UBC Theses and Dissertations
The development of an upper cervical spine model for use in an omnidirectional surrogate neck Romani, Sarah
Safety devices meant to protect the head and neck are often evaluated with the use of an anthropometric test device. Anthropometric test devices are designed for a specific loading scenario and typically are biofidelic only in that application. There is no single surrogate appropriate for the multiplane loading that often occurs in real-world scenarios. In this thesis, I present the development of a surrogate upper cervical spine model (C0-C2 vertebrae) for eventual use in an omnidirectional anthropometric test device neck and its validation under quasi-static loading. We obtained CT scans from a 31-year-old male with no cervical spine pathologies from Vancouver General Hospital. These scans were segmented, modified and 3D printed in aluminum. The transverse, alar, and nuchal ligaments were replicated in the model as they are believed to be the most deterministic to the kinematics of the region. For testing, a custom spine machine was used to apply pure moments in flexion-extension, lateral bending, and axial rotation to the specimen at quasi-static rates. Movements of the vertebrae were tracked using a motion analysis system. In this way, the applied moments and corresponding movements of the vertebrae can be recorded and evaluated. Range of motion, neutral zone and mean helical axis of motion were extracted from the resultant moment-rotation plots and compared to the cadaveric literature. Quantitative curve shape analysis was carried out to assess the shape of the prototype moment-rotation curve to those from cadaveric literature. The range of motion and neutral zones in flexion-extension, lateral bending, and axial rotation are within range of the cadaveric results presented. Quantitative curve shape comparisons resulted in biofidelity ratings from fair to excellent. The mean helical axis of motion was aligned with that reported in cadaveric studies in axial rotation and slightly anterior to what was expected in flexion-extension. Reproducing the kinetic and kinematic responses of surrogate spinal segments will aid in the construction of a biofidelic omnidirectional durable surrogate neck. Such a neck could be used to evaluate, improve, and optimize head and neck safety equipment for transportation, occupational, and sports settings.
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