In vitro biomechanical testing of the spine is an important method for evaluating new surgical methods and components, prior to in vivo implementation. This relies upon special laboratory tools and techniques to create spinal motion and loading similar to those experienced in the body. In this thesis, two different studies were performed to evaluate the effects of spinal fixation and motion. The first study compared the fixation of a novel hollow screw and a conventional solid screw in an in vitro sacral model. Screws were tested in seven cadaveric sacra and subjected to stair-cased cyclic flexion- extension loading to simulate the clinical loading scenario. The hollow screw was less resistant to loosening compared to the solid screw in this model. In the second part of this thesis, a spinal loading simulator was developed as a modification to an existing Instron® materials testing machine to produce motion in a multi-segment spine using applied pure bending moments (i.e. flexibility protocol). A custom-designed 2D optical tracking system was used to record the planar motion achieved. An experimental validation study was performed using the developed apparatus, and showed the device was capable of independently producing repeatable and reproducible spine motions (i.e. flexion-extension, lateral bending, and axial rotation) in a single cadaveric specimen. Future work will focus on the continued development of the simulator for use in the assessment of spinal orthopaedic interventions
