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.

Can we do better at measuring patient-reported outcomes after cranioplasty? A systematic review.

Measuring quality of life (QOL) after cranioplasty is increasingly evident as a necessary component of patient-centered care. For data to be useful in clinical decision-making and approval of new therapies, studies must utilize valid and reliable instruments. Our objective was to critically appraise studies evaluating QOL in adult cranioplasty patients and determine validity and relevance of the patient-reported outcome measures (PROMs) used. Electronic databases of PubMed, Embase, CINAHL, and PsychINFO were used to identify PROMs measuring QOL in adult patients with cranioplasty. The methodological approach, cranioplasty outcomes, and domains measured by the PROMs were extracted and summarized descriptively. A content analysis of the identified PROMs was completed to identify the concepts measured. From 2236 articles identified, 17 articles containing eight QOL PROMs met the inclusion criteria. None of the PROMs was specifically validated or developed for adults undergoing cranioplasty. The QOL domains included physical health, psychological health, social health, and general QOL. These four domains encompassed 216 total items among the PROMs. Appearance was only assessed in two PROMs. To our knowledge, there are currently no validated PROMs that comprehensively measure appearance, facial function, and adverse effects in adults undergoing cranioplasty. There is an urgent need to develop PROMs to measure QOL outcomes rigorously and comprehensively in this patient population to inform clinical care, research, and quality improvement initiatives. Findings from this systematic review will be used to derive an outcome instrument containing important concepts related to QOL in patients who undergo cranioplasty.

The Transverse Facial Artery as a Recipient Artery in Neuroplastic Surgery Microvascular Reconstruction.

Microvascular reconstruction in the craniofacial region is particularly challenging due to a paucity of adequate recipient vessels. The facial vessels are commonly utilized; however, in neurocranial reconstruction, the distance from the defect to the vessels may require the use of interposition vein grafts. The superficial temporal vessels, which have the benefit of closer proximity, are often compromised or injured in patients with previous neurosurgical procedures or radiation therapy. Here, we describe the use of the transverse facial artery as a recipient for a latissimus dorsi free flap for scalp reconstruction in a 63-year-old man with a compromised scalp from multiple surgeries and radiation therapy for glioblastoma multiforme. The patient had extensive scarring, temporalis muscle wasting, thinning of the overlying scalp, and notable alopecia. On surveillance imaging, he was found to have an area on the brain concerning for tumor recurrence, for which a surgical biopsy was recommended, with a significant risk of postoperative wound healing complications. We present the use of the transverse facial artery in this case as a recipient artery for free flap reconstruction of the scalp.

Cranioplasty Outcomes From 500 Consecutive Neuroplastic Surgery Patients.

BACKGROUND: Cranioplasty is critical to cerebral protection and restoring intracranial physiology, yet this procedure is fraught with a high risk of complications. The field of neuroplastic surgery was created to improve skull and scalp reconstruction outcomes in adult neurosurgical patients, with the hypothesis that a multidisciplinary team approach could help decrease complications. OBJECTIVE: To determine outcomes from a cohort of cranioplasty surgeries performed by a neuroplastic surgery team using a consistent surgical technique and approach. METHODS: The authors reviewed 500 consecutive adult neuroplastic surgery cranioplasties that were performed between January 2012 and September 2020. Data were abstracted from a prospectively maintained database. Univariate analysis was performed to determine association between demographic, medical, and surgical factors and odds of revision surgery. RESULTS: Patients were followed for an average of 24 months. Overall, there was a reoperation rate of 15.2% (n = 76), with the most frequent complications being infection (7.8%, n = 39), epidural hematoma (2.2%, n = 11), and wound dehiscence (1.8%, n = 9). New onset seizures occurred in 6 (1.2%) patients.Several variables were associated with increased odds of revision surgery, including lower body mass ratio, 2 or more cranial surgeries, presence of hydrocephalus shunts, scalp tissue defects, large-sized skull defect, and autologous bone flaps. importantly, implants with embedded neurotechnology were not associated with increased odds of reoperation. CONCLUSIONS: These results allow for comparison of multiple factors that impact risk of complications after cranioplasty and lay the foundation for development of a cranioplasty risk stratification scheme. Further research in neuroplastic surgery is warranted to examine how designated centers concentrating on adult neuro-cranial reconstruction and multidisciplinary collaboration may lead to improved cranioplasty outcomes and decreased risks of complications in neurosurgical patients.

The Impact of Hydrocephalus Shunt Devices on Quality of Life.

BACKGROUND: Despite advances in hydrocephalus shunt technology and improvement in hydrocephalus management, many patients have chronic disability and require multiple surgeries throughout their lifetime. There is limited data from patients' perspective regarding the impact of shunt devices on quality-of-life. METHODS: A cross-sectional survey was developed to evaluate the impact of shunt devices on patient quality-of-life. The survey was distributed via social media platforms of the Hydrocephalus Association, and patients self-selected to anonymously complete the online questionnaire. A literature review was performed to contextualize the findings from the survey. RESULTS: A total of 562 survey responses were obtained from a network encompassing 35,000 members. The mean age was 30 years old (0.5-87), and 65% identified as female. Eighty one percent underwent at least 1 shunt revision surgery, with a reported average of 10 shunt revision surgeries per patient (1-200 surgeries). Occlusion, shunt migration and infection were the leading causes for revision at 60%, 47%, and 35%, respectively. In addition, 72% of patients reported pain and discomfort from the device, and 68% expressed avoidance of certain activities due to "fear of bumping shunt." Despite numerous articles discussing shunt technology, a review of the literature indicated a paucity of studies specifically evaluating the burden of shunt devices from a patient/caregiver perspective. CONCLUSIONS: The findings from this study suggest long-term physical and psychosocial burden associated with shunt devices. Importantly, this study highlights the need for concerted efforts to develop validated tools to study patient reported outcomes as it relates to neurocranial implanted devices.

Translucent Customized Cranial Implants Made of Clear Polymethylmethacrylate: An Early Outcome Analysis of 55 Consecutive Cranioplasty Cases.

BACKGROUND: Large skull reconstruction, with the use of customized cranial implants, restores cerebral protection, physiologic homeostasis, and one's preoperative appearance. Cranial implants may be composed of either bone or a myriad of alloplastic biomaterials. Recently, patient-specific cranial implants have been fabricated using clear polymethylmethacrylate (PMMA), a visually transparent and sonolucent variant of standard opaque PMMA. Given the new enhanced diagnostic and therapeutic applications of clear PMMA, we present here a study evaluating all outcomes and complications in a consecutive patient series. METHODS: A single-surgeon, retrospective, 3-year study was conducted on all consecutive patients undergoing large cranioplasty with clear PMMA implants (2016-2019). Patients who received clear PMMA implants with embedded neurotechnologies were excluded due to confounding variables. All outcomes were analyzed in detail and compared with previous studies utilizing similar alloplastic implant materials. RESULTS: Fifty-five patients underwent cranioplasty with customized clear PMMA implants. Twenty-one (38%) were performed using a single-stage cranioplasty method (ie, craniectomy and cranioplasty performed during the same operation utilizing a prefabricated, oversized design and labor-intense, manual modification), whereas the remaining 34 (62%) underwent a standard, 2-stage reconstruction (craniectomy with a delayed surgery for cranioplasty and minimal-to-no implant modification necessary). The mean cranial defect size was 101.8 cm. The mean follow-up time was 9 months (range, 1.5-39). Major complications requiring additional surgery occurred in 7 patients (13%) consisting of 2 (4%) cerebrospinal fluid leaks, 2 (4%) epidural hematomas, and 3 (4%) infections. In addition, 3 patients developed self-limiting or nonoperative complications including 2 (4%) with new onset seizures and 1 (2%) with delayed scalp healing. CONCLUSIONS: This is the first reported consecutive case series of cranioplasty reconstruction using customized clear PMMA implants, demonstrating excellent results with regard to ease of use, safety, and complication rates well below published rates when compared with other alloplastic materials. Clear PMMA also provides additional benefits, such as visual transparency and sonolucency, which is material specific and unavailable with autologous bone. Although these early results are promising, further studies with multicenter investigations are well justified to evaluate long-term outcomes.

Investigation of a Valve-Agnostic Cranial Implant for Adult Hydrocephalus Patients Requiring Ventriculoperitoneal Shunting.

INTRODUCTION: Currently, the most effective treatment strategy for adults with hydrocephalus involves cerebrospinal fluid diversion by means of a shunt system, most commonly ventriculoperitoneal shunts (VPS). Ventriculoperitoneal shunting is associated with high complication and/or revision rates, in part due to the high-profile programmable valve designs. Thus, the valve-agnostic cranial implant (VACI) was designed and investigated as a safe and effective method of reducing the valve's high profile and is currently undergoing clinical trials. As such, the objective of this study was to collate preliminary, multi-institutional data of early outcomes using a VACI approach for patients requiring VPS by way of an Institutional Review Board approved registry. METHODS: A total of 25 adult patients across 4 institutions and 6 surgeons underwent VACI placement for VPS based on preoperative evaluation and perceived benefit. Patient demographics, operative details, and preliminary outcomes are presented here. RESULTS: Valve-agnostic cranial implant placement via a limited size craniectomy at time of shunt revision was performed with no adverse events. Over an average follow-up period of 1 year (394 ±â€Š178 days), 92% of patients experienced no major shunt-related or scalp-related complications. There were 2 cases with a major complication requiring reoperation: 1 shunt tubing extrusion and 1 case of meningitis. The most frequent postsurgical intervention seen in this study was related to adjustment of drainage: a non-invasively performed valve reprogramming after initial shunt placement when proper flow rate is being established. Of the 8 cases of drainage adjustment, all but 1 (88%) were receiving a VPS for the first time, with the exception undergoing a fourth shunt revision. All instances of improper flow were treated non-surgically and remediated effectively via shunt reprogramming in clinic. Removal of the VACI was not indicated in any treatment course. In this way, all complications as they relate to the shunt valve were minor and required nonsurgical intervention, and no complications reported were directly or indirectly caused by using the VACI. CONCLUSION: Preliminary findings from this multicenter trial suggest promising outcomes with a low complication rate for patients with hydrocephalus undergoing VACI placement during VPS. Ongoing research will continue to provide a more robust clinical picture of VACI in hydrocephalus management as more data becomes available.

Risk of Complications in Primary Versus Revision-Type Cranioplasty.

INTRODUCTION: Cranioplasty (CP) is a multifaceted procedure in a heterogenous patient population, with a high risk for complication. However, no previous large-scale studies have compared outcomes in primary (ie, first attempt) CP versus revision CP (ie, following previous attempts). The authors, therefore, analyzed long-term outcomes of 506 consecutive primary and revision CPs, performed by a single surgeon. METHODS: All CPs performed between 2012 and 2019 were analyzed under IRB protocol approval. Surgeries were categorized as either primary (no previous CP; n = 279) or revision CP (at least one previous CP; n = 227). Complications were defined as either major or minor. Subgroup analyses investigated whether or not CP complication risk directly correlated with the number of previous neuro-cranial surgeries and/or CP attempts. RESULTS: The primary CP group experienced a major complication rate of 9% (26/279). In comparison, the revision CP group demonstrated a major complication rate of 32% (73/227). For the revision CP group, the rate of major complications rose with each additional surgery, from 4% (1 prior surgery) to 17% (2 prior surgeries) to 39% (3-4 prior surgeries) to 47% (≥5 prior surgeries). CONCLUSION: In a review of 506 consecutive cases, patients undergoing revision CP had a 3-fold increase in incidence of major complications, as compared to those undergoing primary CP. These results provide critical insight into overall CP risk stratification and may guide preoperative risk-benefit discussions. Furthermore, these findings may support a center-of-excellence care model, particularly for those patients with a history of previous neuro-cranial surgeries and/or CP attempts.

First-In-Human Experience With Integration of Wireless Intracranial Pressure Monitoring Device Within a Customized Cranial Implant.

BACKGROUND: Decompressive craniectomy is a lifesaving treatment for intractable intracranial hypertension. For patients who survive, a second surgery for cranial reconstruction (cranioplasty) is required. The effect of cranioplasty on intracranial pressure (ICP) is unknown. OBJECTIVE: To integrate the recently Food and Drug Administration-approved, fully implantable, noninvasive ICP sensor within a customized cranial implant (CCI) for postoperative monitoring in patients at high risk for intracranial hypertension. METHODS: A 16-yr-old female presented for cranioplasty 4-mo after decompressive hemicraniectomy for craniocerebral gunshot wound. Given the persistent transcranial herniation with concomitant subdural hygroma, there was concern for intracranial hypertension following cranioplasty. Thus, cranial reconstruction was performed utilizing a CCI with an integrated wireless ICP sensor, and noninvasive postoperative monitoring was performed. RESULTS: Intermittent ICP measurements were obtained twice daily using a wireless, handheld monitor. The ICP ranged from 2 to 10 mmHg in the supine position and from -5 to 4 mmHg in the sitting position. Interestingly, an average of 7 mmHg difference was consistently noted between the sitting and supine measurements. CONCLUSION: This first-in-human experience demonstrates several notable findings, including (1) newfound safety and efficacy of integrating a wireless ICP sensor within a CCI for perioperative neuromonitoring; (2) proven restoration of normal ICP postcranioplasty despite severe preoperative transcranial herniation; and (3) proven restoration of postural ICP adaptations following cranioplasty. To the best of our knowledge, this is the first case demonstrating these intriguing findings with the potential to fundamentally alter the paradigm of cranial reconstruction.

Optimal Timing of Secondary Alveolar Bone Grafting: A Literature Review.

PURPOSE: Secondary alveolar bone grafting (SABG) during mixed dentition is the standard of care for alveolar clefts. However, early SABG at 4 to 7 years of age before the eruption of lateral incisors versus late SABG at 8 to 12 years of age before the eruption of maxillary permanent canines is still debated. The purpose of this study was to perform a systematic review of the literature to evaluate the outcomes of early SABG in residual bone volume or degree of bone resorption, maxillary canine movement or impaction rate, complications, and esthetic outcomes and to compare outcomes of early versus late SABG. MATERIALS AND METHODS: A comprehensive search of the PubMed database was performed according to PRISMA guidelines. Keywords for alveolar cleft repair and inclusion criteria were used to screen articles for final review. RESULTS: The initial search yielded 6,278 articles, of which 4 retrospective and 4 prospective studies were chosen for final review. Of these, 7 studies compared outcome variables between early and late SABG and 1 looked at bone formation of patients who underwent only early SABG. For outcome variables, 3 studies assessed bone volume with radiographic evaluation, 2 estimated maxillary permanent canine impaction rate, 1 evaluated surgical complications, operative time, and length of hospital stay, and 1 looked at anterior incisor crown length. Overall, 6 studies concluded that early SABG provides a better outcome than late SABG and 2 found comparable results across the aforementioned variables. CONCLUSIONS: This review suggests that the existing data support the concept of early SABG; however, the data are not sufficient for a definitive conclusion. A well-planned prospective study is needed to further investigate the rationale for early SABG.