By Annette M. Boyle
BALTIMORE – If practice makes perfect, then stroke patients at the VA Maryland Health Care System in Baltimore should have a great boost in relearning the ideal walking gait, with some help from the Anklebot.
The device allows patients to move their ankles with a robotic “coach” 1,000 times in a typical therapy session rather than the 80 times patients working only with a human physical therapist would experience.
“The Anklebot doesn’t experience fatigue the way a physical therapist does, so patients can perform many more movements each session,” said Neville J. Hogan, PhD, director of the Newman laboratory for biomechanics and human rehabilitation and a professor at the Massachusetts Institute of Technology.
Improving walking in patients who have hemiparetic gait following stroke has long-term benefits. More than 70% of patients fall within the first six months following a stroke as a result of gait or balance issues, increasing the risk of potentially devastating hip fractures and other injuries.
The Anklebot is an exoskeletal robotic system that can move a patient’s foot in a full range of motion. Mounted on a knee brace and connected to a specially designed shoe that uses switchplates to measure the force, direction and angle of movement, the Anklebot provides a modulated boost to get the foot moving correctly.
In seated therapy, the patient responds to a visual display by trying to move the foot to a certain point to play a video game. “If they can’t make the movement at all, the robot will push them in the right direction. If they can initiate, even just a tiny movement, even in the wrong direction, the robot will guide them to the proper position,” Hogan said.
The technology “permits the patient to do as much as he can, then, as in coaching, helps them improve by using a built-in algorithm to progressively raise the bar,” Hogan told U.S. Medicine. Over time, the Anklebot offers less assistance while increasing the speed and number of movements the patient must perform.
As with passive-motion machines that simply rotate patients’ feet through the range of motion, the Anklebot improves joint mobility. Unlike them, it also improves function. “That was the first of the surprises,” Hogan said. “The first study at the Baltimore VA showed that even this form of treatment [seated] increased overall walking speed.”