The fact that this is not the actual intention of the robot suit however is often being neglected. In fact, exoskeletons facilitate a special form of therapy that returns at least a small portion of independence to the respective person. This doesn’t actually cure people, but makes them mobile enough to where they can move with walking supports or walking frames.
Medical scientists under Professor Thomas A. Schildhauer, Medical Director of the Department of Surgery at the Bergmannheil University Hospital in Bochum are researching therapy using the Hybrid Assistive Limb Exoskeleton, HAL in short. In the affiliated Center for Neurorobotic Movement Training (German: Zentrum für Neurorobotales Bewegungstraining, ZNB), paraplegics or stroke patients train under clinical practice conditions with the robot suit.
The HAL exoskeleton originally comes from Japan and was developed by Dr. Yoshiyuki Sankai. It works with EMG electrodes that are attached to the lower extremities, the knee and hip area. The suit detects nerve impulses via the surface of the skin, analyzes and amplifies them so that the patient is able to move with the help of integrated electric motors. “The bioelectric signals are registered via sensors and analyzed by the power unit, which then knows which muscle group just sent the signal,“ explains Oliver Cruciger, attending physician of the studies at Bergmannsheil. The patient deliberately directs and controls his or her movements and is supported by the robot suit at the same time. This is what makes the HAL system so unique: unusual body functions are replaced or rather supported. This way, paraplegics are able to perform movements like standing or walking under certain conditions. Pressure sensor plates recognize the patient’s supporting leg and automatically move the non-supporting leg. The exoskeleton effectively supports and amplifies the patient’s movements, so that a significant increase in mobility can be achieved.
However, residual function in the hip and knee area is essential for therapy purposes. “We are primarily able to effectively train patients with motor incomplete paraplegia sub C7 (below the last spinal cord segment). You can also treat complete paraplegia in terms of Conus-Cauda Syndrome if there is minimal residual motor function in the knee and hip area,“ reports Cruciger. Medical scientists talk about incomplete paraplegia if the spinal canal and the spinal cord were only partially severed due to an accident or tumor for example. Depending on the lesion size and the respective degree of transection, residual function in movement or rather sensitivity can be maintained.