Large skull defects as a result of craniectomies due to cerebral insults, trauma, or tumors create functional and aesthetic disturbances for the patient. Cranioplasty with implants in these cases are an alternative to autogenous bone transplantation. In our clinic, customized titanium or optima poly-ether-ether ketone (PEEK) implants are used to reconstruct craniectomy defects. To compare the two materials we investigated the structural changes of the implants fixed to a sintered polyamide skull model under mechanical stress in four simplified models. In a standard testing machine, the models were subjected to a load under a quasi-static loading rate of 1.925 mm/min. Fractures of the PEEK implants occurred at a force of 24.2 and 24.5 kN with a displacement of 8.4 and 8 mm. The titanium implants showed no deformation, but extensive damage was seen in the polyamide skull models. The highest pressures achieved were 45.8 and 50.9 kN. In a simplified model with quasi-static loading, both implants withstood forces that were higher than those capable of causing skull fractures. It seems that the mechanical properties of PEEK could provide better protection when used for cranioplasty in patients after craniectomy if reconstruction with autogenous bone is not possible.

No abstract

The overall objective of this guideline is to provide up-to-date, evidence-based recommendations for the diagnosis and surveillance of all symptoms in children and adults with either basal cell naevus syndrome (BCNS), a clinical suspicion of BCNS, or a parent with BCNS. In the last two groups, the guidelines should be followed until the diagnosis of BCNS can be rejected with certainty. The guideline aims to:• Update and expand on the previous guidelines by an appraisal of all relevant literature from January 2011 up to January 2021• Address important, practical, clinical questions relating to the primary guideline objective• Provide guideline recommendations • Discuss potential developments and future directions The guideline is presented as a detailed review with highlighted recommendations for practical use in the clinic by dermatologists and other healthcare professionals, including general practitioners, clinical geneticists, paediatricians, ophthalmologists, craniomaxillofacial surgeons, neurologists, cardiologists and psychologists. ExclusionsThe guideline does not cover therapeutic recommendations for (nondermatological) symptoms, as the guideline mainly focuses on screening and follow-up of symptoms. Therapeutic recommendations for basal cell carcinomas (BCCs) in general have been published in international BCC guidelines. 1,2 Stakeholder involvement and peer reviewThe guideline was developed at the Maastricht University Medical Centre (MUMC+), the Dutch BCNS expert centre accredited

The proposed classification reflects the degree of difficulty in designing and manufacturing of implants and can be very useful when comparing treatment results of skull defects for clinical or scientific purposes.