A Novel Porcine Intervertebral Disc Degeneration Model Induced by Annular Injury: Characterization with MRI and Histopathologic Findings

초록

PURPOSE : Appropriate animal models of disc degeneration are critical for the study of proposed interventions as well as to further delineate the degenerative process. The purpose of this study was to characterize a porcine model for disc degeneration with MRI studies and histological analysis. MATERIALS AND METHODS : Twelve porcine animals were used (weight range 60-80kg) to study degeneration in the lumbar spine. Under fluoroscopic guidance, the disc was percutaneously punctured with a 3.2 mm diameter trephine to a 5mm depth into the annulus fibrosus. Control and experimental levels were randomized among six levels in the lumbar spine. MRI grading and disc height was serially recorded preoperatively and postoperative at 5, 13, 26, and 39 weeks. Animals were sacrificed in groups of three at 7, 15, 28 and 41 weeks post-injury and the discs were examined for histolopathological findings RESULTS : The annular injury demonstrated consistent and sequential and progressive degeneration on MRI and histopathological studies from the time of injury to the final timepoint. The disc height and the disc height index also sequentially decreased from the injury timepoint in a consistent manner. The uninjured control levels did not show any progressive degeneration and maintained their normal state. CONCLUSION : Based on the MRI and histopathological findings, the authors demonstrated and characterized reliable sequential disc degeneration in a porcine model after a percutaneously injury to the annulus fibrosus. In the early stages, as soon as 5 weeks after injury, significant disc degeneration was seen on MRI grading with decrease of disc height. The degeneration was progressive and did not improve by the final timepoint of 39 weeks.