A study funded by the National Institute on Disability, Independent Living, and Rehabilitation Research (NIDILRR).
People with mobility disabilities may need to use a wheelchair, part time or full time, to get around. For these wheelchair users, this equipment is of paramount importance for maintaining independence and maximizing quality of life. This is especially true for those that use wheelchairs as their primary means of functional mobility. A growing body of research suggests that both manual and power wheelchairs have frequent failures that require repair. Among the many parts of a wheelchair, casters are often the cause of these failures. Casters are the small, pivoting wheels typically found on the front of wheelchairs but can also be found on the back of some power wheelchairs. They are important, because they help with maneuvering the wheelchair (e.g., quickly turning the wheelchair and changing direction), especially over bumps and curbs.
Further complicating matters is the fact that wheelchair repairs can take a significant amount of time to complete. For example, a report from the Veterans Health Administration suggested that nearly half of wheelchair repairs took more than a month to complete. Delays in wheelchair repairs are strongly related to poor health outcomes and a decline in quality of life among wheelchair users. They may experience increased risk for pressure injuries and hospitalization, and a decrease in feelings of health and wellness. Previous research has shown that preventative wheelchair maintenance reduces the number of wheelchair breakdowns and subsequent decline in health outcomes, but wheelchair users or caregivers may not be fully trained in how best to maintain their equipment for the long term. In a recent NIDILRR-funded study, researchers looked at wheelchair caster failures across several wheelchair types and manufacturers. The researchers wanted to compare the wheelchair caster longevity between different models. They also wanted to see whether regular preventative maintenance would reduce caster failure among the different wheelchair models.
For this study, researchers at the Rehabilitation Engineering Research Center on Improving Health and Function Through Use of Performance Standards in Wheelchair Selection looked at data from the Wheelchair Repair Registry (WRR), a database of mobility device failures and repairs. They looked at the number of caster failures and repairs reported for manual and power wheelchair manufacturers and their wheelchair models between January 2017 to October 2019. Wheelchair models were sorted into two groups: Manual wheelchairs and power wheelchairs. These two groups were further subdivided into five model types based on user needs for seat functions and supports and for maneuverability over terrain:
- Manual Wheelchairs
- Tilt-in-space wheelchair for less active users that require customized seating and positioning support and who may be dependent on caregivers to push the wheelchair.
- Ultralight wheelchair for users who actively self-propel both indoors and outdoors.
- Power Wheelchairs
- Models designed for users needing power mobility with minimal power seat function and limited use on uneven surfaces.
- Models designed for users needing multiple power seat functions and frequent use over thresholds, curbs, and other obstacles.
- Models designed for users needing maximal power seat function and maximal maneuverability on terrain outside of the home.
The researchers looked at the number of caster repairs and failures for each model type. Caster failures were categorized as either high-risk failures or low risk failures based on the potential damage to the wheelchair and risk of injury for the user. High-risk failures included caster wheel fractures and bent parts. Low risk failures included bearing failure and worn-out tires. Service repairs related to adjustment or lubrication of caster parts, performed while repairing or replacing another part, were considered preventative maintenance. The researchers analyzed 6470 total caster failures for those 5 manual wheelchair and power wheelchair model types, and 151 service repairs for the 2 manual wheelchair models.
The researchers found the following results:
- For manual wheelchairs, tilt-in-space wheelchairs had nearly double the percentage of high-risk failures compared to ultralight wheelchairs.
- For power wheelchairs, the high-risk failures increased steadily from 15% to 36% with the increase in seat functions and usage maneuverability demands.
- The high-risk caster failures occurred within 1-2 years of wheelchair use across model types.
- Maintenance performed during wheelchair service repairs decreased incidence of high-risk failures among manual wheelchairs.
In this study, the wheelchair models which were used by people with more complex rehabilitation needs and increased seating support were more likely to experience high-risk caster failure. According to the authors, this may put users of these manual and power wheelchairs at higher risk for injury or other adverse events. The authors also noted that the ultralight wheelchairs were serviced more frequently than tilt-in-space wheelchairs. This suggested that preventative maintenance may contribute to decreasing the risk of wheelchair caster failure. This also suggested that users of tilt-in-space wheelchairs and their caregivers may benefit from additional training related to addressing preventative maintenance.
According to the authors, occurrence of high-risk caster failure within 1-2 years suggested that standardization of caster quality may be needed. In addition, maximizing the wheelchair skills of the users, such as how to safely handle curbs and road bumps, may prolong the safe use of the wheelchair casters and supporting wheelchair parts. While this study offers an early insight into the importance of wheelchair quality and maintenance in reducing the risk of adverse effects for wheelchair users, the authors indicated that additional research may be warranted to further investigate wheelchair caster design and quality.
To Learn More
The University of Pittsburgh Model Center on Spinal Cord Injury is currently evaluating the effectiveness of a web-based wheelchair maintenance training course. To learn how to participate, or try the course without participating in the study, visit http://www.upmc-sci.pitt.edu/maintenance
The Model Systems Knowledge Translation Center offers evidence-based information and resources for people with spinal cord injury, including the factsheet Maintenance Guide for Users of Manual and Power Wheelchairs.
To Learn More About this Study
Mhatre, A., Pearlman, J., Schmeler, M., Krider, B., and Fried, J. (2021) Community-based wheelchair caster failures call for improvements in quality and increased frequency of preventative maintenance. Spinal Cord, 2021. This article is available from the NARIC collection under Accession Number J87411 and in full text from the publisher.