UBC Theses and Dissertations
Spinal cord deformation during axial impact injury of the cervical spine Saari, Amy
Head-first impact can occur during home and occupational falls, automotive rollovers, various sports, and other activities. These incidents often result in both spinal column and spinal cord trauma. To better understand the resulting bony and neurological injuries, and to develop devices to prevent them, several investigators have studied the response of the cervical spinal column under axial impact. In general these studies have not related the spinal column injuries sustained to the accompanying spinal cord injury. As such, the relationship between these two aspects of trauma is not well understood. Furthermore, most of the models used to study dynamic axial impact do not account for musculature present in vivo which may influence the response of the model to the impact. The objectives of this work were to develop an appropriate cervical spine model that incorporates the effect of musculature so as to assess its effect on the kinematic response of the cervical spine to the impact, and to quantify spinal cord deformation during injury sustained during dynamic head to ground impact. Insight into the relationship between spinal column and spinal cord injuries could improve animal models used to study spinal cord injury at a cellular level by providing data on depth and area of compression and velocity of compression. Previously there has been little data on these parameters which are needed to recreate clinically relevant injuries in these animal models. The impact model developed for this work was a cadaveric human cervical spine model that used a follower preload to simulate vertebral loading due to musculature. A novel method of visualizing the deformation of the spinal cord paired high speed cineradiography with a radiodense biofidelic surrogate spinal cord placed within the cadaveric human cervical spine. This system provided a continuous sagittal profile of the spinal cord deformation resulting from the impact induced injuries. The influence of the simulated musculature was assessed via the response of the spine to impact. During impact none of the specimens were observed to respond with a snapthrough and/or complex buckling response as has been previously reported in axial impact studies. The corresponding spinal cord deformations were used to correlate injury mode to severity of cord damage. The degree and velocity of the compression of the spinal cord were used to determine the expected neurological injury from in vivo animal tests assessing these in terms of probability of recovery. Thus the relationship between bony injury and neurological injury could be made in an in vitro model.
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