Musculoskeletal disorders (MSDs) are among the most common and painful of occupational injuries. Most employers can reduce the risk of these injuries by reorganizing the workspace based on ergonomic principles. However, for many people, the particular environment they work in, or task they perform, make the use of such controls almost impossible.
A new and innovative technology may be just the solution. The exoskeleton, a rigid structure worn on the outside of the body, has been proven to reduce the physical stresses that cause MSDs. As a new technology, exoskeletons are the subject of many studies and tests conducted in occupational settings. Their capabilities and potential disadvantages are still being worked out. Safety managers have many factors to consider before knowing whether this new technology will be effective in reducing musculoskeletal disorders in the workplace.
Exoskeletons may prove useful in almost any workplace since the need for the device depends mostly on the task being performed, says Catherine Trask, Canada research chair in ergonomics and musculoskeletal health and associate professor at the University of Saskatchewan in Saskatoon. These tasks are common in construction, which require a lot of heavy manual material handling and awkward postures.
Manufacturing, too, involves many tasks that entail common ergonomic risk factors: awkward postures, repetitive work, different forces and exposure to vibration. Other industries that may see exoskeletons as a way to decrease MSDs include logistics, shipping, electronics and agriculture.
Additionally, the devices may help older workers continue working. There is also research being done into whether they could be useful for people returning to work after an injury, Trask says.
“Could they be used in the same way other types of braces might be worn while someone is retraining into their job and their body is recovering? That is still an open question.”
Beyond industrial use, one major application for exoskeletons is in the military, where they are intended to increase soldiers’ strength, endurance and speed. In health care, they assist in the rehabilitation of people with spinal cord injuries.
Exoskeletons are classified as “active” or “passive.” Active, or powered devices, operate by means of electric motors or batteries. With passive devices, human movement propels the device, which works through materials, springs or dampers.
Industrial exoskeletons include whole-body, upper-body and lower-limb devices. Upper-body devices, which look like a complex backpack, are designed to support the arms to reduce muscle and joint fatigue. They decrease risk of shoulder injuries, common among workers doing overhead work. When the worker raises their arms, the device engages, creating a sensation that something is pushing up the elbows. Those worn on the lower body support the knee or the back.
“As you bend forward, rather than your back muscles and the discs and ligaments in your back needing to support you, this structure helps pass the load onto your legs. So, if you’re bending forward to pick something up, the exoskeleton would make both the bending over and the coming back up a little easier on your back,” Trask says.
Ford Motor Company started developing and testing exoskeletons several years ago, in partnership with vendors and the United Auto Workers union, to try to reduce injuries in the shoulder and lower back, says Marty Smets, technical expert in human systems and advanced manufacturing at Oakville, Ont.-based Ford Motor Company.
“Shoulders are unique joints. They are very fatigable joints. The accumulation of fatigue can lead to musculoskeletal injuries,” he says. “Workers with shoulder injuries usually have to be away from work two to three times longer than those with back injuries.”
In 2018, Ford conducted trials of spring-powered devices in about 20 facilities worldwide, monitoring the feedback from operators.
“Putting a small number of devices in different regions helps me understand how we can manage these devices globally,” Smets says. “Over the next couple of years, as the devices get lighter, cooler, easier to use and more comfortable, we will ramp up our uptake.”
A year ago, the company launched a two-year study at its Oakville assembly plant that will monitor the use of arm-support exoskeletons among workers doing overhead work. There will also be a control group. The purpose of the study is to gather long-term data on the use of exoskeletons in the workplace.
“What we know from the lab studies we’ve conducted is that the risk factors are being reduced. The amount of activation in the muscle fibres of the shoulder declines by 10 to 40 per cent. Less muscle activation means you’re working at a lower percentage of your maximum capability, and that correlates with a lower injury risk,” Smets says.
At the six-month point, Smets says, they found statistically significant decreases in self-reported discomfort across the upper back, in the wrist and in the neck, as well as trends of decreasing discomfort in the shoulder.
“Those who are using exoskeletons have significantly less discomfort in those body regions than those performing the same work without an exoskeleton.”
In another year, Smets adds, they hope to find not only significant declines in subjective discomfort, but also fewer injuries among the workers doing overhead work.
In Saskatchewan, Trask has recently launched a research project looking into the utility of exoskeletons among agricultural workers. While farmers perform more varied work than workers on a factory assembly line, they are required to do a lot of ground-level work. As an industry, farming has high rates of back pain, especially low back pain. Due to their rural location and long workdays, farmers often don’t have the same access to care for chronic back pain as do people in urban areas. During the study, farmers will wear the upper body type of exoskeleton.
Using a portable electromyography (EMG) system in the field, researchers will measure the electrical activity of the study participants’ muscles, Trask says. This will allow them to assess how hard the back muscles are working. Researchers will also have some inertial sensors to assess how fast a participant’s limbs are moving and what kinds of postures people are getting into.
In addition to collecting objective, quantitative data, the scientists also want to visit farms to see how the task performance varies with and without the exoskeletons, as well as to interview the farmers about their subjective experience: What did they like about wearing the exoskeletons? What challenges did they encounter? What other types of activities do they think the devices could be useful for?
One central issue they’re trying to determine is how practical exoskeletons will be. Does the cost-benefit trade-off make sense for the farmer? If a farmer has to get in and out of a tractor frequently, it may not be practical for them to wear a device that has some rigid structure on the back and the legs. The device may make it too tricky to safely climb in and out of a piece of machinery.
“We know that in a lab exoskeletons can decrease the physiological load so people get less fatigued when they’re using an exoskeleton. They do decrease awkward posture in the spine. They decrease the biomechanical load on the spine, the compressive forces in the spine. The question is whether in a real-world environment it’s possible for a worker wearing an exoskeleton to do real tasks and not just lab tasks,” Trask says.
At the Fraunhofer Institute in Stuttgart, Germany, the largest technology research institute in Europe, researchers are working on the “Stuttgart exo-jacket,” a motorized jacket that assists in lifting heavy weights. It can lift 15 kilos (about 33 pounds) on its own, but the intended function is to assist workers to lift up to 40 kilos (about 88 pounds). This would be useful for workers handling suitcases and luggage at an airport, for example, or lifting heavy objects in construction work, says Urs Schneider, the institute’s division director for health and head of Biomechatronic Systems, a research department at the institute.
“It’s like an e-bike or pedelec. You go yourself, but you have a power-assist. When workers lift a suitcase of 40 kilos, the system will support them about 25 per cent. It’s still the same job, but it’s a bit less (of a load). Our intention is that the fatigue will set in a little later and the load peaks on the joints will be reduced so that osteoarthritis of these joints is delayed into the future,” he says. “It’s not a miracle, but we’re trying to reduce the chronic, absolute load on the muscle and the peak load on the joints. And we’re trying to see to it that people don’t work more but go home with a better quality of life and, ideally, have a reduced number of injuries.”
However, he adds, even with the lightest and most efficient technology available, the motor is still very heavy. While weight is not a problem in rehabilitation, where the patient is moving slowly, it makes the use of powered exoskeletons in the workplace, where people often have to move very quickly, almost impossible.
“Do you want something heavy on your body to help you lift something?” Schneider says, adding that research labs around the world are working to develop lightweight powered exoskeletons. He expects they won’t really be a big part of the market until about five years from now.
In contrast to the powered devices, passive devices are lightweight, usually less than 3 kilos. While they have this advantage, and thus are more practical, Schneider says, their overall ergonomic effectiveness is much less than that of power-assist devices. They are also very task-specific. Still, they may help to reduce osteoarthritis in the shoulder, problems in the hip joint and may help prevent tennis elbow and carpal tunnel syndrome. They may also delay spinal issues, especially of the lumbar spine.
Generally, Trask says, the effectiveness of exoskeletons in the workplace depends on which device is being used and what task needs to be done. Before buying a device, an employer should carefully consider what the goals are for the exoskeleton.
“An exoskeleton can work in some circumstances and not others,” she says. “As with any safety intervention, we want to make sure there is a good match between the workers, the task they need to do and the exoskeleton that we’re choosing for them.”
Smets says even small companies should consider providing an exoskeleton to employees, despite the expense. The potential hazard for a worker should be the central guiding factor in the decision to provide an exoskeleton. For example, the person at a television station who holds a boom microphone or a carpenter who spends many hours sanding a surface above their head could benefit profoundly from such a device.
“A small employer could get value out of some of these devices if it was the right job. If 50 per cent or more of your work is overhead, the preference would be to use the device for at least a portion of the workday to reduce the fatigue build-up,” Smets says.
As with anything new, employers should be cautious about unintended consequences, Trask says. An exoskeleton could constrain twisting or lateral movement, which may reduce ability to perform some tasks. Or, if someone needs to drive a lot during their work, or they’re on and off different machinery, then some styles of exoskeletons might not be appropriate.
Using a device might also introduce a new problem. The introduction of the combine, for example, eliminated many ergonomic risk factors that resulted from harvesting wheat with a scythe. But it created the new hazards of sedentary work and whole-body vibration, which arises from sitting on the machinery for hours at a time and which likely contributes to farmers’ high rates of back pain.
“Consider what the exoskeleton can help with, but also where it might introduce a limitation. Make sure there are not some unintended consequences. You need to be sensitive during that trial phase to what the range of outcomes might be because it’s not always what you expected,” Trask says.
Moreover, many workers find exoskeletons to be very uncomfortable and don’t like the way they look. In Germany, Schneider says, some companies that bought the devices ended up putting them in storage because workers didn’t like them.
“Yes, it is about function, but it is also about comfort and aesthetics and user acceptance. Only if the device is comfortable will the workers be compliant. And some look funny. On an assembly line, for example, if you have eight male workers and one of them looks funny, the device won’t last five minutes. So, some improvement in comfort and looks has to be made in many of them,” he says, adding users often have very different reactions.
“Some people love them and wear them all day. They say they would buy the devices out of their paycheque if someone ever took them away from them. And others say, ‘It doesn’t really fit me, it’s not comfortable, I can’t move naturally in it, it’s too warm,’” he says.
The fact that the devices tend to increase body temperature remains the biggest barrier to the adoption of exoskeletons, he says, adding the safety team at Ford is now looking for cooling solutions.
Differences in body shape can present problems for the exoskeleton, too. An adjustment to the spine post of the exoskeleton can be made to accommodate different torso heights. Still, Smets adds, people who are five feet three inches tall or shorter can be difficult to fit. An employer may need to provide a selection of different products to allow for workers’ different sizes and shapes.
It usually takes a few weeks for an operator to break in the material and adjust it to their body height and weight, Smets says. Each person should have their own device and not be sharing it, for sanitary reasons but also to avoid constant re-adjustments.
Exoskeletons are also very expensive. The arm support devices currently used in the Ford trials range from $4,000 to $7,000. On the other hand, he adds, the cost of the device should be compared with the cost to heal a shoulder injury, which for Ford can be more than $100,000.
While exoskeleton technology seems futuristic now, in 10 years’ time it will likely be a natural part of many workplaces, Smets says. The capabilities of the technology will grow quickly, and the difficulties we see now will be worked out.
“These are all new devices. All these little challenges are just a result of the fact that we are in the first and second generation of the devices,” he says. “They’ve just come to market in the past three to four years and they’re only going to get better.”
Linda Johnson is a Toronto-based freelance journalist who has been writing for COS for eight years.
This article originally appeared in the June/July 2019 issue of COS.
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