Thousands of Americans face life in a wheelchair or have had the use of their limbs impaired due to spinal-cord injuries.

But a new device being created by neurophysiologists from the UCLA Brain Research Institute and NASA space engineers could help rehabilitate spinal-cord patients and possibly allow those currently confined to wheelchairs to walk again.

The device, still in the development phase, will look like a treadmill with robotic "arms" that attach to the patient's legs, guiding the legs properly on the moving treadmill. The device is also fitted with a harness to support the patient's weight.

"We see tremendous potential for rehabilitation that uses this form of therapy," said Reggie Edgerton, professor of physiological science and neurobiology at UCLA and principal investigator on the project. The device could be part of clinical trials at UCLA in about three years. "Our expectation is that whatever level or severity of injury, this device will enable subjects to recover to a higher level than they do currently and recover faster."

Physiologist Reggie Edgerton.

Researchers have found that the spinal- cord network has the intrinsic capability to interpret complex sensory information, such as what position the legs are in and how much load is being borne by the legs. With that information, the spinal cord can generate activation patterns for standing, stepping and other actions.

And because the neural pathways are very plastic, patients using this device are able to make the appropriate mechanical movements and, through repetitive action, teach the spinal cord to learn the motor task, Edgerton said.

"In the severely injured, the device may do a lot of work," explained Edgerton, "but as the subject learns to perform this task, the robot will do less work and the subject more work, ideally to the point where the device does no work."

In addition, the robotic stepper will reduce costs for rehab centers, Edgerton said, because it reduces the number of therapists needed to carry out the normally labor-intensive intervention. Therapists can then focus more effectively on administering the therapy.

"This system can do the work of four therapists and help monitor a patient's progress in a controlled manner," said Jim Weiss, program manager for collaborative neural repair at NASA's Jet Propulsion Laboratory in Pasadena. Robotic engineers there are working on the device with the UCLA team.

While therapists can only sense and observe a patient's progress, the robotic device takes precise measurements of the person's force, speed, acceleration and resistance, counting each step the patient takes. These measurements help therapists monitor patients' day-to-day progress and provide feedback on the effectiveness of the therapy. The stepper's control system also uses these measurements to adjust the device to each patient's needs.

According to Weiss, this same device could someday help astronauts walk safely after prolonged periods in space, such as extended missions on the International Space Station.