The time to completely reduce swelling after knee surgery is mainly determined by the severity of the condition, the surgical method, post-operative care and recovery, etc. It usually takes about 3 weeks to 6 months, but specific cases should be treated differently, and the length of time varies. If the knee joint is only mildly damaged by soft tissues and the surgery is only performed with stitches, the postoperative swelling and recovery time is generally shorter, and the swelling can be completely reduced in about 3 to 4 weeks’ time. If the knee injury is more serious, such as meniscus damage and ligament rupture, meniscus and ligament reconstruction through arthroscopic surgery is needed, and it may take 2 to 5 months for the swelling to completely repair after surgery. In the case of severe fractures such as comminuted fractures, those who require incision surgery will need cast immobilization after surgery. The recovery time for swelling may be longer, especially for elderly patients, and may reach 3 to 6 months or even longer. If the above cases are properly cared for in the later stages, the time for complete swelling reduction may be shortened. However, if inflammation occurs, the time to complete swelling reduction may also be prolonged. In the above cases, it is recommended to go to the hospital for regular checkups, and if there is any abnormality, it is recommended that regular treatment be carried out under the guidance of the doctor in a timely manner.