The Effect of Cerebrospinal Fluid on the Biomechanics of Spinal Cord

In Brief Study Design. A biomechanical study using ex vivo bovine spinal cord and dura, and a synthetic surrogate spinal cord with bovine dura. Objective. To investigate the effect of cerebrospinal fluid (CSF) on spinal cord deformation characteristics and to evaluate the biofidelity of a new surrogate spinal cord using an ex vivo bovine model of the burst fracture process. Summary of Background Data. Spinal cord injury is associated with significant personal, economic and social costs. The role of CSF during the injury event and its effect on the spinal cord deformation and neurologic injury is not well understood. Such knowledge could inform preventative strategies and clinical interventions and aid the development and validation of experimental and computational models. Methods. The transverse impact of a propelled bone fragment analogue with bovine and surrogate cord models was recorded with high speed video and the images analyzed to determine deformation trajectories. Each cord specimen was tested in 3 states: with dura and CSF, with dura only, and without dura. The effect of these states on deformation magnitude, duration, and energy loss parameters was assessed. Results. The estimated spinal cord deformation was significantly reduced, although not eliminated, in the presence of CSF when compared to the bare state. The duration of deformation was generally increased in the presence of CSF, though this difference was not statistically significant. This may indicate a reduction in the cord-fragment interaction force for a given impulse. The dura was found to have no significant effect on deformation parameters for the bovine spinal cord. The deformation of the surrogate cord gave similar trends for the different states in comparison to the bovine cord, but was significantly less than the bovine spinal cord for all conditions. Conclusion. The results indicate that the protective mechanism of CSF may not eliminate cord deformationunder the high energy transverse impact characteristic of a burst fracture. However, CSF may contribute to a lessening of cord deformation and applied force. Fresh spinal cords with intact dura were harvested from cows shortly after slaughter. The bovine spinal cords and a novel physical spinal cord model were subjected to transverse impacts to evaluate the protective effect of the cerebrospinal fluid (CSF). The spinal cord deformations were reduced in the presence of CSF.