Polydactyly is the most common congenital deformity of the hand in the Chinese population, and is most commonly seen next to the thumb. Polydactyly is a chromosomal disorder, and many are genetically related. However, this condition is one of the most common malformations in pediatrics. During pregnancy, chromosomal testing may be recommended only in combination with other malformations and/or mental abnormalities. What are the causes of polydactyly? Polydactyly is also one of the more common congenital malformations in children, where the presence of the disease is detected as soon as the baby is born and the symptoms are obvious. Polydactyly has a significant impact on the function and appearance of the fingers. So what are the causes of polydactyly, here is a detailed understanding. Some cases are genetic and intergenerational. Environmental factors on the embryonic development process, such as certain drugs, viral infections, trauma, radioactive material stimulation, especially the recent industrial pollution can become teratogenic factors limb bud germ base differentiation early damage is an important cause of polydactyly. Polydactyly of the thumb is due to abnormal development of the ectodermal apical ridge, proximal extension of the lateral apex of the thumb and delayed regression. Symptoms of polydactyly In polydactyly, multiple fingers can be single or multiple, or bilateral polydactyly; polydactyly is divided into three categories: radial polydactyly, central polydactyly, and ulnar polydactyly, with radial polydactyly being the most common, followed by ulnar polydactyly, and central polydactyly being rare. Polydactyly can occur at the end of the finger, proximal phalanges, connected to the normal phalanges or metacarpals, or at the side of the metacarpophalangeal and interphalangeal joints. Some polydactyly can be the result of repetitive development of a particular finger, with corresponding metacarpal polydactyly, forming a six-fingered hand or even a heavy hand deformity, but it is less common. The shape and structure of the polydactyly can vary widely, from a dermatomal redundancy to a complete finger, and it can be difficult to distinguish a normal finger from a polydactyly, making the surgical decision difficult. The angle of growth of the polydactyly also varies, with some polydactyly being at right angles to the radial or ulnar margins of the hand. The polydactyly may exist alone or in conjunction with other deformities, such as compound thumb deformity; some have 3 or 4 extra fingers, forming a “mirror hand” deformity. The ulnar polydactyly can be accompanied by various other deformities, such as syndactyly, trigeminal thumb, spinal deformity, nail dysplasia, etc. Central polydactyly is often accompanied by syndactyly, which is more common bilaterally and named as polydactyly, and central polydactyly is often a kind of split hand deformity. X-ray examination should be performed for polydactyly to clarify its osteoarthritic condition and to provide a basis for surgery. Surgical excision Congenital polydactyly is a hand deformity that has a great impact on the patient. The best time to operate on congenital polydactyly is to preserve the fingers that are close to normal in shape and function and to remove the redundant fingers that have obvious deformities and poor function. The timing of surgery depends on the specific case of polydactyly. Early consultation with a specialist is recommended to determine the timing of surgery.