The bones in the legs ring mainly for the following three reasons: 1, joint degeneration, such as the knee, ankle and hip joint parts are most likely to local cartilage wear, degeneration, joint surface becomes uneven, so that in the process of activity will lead to cartilage and cartilage friction, squeezing force increases, it is easy to appear the sound of bones. If the bone parts have osteophytes and calcified lesions, it will also lead to a further increase in friction during flexion and extension activities, which will lead to more pronounced ringing. 2, some joints have congenital underdevelopment, such as patellofemoral joint grinding deviation or congenital hip dislocation, there may be bone ringing during activities. 3, some bone parts of the leg have many muscles, ligaments and other Soft tissues attached, when these soft tissues due to strain, cold or trauma, resulting in a decline in local elasticity and toughness, in the process of activity will appear soft tissue and bone plucking, will also appear bone ringing.