Popping joints

Q: My four-month-old son’s knee and ankle joints often make a popping sound when he moves. It doesn’t seem to hurt him, but should I be concerned?

A: Painless popping sounds of knee and ankle joints are most likely nothing to worry about. I would mention it to his doctor so he will check to see the joints have the normal range of movement. However, popping sounds coming from the hips may be more serious and need to be checked quickly. The sound may indicate improper placement of the thigh bone (femur) in the hip. If not treated, this can cause poor joint shaping and mobility problems down the road.