34 patients who were scheduled for knee, femur, or spine surgeries were randomized to either an alternate sequential compression device group (ASCD), which used an SCD Express device, or a simultaneous sequential compression device group (SSCD), which used a DVT-3000 device. The aim of the study was to compare venous hemodynamic changes and their clinical influences when using an ASCD versus a SSCD in populations with high risk of venous thromboembolic complications. Duplex ultrasonography examinations were performed for the detection of deep vein thrombosis (DVT), as well as the evaluation of venous hemodynamics. Data was gathered on postoperative days 4 and 7. Results demonstrates that there were no significant differences in presence of DVT or in hemodynamic factors between the alternate and simultaneous device groups..