Association between Modic changes and endplate sclerosis: Evidence from a clinical radiology study and a rabbit model

PURPOSE: To analyse the presence of endplate sclerosis in patients with various types of Modic changes (MCs) and to confirm the results using a rabbit model. METHODS: Participants in the clinical study included 1023 consecutive inpatients with lumbar degenerative disease who attended the Department of Orthopaedics between August 2011 and August 2015. All patients underwent computed tomography (CT) and magnetic resonance imaging of the lumbar spine. In those patients with MCs, endplate sclerosis was evaluated from sagittally reconstructed CT images. In addition to the clinical study, MCs type I, II and III were initiated using a previously developed rabbit model of MCs. Specimens of MCs type I, II and III and normal endplates were harvested, bone mineral density and bone volume/tissue volume of “treated” vertebrae were evaluated using μCT and osteogenic protein expressions of runt-related transcription factor 2 and osteocalcin were assessed using immunohistochemical staining. Measurements were compared between vertebrae with normal endplates and those with different types of MCs. RESULTS: Of 1023 patients, 214 (20.9%) had MCs in one or more endplates; these changes affected 1044 (10.2%) of 10230 endplates. Type I, II and III MCs were seen in 164 (1.6%), 838(8.2%) and 40 (0.4%) endplates, respectively. Of 1044 endplates with MCs, 274 (26.2%) showed evidence of sclerosis on CT images including: 26/164 endplates (15.8%) with type I MCs, 208/838 (24.8%) with type II and 40/40 (100%) with type III. HU (CT value) ratios for sclerotic and nonsclerotic endplates with MCs were 2.0 ± 0.3 and 1.1 ± 0.1, respectively. In the animal study, the bone mineral density, bone volume/tissue volume and expression of runt-related transcription factor 2 and osteocalcin of endplates with type I and II MCs were higher than those of normal endplates and lower than those of endplates with type III MCs. CONCLUSION: Sclerosis can occur in endplates with any type of MCs. However, the clinical and animal study suggests that sclerosis is greatest in endplates showing type III MCs. THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE: The study showed that sclerosis can occur in endplates with MCs type I, II and III. In patients with endplate sclerosis on plain radiographs or CT scans, the endplate can still represent an inflammatory process associated with chronic lower back pain.