Effects of Endplate Healing Morphology on Intervertebral Disc Degeneration after Pedicle Screw Fixation for Thoracolumbar Fractures

Abstract

Background: The cartilage endplate plays an important role in the stress distribution and nutrition metabolism of intervertebral disc. The healing morphology of the endplate after spinal fracture and its effect on the intervertebral disc degeneration are still unclear. Methods: 51 patients with single-level thoracolumbar fractures underwent posterior open reduction and pedicle screw fixation. Combined with the initial CT and MRI images, the endplate injury was defined as three types, which are unilateral endplate injury, bilateral endplate injury and no endplate injury. According to the location of the injury in the endplate, it was further divided into endplate central injury and endplate peripheral injury. The degree of post-traumatic disc lesions and disc degeneration during follow-up were classified based on the Sander classification and the Pfirrmann classification, respectively. According to the T1 image of MRI in the final follow-up, the healing morphology of endplates was classified into three types including the increased endplate curvature, the irregular healing and the traumatic Schmorl nodes. Results: Cartilage endplate fractures are closely related to the degree of degeneration of the intervertebral disc (P=0.003). Injuries in different parts of the endplate have no significant effect on the intervertebral disc degeneration (P=0.204). The healing morphology after endplate fracture significantly affected the degree of intervertebral disc degeneration (P=0.001). The comparison of groups showed that the effects of irregular healing and traumatic Schmorl nodes on disc degeneration were not statistically different, but were significantly different from those with increased curvature. Conclusions: Increased endplate curvature, irregular healing and traumatic Schmorl nodes are three common forms of healing. The irregular healing and the traumatic Schmorl nodes are closely related to intervertebral disc degeneration. The existence and severity of the endplate injury can provide valuable information for individualized clinical decision-making processes.