It’s well-known that lifting a patient poses a risk to your low back, but a new study shows that pushing patients in a wheelchair can also cause spinal injury. And many people don’t know how much they should safely push.
“Collectively, patient handling is one of the riskiest jobs out there,” say study authors William S. Marras, PhD, CPE, director of the Spine Research Institute and Honda Chair Professor of Integrated Systems Engineering at The Ohio State University, and Eric Weston, Graduate Research Associate at The Ohio State University.
“It is well known that there is a significant risk of low back injury associated with lifting patients, and this study shows that there is a risk of low back injury associated with pushing them as well,” they say.
A Look at the Study Findings
The research team observed 62 volunteers (31 men and 31 women, average age of approximately 25 years) as they pushed against a simulated wheelchair attached to a braking system with adjustable resistance.
The resistance started low and gradually increased until the volunteers said they could no longer move the simulated wheelchair. Throughout the exercise, researchers evaluated the forces on their intervertebral discs.
The researchers discovered that the participants, on average, pushed 17-18% past the point they should have stopped.
The authors say the most surprising result of the study was that wheelchair pushing poses a risk for low back injury at relatively low patient weights. Even under the most ideal conditions, the authors say the risk of injury to the low back is expected to begin when pushing patients weighing around 100 kg (or about 220 pounds) and increases with increased patient weight.
“With rising obesity in the United States, patients are getting heavier and harder to push, and it is expected that patients may weigh well past this 100 kg threshold,” say Dr. Marras and Weston.
The researchers also found that turning a wheelchair posed a greater risk to the spine compared to pushing in a straight line. Turning requires more work from the abdominal stabilizing muscles, and the turning motion increased spinal forces by about 40%.
Moreover, the authors expect that risk to the low back would be even higher under non-ideal conditions that weren’t measured in this study (such as pushing up a ramp or across carpet).
How can pushing a wheelchair hurt your back? When you push against a heavy load, your spine compresses. When you push repeatedly, it speeds up the wear and tear process on your intervertebral discs, leading to degenerated discs.
Dr. Marras and Weston say the intervertebral discs found between each of the spinal vertebrae are the largest structures in the body that do not receive a direct blood supply.
“In a healthy disc, nutrients diffuse through the endplates that are found at each disc,” explain Dr. Marras and Weston. “However, when heavy loads are repeatedly placed onto the low back, small micro-fractures and scar tissue develop on the endplates that disrupt this diffusion process.”
The reduced nutrient supply to the disc results in disc degeneration. When your spinal discs degenerate, your discs shrink and may begin to put pressure on your spinal nerves, causing pain.
What the Study Findings Mean for You
Unfortunately, Dr. Marras and Weston say there is not much you can do to condition yourself when it comes to wheelchair pushing safety.
“Using your body weight by leaning forward while pushing may help to reduce the loads onto the low back slightly, but it’s also important to note that leaning forward would also increase the potential for the caregiver to slip and fall,” they note.
Instead, Dr. Marras and Weston recommend that the emphasis be placed on designing interventions for wheelchair pushing and turning.
“For example, a motor-assisted chair could help to propel the patient when the required pushing forces begin to exceed our recommended limits,” they say. “Likewise, slightly wider handles could help to reduce the torques required to turn patients in wheelchairs.”
Dr. Marras and Weston also point to existing technology aimed at reducing injuries when lifting patients, such as floor-based and ceiling-based mechanical lifts, as good tools to use to improve patient handling.
“Workers may reduce their risk of injury by utilizing these interventions rather than manually handling patients,” they say.
More About the Spine Research Institute
Founded in 2012 at The Ohio State University, the Spine Research Institute aims to prevent, understand, and treat musculoskeletal disorders, including low back pain. The institute includes multi-disciplinary experts who seek innovative ways to treat spinal conditions. You can learn more about the Spine Research Institute here.