Page 199 - Clinical relevance of current materials for cranial implants
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                                Using preoperatively planned and designed cranial implants, the operation time will be shortened because it is then possible to design and manufacture the cranioplasty before the operation. PEEK has a high biocompatibility, high chemical resistance and a low toxicity9. PEEK does not have osseointegration abilities9 and thus no commensurately grow with the cranium will occur, so it seems that PEEK is not a preferable material in pediatric patients.
Titanium is also a material used for cranioplasties. It has a low infection rate, high biocompatibility and has biological inertness. On the other hand, it is radiopaque and conducts cold and heat. The costs of a titanium implant are relatively high10. Current literature recommends titanium cranioplasties for the pediatric population 11–13. However, this material still seems to be suboptimal. Until the age of 20 years, the cranium grows physiologically14. Before the age of 20 years a titanium cranioplasty is therefore not the optimal solution since it will not grow commensurately with the cranium. This may result in higher complication and reoperation rates and may require a new cranioplasty at a later age. This is also the case for PMMA and PEEK implants, and therefore these are not recommended for the reconstruction of cranial defects in growing children. Similarly, autologous bone appears to be suboptimal for cranial reconstruction in children due to the higher resorption and infection rates that were found in earlier studies in this population3,15. Hydroxyapatite is reported to be a better option for the pediatric population, because of its ability to regenerate bone11. Studies have proven that hydroxyapatite will convert into bone. An important disadvantage of hydroxyapatite is that it will remain brittle for a prolonged period of time (probably several months till years). This implies that the patient may not be sufficiently protected and needs to wear a helmet for a longer period of time16.
Optimization of the cranioplasty procedure
Another challenge is to optimize surgical treatment of the reconstruction after a decompressive craniectomy. Different tools for further optimization were described in chapter 6. A 3D virtually designed template and mold can be used to generate a pre- planned outline of the defect and create an exact fit of the concomitantly manufactured cranioplasty6. The surgeon follows the outline of the template to create the defect as planned. This may also be feasible in acute situations, as confection templates and implants can be used in for example primary trauma and in vascular emergencies.
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General discussion and future perspectives
  




























































































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