Community-based wheelchair caster failures call for improvements in quality and increased frequency of preventative maintenance

Wheelchairs are essential mobility devices for many people with spinal cord injuries, yet field and laboratory evidence shows frequent failures of both manual and power wheelchairs. Between 45–63% of wheelchairs experience failures and/or repairs within six months, and about one-third of failures lead to adverse consequences such as injuries. Front caster failures account for a substantial portion of all failures and can be particularly risky, potentially causing tips, falls, and hospitalizations. Repair delays are common and can lead to loss of access to work, school, and community participation, as well as health complications such as pressure injuries and reduced self-perceived health. Evidence indicates preventative maintenance and active checkups can reduce accidents, but current reimbursement policies typically do not cover service repairs, placing responsibility on users who often lack resources and training. Few studies have specifically examined caster failures, their risk to users, and how preventative maintenance mitigates risk. Understanding the frequency and types of high-risk caster failures across wheelchair models is needed to inform design, testing standards, part selection, repair, and maintenance strategies. This study performs a secondary analysis of community-reported caster failures across manufacturers and models in the Wheelchair Repair Registry (WRR), explores the relationships among failure types, models, and manufacturers, evaluates differences in caster survivability, and assesses the effect of service repairs on caster failures.

Data source: The Wheelchair Repair Registry (WRR), developed by the Rehabilitation Engineering Research Center at the University of Pittsburgh, aggregates repair claims logged by repair technicians via LaborTracker from a network of wheelchair suppliers. The registry contains over 60,000 repairs across more than 5000 devices from 25 manufacturers (approximately 60% power wheelchairs, 35% manual, 5% scooters). Model classification: Wheelchair models were assigned HCPCS codes from order forms; manual models were categorized by feature/function (e.g., tilt-in-space, ultralightweight), and power models were assigned Group 2, 3, or 4 based on configuration. For each model, the number of casters and failures was computed. Inclusion period and cleaning: Caster repairs and failures reported from January 2017 to October 2019 for all manual and power wheelchair manufacturers/models were selected. Duplicate or missing ticket/failure entries were removed. Models with at least 100 caster failures in total were included. Failure categorization: Failure types were classified by risk to the user and to wheelchair components: high-risk (caster wheel fracture, bent part) and low-risk (bearing failure, worn-out tire). Service repairs were defined as adjustments and lubrication of caster parts performed during repair/replacement of another part and considered preventative maintenance. Statistical analysis: Chi-square tests for independence evaluated relationships between failure type and model, and between failure type and manufacturer. Kaplan–Meier survival curves were fitted to high-risk failures for casters with known purchase dates; log-rank tests compared survival across models/manufacturers. Linear regression assessed the association between service repairs (manual wheelchairs) and high-risk failures. Significance threshold p < 0.05; analyses were performed manually.

- Dataset: 6470 caster failures and 151 service repairs across 4 manufacturers and 5 wheelchair model categories were analyzed. - Associations: Failure type distributions differed significantly by manufacturer and by model. • Manufacturer M2 (manual models): χ²(3, N=704)=42.15, p<0.05. • Manufacturer M4 (power Group 2–4): χ²(6, N=4098)=207.66, p<0.05. - High-risk failure burden by model: • Manual: Tilt-in-space models had approximately twice the proportion of high-risk caster failures compared with ultralightweight models. • Power: Group 3 and Group 4 users experienced 15–36% higher proportions of high-risk caster failures than Group 2 users. - Survival analysis: Among Group 3 power wheelchair casters with known purchase dates, significant survivability differences were observed between manufacturers M2 and M4 (log-rank: χ²(1, N_M2=224, N_M4=199)=5.36, p<0.05), indicating faster breakage for M4 casters. - Preventative maintenance: For manual wheelchairs, service repairs were strongly and negatively correlated with high-risk caster failures (F(1,2)=47.75, p<0.05; R²=0.96), suggesting that more service repairs are associated with fewer high-risk failures. - Representative counts (Table 2 excerpts): Example high-risk counts include Group 3 M4 (577 wheel fractures, 16 bent parts) and Group 3 M2 (102 wheel fractures, 20 bent parts); low-risk counts such as Group 2 M4 (338 bearing failures, 1053 worn-out tires).

Findings demonstrate substantial, model- and manufacturer-specific variability in the risk profile of caster failures. Users requiring greater seating support (tilt-in-space manual wheelchairs) and those with complex rehabilitation needs (Group 3 and 4 power wheelchairs) bear a higher burden of high-risk caster failures, directly addressing the study objective to identify frequency and relationships across models and manufacturers. Survival analyses further show that certain manufacturers (e.g., M4) have casters that fail sooner than comparable models (M2), highlighting quality disparities with potential clinical and policy implications. High-risk caster failures occur within 1–2 years of use, consistent with prior community and standards testing studies, underscoring the need for improved caster durability and quality assurance. Preventative maintenance appears protective: greater frequency of service repairs is associated with fewer high-risk failures, supporting community evidence that active checkups reduce accidents. The results advocate for the adoption and enforcement of standardized caster testing (e.g., emerging ISO standards), incorporation of preventative maintenance practices and user/provider training, and informed procurement decisions based on independent testing and performance data. Policy-level changes, including incentivizing service repairs and requiring minimum testing standards for approval and disclosure, could reduce failures and adverse outcomes, particularly for vulnerable user groups.

Wheelchair users who rely on products providing greater seating support and complex rehabilitation care experience higher rates of high-risk caster failures. Preventative maintenance, as reflected by service repairs, is associated with significant reductions in high-risk failures. Enhancing caster quality through standardized testing and improving maintenance practices and training are necessary to reduce failures, mitigate injury risk, and improve health and quality of life for wheelchair users.

The WRR-based dataset lacks information on wheelchair setup and provision, user training, user- or caregiver-led maintenance, user demographics, technician training, and environmental use conditions that could influence failure types and frequencies. Wheelchairs in use that did not experience caster failures were not captured in WRR and therefore not analyzed, potentially biasing estimates. Limited availability of purchase dates constrained survivability analyses to specific models/manufacturers. Prior literature reporting 45–63% six-month failure rates provides external reference but not direct comparators for this dataset.