Tania Lam is looking closely into how robotic gait devices like the Locomat® can assist patients - photo by Martin Dee

UBC Reports | Vol. 53 | No. 4 | Apr. 5, 2007

Rehab Robot Does Heavy Lifting

By Lorraine Chan

Over the past few months, the School of Human Kinetics’ Tania Lam has been keeping close company with the Lokomat®, one of only two rehab robots in Canada.

The Lokomat, a $300,000, robotic gait device, uses cutting-edge Swiss technology for body weight-supported treadmill training (BWSTT), a promising treatment strategy following neurological injury.

“I’m hoping to develop new rehabilitation strategies for patients with stroke or spinal cord injury,” says Asst. Prof. Lam. “The partial or complete loss of walking ability is probably one of the most debilitating consequences of neurological damage.”

Lam explains that neurological injury interrupts signals from the brain. Her work probes the subtle interplay of neural commands, muscle response and sensory input required for walking.

The Lokomat works by suspending the patient in a harness attached to an overhead frame to stabilize balance. The legs and feet are held within two metallic arms attached to a frame suspended over a treadmill. Computer-controlled motors in each joint of the arms produce walking motions for the patient. The Lokomat uses sensors to measure the position and force produced by the legs during walking.

“When patients have been able to recover, it’s not always clear what changes or adaptations have occurred in the nervous system to enable functional improvements.”

Lam says that UBC is in a unique and strategic position to investigate these types of questions thanks to the arrival of the Lokomat and collaborative links with the International Collaboration on Repair Discoveries (ICORD).

Her study will use customized software to regulate and monitor the action of muscles and joints of the legs, the speed of the treadmill and the amount of body weight support.

“My approach is to help augment the activity of the neural circuits through sensory input from the legs,” explains Lam, who trained as a post-doc with Prof. Volker Dietz, one of the original developers of the Lokomat, at the Spinal Cord Injury Centre at the University of Zurich’s Balgrist University Hospital.

In the only study of its kind, Lam is exploring ways to better activate the flexor muscles. Flexor muscles cross the foot in front of ankle, in front of the hip and behind the knee. These muscles are used to lift the foot up and forward and are pivotal for walking safely during the “swing phase,” says Lam.

“Each time we take a step, lift our leg over obstacles or climb stairs, we need to ensure the flexor muscles are properly activated. Someone who doesn’t have enough strength during the swing phase will stumble or drag their feet.”

Lam can program the Lokomat software to vary the motor’s resistive force against the patient’s leg movements during the swing phase. “It would mimic the feeling of walking under water to give sensory input to flexor muscles.”

She will then assess how effective this approach is for improving patients’ muscle function. To date, rehabilitation of flexor muscles has depended on using an L-shaped leg brace to keep the foot up so it doesn’t drag or using electrical stimulation to encourage muscles to flex the foot.

Lam says BWSTT has gained increasing favour as a way to help people with stroke or incomplete spinal cord injury regain use of their legs. But therapists find that manual BWSTT has its limitations since it requires numbers and heavy physical work.

“One therapist stabilizes the patient’s pelvis, while another one to two therapists manually move the person’s legs in a stepping motion,” explains Lam.

With the Lokomat, a sole therapist could facilitate a patient’s BWSTT. More importantly, the computer-controlled motors and sensors allow for standardized treatments for research, which wouldn’t be possible with therapists whose strength or speed may vary with each session.

In Canada and the U.S., 300,000 people are living with spinal cord injuries and there are 11,000 new cases each year. About half these patients have “incomplete” spinal cord injury which means they still retain some sensation and function and may be able to recover mobility through rehabilitation.

Lam’s research has received support from the Canada Foundation for Innovation.