A bioengineering investigation of the design and fit of cervical collars

Cervical collars are widely used to support the head and neck in the management of instability caused by disease, trauma, or surgical interventions. While collars aim to reduce pain, promote recovery, and minimise musculoskeletal or neurological complications, they are also directly associated with the development of pressure ulcers. Cervical collar-related pressure ulcers present a significant burden on healthcare systems and negatively affect user wellbeing. Poor fit contributes to discomfort and device abandonment, increasing the risk of further medical complications. However, design and fitting standards are limited, and manufacturer instructions often lack clarity. Consequently, the biomechanical, perceptual, and physiological factors that influence collar fit remain poorly understood, with most research to date focusing only on range-of-motion restriction and interface pressures. Improved collar design and fitting practices could help prevent the costly consequences of pressure ulcers. This research aimed to investigate cervical collar design and fit using state-of-the-art methods for monitoring device-related pressure ulcer risk. A multi-modal approach was adopted, integrating in vivo, in vitro, and in silico methodologies. In vivo testing on healthy participants assessed biomechanical, perceptual, and physiological indicators of fit. In vitro testing examined interface conditions under controlled collar tensioning. A baseline finite element model was developed to characterise collar biomechanics and later extended into a parameterised, population-based model to explore fitting outcomes across morphological variability. The in vivo study revealed significant differences between collar designs in interface pressures, discomfort, and microclimate, with microclimate variations strongly influenced by interface materials. High inter-subject variability indicated that morphological differences substantially affect fitting outcomes. The in vitro work demonstrated design-specific relationships between collar tension and interface pressure, showing that some collars pose a greater risk when overtightened. The baseline finite element model identified key considerations for model development, including material modelling and meshing strategy. The population-based model showed substantial variation in pressure ulcer risk factors across morphologies and highlighted possible gender bias in optimal fitting outcomes. Overall, this multifactorial approach integrating in vivo, in vitro, and in silico methods proved effective in characterising cervical collar design and fit. The findings advance understanding of collar biomechanics and provide evidence to inform standards and guidance for safer, more effective cervical collar design and fitting.