The pain in the knee when standing up may be caused by physiological factors such as prolonged standing and sitting for a long time, or it may be caused by pathological factors such as knee injury and joint inflammation. 1. Physiological factors: keeping a position for a long time, such as standing for a long time and sitting for a long time and other factors, can lead to the phenomenon of knee joints slightly jammed, the symptoms of a moment of pain, is a normal physiological phenomenon, the activities of the limbs can be restored, do not need to be treated. 2. Knee injuries: trauma can lead to knee injuries such as ligament injuries, meniscus injuries, etc., knee activities due to the free soft tissues jammed or interlocked, there can be a momentary pain in the knee stand up symptoms, there may be impaired activity. 3. Joint inflammation: when patients have osteoarthritis, rheumatoid arthritis, rheumatoid arthritis and other inflammatory diseases, due to joint osteophytes, cartilage wear and inflammation and other joint lesions, it can lead to the symptoms of knee pain when standing up. The knee pain can also be caused by other reasons, it is recommended that patients go to the hospital in time to improve the relevant examination for targeted treatment.