Generally speaking, if the whole lower limb or foot and calf of the affected side is swollen after knee replacement, then it indicates that the probability of deep vein thrombosis in the lower limb is higher, and active treatment is needed. Knee arthroplasty is a major surgery, due to the use of tourniquet during the operation as well as the localized surgical trauma of the knee joint, it can lead to the endothelial damage of the venous blood vessels of the lower limbs, which is prone to the formation of venous thrombosis of the lower limbs. In addition, the hypercoagulable state of the body caused by the surgery and the factors such as prolonged bed rest and limb inactivity after the surgery cause the blood to stagnate, which further increases the probability of lower extremity deep vein thrombosis. Generally lower limb DVT will cause swelling and pain in the affected lower limb, which usually manifests as swelling of the whole affected limb or foot and calf, etc. This is highly suggestive of lower extremity DVT and requires active diagnosis and treatment. If the swelling of the leg is obvious after knee replacement, you should consult a doctor in time, improve the lower limb vascular ultrasound and other examinations, make a clear diagnosis and then follow the doctor’s instructions for treatment, so as to avoid delaying the condition and avoiding the risk of thrombus dislodgement.