Pain in the knee after strenuous activities indicates that there may be ligament damage or meniscus damage in the knee, which needs to be examined in time in the hospital, either by taking a frontal and lateral view of the knee, or by taking an MRI to further clarify the situation. If the ligament is damaged, conservative treatment is needed, such as immobilization with a brace and limiting strenuous activities of the knee. It is important to check whether there is any fluid in the knee joint. If the fluid is relatively small, it can usually be absorbed by itself. If there is more fluid, symptomatic treatment may be needed. Most meniscus injuries are caused by improper force or twisting when the knee is flexed, resulting in meniscus injury. If it is more serious and there is a meniscus rupture, arthroscopy is also needed for examination and treatment to suture or remove the torn meniscus and relieve pain.