Popliteal cyst, if left untreated, can produce pain, knee joint function limitation, etc., as follows: First, pain: popliteal cyst will continue to increase, compression of adjacent nerves, blood vessels, as well as the joint capsule, which will cause local pain symptoms, can make the pain radiate to the calf and foot, resulting in muscle atrophy of the calf and foot, and even activity limitation. Second, limited knee joint function: popliteal cyst will continue to increase, indicating that the popliteal cyst is connected with the knee joint cavity, and the knee joint lesions will continue to aggravate, which will ultimately lead to a large amount of fluid accumulation in the knee joint, swollen joints, limited joint activities, and can’t walk with weight, especially long-distance walking, and standing for too long will also produce discomfort. Therefore, popliteal cyst, if left untreated, will produce the above manifestations, affecting the patient’s normal life and work, it is best to timely treatment.