N fossa cyst, also known as “Baker’s cyst”, is a synovial cyst in the medial head of the gastrocnemius muscle, which is a common orthopedic disease. However, due to the deep location of the N fossa cyst and the abundance of nerves and blood vessels in the N fossa, the open surgical incision is large and widely exposed, and postoperative scar adhesions are likely to occur locally, which not only affects the aesthetics and function of the knee, but also easily recurs after surgery. The new arthroscopic resection of N-fossa cysts by Professor Bai Lunhao, director of the joint and sports medicine ward, has fundamentally solved these problems and opened up a new path for the treatment of N-fossa cysts. The advantage of arthroscopic treatment of N fossa cyst is that it can find the cyst tip under direct arthroscopic view and thus peel off the cyst completely, which greatly reduces the possibility of recurrence after surgery, and at the same time can avoid damage to nerves and blood vessels in the N fossa, causing minimal trauma to the knee joint, and the patient can get out of bed on the first day after surgery. The surgery only makes two very small incisions in the N fossa, and the scar is almost invisible after recovery, so female patients no longer have to wear long pants to cover up the “defect” in the N fossa in the hot summer, and can dance lightly and show their beauty in the summer.