Engineering an End to Back Pain

Marit Johnson, a PhD candidate at SD Mines, is focusing her research on intervertebral discs in the lower back.

There is a good chance you are sitting down right now. It’s possible you’ve been sitting all day, or maybe you’ve even been sitting every day for the last few decades.

“There is a trend in the 21st century that 80 percent of our jobs require sitting, and it’s even more so when you include leisure time,” says Marit Johnson (CE 96), a PhD candidate in biomedical engineering at SD Mines.

You may guess that spending all this time in a chair is not so good for your health. In fact, research is now showing prolonged sitting may contribute to lower back pain. “Eighty percent of us will experience back pain in our lifetime,” says Johnson. "If your job requires long hours in a chair, back pain can be a real issue."

Johnson’s research is focused on the intervertebral discs of the lower back. These discs are in between the vertebrae, or bones, of the spine, and their softer tissue provides cushion and flexibility. They are key components of a healthy and functional spine.

Research shows that intervertebral discs need to exchange fluid to maintain a healthy environment, similar to how our bodies need breathing to exchange carbon dioxide with oxygen for our survival. “Typically, when we wake up in the morning we’re taller,” says Johnson. At night when we sleep the discs pull in fluid and they expand. As the day goes on, that fluid gets pushed back to the vertebra again. In this cycle, the discs provide cushion, take in nutrients and discharge waste products. But when discs are injured, this process is disrupted, cushioning is compromised and sitting becomes difficult. “Sitting for people with disc issues is very uncomfortable and can be very painful,” says Johnson.

Johnson is exploring the design of a device that could temporarily relieve pressure on the spine while giving the intervertebral discs a chance to “breathe” properly. An ideal device would give the spine a bit of a pull, or traction, while in a sitting posture, and allow a person to continue working with their arms. Johnson is leading testing on a simulation apparatus she designed.

She uses a stadiometer to measure spine height before and after a short period of sitting in traction in order to capture the spinal height changes that result from the discs pulling fluid in. Currently, spinal traction therapy is available lying down with either manual or mechanical traction, via aquatic vertical hanging or inversion tables. Johnson’s research aims to allow this therapy to be made available while sitting. This would give a patient the chance to keep working at a desk while receiving this type of application. She says the focus is on helping those with disc injuries who must sit on the job. It could also potentially slow down the impacts to discs from prolonged-sitting occupations.

Johnson brings a unique background to this research. After finishing her degree in civil engineering at Mines, she spent a few years in the field and then decided to go back to school to follow a second passion–physical therapy. She has spent 15 years as a physical therapist, and during this time she was constantly thinking about solutions to problems she encountered in patients. “In the back of my head is the engineer, the innovator, and I need to take what I learned at the clinic and develop these ideas. (In order to do this) I need to understand and speak both medicine and engineering,” she says about the biomedical engineering field.

Biomedical engineering is multidisciplinary. “You have to know a little about many areas to pull in people who are experts in various subject matters,” she says. Johnson’s research at Mines involves backgrounds in biomechanics, industrial engineering, ergonomics, and human factors, including assistance from the University of South Dakota physical therapy department.

Johnson is now beginning the next phase of her research. She is set to finish her PhD at Mines in the spring of 2019 and if all goes well, her work could turn into a new way to help alleviate lower back pain associated with sitting. 

Last edited 7/30/2018 7:35:16 PM

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