Biomechanical characteristics of first coronal reverse vertebrae in degenerative lumbar scoliosis: A study using finite element analysis

Background: Whether the first coronal reverse vertebrae (FCRV) can directly cause biomechanical changes in adjacent segments remains unclear. Objective: This study aimed to explore the biomechanical changes in adjacent discs of FCRV to better understand the stress distribution of degenerative lumbar scoliosis. Methods: According to the plain computed tomography scan data of the T11–L1 segment of a degenerative lumbar scoliosis patient, T12 was the FCRV, and a 3-dimensional finite element model was established accurately. The T11–12 segment disc was defined as the adjacent upper disc (UD), axial section as half of the UD. Similarly, T12–L1 disc was the adjacent lower disc (LD), axial section as half of the LD. The biomechanical changes in adjacent discs of the FCRV under different loads were assessed. Results: Rotational load was the highest under different loads, but it is usually instantaneous. It was noted that the LD was subjected to significantly greater stress magnitudes under neutral standing. Although the adjacent discs of the FCRV did not differ significantly with regard to shear stress, a striking difference was noted when the concave and convex sides were considered individually. The concave sides of the adjacent disc were subjected to greater stress under the neutral standing or lateral bending compared with the convex side. Furthermore, the concave sides of the UD, half of the UD (HUD), and HLD were subjected to significantly greater stress under the neutral standing compared with the convex side. Conclusions: The distal adjacent disc of the FCRV may be at greater risk of degeneration because of taking on more force. These findings can contribute to further treatment planning for the patient and aid physicians’ management decision-making.