Wheelchairs are crucial for mobility and independence for many individuals with spinal cord injuries, yet they are prone to frequent failures. Studies show that 45-63% of wheelchairs experience failures or repairs within six months, with one-third resulting in adverse consequences like injuries. Caster failures account for a significant portion of these issues, posing risks such as falls and hospitalizations. Repair times can be lengthy, causing users to experience physical and financial hardships. Preventative maintenance, while shown to reduce accidents, is often neglected due to lack of user knowledge, tools, and insurance coverage. This study aims to analyze community-based caster failures across various wheelchair models and manufacturers to understand the frequency and risk associated with these failures and the potential impact of preventative maintenance.

Existing research demonstrates high rates of wheelchair failures, with casters being a major contributor. Studies have highlighted the relationship between wheelchair breakdowns and adverse user outcomes, including injuries, pressure sores, and hospitalizations. The lack of preventative maintenance, often due to user limitations and lack of insurance coverage, exacerbates these issues. While some studies address wheelchair maintenance and its impact on accident rates, there is limited research specifically focusing on the types and variations of caster failures across different wheelchair models. This gap in knowledge necessitates further investigation to inform design, quality testing, repair, and maintenance strategies.

This study used secondary data analysis of wheelchair failures and service repair logs from the Wheelchair Repair Registry (WRR), a database containing repair claims from a network of wheelchair suppliers. The data included information on wheelchair manufacturers, models, and types of caster failures. Caster failures were classified as either high-risk (wheel fracture, bent part) or low-risk (bearing failure, worn-out tire). Repairs categorized as service repairs (preventative maintenance) were also identified. Data from January 2017 to October 2019 was selected. Chi-square tests were used to analyze relationships between failures and manufacturers and models. Kaplan-Meier survival curves and log-rank tests assessed differences in survival rates across models. Linear regression evaluated the association between service repairs and high-risk failures. Only models with at least 100 caster failures were included in the analysis.

A total of 6470 caster failures and 151 service repairs were analyzed across four manufacturers and five wheelchair models. Failure types were significantly associated with both manufacturers and models. Tilt-in-space wheelchairs showed nearly twice the proportion of high-risk failures compared to ultralightweight models. Power wheelchairs (Groups 3 and 4) experienced 15-36% more high-risk failures than Group 2 models. Survival analysis showed significant differences in survival rates of Group 3 wheelchair casters between manufacturers M2 and M4. Service repairs for manual wheelchairs were negatively correlated with high-risk failures (R²=0.96). High-risk failures commonly occurred within 1-2 years of wheelchair use.

The findings demonstrate significant variability in caster performance across manufacturers and models. Users requiring higher levels of seating support and complex rehabilitation needs are at increased risk for high-risk caster failures leading to injuries and adverse consequences. The negative correlation between service repairs and high-risk failures underscores the importance of preventative maintenance. Differences in survival rates between manufacturers highlight the need for improved caster quality and standardization. The study suggests a need for improved manufacturing standards, increased emphasis on preventative maintenance, and user training. Improved caster testing protocols can provide valuable feedback to manufacturers during the design process.

Wheelchair caster failures pose significant risks to users, impacting their health and quality of life. This study highlights the disproportionate impact on users of complex rehabilitation needs and the importance of preventative maintenance. Improvements in caster quality, along with increased frequency and access to service repairs, are essential to mitigate these risks. Future work should focus on laboratory testing of caster designs, expanding the WRR dataset, and studying the impact of various factors (user training, usage conditions) on failure rates.

The study's limitations include missing data on wheelchair setup, user training, user-led maintenance, user demographics, and use conditions. The WRR data only includes wheelchairs that experienced failures, neglecting those without issues. The lack of data on specific maintenance practices prevents comprehensive analysis of their effect.