Development and Biomechanical Testing of an Artificial Vertebral Body

Significant advances in spinal surgery have been made with new devices that restore the biomechanical characteristics of the injured or degenerated human spine. Laboratory testing of implants is crucial for safety and efficacy, and one of the mainstays of testing remains the use of cadaver models for biomechanical analysis. Logistical difficulties of using biological tissues include storage, handling, and a heterogeneous nature that results in significant interspecimen variability. Artificial spine models have been developed for motor vehicle crash tests and fatigue testing of implants. However, these models do not replicate the morphometric details of the human vertebrae or spinal column. The purpose of this project was to develop a morphometric model of a human vertebra for biomechanical testing. A morphometric model of the T9 human vertebra was developed from computed tomography scans, and a physical model was produced via rapid prototyping. This prototype was used to create a series of models based on two (foaming polyurethane and plaster) materials. The vertebral bodies from the models were tested under compression loading and compared to a group of human cadaveric T9 vertebrae. Solid models made from plaster lacked the viscoelastic component present in the human cadavers. Rigid foaming polyurethane responded with a mechanical behavior more consistent with the cadaveric specimens