In clinical practice, patients with prolonged knee flexion and pain are caused by prolonged knee flexion, which stimulates the quadriceps muscle group and increases the pressure in the muscle to produce a large amount of inflammatory factors that can affect the metabolism of lactic acid in the quadriceps muscle, resulting in pain. If the patient has osteoarthritis of the knee joint due to bone proliferation and degeneration in the knee joint, prolonged knee flexion can cause friction of the cartilage, which can cause pain and affect the patient’s weight-bearing activities, as well as swelling and pressure pain in the knee joint. In addition, prolonged knee flexion can also injure the cartilage, meniscus, synovium, fat pad and other tissues in the knee joint, which can also cause pain.