Bionic exoskeletons, battery-powered external bodysuits that walk people with paralysis, can now be found in rehabilitation and research facilities around the world; a few are even available for in-home use. These devices allow people with paralysis due to spinal cord injury (SCI) to walk overground rather than use a wheelchair. After a relatively short training period, most people are able to be walked in the device, albeit slowly, with little assistance. Despite this, bionic exoskeletons are rarely used by people with SCI in their normal activities of daily living. Why is this?
Well, it’s still not clear exactly what they are good for… should they be used for rehabilitation? Or are they more useful for exercise? Are there benefits to using an exoskeleton, instead of a wheelchair, throughout the day as a basic mobility device? Clinical researchers at The Miami Project have been conducting experiments to try to figure all this out…
Two years ago we reported on a pilot study that was conducted at The Miami Project to explore the physiological responses to overground bionic ambulation in persons with complete thoracic-level SCI. Subjects walked in the Ekso Bionics exoskeleton (Ekso) 3 times a week for 6 weeks. The results showed that subjects were able to achieve walking speeds and distances similar to persons with motor incomplete SCI not using the device, but not as good as community walking speeds and distances. In addition, all of the research subjects reported a reduction in pain over the study period. However, no rehabilitation or exercise benefits were shown, which suggest that the exoskeleton might be best suited for mobility. Results from this study were published in 2014.
Understanding therapeutic benefits of overground bionic ambulation: exploratory case series in persons with chronic, complete spinal cord injury. Kressler J, Thomas CK, Field-Fote EC, Sanchez J, Widerström-Noga E, Cilien DC, Gant K, Ginnety K, Gonzalez H, Martinez A, Anderson KD, Nash MS. Arch Phys Med Rehabil. 2014 Oct;95(10):1878-1887.e4. doi: 10.1016/j.apmr.2014.04.026. Epub 2014 May 17.
To follow up on that work, Dr. Jennifer Maher, a postdoctoral associate in the lab of Dr. Mark Nash, is digging deeper and exploring whether cardiovascular or metabolic changes occur in response to walking in bionic exoskeletons. She and a team of researchers (Carsten Bach Baunsgaard, Anne Palermo, Jan Gerven, and Luisa Betancourt) are walking subjects with SCI in the Ekso and measuring oxygen consumption, metabolic function, and various aspects of cardiovascular hemodynamics. They hope that this information will help to understand the role of bionic exoskeleton use in people with paralysis due to SCI – in addition to mobility, can there be an internal health benefit? Preliminary results suggest there is increased circulation during extending walking in the bionic.
So, what can we honestly expect from bionic exoskeleton development in the future? The walking will probably always be somewhat slow, with challenges on turning, stepping, and obstacles, but the battery life can likely be extended. However, the research being done at The Miami Project and other institutions will help to direct and advance the field in the direction where it can make the biggest impact for people with SCI. Potential benefits of exoskeleton walking in the future may include: better blood pressure regulation or improved circulation due to being in an upright posture, osteoporosis and fracture prevention due to weight bearing, improved fitness or blood sugar control due to exercise, or gait re-education and plasticity for people with incomplete SCI. But most importantly, the price of all exoskeletons needs to be reduced dramatically so that more people can access the potential benefits of these exciting advances in engineering.