Meniscus plays an important role in the maintenance of normal function of the knee joint and in the stability of the knee joint. At the same time, the knee joint is the most vulnerable joint among all the joints in the body, and the lateral collateral ligaments, cruciate ligaments, and meniscus, which stabilize the knee joint, should be protected and repaired to the maximum extent possible in the management of the knee joint. Therefore, if the meniscus is injured, it should be promptly consulted for a clear diagnosis and treated in an appropriate manner. Arthroscopy is preferred at an early stage and minimally invasive treatment is performed accordingly. If the meniscus injury is not severe or is less than 5 mm in size and occurs at the edge of the blood supply, non-surgical treatment can be used. If non-surgical treatment is ineffective or if the meniscus injury is severe, surgical treatment may be used. If the joint effusion occurs after surgery, it is usually caused by rough operation, incomplete hemostasis, or too early weight-bearing activities on the ground after surgery. Generally speaking, it is possible to strengthen the isotonic contraction of the quadriceps muscle, avoid knee extension activities, and delay the weight-bearing time, and then it can subside. If the effusion is large, the fluid can be withdrawn under strict aseptic operation and then bandaged with elastic bandage with pressure.