Hello I understand your concern. The knee replacement surgery is associated with a high risk of a deep vein thrombosis, which is a formation of blood clots in the deep veins of the leg. The risk of deep vein thrombosis changes according to risk factors like obesity, sex, age. I m sure that your doctor will take all the necessary measures to prevent that accident by giving you a blood thinner and using a compression stockings. You should discuss that complication with your doctor to have all the answers before the surgery and to make the prevalence risk/benefits of that surgery. Hope I answered your question Wish you a speedy recovery Best regards Dr. Noor Farid