The pain behind the knee after squatting for a while may be caused by popliteal cyst, fasciitis, meniscus injury, osteophytes and other diseases. 1. Popliteal cysts: cysts in the popliteal fossa cause increased pressure in the popliteal fossa, which may cause pain after squatting for a while. 2. Fasciitis: prolonged and strenuous exercise will lead to strain of muscles and tendons around the knee joint, if you don’t pay attention to warmth, localized cold and other acute stimuli, may induce the above symptoms. 3. Meniscus injury: when you get up after squatting, the damaged posterior horn of meniscus will be squeezed and rubbed, and the symptoms of pain at the back of the knee may occur, which may be accompanied by swelling of the knee area and impaired activity. 4. Osteoplasia: Bone degeneration in the knee joint will induce the above symptoms, and joint deformity and joint friction sound may also occur. There are many other reasons for the pain behind the knee after squatting for a while, and if the symptoms continue to be unrelieved, you should go to the hospital in time to find out the cause of the disease and then target treatment.