Sheep Lumbar Spine Disc Mechanics

Lumbar spines were harvested from twenty skeletally mature sheep previously obtained for a non-spine animal study. All musculature and soft tissue were dissected and facets and transverse processes removed to eliminate any facet and tranverse process contributions on disc mechanics. Bone-disc-bone units, were prepared by making parallel cuts through the vertebral bodies above and below the disc at lumbar spine level L4-L5. Samples were potted in polymethyl-methacrylate bone cement. Kirschner wires were placed through the bone cement and vertebral body to increase pull out strength. The potted samples were wrapped in saline soaked gauze throughout preparation to prevent dehydration. Prior to each mechanical testing step, the sample was thawed and hydrated for 18 hours in a 4°C refrigerated PBS bath to establish a uniform initial hydration condition.^{33 (link)}