An improved biomechanical testing protocol for evaluating multilevel cervical instrumentation in a human cadaveric corpectomy model

Spinal instrumentation is commonly used to stabilize the multi-level strut-grafted cervical spine. There are no standard tissue-based testing protocols for evaluating spinal devices. An improved biomechanical testing protocol was developed to study the strut-graft mechanics of the instrumented cervical spine in flexion and extension. The biomechanical stability of two different anterior cervical plating systems were evaluated and compared to the harvested condition. A force sensing strut-graft (fssg) was used to measure the axial compressive load. Parameters of stiffness, segmental vertebral motion, and strut-graft loads were statistically compared with a one-way anova (p<0.05) to determine differences between the spine conditions. Applying a bending moment distribution across the cervical spine resulted in a motion response that closely matched the in vivo case. Fssg loads were affected by plate application and specific plate design features. The testing protocol has been used to study the biomechanical stability of various multi-level strut-graft cervical instrumentation. Information of strut-graft loads aided in better understanding graft-plate load-sharing mechanics and clinically-observed multi-level instrumentation failure mechanisms.