The reason why the neck of the foot crunches when it is rotated but does not have pain is mainly related to physiological phenomena and injuries. 1. Physiological phenomenon: Generally, when the ankle joint rotates, the surrounding tendons and ligaments rub against the bone of the ankle joint, resulting in a rattling sound. This is a physiologic phenomenon that is not accompanied by pain or dysfunction. However, excessive and frequent friction can cause damage to the bone and tendons, which can lead to pain, swelling and dysfunction. 2. Injury: It may be related to slight inflammation of the ankle joint, which in most cases is related to the sequelae of acute sprains or caused by chronic fatigue injury. In daily life, it is important to pay attention to the protection of the ankle joint, as well as not to rotate the ankle joint regularly to produce this kind of noise. This symptom does not usually have serious consequences, but if pain, swelling or dysfunction occurs, it is necessary to consult a doctor for examination.