Popliteal cysts, if left untreated, can produce pain and limited knee function, as follows: First, pain: popliteal cysts will continue to increase in size, compressing adjacent nerves and blood vessels, as well as the joint capsule, which can cause local pain symptoms, which can cause pain to radiate to the calf and foot, causing muscle atrophy of the calf and foot, and even limited movement. Second, the function of the knee joint is limited: popliteal cysts will continue to increase, indicating that popliteal cysts are connected to the knee joint cavity, and the knee joint lesion will continue to worsen, which will eventually lead to a large amount of fluid in the knee joint, joint swelling, joint activity is limited, and can not walk with weight, especially long-distance walking, standing for too long will also produce uncomfortable symptoms. Therefore, popliteal cysts, if left untreated, will produce the above-mentioned manifestations and affect the patient’s normal life and work, and should preferably be treated promptly.