Powered Exoskeletons for Spinal Cord Injury

Impaired walking is a devastating consequence of spinal cord injury (SCI), affecting about 300,000 people in the U.S. alone according to the National Spinal Cord Injury Statistical Center. Individuals of decreased mobility are predicted to live shorter and lesser-quality lives.

One emerging technology offers relief: The “powered exoskeleton” is a broad category of wearable devices designed to increase limb strength and endurance, a concept established frequently in science fiction (think Iron Man).

In the context of SCI, such devices can be placed over paralyzed or weakened limbs to restore walking ability. They facilitate sit-to-stand transitions, over-ground walking, stair-climbing motions, etc. by “driving” the user’s hip and knee joints into desired trajectories. Some devices operate manually via joystick; others take information from built-in sensors to determine and execute the user’s intentions.

While designs vary considerably, they embody several common features:

Component Action
Force sensor Detect foot-ground contact
Crutch Distribute weight and balance user
Actuator Control dorsiflexion and plantar flexion

Powered exoskeletons are positively impacting individuals with SCI in academic and rehabilitation settings, revealing tremendous opportunity for product growth. The largest limiting factor right now is perhaps a lack of standardization in study protocols. Models are subject to extensive research, but collectively, they remain elusive. Complicating matters further, SCI encompasses myriad levels of injury — studies poorly reflect this.

Indeed these challenges are tough to overcome, and it will be interesting to follow regulation trends within the FDA as a result. Powered exoskeletons continue to infiltrate the SCI population, nonetheless, where they are generally well-received. Consider ReWalk, the first FDA-cleared exoskeleton for both personal and clinical use:

This tranquil, dream-like trance of a feature surely appeals to emotion in demonstrating the life-changing capabilities of exoskeleton technology. ReWalk mimics natural gait using battery-powered motors at the joints. It is operated by a wireless remote control and an array of sensors that detect subtle changes in the user’s center of gravity.

Taken literally from its prefix, ReWalk’s motto is simple and elegant: Walk again. The SCI community is well-aware that it is not so simple, however. This technology faces a host of integration issues, the most pressing of which is sheer cost. Its price point at $70-85k per unit puts ReWalk beyond the reach of many patients, and health insurance companies seldom offer assistance. Those who manage to get their hands on it suggest that the highly-praised slim fit is deceiving. Weighing in at about 50 pounds, the device is actually quite limited in terms of comfort and maximum speed. A motorized wheelchair seems to be the more practical, efficient, and foolproof solution for mobilization, then — especially in the eyes of insurance companies — so why ReWalk?

Ultimately, no one can answer that but the patients themselves and maybe their healthcare providers. No one would look twice at someone passing along in a wheelchair, and that aspect is really important to some people. Others find light in serving as ambassadors for novel and brilliant technology, and ReWalk would serve them well. Maybe it has nothing to do with what other people think or what’s more practical. Being able to stand on your own two feet and feel that you’re walking is arguably the be-all and end-all; in that case, powered exoskeletons make life worth living.

“Powered exoskeletons for bipedal locomotion after spinal cord injury” is a topical review that was recently published in the Journal of Neural Engineering. For full access, click here.

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