Anyone who has had knee surgery in our department will know that the nurses and rehabilitation staff repeatedly emphasize “ankle pump exercises” before surgery. Why do we need to do “ankle pump exercises”? After surgery, the affected limb is usually in a braked state and the amount of movement in the leg is greatly reduced. As a result, the blood flow will be reduced, just like the river flowing in the vein becomes stagnant water, then the probability of venous thrombosis will be greatly increased, especially for some elderly patients and patients with high blood lipid level, the probability of thrombosis will be higher. Of course, it is not true that young people do not develop thrombosis, so all patients must perform a lot of postoperative ankle pump exercises to reduce the probability of thrombosis. If a venous thrombosis occurs, severe swelling and pain in the lower extremities will soon occur, and if the thrombus is dislodged, it is likely to flow with the blood vessels to the lungs, which would be a very fatal situation. So patients must pay attention to it! How to do the “ankle pump exercise”? After the anesthesia subsides, you can start the ankle pump exercises immediately after the surgery: do the maximum range of toe flexion and dorsiflexion with both feet at the same time. Stay at the maximum range for about 5 seconds each. The total number of reps is usually 500-1000 a day. Generally, ankle pump exercises are continued until about 2 months, by which time most patients have also begun to use their lower extremities for mobility and the risk of blood clots is gradually reduced.