Sounds in the joints are not necessarily pathological. The cartilage, joint capsule, synovial membrane, ligaments and tendons of the baby’s joints are not yet well developed, so sometimes it is normal for them to make a sound when moving. The popping of joints in children is related to the weakness of their muscles and ligaments and the shallowness of their joint sockets. The ligaments around the joints of children are lax and there is cartilage plate at the end of the long bones, so when the joints do flexion and extension activities, there is a popping sound, which will disappear as the child gets older and the ligaments become stronger and the muscles develop. This is not a disease, it is a physiological phenomenon. If this is caused by this condition, the sound will gradually disappear as the joints and surrounding tissues gradually develop and improve. However, if it is caused by a disease, such as abnormal tissue in the joints, the joints will make a crisp sound when moving and will be accompanied by pain. Once a mother finds that her baby has a painful reaction, she should take her baby to the hospital for a diagnosis. There is also a rare congenital deformity called “lateral disc meniscus” that can cause the knee to pop or to lock up when walking. It is recommended that you monitor your child closely and go to the hospital for testing if necessary.