Microstructural analysis of three-dimensional canal network in the rabbit lumbar vertebral endplate

Insufficient nutrient supply through vertebral canal structures to the intervertebral disc (IVD) has been considered as an important contributor for disc degeneration. Despite previous canal structure characterization studies using histology, scanning electron microscopy, and angiography, among others, their three-dimensional (3D) topology inside the vertebral endplate remains poorly understood. This study aims to characterize the 3D canal structure in the rabbit lumbar vertebral endplate using micro computed tomography (μCT). Vertebral endplates were imaged using high-resolution μCT with 1.4 × 1.4 × 1.8 μm voxel size. Diameter, length, orientation, and depth starting from the vertebral endplate surface were analyzed for each canal using individual 3D canal models from the vertebral endplate scans. In the layer underneath the vertebral endplate, at a mean depth of 76.2 μm, longitudinally-oriented relatively short-length (57.6 μm) and small diameter (45.7 μm) canals were dominant. Large-scale canals with a mean diameter of 152.1 μm running parallel to the endplate surface were isolated at the depth of 224.1 μm. These canals were connected to both IVD and bone marrow spaces through vertically oriented canals.