Clinically, the popliteal fossa is located at the back of the knee joint, that is, the connecting part of the distal femur and the proximal tibia, where the tibial nerve, the tibial artery and the common peroneal nerve mainly run. Long-term chronic exertion, strain injury, acute trauma or prolonged exposure to cold in the popliteal fossa can lead to soft tissue injuries in the popliteal fossa, such as semitendinosus and semimembranosus injuries. The patient will have localized swelling, obvious pressure and pain, and the knee flexion and extension activities will be seriously affected. In addition, if the patient suffers from popliteal cysts, it will compress the local tibial nerve, tibial artery, which will affect the blood circulation of the lower limbs, and the patient will feel that the lower limbs have decreased skin sensation, muscle strength, etc. Ultrasonography can be done to make a clear diagnosis.