Patellar surgery nearly a year wound is still red, the possible causes are infection, surgical wound scar tissue hyperplasia, traumatic arthritis and so on. 1. Infection: patellar surgery nearly a year wound is still red, may be caused by postoperative local infection. 2. Surgical wound scar tissue hyperplasia: it may be the formation of scar tissue hyperplasia after patellar surgery and wound closure, resulting in the phenomenon of redness and swelling. 3. Traumatic arthritis: may be nearly a year after patellar surgery, the knee joint activities are more frequent, which causes traumatic arthritis, redness and swelling around the joints. Patellar surgery nearly a year the wound is still red, there may be other reasons, it is recommended to go to the regular hospital in a timely manner, improve the relevant examination, clear the cause of the disease, under the guidance of the doctor for targeted treatment or treatment.