Deep squatting joint ringing may be a normal phenomenon, or it may be caused by patellar cartilage injury, meniscus injury and other factors. 1. Normal phenomenon: when squatting, there is friction and collision between the cartilage surfaces, or ligaments and bone edges of the joints produce friction, there may be physiological popping, this situation is generally a normal phenomenon. 2. Patellar cartilage injury: under normal circumstances, the patella and femur is generated between the sliding friction, if the patellar cartilage injury, may lead to direct friction between the patella and the femur, so squatting will sound. 3. Meniscus injury: if meniscus injury, squatting, or knee flexion and extension movements, may lead to damage to the meniscus stuck in the joint between the femur and tibia gap, thus making a sound. If the joint often rattles during deep squatting, you should seek prompt medical attention to avoid delaying your condition.