Effect of customized 3D-printed hip protectors on user compliance in older adults in care homes: protocol for a cluster randomized controlled trial

Background Hip fractures are a major health concern among older adults, particularly in residential care homes where the risk of falls and fall-related injuries is substantially higher than those in community settings. Hip protectors have been shown to reduce the risk of hip fracture when worn during a fall; however, poor user compliance limits their effectiveness. Conventional hip protectors are often uncomfortable and poorly fitted, which discourages regular use. Customized hip protectors produced through 3D printing technology may improve comfort and fit, potentially enhancing adherence. This study aims to evaluate the effectiveness of customized 3D-printed hip protectors in improving user compliance and reducing fall-related hip injuries among older adults in care homes. Methods This study is a 12-month, two-arm cluster randomized controlled trial conducted in residential care homes in Hong Kong. Thirty care homes will be randomly allocated to either the intervention group or the control group, with approximately 10 participants recruited from each home (total n = 300). Participants in the intervention group will receive customized 3D-printed hip protectors in the size that best fits their body size and pelvic shape, while those in the control group will receive conventional hip protectors. All participants will be encouraged to wear hip protectors for 12 months. The primary outcomes include acceptance rate, adherence rate (day and night), percentage of protected falls, and percentage of protected residents. Secondary outcomes include incidence of hip injury, adverse effects related to hip protector use, costs of using hip protectors, and perceived benefits reported by older adults and care staff. Quantitative data will be analysed using regression models and generalized estimating equations to account for clustering, while qualitative interview data will be analysed using thematic analysis. Discussion This trial will determine whether customized 3D-printed hip protectors improve acceptance of and adherence to hip protectors among older adults in care homes, compared with conventional hip protectors. If they do, the findings could support the use of customized hip protection as part of fall-injury prevention in residential care. Trial registration Chinese Clinical Trial Registry: ChiCTR2500111563. Registered on 3 November 2025.