Swelling of the feet and calves is mainly caused by deep vein thrombosis, which is usually seen in patients who have had injuries to the back of the calves, who have been bedridden for a long time, and who have been externally fixed in casts and braces. Once the thrombus is formed, the venous return becomes dysfunctional, resulting in the accumulation of more and more venous blood in the distal end and swelling of the legs and feet. If there is thrombosis, a filter can be placed in the inferior vena cava to prevent the thrombus from dislodging into the lungs and causing pulmonary embolism, and after good protection, interventional surgery can be performed to remove the thrombus and thrombolytic therapy.