53 Serwylo sustained compression fractures to the end plates of three lumbar vertebrae, at levels L2, L3 and L4. Two orthopaedic surgeons, called by Serwylo, considered that Category II did not apply to Serwylo's injury, because the first element of 'Structural Inclusions' in that category is confined to the compression of one vertebral body, which was not that case. In their opinions, Category IV was appropriate because Serwylo had fractures at three vertebral levels. For each of those surgeons the multilevel fractures were sufficiently serious to justify inclusion in Category IV, because such fractures involve greater deforming forces, or a significant degree of impact, exerted on the spine than would occur with a fracture involving a single vertebra. The other surgeon, called by the insurer, disagreed. In his opinion, Serwylo did not qualify for inclusion in Category IV, because the fractures to the superior end plates of the L 3, L 4 and L 5 vertebrae were minor, and, as such, did not constitute spine segment structural compromise. His opinion was that structural compromise to the spine required something which disrupts, or had real capacity to disrupt, the spinal canal, or the ability of the spine to provide postural support. Because no such disruption was evident, there was no spine segment structural compromise.