In a word, skull repair is not a difficult operation in the field of neurosurgery (because it does not need to touch the brain), and the risk factor is not very high, but whether it is suitable for each patient depends on the specific situation of the patient. If the depressed part of the skull is only 3 cm, which is protected by temporal muscles in the temporal part, and the elderly have less exercise and are not easy to be traumatized again, then there is always a certain risk in the operation, and there is no need to do skull repair surgery.
Now with the technology of skull cryopreservation, the patient's autogenous bone flap can be preserved completely for several years. When the patient needs to be repaired after operation, the self-preserved bone flap can be put back to the depressed part of the patient at any time to achieve a perfect state of seamless joint. At present, it has been used routinely in Beijing Tiantan Hospital and Beijing Institute of Neurosurgery.
The following is a little bit about skull repair, hoping to help friends who need to know this knowledge:
After skull defect, due to the lack of complete skull protection, a series of symptoms will occur, such as headache, dizziness, nausea, limb weakness, chills, fear of vibration and so on. At the same time, it will produce psychological insecurity and affect the mood of patients. Abnormal appearance will also make it difficult for patients to participate in normal work and social interaction, which is clinically called skull defect syndrome. Therefore, it has been recognized in the field of neurosurgery that it should be repaired in time. At present, there are many materials and methods for skull repair, each with its own advantages and disadvantages. Scholars at home and abroad have different views, which are summarized as follows.
1 maintenance materials
The ideal materials for skull repair should be: good histocompatibility, non-toxic and non-carcinogenic; Chemical stability, not easy to be corroded, is a poor conductor of electricity and heat; Does not interfere with x-rays, and has no adverse effects on CT, MRI, EEG and other examinations; Tough and durable, strong impact resistance, not easy to age; Convenient materials, easy shaping, convenient disinfection and low price, and can be fused or bridged with bone window; For children, to adapt to the growth of the skull, it will not be deformed or infected for decades. The materials currently used are as follows.
1. 1 polymer material
1. 1. 1 polymethyl methacrylate (PMMA) is hard and can be molded by heating. Thermal insulation, which has no effect on X-ray and nuclear magnetic resonance examination, has been widely used at home and abroad. Its disadvantages are that its mechanical properties are worse than that of human skull, mainly its brittleness and poor impact resistance. When hit by the second accident, plexiglass is easy to break and stab brain tissue. Tissue reaction after implantation is heavy and easy to age. It is reported that the incidence of postoperative subcutaneous hydrops is as high as 65.6% [1]. Later, some scholars improved plexiglass by adding reinforcement fiber (short carbon fiber) to make short carbon fiber reinforced polymethyl methacrylate. That is to say, a certain amount of short carbon fibers are added to granular polymethyl methacrylate, and then mixed and heated to make a plate with a thickness of 2mm, 18cm× 12cm. After testing, its tensile elastic modulus (stiffness) and impact strength are two times higher than that of plexiglass, and its hardness is higher than that of skull. The coefficient of linear expansion is equivalent to that of PMMA at -400℃ at room temperature. In the medium resistance test, there is almost no obvious weight gain and compatibilization at room temperature for 350 hours. Randomly oriented fibers in sheet die composites can prevent crack propagation. It has the advantages of thin plate, light weight, good impact resistance, no release of toxic substances and no influence on ct and MRI examination. But it needs electric furnace heating or alcohol lamp baking [2].
1. 1.2 bone cement is mainly composed of polymers of methyl methacrylate and butyl acrylate, and it has two components, namely powder and solvent, and is now on the market. After blending, it can be quickly solidified at room temperature, and it can be shaped in time in the dough stage before solidification. Its advantages are reliable mechanical performance, simple molding and satisfactory cosmetic effect. Some scholars add gentamicin to the preparation, which can increase its anti-infection ability [3]. The disadvantage is that it has a strong smell when it is prepared, and it generates heat when it is cured, so it needs to be washed and cooled. The patch is fragile after forming, and the incidence of hydrops after drainage is still high (1 1.8%) [4].
1. 1.3 silicone rubber is mainly two layers of methyl vinyl silicone rubber with knitted polyester mesh, which is molded after molding and high temperature and high pressure vulcanization. When applying, cut the corresponding parts as needed and do a little trimming. The advantages are good histocompatibility, convenient disinfection, cutting and fixation, no influence on various inspections, heat preservation, satisfactory appearance and bearing certain impact force, while the disadvantages are not easy to shape, unstable fixation and high incidence of postoperative hydrops.
1.2 metal materials In recent ten years, various metal products have appeared, such as gold, silver, aluminum, tantalum, chromium, titanium, etc., which have been reported for skull repair. Among them, titanium is widely used in clinic, and its shapes are titanium plate, titanium mesh, titanium belt and so on. The common characteristics of these metal materials are stable chemical properties, no rejection or allergic reaction, strong impact resistance, easy cutting and molding, sterilization and disinfection without deformation. The disadvantage is thermal conductivity. Because of the high thermal conductivity, the head becomes sensitive to the external temperature difference after operation, resulting in discomfort. Long-term temperature difference changes can also cause chronic damage to brain tissue [5]. Some subcutaneous hydrops occurred after operation (14.3%) [1]. At present, most materials are imported and expensive.
.3 Allogeneic bone material
1.3. 1 heterogeneous materials 1682 It has been reported abroad to repair skull defects with dog bones and ivory, but similar reports have rarely been seen since then. Roux used coral bone as a repair material, saying that it can promote the formation of new bone, and coral bone as a scaffold was gradually absorbed and replaced by autologous bone, with good results [6]. There are also reports in China that ilium and buffalo horn have been used to repair skull defects with satisfactory results. However, this kind of material is difficult to obtain, prepare and shape, and the body has certain rejection, so it is rarely used in clinic.
1.3.2 allogenic material 1893 some foreign scholars have applied human cadaveric bone to clinic, and the short-term effect is acceptable. However, with the passage of time, it was found that many patients had obvious necrosis and absorption at the repair site, and the rejection of the body was very obvious. Some domestic scholars use fresh cadaver skulls combined with bone morphogenetic protein to repair skull defects. BMP is a non-collagen hydrophobic glycoprotein, which has strong osteogenic induction ability, and can induce undifferentiated mesenchymal cells in vivo to differentiate into cartilage or osteoblasts, so it has the ability to promote osteogenesis and repair bone defects. After 65,438+0 ~ 2 years of follow-up, X-ray and 99Tc bone imaging confirmed that the new bone grew vigorously and the effect was good [7]. Some scholars use the fresh fetal skull as a repair material [8]. The fresh fetal skull 6 months after induced labor is aseptically taken out, soaked in gentamicin solution, and stored in refrigerator alcohol for later use, which can be stored for 3 months. After a follow-up of 1 ~ 2 years, no bone resorption was found by X-ray examination, and the bone density of the transplanted skull was basically the same as that of the normal skull. Single molecule bone mineral analysis showed that the bone density of the implanted bone was basically the same as that of the surrounding bone, which confirmed that all the transplanted bones survived without rejection. However, the early impact resistance is poor, and it takes some time to regenerate and thicken after implantation, so fetal bone is not easy to obtain.
In recent years, some scholars have studied the preparation of bone matrix gelatin (BMG) by decalcification and degreasing of allogenic bone for skull repair. After continuous chemical treatment with chloroform and methanol, the obtained allogenic bone becomes insoluble bone matrix gelatin. Under the optical microscope, it is homogeneous, osteoblasts disappear, while BMG's osteoblasts are still active. This is related to bone morphogenetic protein [9]. Bone morphogenetic protein (BMP) is a low molecular weight acidic glycoprotein, which binds to the host mesenchymal cell receptor in vivo and induces mesenchymal cells to differentiate into osteoblasts. In the early stage of bone grafting, with the absorption of BMG, bone morphogenetic protein was released, which stimulated the periosteal tissue around BMG to form rich fibrous callus. Under the continuous action of bone morphogenetic protein, mesenchymal cells in fibrous callus are transformed into fibroblasts, osteoblasts, osteoblasts and osteoblasts. The latter secretes bone matrix, embeds itself in it, forms new bone tissue, and finally repairs bone defect. The experiment shows that the rejection reaction of allogenic bone matrix gelatin is lower than that of non-decalcified bone matrix gelatin, and the osteogenesis time is short and the osteogenesis ability is strong. It has been used in clinic on the basis of successful animal experiments [10].
1.4 Autologous material Autologous bone is an ideal skull repair material, which is mainly taken from ribs, scapula and skull. Bone healing can be achieved after repair, and the body has no rejection reaction, and it is not easy to accumulate fluid and infection. After healing, the impact strength is close to normal, and the patient has no psychological disorder. At present, there are still different opinions on how to survive after autologous bone transplantation and the source of new bone. It is more inclined that the surviving bone cells in the autogenous bone flap, the surrounding proliferative connective tissue (some cells can be transformed into osteoblasts) and periosteized bone all participate in the formation of new bone [1 1].
1.4. 1 bone flap The preservation of bone flap can be divided into two categories: (1) self-preservation: the bone flap is preserved under the subcutaneous or cap aponeurosis of abdominal wall and thigh, and 1 ~ 3 months later it is taken out and replanted. Kang [12] first reported 20 cases of bone healing after replantation. At present, many medical units in the country are carrying out it. (2) Preservation in vitro: Soak the free bone flap in honey, alcohol, chlorhexidine glycerin and other liquids to keep it sterile. It was also preserved by freezing and irradiation (13 ~ 15). For example, when the dose reaches 25Gy, all bacteria can be killed, and the pathological examination of the auxiliary bone flap is no different from that of fresh bone, and the biological activity of the bone flap can still be maintained (16). The skull flap preserved for more than 2 years was examined by light microscope, and the normal structure of bone was basically preserved. However, after the bone flap in vitro was soaked and fixed in alcohol, all the bone cells died, but the normal bone structure composed of organic matter and calcium salt was not destroyed [13]. Healing mechanism: New blood vessels from the implanted bed grow into the bone flap along the haversian canal and bring in interstitial cells that can differentiate into osteoblasts in the future. Bone flap can induce the surrounding connective tissue to produce osteoblasts, which can be used as scaffold materials and finally be creeping substitution by new bone. The advantage is that it can reduce the pain brought to patients by burying bone flap in another part, achieve bone healing and have beautiful appearance. The disadvantage is that the healing time is long, sometimes dead bones can be formed, and the chance of infection increases. Long-term follow-up reports bone flap absorption.
1.4.2 After the external decompression operation (tension reduction suture) is completed, the free bone flap is crushed, or the bone fragments collected during skull drilling are evenly spread on the epidural space in the bone defect area, and the repair operation is completed at one time by using the time difference between brain edema and skull growth. Histological and radiological results showed that the fresh broken bone survived within 2 weeks after operation and played a role as a bridge. After 2 weeks, new bones began to produce, which came from the survival of bone cells in broken bones or from the transformation of host connective tissue cells. By the end of the fourth week, the shape of the bone graft site had been completely fixed. Because there is a gap between the bone fragments in the bone window, it is beneficial to the regeneration of blood vessels. This new bone formation theory was named "creeping substitution" by Phemister in 19 14. Some scholars call this method "one-time external decompression of skull plastic surgery" [17]. Its advantages are simple operation, completing the second operation at one time, alleviating the pain of patients, shortening the course of disease, saving costs, poor predictability and unconditional reoperation, which is more suitable for allergic patients and children. The disadvantage is that there are uncertain factors of intracranial pressure before the formation of new bone, which may form unsightly bone healing in the bone defect area and make the operation fail
1.4.3 The animal experiment of skull inactivation and replantation showed that boiling skull bone flap in 100℃ water for 25 ~ 30 min could inactivate all cells without destroying bone structure, which created conditions for bone regeneration. The implanted bone flap gradually revived in the way of creeping substitution through the osteogenesis of normal bone and periosteum around it. Although the trabecular arrangement of new callus is irregular and unstable, it can restore the normal skull structure after the callus is transformed and shaped [6]. Bao [18] used this method to treat 68 patients with skull lesions and achieved good results. In 1 case, the bone flap was inactivated by high pressure, and the bone graft gradually collapsed and developed 2 months after operation, and the second repair bone graft was almost completely absorbed 6 months later. At the same time, it is emphasized that the boiling time is too short to achieve the purpose of inactivation, and too long will lead to serious damage to the basic structure of bone, so it must be bandaged by pressure after operation
2 repair time and method
2./kloc-The head circumference of children under 0/5 years old grows rapidly, so skull repair is not recommended for children under 5 years old. The head circumference of children aged 5 ~ 10 grows slowly and can be repaired, but there is room for it. Generally, the skull replacement material should exceed the bone margin by 0.5cm, and the head circumference will not increase after 10 years old, so this kind of operation is best placed after 10 years old. In addition, it should be considered that children have strong ability to form membranous bone, and some children may not need secondary surgery because of new bone formation. It is generally believed that the repair time is 3 months after the first operation, and the infected person should be extended to more than half a year. At present, many scholars advocate that patients should be repaired as soon as possible according to their general situation, the degree of craniocerebral injury, the changes of intracranial pressure and whether to use bone flap to bury them under the skin, so as to alleviate or eliminate a series of symptoms caused by long-term skull defects. If it is repaired with broken bones or bone fragments, it will be completed in the first operation. The replantation time of buried autogenous bone flap should be controlled within 2 months, and it should not be more than half a month if the aponeurosis buried under the cap is used for traction reduction [19].
2.2 Repair methods Skull substitutes are mostly made into porous or grid shape, which has the advantage of facilitating the drainage of subcutaneous and epidural effusion, and riveting and fixation after tissue grows in can accelerate tissue healing. The bone flap should be implanted in the original position, that is, under the epidural space and the temporal muscle, and the temporal muscle should not be placed under the bone flap, so as to avoid the repeated action of the temporal muscle transmitting force to the meninges, affecting the cerebral cortex and causing adverse consequences. Before exposing the bone window, the water sac should be peeled off first, and the epidural injection should be carefully carried out to make the adhesion between the dura mater and the cap aponeurosis or temporalis myofascia become edema and loose. After the skin is cut, the dura mater is found first, and the edema and loose tissue outside the dura mater are separated sharply, leaving only the dura mater or the original expanded fascia, fully exposing the bone defect area. The repair material is plastically anastomosed with the defect area, and then it is firmly fixed. The fixing method can be 10 silk thread, thin steel wire, EC glue, memory alloy skull nail, titanium nail, etc. When children are mending, they can also fix the slot on the edge of the patch with screws and let it slide by itself to adapt to the increase of head circumference.
What needs special emphasis is repair: (1) Don't pull the flap forcibly when separating the flap, otherwise it will cause brain contusion, cerebral hemorrhage and postoperative epilepsy. (2) If tension-reducing suture was not performed in the first operation, a thin layer of myofascia should be left as the meninges when stripping the protomeninges in the second operation to avoid cerebrospinal fluid leakage. (3) Any skull substitute needs a satisfactory shape. Doctors are required to carefully and repeatedly observe the symmetry of the patient's skull before operation, so as to be aware of it and prevent postoperative plastic dissatisfaction from affecting the appearance. (4) When using skull substitute materials, it must overlap with the edge of skull window for a certain distance. If not handled properly, there will be a "stepped" appearance after operation, which will affect the surgical effect. (5) If bone cement is used for repair, normal saline should be continuously used for cooling during the shaping process, so as to avoid the heat generated during the solidification of bone cement from damaging brain tissue. (6) If autogenous bone flap is used for repair, the edge of bone window should be fully exposed to form close bone-bone contact, and connective tissue or scar tissue should not be mixed in the bone seam to affect healing. (7) The meninges in the center of the bone flap should be suspended with 1 ~ 3 needles to prevent the formation of epidural hematoma. (8) At the end of the operation, a drainage tube should be placed, and the drainage tube should be removed after 24 ~ 48h.
3 Development prospect forecast
It should be said that the technology is relatively mature and widely used in clinic, which relieves the worries of a large number of patients. However, after thinking about it, there are still some unsatisfactory places, such as the physical and chemical indexes of the prosthesis can not be consistent with the skull, nor can it be integrated with the skull; Most of them need a second operation, which increases the pain and cost of patients. Although one-time cranioplasty and external decompression and autogenous skull flap traction reduction can be completed in one operation, they are limited by surgical indications and reduction time. Secondary intracranial hemorrhage, cerebrospinal fluid leakage, epilepsy, infection and other complications may occur when the flap is peeled off in the second operation. However, with the development of prosthetic materials and the improvement of medical level, it is believed that there will be better skull substitutes and more ideal surgical methods. In addition to meeting the advantages of the current alternative materials, it should be repaired in time whenever it is needed, and it is best not to have a second operation. Of course, autologous living bone is the most ideal repair material, which can completely heal with the skull. After operation, the temporal muscle and occipital muscle attached well, and the anatomical level of scalp and skull recovered completely. In short, one operation, autologous materials, good healing and less complications are the goals pursued by this kind of operation in the future.
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