Prone Position Increases the Risk of Postoperative Deep Vein Thrombosis in Cervical Spine Surgery by Limiting Venous Return in the Lower Limbs.

STUDY DESIGN:Retrospective clinical study with confirmatory evaluation in healthy volunteers. OBJECTIVE:To investigate the association between deep vein thrombosis (DVT) and surgical position after cervical spine surgery. SUMMARY OF BACKGROUND DATA:It is unclear whether posterior cervical surgery using the prone position increases the risk of postoperative DVT relative to anterior cervical surgery. METHODS: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 blood flow velocity and intravascular diameter of the posterior tibial vein (PTV) and popliteal vein (PV) of the subjects were monitored by ultrasound and compared among three positions (supine, prone, and prone with iliac cushions). RESULTS:Multivariate analysis showed that advanced age (>63.5 y old), preoperative varicose veins, D-dimer>0.255 mg/L, bleeding volume>303 mL and prone positioning were significantly associated with DVT after cervical spine surgery. The results of vascular ultrasound showed that blood flow velocities of PV and PTV in the prone position with cushions were significantly lower than those in the supine position. The diameter of PV in 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. CONCLUSIONS: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 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. LEVEL OF EVIDENCE:3.