, PhD, of Shirley Ryan AbilityLab and Northwestern University; Levi Hargrove, PhD, of Shirley Ryan AbilityLab and Northwestern University; and Kevin Lynch, PhD, of Northwestern University.
About Shirley Ryan AbilityLab
