Cranial defects are a relatively common disorder in neurosurgery, such as head trauma, brain hemorrhage, brain tumor, cerebral infarction, etc., may leave cranial defects after craniotomy, and there are a large number of patients with cranial defects of all ages, and children are no exception. The most advanced material is the emerging polyether ether ketone PEEK material, which is a special polymer material, and its performance is comparable to that of autologous cranial bone, which is comfortable, protective and aesthetic after being placed in the human body. Some parents of pediatric patients worry that their children will grow faster and their heads will become bigger, so they worry whether they need to replace the material in the future. Does peek cranial repair for children need to be replaced again in adulthood? No, there is a limit for repairing pediatric patients with skull defects. According to the neurosurgery guidelines, the age limit is 3 years: skull repair is not recommended for pediatric patients under 3 years old, and only for those over 3 years old. Why is this threshold set? Because in children under 3 years old, the skull is in a period of rapid development, and the growth may change a lot, so if skull repair is done at this time, there may be a mismatch of materials in the future; whereas in children over 3 years old, the skull is basically formed, and the growth of the skull in the future is not like blowing up a balloon, which increases evenly everywhere, but grows along the bone suture, so as long as the bone window area does not cross the bone suture, then the size of the bone window will not change greatly. Therefore, as long as the bone window area does not cross the bone suture, the size of the bone window will not change significantly, and the skull repair will not need to be replaced in adulthood at this time. Our team is currently using advanced polyetheretherketone PEEK materials extensively to perform PEEK cranioplasty, including in pediatric patients, with good results.