Thigh joint crunching may be a normal physiological phenomenon, or it may be caused by popping hip, femoral head necrosis and other reasons. 1. Normal physiological phenomenon: thigh joint crunching is generally due to the thigh activities, the cartilage and ligaments around the joints will be in the friction with each other under the action of the ringing sound, most of the cases will not be accompanied by pain. 2. Snapping Hip: It is mostly seen in dancers, athletes or obese people who use the hip joint for a long time, which leads to the damage of the soft tissues around the joint and the limitation of the joint activities, causing the snapping and pain of the hip joint. 3. Necrosis of femoral head: When necrosis of femoral head occurs, it will cause local collapse. This will cause serious damage to the joints, so the thigh joints will also be crunching when moving. When the thigh joints crunching, it is recommended to go to the hospital for professional examination to clarify the cause of the disease and timely treatment.