Rickets generally refers to vitamin D deficiency rickets, a systemic, chronic, nutritional disease characterized by skeletal lesions due to disorders of calcium and phosphorus metabolism caused by vitamin D deficiency in infants, children and adolescents. It is mainly seen in infants and children under 2 years of age, and typically manifests itself as mineralization deficiencies in the epiphyses of growing long bones and bone tissue. Rickets is clinically divided into the initial, active, recovery and sequelae stages. 1. Early stage (early stage): Mostly seen in infants within 6 months of age, especially those <3 months old, mainly manifesting as non-specific symptoms of increased neuroexcitability, such as irritability, irritability, sleep disturbance, night terrors, excessive sweating (not related to seasons), occipital baldness (infants often shake their heads and rub their pillows due to irritability and excessive head sweating). 2.Activity period (agitation period): In addition to the initial symptoms, the main manifestations are skeletal changes and delayed development of motor functions. Skeletal changes are often most obvious in the fastest growing parts of the body, so there are different skeletal manifestations at different ages. (1) head: ① cranial softening: mostly seen in infants aged 3-6 months, so the cranial bones develop fastest at that time, the softening part often occurs in the central occipital or parietal bones, the fontanelle side is softer, the cranial bones are thin, the cranial softening gradually disappears after 6 months of age; ② square cranium: mostly seen in children aged 7-8 months or above, due to the bony tissue proliferation resulting in bilateral symmetrical elevation of the frontal and parietal bones, forming a square cranium, the heavy ones can be saddle-shaped, cross-shaped cranial shape (3) Delayed enlargement and closure of fontanelle: In severe cases, the closure of fontanelle may be delayed until 2-3 years old; (4) Delayed teething: Teething may be delayed until 1 year old, sometimes the order of teething is reversed, teeth lack enamel and are susceptible to dental caries. (2) Chest: Thoracic deformities are mostly seen in children around 1 year old, such as rickets rib crosstalk, rib diaphragm sulcus (Hao's sulcus), chicken chest, funnel chest. (3) extremities: ① wrist and ankle deformities: mostly seen in children over 6 months of age, the wrist and ankle epiphysis is expanded, resembling a bracelet or ankle bracelet; ② lower limb deformities: seen in children after 1 year of age standing and walking, due to bone softening and muscle joint relaxation, under the influence of gravity in standing and walking can appear "0" shaped legs or "Children within 1 year old may have physiological bending, so only children above 1 year old are examined for lower limb deformity. (4) Other: after learning to sit, it can cause backward protrusion or scoliosis of the spine, and in severe cases, it can cause pelvic deformity and form a flat pelvis. The whole body muscle relaxation, low muscle tone, weak head and neck, sitting, standing, walking and other motor function development is backward, low tone of abdominal muscles cause abdominal bulging like moth abdomen. The formation of conditioned reflexes is slow, expression is indifferent, language development is delayed, immunity is low, often accompanied by infection, anemia, etc. 3, recovery period: after appropriate treatment, the child's clinical symptoms are reduced to disappear, the spirit is lively, muscle tone recovery. 4.After-effects period: Mostly seen in children after 3 years old, clinical symptoms disappear, leaving only different degrees of skeletal deformities, such as O-leg, X-leg, chicken chest, etc.