In general, rotator cuff refers to inversion of the knee. Inversion of the knee in children may be a physiological phenomenon of growth and development of the body, or it may be caused by overloading of the lower limbs, lack of vitamin D in the body and malnutrition. 1. Physiological phenomenon: generally, when the patient is young, the body will appear in the process of development of the knee inversion, as the body gradually develops and matures, this symptom will improve on its own. 2. Lower limb overload: If infants and young children learn to walk too early, resulting in overloading of the lower limbs, it may induce knee entropion. 3. Vitamin D deficiency: or consider the patient’s body vitamin D deficiency, which may induce rickets, thus appearing knee inversion, some patients with sleep disturbance, irritability, irritability, excessive sweating and other symptoms. 4. malnutrition: due to malnutrition or intestinal diseases and other causes of calcium and phosphorus absorption disorders, calcium and phosphorus deficiencies, bone development disorders, bone deformity or articular cartilage dysplasia leading to changes in the inversion of the knee. If the child has physiological inversion of the knee, parents generally do not need to take special treatment measures, so as not to overcorrect and affect the child’s growth and development. However, if the child has obvious discomfort along with the inversion, parents should pay attention to it and bring the child to the hospital in time to clarify the cause of the disease and take relevant treatment measures with the doctor.