Pain that occurs when the knee is bent but not when the patient is standing is often due to meniscal injury. Meniscal injury can cause pain in the knee when bending and walking, but not when standing, and pain that occurs when bending can be caused by the femur and tibia pressing on the meniscus. It cannot be ruled out that the pain is caused by trauma to the knee, wind and cold, or local inflammation, such as knee osteoarthritis. If the patient has this condition, it is recommended to actively go to the hospital for an MRI examination and then choose certain treatment measures according to the examination results.