The Endplate Morphology Changes with Change in Biomechanical Environment Following Discectomy

Bone is a dynamic structure and is known to respond to changes in the load over time, in accordance with Wolff’s law. It states that the bone changes its shape and internal architecture in response to stresses acting on it [1]. Therefore, any structural changes in the spine may lead to bone remodeling due to changes in the optimal stress pattern. The changes in apparent density and thickness of the endplates following discectomy of varying amounts were analyzed. The study design coupled a bone remodeling algorithm based on strain energy density theory of adaptive remodeling with an experimentally validated 3D ligamentous finite element model of the spine. The apparent density and thickness of the index level endplates decreased above and below the region of discectomy. On the other hand, these parameters showed increases at the remaining regions of the endplate. There were no correlations between the amount of nucleus removed and the average percentage changes in apparent density and thickness of endplate above and below the discectomy region. However, the average percentage changes in apparent density and thickness at endplate in the other region increased with increase in amount of nucleus removed. These predictions are in agreement with the clinical observations [2-6].