Pain aggravated nine months after posterior cruciate ligament surgery should be targeted according to the cause. Common causes include secondary rupture of the ligament, muscle atrophy, osteoarthritis of the knee, etc. Rehabilitation training, medication, surgery and other treatments can be chosen. 1. Second ligament rupture: The ligament is ruptured again because of a fall due to strenuous exercise, which can also lead to aggravation of pain. At this time, it is necessary to undergo surgical treatment again, ligament reconstruction surgery. 2. Muscle atrophy: If the patient has been bedridden for a long time after the operation without rehabilitation training, it may lead to muscle atrophy of the lower limbs, which may cause weakness or instability in walking, resulting in pain in the lower limbs or even falling. Active rehabilitation training should be carried out under the guidance of doctors to restore muscle strength as early as possible. 3. Osteoarthritis of the knee joint: mostly seen in the elderly, degenerative changes in the knee joint can appear bone destruction or synovial inflammation, resulting in increased pain in the knee joint. Oral non-steroidal drugs such as diclofenac sodium can be taken for anti-inflammatory and pain relief, and surgical treatment is also needed for serious joint destruction. There are many reasons for the aggravation of pain nine months after posterior cruciate ligament surgery, and it may also be related to gout, knee synovitis and other diseases. If the symptoms continue to be unrelieved, it is recommended to consult a doctor in time to clarify the cause of the disease and then carry out targeted treatment.