Cranial Implants Research Articles

Extrusion‐Based Additive Manufacturing of Cranial Implants Using High‐Performance Polymers: A Comparative Study on Mechanical Performance and Dimensional Accuracy

Fused filament fabrication (FFF) offers great potential to fabricate patient‐specific implants to treat large size defects resulting from craniectomy. Such cranial implants impose critical requirements on material and design. So far, the field has focused on printing cranial implants from polyetheretherketone (PEEK), which is semicrystalline in nature and, therefore, not ideal for FFF because of warping and nonhomogeneous crystallization. Consequently, this work aims at exploring alternative amorphous high‐performance polymers. The tensile and flexural mechanical properties of printed samples from PEEK, polyetherketoneketone (PEKK), and polyphenylsulfone (PPSU) according to ISO standards are compared. Testing of specimens obtained from three orthogonal build directions reveals nearly isotropic mechanical behavior (e.g. ultimate tensile strength differed no more than 8% between print orientations). This enables printing of patient‐specific cranial implants in vertical orientation with minimal support structures, which result in dimensional accuracies in the clinically acceptable range for craniofacial reconstructions. Mechanical assessment via an in‐house designed indentation set‐up shows that both PEKK and PPSU should be considered valid alternatives to PEEK for cranial implants. This work showcases the maturity of FFF for high‐performance polymers and leverages it for complex patient‐specific geometries such as a cranial implant.

Improving deep learning-based automatic cranial defect reconstruction by heavy data augmentation: From image registration to latent diffusion models

Modeling and manufacturing of personalized cranial implants are important research areas that may decrease the waiting time for patients suffering from cranial damage. The modeling of personalized implants may be partially automated by the use of deep learning-based methods. However, this task suffers from difficulties with generalizability into data from previously unseen distributions that make it difficult to use the research outcomes in real clinical settings. Due to difficulties with acquiring ground-truth annotations, different techniques to improve the heterogeneity of datasets used for training the deep networks have to be considered and introduced. In this work, we present a large-scale study of several augmentation techniques, varying from classical geometric transformations, image registration, variational autoencoders, and generative adversarial networks, to the most recent advances in latent diffusion models. We show that the use of heavy data augmentation significantly increases both the quantitative and qualitative outcomes, resulting in an average Dice Score above 0.94 for the SkullBreak and above 0.96 for the SkullFix datasets. The results show that latent diffusion models combined with vector quantized variational autoencoder outperform other generative augmentation strategies. Moreover, we show that the synthetically augmented network successfully reconstructs real clinical defects, without the need to acquire costly and time-consuming annotations. The findings of the work will lead to easier, faster, and less expensive modeling of personalized cranial implants. This is beneficial to numerous people suffering from cranial injuries. The work constitutes a considerable contribution to the field of artificial intelligence in the automatic modeling of personalized cranial implants.

Assessment of cranial reconstruction utilizing various implant materials: finite element study

The human head can sometimes experience impact loads that result in skull fractures or other injuries, leading to the need for a craniectomy. Cranioplasty is a procedure that involves replacing the removed portion with either autologous bone or alloplastic material. While titanium has traditionally been the preferred material for cranial implants due to its excellent properties and biocompatibility, its limitations have prompted the search for alternative materials. This research aimed to explore alternative materials to titanium for cranial implants in order to address the limitations of titanium implants and improve the performance of the cranioplasty process. A 3D model of a defective skull was reconstructed with a cranial implant, and the implant was simulated using various stiff and soft materials (such as alumina, zirconia, hydroxyapatite, zirconia-reinforced PMMA, and PMMA) as alternatives to titanium under 2000N impact forces. Alumina and zirconia implants were found to reduce stresses and strains on the skull and brain compared to titanium implants. However, PMMA implants showed potential for causing skull damage under current loading conditions. Additionally, PMMA and hydroxyapatite implants were prone to fracture. Despite these findings, none of the implants exceeded the limits for tensile and compressive stresses and strains on the brain. Zirconia-reinforced PMMA implants were also shown to reduce stresses and strains on the skull and brain compared to PMMA implants. Alumina and zirconia show promise as alternatives to titanium for the production of cranial implants. The use of alternative implant materials to titanium has the potential to enhance the success of cranial reconstruction by overcoming the limitations associated with titanium implants.Graphical

Investigating intermediate shapes for multi-stage forming of cranial implants

Single Point Incremental Forming (SPIF), a numerically controlled sheet forming technique, excels in adaptability and cost reduction for small-scale production and customized parts. This study explores multi-stage SPIF, focusing on applications in the medical domain, particularly the fabrication of personalized medical implants. Addressing critical challenges related to formability and accuracy, this study emphasizes the significance of multi-stage forming and the importance of the design of intermediate shapes. Forming a cranial implant using one intermediate stage is studied, preliminary in pure Zinc as a cost-effective alternative for heated Ti. The intermediate shape is generated using automatic geometry adaptations such as translating and scaling the CAD model. Nine different experiments are conducted and compared in terms of final geometric accuracy and thickness distributions. The study shows that the proposed intermediate shapes for multi-stage forming significantly improve the geometric accuracy from 1.08 mm mean absolute deviation in traditional single stage forming to 0.41–0.59 mm. However, the used intermediate shapes have a strong but varying effect on thickness distributions throughout the part, showing the importance and sensitivity of the exact intermediate geometry. These insights provide a valuable understanding of the process, shaping the pathway for enhanced utilization of SPIF and setting the stage for future improvements.

Early Challenges in the Implementation of Automated CranialRebuild Freeware for Generation of Patient-Specific Cranial Implant Using Additive Manufacturing: A Pilot Project in Review.

Traumatic Brain Injury (TBI) is a significant global health concern, particularly in low- and middle-income countries (LMICs) where access to medical resources is limited. Decompressive craniectomy (DHC) is a common procedure to alleviate elevated intracranial pressure (ICP) following TBI, but the cost of subsequent cranioplasty can be prohibitive, especially in resource-constrained settings. We describe challenges encountered during the beta-testing phase of CranialRebuild 1.0, an automated software program tasked with creating patient-specific cranial implants (PSCIs) from CT images. Two pilot clinical teams in the Philippines and Ukraine tested the software, providing feedback on its functionality and challenges encountered. The constructive feedback from the Philippine and Ukrainian teams highlighted challenges related to CT scan parameters, DICOM file arrays, software limitations, and the need for further software improvements. CranialRebuild 1.0 shows promise in addressing the need for affordable PSCIs in LMICs. Challenges and improvement suggestions identified throughout the beta-testing phase will shape the development of CranialRebuild 2.0, with the aim of enhancing its functionality and usability. Further research is needed to validate the software's efficacy in a clinical setting and assess its cost-effectiveness.

Acoustically transparent alumina-based cranial implants enhance ultrasound transmission through a combined mechano-acoustic resonant effect

Therapeutic ultrasound for brain stimulation has increased in the last years. This energy has shown promising results for treating Alzheimer’s disease, Parkinson’s disease and traumatic brain injury, among other conditions. However, the application of ultrasound in the brain should trespass a natural but highly attenuating and distorting barrier, the cranium. Implantable ceramic materials can be used to replace part of the cranium as an alternate method to enhance ultrasound transmission. In this work, it is presented the acoustic characterization of alumina ceramic disks that can be employed as cranial implants for acoustic windows-to-the-brain. Alumina samples were prepared using current-activated pressure-assisted densification and were acoustically characterized. Acoustic impedance and attenuation of the samples were determined for different porosities. Additionally, measured and modeled acoustic fields are presented and analyzed in terms of the total ultrasound transmitted through the ceramics. Results indicate a resonant behavior in the alumina disks when the thickness corresponds to a half-wavelength of ultrasound; this resonance permits a total of 95.4% of ultrasound transmission; for thicknesses out of the resonant zone, transmission is 53.0%. Alumina proves to be an excellent medium for ultrasound transmission that, in conjunction with its mechanical and optical properties, can be useful for cranium replacement in mixed opto-acoustic applications.

Is Polyetheretherketone an Effective Alloplastic Material in Comparison to Titanium in Calvarial Reconstruction.

Polyetheretherketone (PEEK) and titanium (Ti) cranioplasty implants ideal outcomes are good esthetics, long-term stability, and protection of the fragile brain tissue. However, it is unclear whether PEEK implants can offer an equal alternative to Ti implants. This work aimed to critically review papers and case series published on both Ti and PEEK Cranioplasty regarding complications, clinical outcomes, ease of use, esthetics, manufacture and availability, cost and time-saving factors, postoperative quality of life (QOL), as well as their suitability for the fronto-orbito region reconstruction. PubMed database was sourced for published literature in the period 2007 to the end of 2023; a further manual search for articles was carried out on the reference lists of each paper. A total of 48980 papers were found during the initial search, but only 33 articles met the inclusion criteria. A total of 6023 cranial implants, with 3879 being Ti and 1205 PEEK. Titanium was the material of choice in over 64.4% of cases; however, Ti has been in application for many years compared to PEEK. Out of the 33 papers, there was 27 retrospective cohort/analysis/case series and reviews: 1 meta-analysis, 2 systematic reviews and 3 randomized control trials. Four articles commented on the QOL, 15 on esthetics, 7 discussed cost and time-saving without measurable variables, and 7 articles looked explicitly at the complex fronto-orbito region, of which 49% were primary 1-stage surgical reconstructions, 54% were reconstructed with PEEK and 7% Ti (CAD/CAM). There is no absolute consensus for the preference of either material, however, in the fronto-orbito region, PEEK is the material of choice for ease of use, esthetics, and time-saving. However, there are no long-term studies on PEEK cranioplasty, and fewer in comparison with Ti implants. Further research is required in this field. No reliable or measurable data was found to determine the QOL, esthetics, cost, or time-saving elements.

Functional ultrasound imaging of human brain activity through an acoustically transparent cranial window.

Visualization of human brain activity is crucial for understanding normal and aberrant brain function. Currently available neural activity recording methods are highly invasive, have low sensitivity, and cannot be conducted outside of an operating room. Functional ultrasound imaging (fUSI) is an emerging technique that offers sensitive, large-scale, high-resolution neural imaging; however, fUSI cannot be performed through the adult human skull. Here, we used a polymeric skull replacement material to create an acoustic window compatible with fUSI to monitor adult human brain activity in a single individual. Using an in vitro cerebrovascular phantom to mimic brain vasculature and an in vivo rodent cranial defect model, first, we evaluated the fUSI signal intensity and signal-to-noise ratio through polymethyl methacrylate (PMMA) cranial implants of different thicknesses or a titanium mesh implant. We found that rat brain neural activity could be recorded with high sensitivity through a PMMA implant using a dedicated fUSI pulse sequence. We then designed a custom ultrasound-transparent cranial window implant for an adult patient undergoing reconstructive skull surgery after traumatic brain injury. We showed that fUSI could record brain activity in an awake human outside of the operating room. In a video game "connect the dots" task, we demonstrated mapping and decoding of task-modulated cortical activity in this individual. In a guitar-strumming task, we mapped additional task-specific cortical responses. Our proof-of-principle study shows that fUSI can be used as a high-resolution (200 μm) functional imaging modality for measuring adult human brain activity through an acoustically transparent cranial window.

Neuroplastic Surgery Principles of Computerized Surgical Planning in Complex Cranioplasty Reconstruction.

This article explores the evolution and implementation of three-dimensional (3D) models and Computerized Surgical Planning (CSP) for complex cranioplasty reconstruction and the advances in neuroplastic surgery principles for improved surgical outcomes. Over recent years, CSP has revolutionized the field by employing detailed medical imaging to enhance the accuracy and efficacy of 3D models and for the creation of customized cranial implants (CCIs). The study discusses the advancements of solid alloplastic implants to the future of implants with sophisticated and integrated neurotechnology to treat or enhance patient outcomes. CSP can be used to identify and mitigate complications that can occur within cranioplasty reconstruction and to create CCIs to address the postoperative challenge of temporal hollowing. Despite the promising advancements, the article acknowledges the current limitations of CSP, including cost and technological accessibility, and proposes future directions for research and development. The findings suggest that with further improvements in imaging, biomaterials, and manufacturing techniques, CSP in neuroplastic surgery and other specialties will continue to significantly enhance the precision and personalized care of cranioplasty reconstruction.

Point-of-Care 3-Dimensional-Printed Polyetheretherketone Customized Implants for Cranioplastic Surgery of Large Skull Defects.

3-Dimensional (3D) printing has become a common tool to aid implant molding for cranioplastic surgery of large skull defects. Until now, 3D printing of cranial implants itself has not been used, mainly because of medicolegal concerns. With a 3D printer developed for printing medical applications and with implant-grade polyetheretherketone (PEEK) filament available, we established a workflow (in compliance with medical device regulations) to 3D print cranial implants for cranioplastic surgery directly at the point of care (POC). Here, we describe the implementation of 3D printing these PEEK implants for cranioplastic surgery at our academic hospital. A thorough design and 3D printing process, in accordance with local medical device regulations, was developed. Implants are digitally designed based upon pre- and post-craniectomy cranial computed tomography scans by trained 3D printing experts from the department of medical engineering at our institution. Implants are then produced on a medical 3D printer with implant-grade PEEK filament using the fused filament fabrication process. After postprocessing and steam sterilization, implantation for reconstruction of the skull can be performed. Cranioplastic surgery with a 3D-printed PEEK implant was performed at our institution in a patient with a large frontotemporoparietal skull defect after traumatic brain injury with consecutive decompressive craniectomy. No intra- or post-operative complications occurred. Postoperative cranial computed tomography scans showed perfect reconstruction of precraniectomy skull shape. The aesthetic result was promising and satisfactory to the patient. This novel 3D printing workflow enables the production of patient-specific cranial implants from PEEK, to reconstruct large skull defects directly at the POC in accordance with the European Medical Device Regulation. This marks an unprecedented technological and legal advancement, enabling the hospital infrastructure not only to deliver the cranioplastic surgery itself, but also additive manufacturing of the implant directly at the POC.

Finite Element Analysis of Patient-Specific Cranial Implants under Different Design Parameters for Material Selection

This work presents the study of the thickness vs. stiffness relationship for different materials (PMMA and PEEK) in patient-specific cranial implants, as a criterion for the selection of biomaterials from a mechanical perspective. The geometry of the implant is constructed from the reconstruction of the cranial lesion using image segmentation obtained from computed axial tomography. Different design parameters such as thickness and perforations are considered to obtain displacement distributions under critical loading conditions using finite element analysis. The models consider quasi-static loads with linear elastic materials. The null hypothesis underlying this research asserts that both biomaterials exhibit the minimum mechanical characteristics necessary to withstand direct impact trauma at the implant center, effectively averting critical deformations higher than 2 mm. In this way, the use of PMMA cranioplasties is justified in most cases where a PEEK implant cannot be accessed.

Virtual Surgical Planning and Customized CAD/CAM Cranial Implants: Preoperative and Intraoperative Strategies for Temporal Intraosseous Meningioma Resection.

Primary intraosseous meningioma (PIM) is a rare subtype of extradural meningiomas, with the indication for surgical resection in most cases. With an increasing demand for efficient workflows with optimal functional and cosmetical results, techniques for bone reconstruction after resection are developing rapidly. The authors present 2 cases with one-stage cranioplasty after resection of PIM, using 3D technology for preplanned patient-specific implants. In the first case, a premanufactured patient-specific PEEK implant was used for reconstruction; in the second case, a 3-dimensional (3D)-based premanufactured silicon mold was used to produce a customized PMMA implant intraoperatively. Both techniques enabled the surgeons to achieve optimal intraoperative fit of the implant after craniectomy, leading to satisfying functional and cosmetic results. The use of 3D technology, such as Computer-Aided Design and Computer-Aided Manufacturing (CAD/CAM) for the production of patient-specific implants can optimize 1-stage cranioplasty after PIM resection.

Thickness and design features of clinical cranial implants-what should automated methods strive to replicate?

New deep learning and statistical shape modelling approaches aim to automate the design process for patient-specific cranial implants, as highlighted by the MICCAI AutoImplant Challenges. To ensure applicability, it is important to determine if the training data used in developing these algorithms represent the geometry of implants designed for clinical use. Calavera Surgical Design provided a dataset of 206 post-craniectomy skull geometries and their clinically used implants. The MUG500+ dataset includes 29 post-craniectomy skull geometries and implants designed for automating design. For both implant and skull shapes, the inner and outer cortical surfaces were segmented, and the thickness between them was measured. For the implants, a 'rim' was defined that transitions from the repaired defect to the surrounding skull. For unilateral defect cases, skull implants were mirrored to the contra-lateral side and thickness differences were quantified. The average thickness of the clinically used implants was 6.0 ± 0.5mm, which approximates the thickness on the contra-lateral side of the skull (relative difference of -0.3 ± 1.4mm). The average thickness of the MUG500+ implants was 2.9 ± 1.0mm, significantly thinner than the intact skull thickness (relative difference of 2.9 ± 1.2mm). Rim transitions in the clinical implants (average width of 8.3 ± 3.4mm) were used to cap and create a smooth boundary with the skull. For implant modelers or manufacturers, this shape analysis quantified differences of cranial implants (thickness, rim width, surface area, and volume) to help guide future automated design algorithms. After skull completion, a thicker implant can be more versatile for cases involving muscle hollowing or thin skulls, and wider rims can smooth over the defect margins to provide more stability. For clinicians, the differing measurements and implant designs can help inform the options available for their patient specific treatment.

Effects of Home Cage Tunnels on Within-cage Behaviors of Mice with Cranial Implants.

Keeping tunnels in the home cages of mice used in research appears to both reduce handling-related stress and provide environmental enrichment. However, for mice that have surgical implants that extend beyond their body, having tunnels in the home cages could engender concerns for their welfare, including the possibility of them becoming stuck in the tunnel. The goal of this study was to determine how mice with different sizes of cranial implants interacted with a tunnel in their home cage. We used male and female mice with a C57BL/6J background in this study. The mice underwent a either a craniotomy in which they received either no implant (sham), an indwelling cannula used for drug delivery, or a ferrule-type implant. The number of mouse interactions with tunnels was recorded over a 30-min period while the mouse was in its home cage with its tunnel. We found that sham mice interacted significantly more with the tunnels than did mice with either cannulae or ferrule implants. On average sham mice interacted more with the tunnel by walking through or over it whereas mice with either type of implant rarely even touched the tunnel with their heads. Our results indicate that mice with implants do not enter in the tunnels, and thus the tunnel reduces accessible cage-space rather than providing enrichment benefits. These results raise the question of whether tunnels should be routinely available for mice with cranial implants.

Personalized 3D-printed cranial implants for complex cranioplasty using open-source software.

Cranioplasty is a routine neurosurgery treatment used to correct cranial vault abnormalities. Utilization of 3D printing technology in the field of cranioplasty involving the reconstruction of cranial defects emerged as an advanced possibility of anatomical reshaping. The transformative impact of patient-specific 3D printed implants, focuses on their remarkable accuracy, customization capabilities, and enhanced biocompatibility. The precise adaptation of implants to patient-specific anatomies, even in complex cases we presented, result in improved aesthetic outcomes and reduced surgical complications. The ability to create highly customized implants addresses the functional aspects of cranial defects and considers the psychological impact on patients. By combining technological innovation with personalized patient care, 3D printed cranioplasty emerges as a transformative avenue in cranial reconstruction, ultimately redefining the standards of success in neurosurgery. 3D printing allows an excellent cranioplasty cosmesis achieved at a reasonable price without sacrificing patient outcomes. Wider implementation of this strategy can lead to significant healthcare cost savings.

The Effects of Structural & Materials Design on the Mechanisms of Tissue Integration with the 3D Printed Polyether-Ether-Ketone Cranial Implants in Vivo

3D printed polyether-ether-ketone (PEEK) implant has become a popular clinical alternative to implants made of titanium alloy for cranial bone substitutes due to its bone-match properties, however its biological inert hindered the progress of clinical applications of such material. To enhance the tissue integration capability of PEEK implants and promote their long-term stability, cranial implants of gradient porous structures were designed and manufactured via fused filament fabrication (FFF) 3D printing technology in both PEEK and PEEK/HA composites materials, then functionally evaluation of the implants on the tissue in-growth and the osteointegration mechanisms was conducted via animal tests. The 3D printed PEEK scaffold was found to have 2–5 folds of the compressive strength to those of the natural cranial bone. The in vivo studies verified that the porous PEEK/HA scaffold could effectively induce the bone ingrowth to form a stable biointegration boundary surrounding the host bone tissue after 4 weeks of implantation. Moreover, the PEEK/HA scaffold showed no significant advantages in improving the soft tissue in-growth, only making its distribution more evenly. It is also interestingly to find out that the vertically connective pores throughout the implant did not enhance the tissue binding force even though it did promote the nutrient transportation. In conclusion, the use of PEEK/HA composite material and a well-designed porous structure was proved to be an effective approach to improve the biointegration between the implant and host tissues.

Automatic Skull Shape Completion of Defective Skulls Using Transformers for Cranial Implant Design

Cranioplasty is a surgical method that restores the aesthetic and protecting function of a damaged skull by implanting material into the damaged area.Fast and accurate design of patient specific cranial implants is very much required in the process of cranioplasty.The time consumption for designing and manufacturing of patient specific cranial implant has become an obstruction for cranioplasty procedures. Hence, a fully automatic and fast design of cranial implant becomes very important. The cranial implant design processmainly comprises of two steps. The former step concentrates on the automatic skull shape completion of defective skulls to fill the gaps and the cracks created in the skull. While the second step computes the difference between defective input and the completed skull for generating the implant. Currently computer aided design is used for the skull shape completion task which is a time consuming process. The application of deep learning techniques may result to faster and accurate skull shape completionwhich can be used for the design of patient specific cranial implants. This work proposes a novel approach combining 3D U-Net with Transformers for the automatic skull shape completion task.We are using a vision transformer in the encoder section of the 3D U-Net architecture to consider the volumetric skull reconstruction as sequence- to-sequence prediction problem and to efficaciously grasp the global contextual information. The work also compares its performance with the famous variants of 3D U-Net deep network model namely, 3D U-Net and 3D U-Net with attention. From the values resulted for the dice coefficient metric it is clear that the proposed 3D U-Net with transformer approach performs better than the other two models on test images.

Customized anterior temporal augmentation for treating anterior temporal hollowing (ATH) by 3D-printed cranioplasty

BackgroundAnterior temporal hollowing (ATH) leads to unattractive facial asymmetry and significant distress for the patient. This study aimed to correct ATH by a prefabricated cranioplasty using soft-tissue volume augmentation created by 3D printing and to evaluate the esthetic improvement. MethodsThis prospective study was conducted on 19 patients with ATH after brain surgery. Quantitative assessment used Materialized Mimics® and Images® to compare defect volume and quantitative measurement of the “defect value” pre- and post-PMMA implantation. Qualitative assessment was rated by patients on VAS pre- and 6 months post-surgery. ResultsThe mean defect value decreased significantly with the innovative PMMA implant, from 2.42 ± 0.57 cm to 0.57 ± 0.45 cm (p < 0.01). There was a statistically significant reduction between pre- and postoperative defect value: 1.85 ± 0.48 (p < 0.01; 95% CI 2.08–1.61). After PMMA cranial implantation, 100% of patients reported esthetic improvement, 79% (15 out of 20) rating their esthetic improvement with the highest possible VAS score: mean VAS rating, 0.84 ± 1.2 preoperatively, and 4.63 ± 0.83 postoperatively, for a significant mean improvement of 3.789 ± 1.273 (p < 0.01; 95% CI 3.176–4.403). ConclusionsThe innovative PMMA cranial implants created by advanced customized 3D technology successfully managed ATH. This could be a therapeutic alternative for correcting ATH and can be routinely employed in clinical practice.

Sonolucent Cranial Implants: A Window into the Future of Management of Neurosurgical Patients? A Systematic Review and Cost Analysis

Background and ObjectivesComputerized tomography (CT) is a cornerstone of the identification and management of acute changes in neurosurgery patients. In addition to the monetary expense of CT scans, further costs are incurred due to the time of patient transport and radiation exposure. Ultrasounds (US) offer a safe, inexpensive, and bedside alternative to CT but obstacles remain due to decreased penetrance in the adult skull. Sonolucent Cranial Implants (SCI) offer a window for ultrasounds to view intracranial architectures. MethodsThe authors performed a PRISMA guidelines-based systematic review of the literature. Information was extracted from included articles in regards to illness pathology, ultrasound imaging feasibility, comparison to standard imaging, infections, and revisions. Costs were collected in regards to price of implant and follow-up imaging. Results226 articles resulted of which 5 were included in the study. Ninety non-duplicate patients who received SCIs were analyzed. The pathologies of included patients is as follows: 51 patients were after extracranial-intracranial bypass, 37 after VP shunt placement for hydrocephalus, one after tumor resection, and one after cranioplasty following decompressive hemicraniectomy. All studies noted feasibility of ultrasound and comparability to standard imaging following SCI placement. Follow up imaging with trans-sonolucent cranial implant ultrasound was estimated to save up to $4,000 per patient depending on the procedure. ConclusionInitial studies suggest that ultrasound imaging through SCIs is a safe and efficacious alternative to CT imaging in neurosurgical patients. Cost analysis suggests that SCI and subsequent US can offer a cost savings compared to current treatment.

Optimization of Fixations for Additively Manufactured Cranial Implants: Insights from Finite Element Analysis.

With the emergence of additive manufacturing technology, patient-specific cranial implants using 3D printing have massively influenced the field. These implants offer improved surgical outcomes and aesthetic preservation. However, as additive manufacturing in cranial implants is still emerging, ongoing research is investigating their reliability and sustainability. The long-term biomechanical performance of these implants is critically influenced by factors such as implant material, anticipated loads, implant-skull interface geometry, and structural constraints, among others. The efficacy of cranial implants involves an intricate interplay of these factors, with fixation playing a pivotal role. This study addresses two critical concerns: determining the ideal number of fixation points for cranial implants and the optimal curvilinear distance between those points, thereby establishing a minimum threshold. Employing finite element analysis, the research incorporates variables such as implant shapes, sizes, materials, the number of fixation points, and their relative positions. The study reveals that the optimal number of fixation points ranges from four to five, accounting for defect size and shape. Moreover, the optimal curvilinear distance between two screws is approximately 40 mm for smaller implants and 60 mm for larger implants. Optimal fixation placement away from the center mitigates higher deflection due to overhangs. Notably, a symmetric screw orientation reduces deflection, enhancing implant stability. The findings offer crucial insights into optimizing fixation strategies for cranial implants, thereby aiding surgical decision-making guidelines.