Rickets is a chronic nutritional disease caused by the deformation and defects of the bones due to insufficient intake of vitamin D. It is often caused by insufficient intake of vitamin D by mothers of infants and children during pregnancy, resulting in congenital vitamin D deficiency in the womb, or infrequent sun exposure after birth, because Under the action of ultraviolet rays of the sun, 7-dehydrocholesterol under the skin is converted into vitamin D, which is then converted into active vitamin D by the action of liver and kidney hydroxylase, promoting calcium absorption. The main clinical manifestation of rickets is the deformity of bones, such as chicken chest, O-leg, X-leg, square skull, etc. If not treated in time, it will lead to some deformities in growth and development. The clinical manifestations of rickets have the following symptoms: 1. Initial (early): seen within 6 months of age, especially in small infants within 3 months. Most of them are manifestations of increased neuroexcitability, such as irritability, irritable crying, excessive sweating, occipital baldness, etc. In this period, there is often no skeletal lesion, and the skeletal x-ray may be normal or the calcification zone may be slightly blurred. 2. active period (radical period): the disease continues to worsen, and typical skeletal changes such as PTH hyperfunction and abnormal calcium and phosphorus metabolism appear. After 6 months of age, there is also a ping-pong ball-like sensation around the bone gap, but the frontal bone and the central part of the parietal bone often gradually thicken, and by 7 to 8 months of age, the head shape becomes “square skull” and the head circumference is also larger than normal. The epiphysis is enlarged due to the accumulation of bone-like tissue, and a rounded bulge can be touched along the direction of the ribs and the junction of the rib cartilage, from top to bottom like a string of beads, with the 7th to 10th ribs being the most obvious, called rickets string of beads; in severe cases, a blunt circular ring-like bulge can be formed at the wrist and ankle, called hand and foot bracelet. “In children with severe rickets, the lower edge of the thorax forms a horizontal depression, i.e. the rib diaphragm groove or Hao’s groove. 3. Recovery period: After any of the above periods are treated or exposed to sunlight, the clinical symptoms and signs gradually reduce or disappear. Blood calcium and phosphorus gradually return to normal, and alkaline phosphatase needs 1 to 2 months to drop to normal level. After 2 to 3 weeks of treatment, the skeletal X-ray changes improve and irregular calcified bands appear, later the calcified bands become dense and thicken and gradually return to normal. 4.After-effects period: mostly seen in children after 2 years old. Due to severe rickets in infancy and early childhood, there are residual skeletal deformities of different degrees, such as O-leg, X-leg and chicken chest. There are no clinical symptoms, normal blood biochemistry, and the lesions of the skeletal epiphysis disappear on X-ray examination.