The knee rattles when squatting, but there is no pain, it may be due to the following reasons: 1, the more common is in the squatting tendons and bone friction caused by the sound, in the squatting tension of the tendons will rub the bone, especially after the osteophytes are more likely to rub, thus producing a sound. 2, in the squatting knee rattles may be caused by the patella, the patella in the position change will produce a sound, and does not cause pain. The knee is also likely to have a change in meniscus position when squatting, squeezing the meniscus may cause its position to move, so it will lead to a loud sound, if there is no meniscus damage will not lead to pain.