Recently, 50-year-old Zhang encountered a troublesome, left popliteal fossa open up a “big bag”, localized swelling and pain, and knee joints from time to time, “thump” a dare not move, walk with fear, for fear that the knee joint pain up cold. Zhang came to the local hospital’s sports medicine department, the receiving physician patiently and carefully diagnosis, diagnosed as knee meniscus injury with popliteal cysts. Because of the frequent symptoms of knee “interlocking”, it can only be solved by surgery. When Ms. Zhang heard that there was an egg-sized “bag” growing in the popliteal fossa, she was scared: “How long would it take to cut an incision to take it out!” The doctor comforted her and said, “Don’t worry, your meniscus is torn and needs to be treated by arthroscopy. Although the popliteal cyst is at the back of the knee joint, we can now cut off the cyst through arthroscopy from the front, and the popliteal fossa can be solved by only two or three 0.5 cm small incisions without incisions, which can solve the root of the popliteal cyst, and the recurrence rate is lower than that of surgery. surgery with a lower recurrence rate.” Ms. Zhang was very happy and gladly accepted arthroscopic surgery in the Department of Sports Medicine, and started walking on the ground on the second day after the surgery, and she did not feel any pain from the beginning to the end, and the “interlocking sensation” disappeared, and the “big bag” in the popliteal fossa also disappeared, and now Ms. Zhang has completely recovered. Ms. Zhang has completely recovered and was happily discharged from the hospital. Popliteal cyst is a disease caused by the enlargement of the deep bursa in the popliteal fossa or the swelling of the synovial bursa of the knee joint to the back, which can cause pain and swelling at the back of the knee, and can be touched with elasticity of the soft tissue mass. It is most common in middle-aged and elderly people, and is often triggered by lesions in the knee joint cavity, such as osteoarthritis, meniscus injuries, ligament injuries, and so on. The above mentioned diseases can cause fluid accumulation in the joint cavity. When the pressure of fluid accumulation reaches a certain level, it will be extruded to the outside of the joint cavity through the flap structure on the capsule of the knee joint. This flap is one-way, so the joint fluid can only be extruded to the outside of the joint cavity but cannot flow back to the joint cavity, and popliteal cysts are formed when it slowly gathers more and more. Therefore, it is important to treat popliteal cysts in a timely manner by treating the primary lesion in the joint, otherwise the cyst is prone to recurrence. The conventional surgical method is to make a long “S” shaped incision from the popliteal fossa in the prone position, separate the muscle space, find the cyst and remove it, which is a more traumatizing surgery, with a long period of postoperative incision pain and a large scar, which may affect the knee flexion and extension activities and is not aesthetically pleasing. What’s more, conventional incision surgery cannot reveal the lesion inside the knee joint cavity and cannot address the culprit causing the cyst, and there are more chances for the cyst to recur after surgery. Arthroscope is a rod-shaped optical instrument with a diameter of about 5mm to observe the internal structure of the joints. It is an endoscope used for diagnosis and treatment of joint disorders, and the structure of the joints is displayed on the monitor through the imaging system, and almost all parts of the joints can be seen, which is more comprehensive than cutting open the joints, and it is known as “putting the eyes and fingers into the joints”. It is called “putting your eyes and fingers inside the joint. Since the image is magnified, it is more accurate, and the incision is small, less invasive, less scarring, faster recovery, and fewer complications. By treating popliteal cysts through arthroscopy, the one-way flap on the capsule at the back of the knee can be opened, allowing the fluid to flow freely in and out of the joint cavity, and the capsule wall can be removed microscopically to deal with the primary lesions such as meniscus injuries, ligament injuries, cartilage injuries and so on, which effectively reduces the recurrence rate.