Swelling and liquefaction after knee replacement generally takes 20-30 days to heal without a long mouth, and the healing time with infection extends to 2 months. After knee arthroplasty, there is usually swelling in the knee, and the local liquefaction is caused by necrosis of fat cells in the soft tissue of the anterior side of the knee. After 1~2 weeks of postoperative medication change and infection prevention, the fat liquefaction stops, the local tension decreases, and the wound gradually grows back, so the general healing time is 20~30 days after the operation. For mild localized infection and persistent localized redness and swelling of the knee, generally after about 2 months, the swelling subsides, the local tension decreases, and the wound can be healed. Localized swelling liquefaction after knee surgery, it is recommended to actively seek medical attention and treatment under the guidance of physicians.