Parents of patients, and even some medical professionals, often ask if, when and how can cranial defects in children be repaired when their skulls are still growing and developing? To answer these questions, we need to review some history first. Traditionally, it is believed that: children’s skull changes a lot with age, artificial materials fixed in the skull of undeveloped children with poor stability; and with the growth of children, the area of cranial defects become larger, there is a possibility that the repair material falls off; early repair materials will hinder the normal growth of the skull, resulting in asymmetric development of the skull, which affects the development of the brain tissue and the appearance of the head, generally do not advocate the early line of Generally, early cranial repair is not recommended. However, in recent years, more and more clinical and basic researches have gradually revised the traditional viewpoints and supported the appropriate relaxation of surgical indications, and early surgical repair of cranial defects in children has been increasing day by day. (1) All systems of the body are in the stage of growth and development in childhood, and cranial defects have a tendency to grow and repair on their own. It is usually believed that cranial defects with a diameter of 3 cm or less have the possibility of self-healing, but most of the cranial defects with a diameter of more than 3 cm will not heal on their own, and dura mater calcification is often seen. Calcification of the dura mater may limit the development of the brain. (2) Cranial defects disrupt the normal physiological balance of the cranial cavity, causing cerebral vascular dilatation in the defect area, slowing down blood flow, and stagnation of local blood flow in the brain; (3) Cranial defects may become larger with development, with the edges of the defects turned out, and the protruding brain tissues showing progressive atrophy, hydrocephalus, and cystic degeneration, which affects the normal development of the brain tissues. (4) Due to the loss of bony barrier of local brain tissue, coupled with children’s lively and active, it is easy to cause another craniocerebral injury. (5) It is easy to cause dizziness, headache, fear, discomfort in the defect area and other cranial defect syndromes, affecting their social activities. The advantages of early repair of children’s cranial defects: (1) Cranial defects not only hinder the appearance of beauty, but also easily cause psychological pressure to the children, especially school-age children often have a sense of insecurity, early cranial repair can make the children quickly return to a normal state of mind. (2) Early repair can protect the brain tissue in the defective area from re-injury, and at the same time, create good conditions for further growth of the newborn bone to create an ideal skull with normal physiological curvature. (3) 1-3 months after the injury is the fastest period of neurological recovery, early restoration of the integrity of the cranial cavity is a prerequisite for further recovery of neurological function, which not only improves the hemodynamics of the local brain tissue, but also relieves the compression of atmospheric pressure on the brain tissue of the defect area. It can promote the recovery of limb paralysis, aphasia, mental or intellectual disorders associated with the site of injury to varying degrees in some children with craniocerebral injuries in the later stage of the disease. (4) Prolonged cranial defects, locally formed meningeal scars or ossified structures on the brain tissue can cause headaches and seizures, for such children to carry out cranial repair and meningeal scar release, can reduce or prevent seizures. 3, The timing and feasibility of early repair of cranial defects in childhood: Most scholars believe that the minimum age for repair is 4-5 years old, and some reported that cranial repair was performed at the age of 2 years old. Some studies have shown that the immature cranium has a strong self-regulation ability when bound by the outside world, and that the cranium is able to conform to the normal cranial morphology and growth. Therefore, for the age of repair, it can be further appropriately relaxed to 2 years old, this is due to the rapid motor development of infants and young children over the age of 2 years, accidental falls and other injuries increased, the existence of skull defects make the risk of brain injury increased, at the same time, infants and young children over the age of 2 years have a certain thickness of the cranial bone, and can adapt to the length of the titanium nails and the degree of firmness. If the anesthesia and monitoring techniques for infants and young children are available, it is not necessary to stick to a certain age limit when choosing the appropriate repair material. Scholars have different views on the duration of cranial defects, ranging from 1-6 months or more after debridement and decompression surgery. At present, most of the scholars tend to think that it is more appropriate to operate about 1-3 months after the cranial defect, but the premise is that the first surgical incision has been healed, the intracranial pressure is normal, the decompression window tension is not high, and the condition has been stabilized. 4, the choice of materials for cranial repair in childhood: cranial repair is a plastic surgery, in addition to the attention should be paid to the selection of good performance of the repair material, but also must pay attention to the postoperative appearance of the aesthetic effect of the children’s scalp, the skull are thinner, and in the stage of development, the requirements for the surgical material is more stringent. A common clinical material used for cranial bone repair is titanium mesh, which is a metal material, so its cold and heat resistance function will naturally be poor. In addition, titanium mesh is too hard to be molded according to the area of human skull defects. Since children’s intracranial brain tissue and scalp are relatively fragile, titanium mesh is not suitable for children’s skull repair. Currently, there is a very advanced PEEK material for skull repair, which is a kind of polymer material with good thermal conductivity. PEEK is a polymer material with good thermal conductivity. By measuring the defective area of children’s skulls before surgery, the PEEK repair material can be shaped three-dimensionally according to the data obtained from the measurements, and it can be precisely adapted to the human skull during the surgery without postoperative infection and rejection, which makes it a very high-quality material for children’s cranial bone repairs. More importantly, PEEK is a material that can be molded in three dimensions and can be customized according to the different needs of the patient. According to the patient’s brain CT data for the design, the use of 3D printing technology to produce a perfect match with the bone window of the skull repair after the skull is basically no different from their own skull. However, there are not many hospitals that do cranial bone repair with peek at present. It is also a high demand for the technology and professionalism of the doctors who are engaged in peek cranial bone repair in China. Therefore, if you need to have this treatment, it is recommended to choose a more authoritative hospital.