Did the doctor let you out of the hospital without telling you clearly? If it is only meniscus repair surgery (minimally invasive arthroscopy), you can try flexion on the fourth day. It hurts when you bend, but you must stick to your teeth and bend a little more every day. You can basically bend in about half a month, but you should avoid carrying loads, that is, don't walk in a hurry. Knee surgery can't bend straight for a few days. Everyone does. In this case, the earlier you do bending recovery exercises, the easier it is to recover the degree of bending. If the time is too long or you can't bear the pain during exercise, which delays the best time for recovery, and you will have to do loosening surgery in a few months, it will be even more painful. At the same time, don't neglect to press your knees straight, raise your ankles, let your knees hang in the air and straighten your legs. It feels like a "tiger stool" punishment, and it is also very painful, but if it is not, your legs will not be straight, and it is more difficult to touch them than to bend them. Contact the attending doctor in time to ask, and don't delay recovery.