For people who use manual wheelchairs, pushing the wheels is not just transportation – it’s independence and physical activity. But the repetitive force required can take a toll over time on the nerves in hands and wrists.
Brooke Slavens, professor of mechanical and biomedical engineering, has received a new grant from the National Institutes of Health to examine how the mechanics and strength of the arms affect the median nerve, which controls movement and feeling in parts of the hand and fingers, in adults who use manual wheelchairs.
The $3.25 million, five-year award is co-led with a collaborator at the Shirley Ryan AbilityLab in Chicago.
Early warning system for risk
When the median nerve becomes compressed or irritated, it can lead to carpal tunnel syndrome (CTS) with symptoms such as pain, numbness, or weakness in the hand. Studies estimate that between 49% and 73% of wheelchair users experience CTS, far higher than in the general population.
“Our goal is to better understand how the physical demands of wheelchair propulsion interact with arm and hand strength,” Slavens explained. “If the muscles don’t have enough strength to meet those demands, it could potentially lead to chronic nerve injury.”
This research will involve a large, cross-sectional study of manual wheelchair users with spinal cord injuries. By identifying the point where physical demand outweighs the user’s strength, the researchers hope to determine who might be at highest risk for median nerve compression – before symptoms appear.
Affects millions of users
The long-term goal is prevention: giving clinicians the tools to help wheelchair users maintain mobility without developing painful secondary conditions. This could involve training strategies, strength-building, or redesigned wheelchair use techniques.
“Millions of adults in the U.S. use a wheelchair,” Slavens said. “If we can reduce the risk of nerve injury and improve comfort and function, we can make daily life better for many people, while also protecting their long-term health.”
The project is supported by the Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD) of the National Institutes of Health.