Pain in the knee after strenuous activity may indicate damage to the internal ligaments of the knee or damage to the meniscus, which may require prompt examination at a hospital, either by frontal and lateral radiographs of the knee or by MRI. If the ligament is damaged, conservative treatment is needed, such as immobilization with a brace and limiting strenuous knee activity. If the fluid is small, it can usually be absorbed on its own. If there is more fluid, it may require symptomatic treatment. If the meniscus is damaged mostly due to improper force or twisting during knee flexion, causing meniscus damage, if it is more serious and there is a meniscus fracture, it also needs to be examined and treated with arthroscopy to remove the torn meniscus and relieve the pain.