Objectives:To analyze the association between the volume of Modic changes(MC)in the lumbar spinewith the volume and morphology of endplate defects(ED),and investigate the correlation between the associated endplate lesions and low back pain(LBP)symptoms.Methods:The clinical and imaging data of 401 patients with ED examined with lumbar MRI at the Second Affiliated Hospital of Soochow University between October 2020 and October 2023 were retrospectively analyzed.The patients were divided into MC group(204 patients)and non-MC group(197 patients)according to whether or not combined with MC,and the volume of ED was measured in the two groups of patients.The morphology of ED was categorized into typi-cal group(depressed,triangular,and round)and atypical group(rectangular and irregular).The length,width and height of MC were measured in patients of the MC group,and the volume fraction was calculated.The vol-ume fraction of MC was analyzed for correlation with the volume fraction of ED and morphological grouping.Then the intervertebral disc degeneration(IDD)grade of all the patients were evaluated and grouped,and the correlations between the volume fraction of MC and volume fraction and morphology grouping of ED for each IDD group of patients were analyzed separately.The low back pain(LBP)condition was followed-up,and the prevalence of LBP in patients with different ED morphology and with or without MC was compared.Results:In the typical morphology group,there were 369 vertebrae,and 152 vertebrae were combined with MC;In the atypical morphology group,there were 191 vertebrae,and 149 vertebrae were with combined MC.The mean volume fraction of ED in the group with MC was 0.017±0.014,and the mean volume fraction of ED in the group without MC was 0.008±0.007.The mean volume fraction of MC in patients with ED in the atypical group was 0.20±0.13,which was 0.11±0.10 in patients with ED in the typical group,with statistically signifi-cant difference(P＜0.001).Overall MC volume fraction correlated linearly and positively with changes in ED volume fraction(P＜0.001).The volume of MC correlated with the volume and morphology of ED in patients with mild and moderate IDD(P＜0.05);In patients with severe IDD,there was a correlation between the vol-umes of MC and ED(P＜0.001),but there was no correlation between the range of MC and the morphology of ED(P＞0.05).The prevalence of LBP was higher in patients with ED combined with MC than in patients with ED alone(P＜0.05).65 patients were followed up to record the LBP condition,and 30 patients had LBP(24 cases in the MC group and 6 cases in the non-MC group),There was no significant difference in the preva-lence of LBP between patients with different ED morphology(P＞0.05).Conclusions:The volume fraction of lumbar MC shows a significant linear and positive correlation with ED volume fraction;In patients with mild and moderate disc degeneration,the patients with ED of atypical group of morphology tend to have a greater volume fraction than the patients in typical group of morphology;Patients combined with MC have a higher prevalence of LBP.