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A multidisciplinary team of Mayo Clinic researchers and others is looking at the ergonomics of people who use manual wheelchairs. They seek to identify metrics to quantify arm use associated with rotator cuff pathology and progressive degeneration, which will inform development of personalized interventions.
In general, people lose functionality in their rotator cuffs — the shoulder muscles and tendons keeping bones in place — as they age. However, for people with a spinal cord injury who are dependent on their arms for both mobility and daily living activities, this natural progression is accelerated.
The researchers, led by Missy Morrow, Ph.D., section head of the Health Care Systems Engineering section in the Division of Health Care Delivery Research, are conducting a study comparing arm use in individuals with spinal cord injury who use a manual wheel chair, and able-bodied individuals. In their first publication: Inertial Measurement Unit-Derived Ergonomic Metrics for Assessing Arm Use in Manual Wheelchair Users With Spinal Cord Injury: A Preliminary Report, they describe how they used inertial measurement unit sensors worn by the study participants for two days to collect measurements and define risk and recovery metrics. Participants also had shoulder MRIs taken approximately 1 year apart, to evaluate the changes in rotator cuff tendon health over time.
In the paper, they discuss the following questions:
- Were measures of risk informative?
- Were measures of recovery informative?
- Was the risk to recovery ratio informative?
The preliminary results of this study showed that manual wheelchair users experienced longer periods of risk and recovery-based arm use than sex and age-matched able-bodied participants, and manual wheelchair users with rotator cuff pathology progression over one year used their arms in more risk-related postures compared to manual wheelchair users without pathology progression.
The authors conclude that measuring the arm use of manual wheelchair users with spinal cord injury is necessary for future interventional studies focused on reducing risk-related arm use. Although they were unable to assess the physical home and work environments of each individual in this study, the authors suspect a number of contributors to risk of progressive rotator cuff degeneration including "ergonomic and equipment set up of the home and community environments, biomechanical techniques used to complete tasks (such as wheelchair propulsion and transfers), and factors that influence the structural capacity of the tendon (such as medication use and comorbidities such as diabetes)."
Many of these are areas for further research, with the goal of improving the quality of life and well-being of people who rely on a manual wheelchair and their arms for all or most of their daily activities.
This research is a collaboration between the Mayo Clinic Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery, Biomedical Statistics and Informatics, Orthopedic Surgery and Radiology at Mayo Clinic; as well as the Department of Engineering at the University of Michigan in Ann Arbor.
This research is funded by the National Institutes of Health Eunice Kennedy Shriver National Institute of Child and Human Development award R01HD084423.
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