Baby kneecap ringing may be related to physiological factors, knee dislocation. 1. Physiological factors: the human body movement meniscus play a stabilizing joint and buffer the role of pressure, because the baby’s knee joint nest is shallow, ligament is weak, flaccid, on the meniscus of the role of the meniscus to reduce the pull, so the meniscus in the joints of the slide amplitude is larger, faster speed, there can be a popping sound. As the age increases, the knee bone ring can gradually disappear. 2. Knee dislocation: when the baby was hit by external forces, resulting in the destruction of the structure to maintain the stability of the knee joint, or the baby has congenital defects of the knee joint, easy to dislocation of the knee joint, resulting in the tendons next to the knee joint abnormal sliding and cause popping sound. There may be other reasons for the baby’s kneecap ringing, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or treatment.