A retrospective clinical study with confirmatory evaluation in healthy volunteers. To investigate the association between deep vein thrombosis (DVT) and surgical position after cervical spine surgery. It is unclear whether posterior cervical surgery using the prone position increases the risk of postoperative DVT relative to anterior cervical surgery. A total of 340 patients undergoing surgery for degenerative cervical myelopathy were included. Multivariate analysis was used to identify the predictors of postoperative DVT, adjusting for potential confounders. In addition, 45 healthy volunteers were used to study the blood flow velocity and intravascular diameter of the posterior tibial vein (PTV) and popliteal vein (PV) of the subjects, which were monitored by ultrasound and compared among three positions (supine, prone, and prone with iliac cushions). Multivariate analysis showed that advanced age (above 63.5yr old), preoperative varicose veins, D-dimer >0.255mg/L, bleeding volume >303mL, and prone positioning were significantly associated with DVT after cervical spine surgery. The results of vascular ultrasound showed that the blood flow velocities of the PV and PTV in the prone position with cushions were significantly lower than those in the supine position. The diameter of PV in the prone position with cushions was also significantly larger. The blood flow velocity and diameter of PV in the prone position with cushions were significantly lower and larger, respectively, than those in the prone position without cushions. Posterior cervical surgery in the prone position was significantly associated with postoperative DVT. The prone position with iliac cushions may decrease venous flow within the lower extremities due to compression of the iliac veins, obstructing venous return and thus increasing the incidence of postoperative DVT. The prone position without iliac cushions may reduce the potential for DVT. 3.