1.Overview: Congenital polydactyly is the most common congenital disorder in children, and some of them are associated with other systemic malformations such as cardiovascular or urinary. Polydactyly is most often seen on the lateral side of the thumb and the medial side of the little finger, and other fingers are less commonly involved. The incidence of compound thumb deformity is the highest, which has a significant impact on the appearance and function of the hand, and its diagnosis and treatment are the focus of attention of pediatric orthopedic surgeons. 2, the etiology and classification: multiple fingers, toe deformity is mostly unilateral, bilateral involvement accounted for only about 10%. The exact cause of compound bunion deformity is unknown, mostly disseminated, suggesting that the disease is related to environmental factors, not much related to genetic factors. For example, the mother is affected by viral infections, drugs, radiation and other environmental factors during the early 4-8 weeks of pregnancy, when the embryonic limb buds are differentiated, resulting in impaired finger differentiation and malformation. The exception is when the duplication of the thumb is accompanied by three thumbs, some of which are autosomal dominant. 3, symptoms and hazards: children are found to have extra fingers at birth, the type and severity of deformity is diverse, some are connected to the normal fingers only by a narrow vascular nerve wrapped skin tip; some have nails, bone joints, tendons and vascular nerve bundles, and have certain finger activities and sensory functions, resulting in difficulties in surgical selection; some deformities are as serious as ” Some of the deformities are as severe as “crab-like”, with poor finger development, small and deviated fingers, which seriously affect the appearance and function of the hand. In addition to the physiological impact, the child and parents often have psychological problems, psychological concerns will affect the child’s psychological development, affect learning and social life, and even affect future employment, work and marriage. 4, common associated malformations: the most common is associated with cardiovascular, neurological or urinary system malformations, such as congenital heart disease, congenital cerebral dysplasia, etc. For children with suspicion, a comprehensive and systematic physical examination should be conducted. 5, diagnosis: congenital polydactyly can be clearly diagnosed according to the medical history and clinical physical examination, auxiliary examination is mainly X-ray radiography to clarify the type of polydactyly and skeletal joint growth, to provide a basis for the choice of treatment plan, for complex and difficult cases, also feasible spiral CT examination, three-dimensional reconstruction, to further clarify the type and degree of deformity. 6.Treatment mode and indications: After discovering the disorder, we will consult the doctor promptly and make a reasonable and personalized treatment plan according to the condition after doctor-patient communication. The treatment of congenital polydactyly varies according to the degree of the disease. Simple dermatomal polydactyly can be surgically removed in the first month after birth, or in the third month after birth if the safety of anesthesia is considered. For complex polydactyly with articulated skeletal connections, surgical excision can be performed between 6 months and 3 years of age. Before surgery, the level of polydactyly and toe duplication must be evaluated and typed; the degree of development of each part, the stability and mobility of the joint, the degree of deviation of the skeletal axis, and the severity of the finger deformity must also be evaluated. Principles of treatment for duplicated thumb deformity: If there is a difference in the development of the two thumbs, the thumb with poor appearance, lack of function or three phalanges will be removed. If the difference in appearance and function between the two thumbs is not significant, removal of the lateral polydactyly is often chosen. If the polydactyly occurs at the level of the joint, in addition to removal of the polydactyly, a portion of the corresponding proximal articular cartilage surface should be removed and blocked to effectively prevent recurrence of the polydactyly, and the joint capsule and collateral ligaments should be repaired, and the tendons should be transferred and sutured. In general, surgery is recommended for polydactyly before toddlerhood, i.e. 9-12 months after birth. Otherwise, if the abnormal force area is formed on the bottom of the foot after walking, the force area will be removed or changed after surgery, thus affecting the gait. 7, precautions: after surgery for polydactyly, toe deformity need to keep the wound dressing clean and tidy to prevent wound infection; strengthen the child’s nutrition, eat more high-protein food to promote wound healing, appropriate selection of drugs to inhibit scar formation, as far as possible to give the child beautiful, functional hands and feet. 8.Prevention: strengthen health care and nutrition during pregnancy, avoid respiratory infections, gastrointestinal infections, rubella, measles, chicken pox, mumps and other viral infections during pregnancy, avoid exposure to radiation, drugs and other possible embryonic teratogenic factors. 9, expert opinion: polydactyly, toe deformity is a common congenital malformation of children, once found that the child was born with such a problem, parents need to face the correct, neither as some parents take it lightly, they for the skin flab type of polydactyly, at home on their own with thread or hair, etc. ligature, the result of finger necrosis, wound infection septicemia, and even sepsis, to further treatment difficulties; nor should not be overly nervous, trying to solve the problem immediately. Try to solve the problem immediately, because newborn anesthesia has certain risks, so you can wait until the child is full-term to find an experienced doctor to diagnose once to clarify the type and severity of the deformity, in order to decide the best time and treatment plan.