====== Cranioplasty materials ====== {{ ::cranioplasty_materials.jpg?200|}} Across the centuries, many materials have been used for covering bony defects, including coconut shells, bones from both human and non-human donors, metals including gold, silver, [[tantalum]], and titanium and more recently, biosynthetic materials such as resins and ceramics. A review provides an overview of biomaterial implants and bone flap manufacturing methods for [[cranioplasty]] surgery. In addition, tissue engineering and regenerative medicine-based approaches to reduce clinical complications are also highlighted. The potential use of data-driven computer applications and data-driven artificial intelligence-based approaches is emphasized to accelerate the clinical protocols of cranioplasty treatment with less manual intervention and shorter intraoperative time ((Thimukonda Jegadeesan J, Baldia M, Basu B. Next-generation personalized cranioplasty treatment. Acta Biomater. 2022 Dec;154:63-82. doi: 10.1016/j.actbio.2022.10.030. Epub 2022 Oct 19. PMID: 36272686.)). ===== Autologous bone flap ===== see [[Autologous bone flap cranioplasty]]. [[Gold cranioplasty]] ===== Synthetic implants ===== Several materials are available. Each has its advantages and disadvantages. Search is on for an ideal material. [[Polymethylmethacrylate cranioplasty]] and [[polyetheretherketone]] (PEEK) are the most commonly applied today. [[Mesh cranioplasty]] [[Custom made cranioplasty]]. [[Celluloid cranioplasty]] [[Hydroxyapatite Cranioplasty]]. [[PEEK cranioplasty]] [[Fiberglass cranioplasty]] [[Polypropylene polyester knitwear]] [[Tantalum cranioplasty]] [[Titanium cranioplasty]] Acrylic bone cement ---- Split-thickness calvaria When synthetic material is used, the flap should be perforated with a dozen or so drill holes to prevent the accumulation of fluid (either underneath the flap or between the flap and the skull). ---- The choice of [[heterologous]] [[material]]s for [[cranioplasty]] after [[decompressive craniectomy]] is still difficult. The aim of a study of Morselli et al. was to examine the association between material of choice and related complications to suggest the best treatment option. A [[systematic review]] was performed for articles reporting [[cranioplasty]] comparing the following heterologous implants: [[Titanium]], poli-methyl-methacrylate ([[PMMA]]), [[Polyetheretherketone]] ([[PEEK]]) and [[Hydroxyapatite]] (HA). Extracted data included implant materials and the incidence of the most frequent complications. The final selection resulted in 106 papers but according to our rules only 27 studies were included in the final analysis. Among a total of 1688 custom-made prosthesis implanted, 649 were Titanium (38.49%), 298 PMMA (17.56%), 233 PEEK (13.82%), and 508 were HA (30.13%). A total of 348 complications were recorded out of 1688 reported patients (20.64%). In the Titanium group,139 complications were recorded (21.42%); in the PMMA group 57 (19.26%), in the PEEK group 49 (21.03%) and in the HA group 103 (20.3%). If we examine a summary of the reported complications clearly related to cranioplasty (postoperative infections, fractures and prosthesis displacement) versus type of material in multicentric and prospective studies we can see how HA group patients have less reported infections and cranioplasty explantation after infections than PMMA, PEEK and Titanium. On the contrary HA patients seem to have a higher number of prosthesis displacement again if compared with the other materials. Since these data are not derived from a statistically correct analysis they should be used only to help to differentiate the properties of the various heterologous cranioplasties. The ideal material for all heterologous cranioplasty has not yet been identified. The choice of material should be based on the clinical data of patients, such as the craniectomy size, presence of seizures, possibility of recovery, good long-term outcome associated with a cost analysis ((Morselli C, Zaed I, Tropeano MP, Cataletti G, Iaccarino C, Rossini Z, Servadei F. Comparison between the different types of heterologous materials used in cranioplasty: a systematic review of the literature. J Neurosurg Sci. 2019 Oct 7. doi: 10.23736/S0390-5616.19.04779-9. [Epub ahead of print] PubMed PMID: 31599560. )). ---- Based on the available evidence till 219, fresh bone grafts and titanium mesh demonstrated the lowest surgical-site infection, surgical-site occurrence, and graft failure rates. Banked bone flaps had the highest overall surgical-site complications and graft failures. Pediatric cranioplasty outcomes studies are needed to evaluate current and novel cranioplasty materials ((Abu-Ghname A, Banuelos J, Oliver JD, Vyas K, Daniels D, Sharaf B. Outcomes and Complications of Pediatric Cranioplasty: A Systematic Review. Plast Reconstr Surg. 2019 Sep;144(3):433e-443e. doi: 10.1097/PRS.0000000000005933. PubMed PMID: 31461029. )). Available [[evidence]] on the [[safety]] of [[cranioplasty materials]] is limited due to a large diversity in study conduct, patients included and outcomes reported. [[Autologous bone graft]]s appear to carry a higher failure risk than [[allograft]]s. Future publications concerning cranioplasties will benefit by a standardized reporting of surgical procedures, outcomes and graft materials used ((van de Vijfeijken SECM, Münker TJAG, Spijker R, Karssemakers LHE, Vandertop WP, Becking AG, Ubbink DT; CranioSafe Group. Autologous bone is inferior to alloplastic cranioplasties Safety of autograft and allograft materials for cranioplasties, a systematic review. World Neurosurg. 2018 Jun 4. pii: S1878-8750(18)31147-1. doi: 10.1016/j.wneu.2018.05.193. [Epub ahead of print] Review. PubMed PMID: 29879511. )). A literature review in 2016 emphasizes the benefits and weaknesses of each considered material commonly used for [[cranioplasty]], especially in terms of infectious complications, fractures, and morphological outcomes.As regards the latter, this appears to be very similar among the different materials when custom three-dimensional modeling is used for implant development, suggesting that this criterion is strongly influenced by implant design. However, the overall infection rate can vary from 0% to 30%, apparently dependent on the type of material used, likely in virtue of the wide variation in their chemico-physical composition. Among the different materials used for cranioplasty implants, synthetics such as [[polyetheretherketone]], [[polymethylmethacrylate]], and [[titanium]] show a higher primary tear resistance, whereas [[hydroxyapatite]] and [[autologous bone]] display good biomimetic properties, although the latter has been ascribed a variable reabsorption rate of between 3% and 50%. In short, all cranioplasty procedures and materials have their advantages and disadvantages, and none of the currently available materials meet the criteria required for an ideal implant. Hence, the choice of cranioplasty materials is still essentially reliant on the surgeon's preference ((Zanotti B, Zingaretti N, Verlicchi A, Robiony M, Alfieri A, Parodi PC. Cranioplasty: Review of Materials. J Craniofac Surg. 2016 Aug 19. [Epub ahead of print] PubMed PMID: 27548829. )). ---- In 19th century, the use of bone from different donor sites, such as ribs or tibia, gained wide population. Many different types of materials were used throughout the history of cranioplasty. With the evolving biomedical technology, new materials are available to be used by the surgeons. Although many different materials and techniques had been described, there is still no consensus about the best material, and ongoing researches on both biologic and nonbiologic substitutions continue aiming to develop the ideal reconstruction materials. Cranioplasty can be performed either with gold-standard, [[autologous bone flap]]s and osteotomies or alloplastic materials in skeletally mature patients. Recently, custom computer-generated implants (CCGIs) have gained popularity with surgeons because of potential advantages, which include preoperatively planned contour, obviated donor-site morbidity, and operative time savings. A remaining concern is the cost of CCGI production. ---- An experimental model was developed in an indoor gun range. CAD cranioplasties with a material thickness of 2-6 mm, made of titanium or PEEK-OPTIMA(®) were fixed in a watermelon and shot at with a .222 Remington rifle at a distance of 30 m distance, a .30-06 Springfield rifle at a distance of 30 m, a Luger 9 mm pistol at a distance of 8 m, or a .375 Magnum revolver at a distance of 8 m. The CAD cranioplasties were subsequently inspected for ballistic effects by a neurosurgeon. Titanium CAD cranioplasty implants resisted shots from the 9 mm Luger pistol and were penetrated by both the .222 Remington and the .30-06 Springfield rifle. Shooting with the .357 Magnum revolver resulted in the titanium implant bursting. PEEK-OPTIMA(®) implants did not resist bullets shot from any weapon. The implants burst on shooting with the 9 mm Luger pistol, the .222 Remington, the .30-06 Springfield rifle, and the .357 Magnum revolver. Titanium CAD cranioplasty implants may offer protection from ballistic injuries caused by small caliber weapons fired at short distances. This could provide a life-saving advantage in civilian as well as military combat situations ((Lemcke J, Löser R, Telm A, Meier U. Ballistics for neurosurgeons: Effects of firearms of customized cranioplasty implants. Surg Neurol Int. 2013 Apr 3;4:46. doi: 10.4103/2152-7806.110027. Print 2013. PubMed PMID: 23607068; PubMed Central PMCID: PMC3622352. )). ---- [[Methylmethacrylate]] and porous [[polyethylene]] (PP) were resistant to fracture and disruption. MMA provided the greatest neuroprotection, followed by PP. Autologous bone provided the least protection with cranioplasty disruption and severe brain injury occurring in every patient. Brain injury patterns correlated with the degree of cranioplasty disruption regardless of the cranioplasty material. Regardless of the energy of impact, lack of dislodgement generally resulted in no obvious brain injury ((Wallace RD, Salt C, Konofaos P. Comparison of Autogenous and Alloplastic Cranioplasty Materials Following Impact Testing. J Craniofac Surg. 2015 Jul;26(5):1551-7. doi: 10.1097/SCS.0000000000001882. PubMed PMID: 26114508. )). ===== Sonolucent cranioplasty ===== see [[Sonolucent cranioplasty]]. ===== References =====