The pain of squatting and not being able to stand up may be caused by acute injury, osteoarthritis of the knee joint, rheumatoid arthritis and other factors. 1. Acute injury: meniscus injury or ligament injury may lead to pain in the knee joint area, the pain will be aggravated when squatting and standing up, and not able to stand up, which may lead to activity limitation in severe cases. 2. Osteoarthritis of the knee joint: it may be related to degenerative disease of the knee joint, which may cause aseptic inflammation of the knee joint, and in serious cases, it may lead to pain in squatting and not being able to stand up, and it may be accompanied by symptoms such as rattling, stiffness, swelling, and so on. 3. Rheumatoid arthritis: symptoms may be related to environmental factors, such as a long time in the damp and cold environment, will make the knee joint symptoms, will lead to squatting pain in the leg can not stand up, may also be accompanied by joint redness, swelling and other symptoms. Leg squatting pain can not stand up, and lasts for a long time, it is recommended to seek medical examination and treatment to avoid delaying the condition.