Objectives:To investigate the morphological characteristics of the lower cervical vertebrae in Chinese Han multilevel cervical spondylotic myelopathy(MCSM)patients and to compare it with European Caucasian MCSM patients.Methods:The MCSM patients who underwent expansive single open-door lamino-plasty(EOLP)between December 2016 and May 2022 at the Affliated Drum Tower Hospital,Medical School of Nanjing University and Clinique Du Parc,France were divided into two groups based on ethnicity.Group A consisted of 80 Chinese Han MCSM patients(42 males and 38 females,mean age 62.3±10.5 years),while group B consisted of 29 European Caucasian MCSM patients(15 males and 14 females,mean age 58.4±12.6 years).The lamina inner width(LIW)at hinge place,lamina outer width(LOW)at hinge place,lamina axis length(LAL)and lamina transverse angle(LTA)of the patients were measured on CT plain scan images before operation.Independent sample t-test was performed to compare the differences in C3-C7 imaging parameters between the two groups.Results:LIW and LOW decreased from C3 to C5,and increased from C5 to C7 in both groups.Group A was significantly smaller in LAL at each level than group B(C3:12.1mm vs 13.4mm;C4:12.5mm vs 13.5mm;C5:12.8mm vs 13.9mm;C6:13.1mm vs 14.4mm;C7:13.5mm vs 14.4mm),while larger in LIW(C3:2.8mm vs 2.4mm;C4:2.4mm vs 1.9mm;C5:2.2mm vs 1.7mm;C6:2.7mm vs 2.3mm;C7:4.1mm vs 3.7mm)with significant differences in C3-C6(P＜0.05).No significant differences were found in LOW and LTA between the two groups at each level(P＞0.05)Conclusions:In Chinese Han and European Caucasian MCSM patients,C5 is the thinnest lamina among the lower cervical vertebrae with the highest risk during grooving in EOLP,and the risk is theoretically higher in Chinese Han MCSM patients than that in Caucasian MCSM patients.