The creaking of the knee with the sound of grinding bone is mainly seen in discoid meniscus, meniscus tear, iliotibial bundle friction syndrome, osteoarthritis and ligament injuries, and it is necessary to improve the auxiliary examination in order to clarify the etiology of the disease, and it may also be physiological reasons. 1. Discoid meniscus: it is a kind of deformity change of meniscus, preferably occurring on the lateral side, with decreased elasticity and strength, which makes it easier to have tear injury. The patient’s knee may pop when moving. 2. Meniscus tear: there is a history of trauma to the knee joint, which is a tear of the meniscus. In addition to causing pain and interlocking of the knee joint, the knee joint may pop when the patient is walking or squatting. 3. Iliotibial fascia friction syndrome: mostly seen in long-term running patients, is the long-term iliotibial fascia and the lateral epicondyle of the femur friction caused by the patient manifested as pain in the outer side of the knee joint, when walking can also be seen in the knee joint sound. 4. Osteoarthritis: belonging to the degenerative changes in the knee joint, the cartilage in the knee joint is seriously worn out, and in the process of knee extension and flexion, the knee joint sound can occur. 5. Ligament injury: after ligament injury caused by trauma, the stability of the knee joint decreases, and friction between the upper and lower joint surfaces of the knee joint is likely to occur, which results in the sound of the knee joint. After eliminating the physiological reasons, it is recommended that patients go to the hospital to improve the auxiliary examination, in order to clarify the condition, and then give the relevant treatment by professional physicians.