Page 201 - Clinical relevance of current materials for cranial implants

A randomized clinical trial (RCT) should be conducted to gain further insight into the specific characteristics and biological behavior of different materials (titanium, PMMA, hydroxyapatite and PEEK) used in adult patients requiring a cranioplasty. Before commencing such an RCT, a Delphi Study is advocated to reach consensus on common procedures for cranioplasty. Important parameters to take into account in this study are:
. material used for cranioplasties
. use of antibiotics
. use of surgical drains
. post-operative wound care
. time interval between the decompressive craniectomy and cranioplasty with a alloplastic material.
General discussion and future perspectives
Another important characteristic is the ability to sterilize an implant. All cranioplasties should be sterile before they can be implanted in the patient. Chapter 9 investigated the effect of different sterilization protocols on different types of PMMA or PMMA- based materials. The sterilization method could significantly influence the material properties of cranial implants. We showed that ethylene oxide gas (EtO), hydrogen peroxide gas plasma (HPGP) and γ-irradiation are suitable techniques for the sterilization of PMMA without impact on the material properties. The use of γ-irradiation promotes the effective flexural strength and it seems that the material becomes stronger in a wet environment. Before a new material is used for creating a cranial implant it is important to also investigate the effect of the sterilization process on the mechanical properties of the material. Biological responses of the sterilization process are important, as the material surface may change due to the sterilization itself, with a possible different impact on the human tissue.
FUTURE PERSPECTIVES
Based on recently published literature it is plausible that the need for cranioplasties will increase in the future17. Cranioplasties are necessary until bone-induction and/ or bone-conducting methods are available. But as long as those medical devices are not developed for this purpose the patient still depends on a cranioplasty to ensure protection of the brain and to improve quality of life. As described in this thesis there is still a need for the development a new material for cranioplasty which includes the properties as mentioned above. Hence, we propose some studies that would contribute to a convincing, evidence-based answer on the question which material will be preferred for a cranioplasty.
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