Some mothers will find that when their babies move, sometimes there is a noticeable ringing sound in the knee joint, and sometimes there is a bouncing sensation, what is going on? 1, dislocation Baby’s body functions are not fully developed, parents in the usual care process a little inattention is likely to cause the baby’s joint dislocation and other situations, dislocation leads to abnormal sliding of the tendons next to the knee joint and cause a popping sound. 2, meniscus abnormalities There are a small number of children, because the shape of the meniscus is abnormal, thick edge, the central depression, closer to the circular shape, so called “disc meniscus”, in this case, more likely to appear joint popping. Diagnosis can be confirmed by MRI of the joint, if it is really clear that “disc meniscus”, generally does not affect children walking, normal activities, but when they grow up, if you play soccer and other strenuous sports, need to be careful, otherwise, easy to damage the meniscus. 3, ligamentous laxity Small infants have a shallow knee fossa and a meniscus structure in the knee joint, which is two pieces of cartilage cushion in the joint, playing a role in stabilizing the joint and cushioning the pressure, with ligamentous tissues around the meniscus limiting the activity, when the knee joint does flexion and extension activities, the meniscus will slide quickly in the joint to adapt to the change in joint position. Because the ligaments of young infants are weak and lax, the meniscus is very mobile and slides over the joint surface of the knee to a certain degree, resulting in a “popping sound”. As they get older, the ligaments become thicker and the structure of the knee joint is gradually altered, and this joint popping noise disappears. Therefore, in most cases, babies with popping knees should not worry. What kinds of rattles should parents be aware of? If your baby’s joint movement is limited, if there is a sound during knee movement and your baby is in pain, then you should take your baby to the hospital. If your baby has a popping sound in the hip joint, you must consider the possibility of congenital hip dislocation. Once you find the hip joint popping, you should go to a pediatric orthopedic surgeon for an examination without delay.