Role of Plastic Surgery in the Treatment of Titanium Mesh Exposure Following Cranioplasty.

BACKGROUND: Titanium mesh cranioplasty is the most common strategy for the repair of skull defects. However, as the frequency of cranioplasty increases, the incidence of titanium mesh exposure following cranioplasty increases as well. This study aimed to investigate the methods and outcomes of plastic surgery in the management of titanium mesh exposure following cranioplasty. METHODS: Patients with titanium mesh exposure following cranioplasty were retrospectively selected from January 2016 to August 2021. Titanium mesh exposure was corrected with reconstructive plastic surgery, including skin grafting, expander insertion, partial removal of the exposed mesh, replacement of the mesh, or flap transplantation. RESULTS: This study included 21 patients with titanium mesh exposure with surgical site infection and a variant of scalp deformity. The age of the patients ranged from 18 to 74 years, with the mean age being 54 years. All patients underwent reconstructive plastic surgery and exhibited complete wound healing. The follow-up period ranged from 17 to 90 months. One patient experienced titanium mesh re-exposure and subsequently underwent an additional procedure for the partial removal of the exposed mesh. No serious complications were observed postoperatively. CONCLUSION: Reconstructive plastic surgery can facilitate wound healing at the titanium mesh exposure site following cranioplasty. However, an individualized treatment strategy is required for each patient, and complications should be managed by adopting standard measures.

Cranioplasty in Oman: Retrospective review of cases from the National Craniofacial Center 2012-2022.

Objectives: Cranioplasty is a complex craniofacial and neurosurgical procedure that aims to reinstate the architecture of the cranial vault and elevate both its aesthetic and neurological function. Several reconstructive materials have been thoroughly explored in the search for the optimal solution for cranioplasty. This study aimed to evaluate different material used for cranial reconstruction in Oman. Methods: This retrospective study included all patients who had had cranioplasty procedures performed at Khoula Hospital, Muscat, Oman, from 2012 to 2022. Demographic information, the characteristics of the cranial defect and any complications that occurred post-operatively were analysed. Results: A total of 47 patients were included in this study. The most common cause of cranial defects was craniectomy following traumatic head injury (70.2%) along with excision of fibrous dysplasia (10.6%). The most frequently utilised material for cranial repair was autologous bone grafts (n = 28), followed by polyetheretherketone (PEEK; n = 14). Interestingly, the replacement of bone grafts from previous craniectomy showed a notably high resorption rate (71.4%), in contrast to split calvarial grafts (0%) and other types of bone grafts (14.3%). Additionally, delayed graft infection was observed in 3.6% of the bone graft group and 7.1% of the PEEK group. Conclusion: Patient-specific alloplastic implants such as PEEK have gained popularity for large and complex cranioplasty, as they provide excellent aesthetic outcomes and leave no donor site morbidity. In contrast, bone grafts remain the gold standard for small to medium-sized cranial defects.

The Establishment of Calvarial Suture-Bony Composite Defects in Rats: A Standardized Model for Suture-Regenerative Therapy Investigation.

Large-scale calvarial defects often coincide with cranial suture disruption, leading to impairments in calvarial defect restoration and skull development (the latter occurs in the developing cranium). However, the lack of a standardized model hinders progress in investigating suture-regenerative therapies and poses challenges for conducting comparative analyses across distinct studies. To address this issue, the current protocol describes the detailed modeling process of calvarial suture-bony composite defects in rats. The model was generated by drilling full-thickness rectangular holes measuring 4.5 mm × 2 mm across the coronal sutures. The rats were euthanized, and the cranium samples were harvested postoperatively at day 0, week 2, week 6, and week 12. µCT results from samples collected immediately post-surgery confirmed the successful establishment of the suture-bony composite defect, involving the removal of the coronal suture and the adjacent bone tissues. Data from the 6th and 12th postoperative weeks demonstrated a natural healing tendency for the defect to close. Histological staining further validated this trend by showing increased mineralized fibers and new bone at the defect center. These findings indicate progressive suture fusion over time following calvarial defects, underscoring the significance of therapeutic interventions for suture regeneration. We anticipate that this protocol will facilitate the development of suture-regenerative therapies, offering fresh insights into the functional restoration of calvarial defects and reducing adverse outcomes associated with suture loss.

Low Prevalence of Clinically Significant Hyponatremia following Cranial Vault Reconstruction for Single-Suture Craniosynostosis.

BACKGROUND: Patients are commonly monitored for hyponatremia after intracranial procedures, yet the prevalence of hyponatremia after cranial vault reconstruction (CVR) remains unclear. The purpose of this study is to define the prevalence, risk factors, and complications of hyponatremia after CVR to optimize postoperative sodium surveillance protocols. METHODS: Patients with nonsyndromic, single-suture craniosynostosis who underwent primary CVR between 2009 and 2020 at Michigan Medicine were included (n = 231). Demographic, intraoperative, and postoperative characteristics were compared by postoperative hyponatremia status at P < 0.05 significance. Hyponatremia was defined as mild (<135 mEq/L), moderate (<130 mEq/L), or severe (<125 mEq/L) based on the lowest postoperative laboratory draw. RESULTS: Twenty-three patients (10.0%) developed mild postoperative hyponatremia. No patient developed moderate or severe postoperative hyponatremia. On multivariable regression, decreased preoperative sodium level (P = 0.03) and decreased preoperative weight (P = 0.02) were significantly associated with mild postoperative hyponatremia. No patient developed complications or required hospital readmission because of hyponatremia. CONCLUSIONS: This large retrospective cohort study of patients with nonsyndromic single-suture craniosynostosis demonstrated a 10% prevalence of mild, clinically inconsequential hyponatremia and 0% prevalence of moderate or severe, clinically significant hyponatremia after primary CVR. Patients with low preoperative sodium level or weight were at increased risk for developing mild postoperative hyponatremia. The results suggest that patients with preoperative sodium greater than 140 mEq/L or preoperative weight greater than 10 kg may be candidates for limited postoperative sodium surveillance; however, future prospective studies are warranted before implementation. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, III.

Cranial Repair in Children: Techniques, Materials, and Peculiar Issues.

Cranial repair in children deserves particular attention since many issues are still controversial. Furthermore, literature data offer a confused picture of outcome of cranioplasty, in terms of results and complication rates, with studies showing inadequate follow-up and including populations that are not homogeneous by age of the patients, etiology, and size of the bone defect.Indeed, age has merged in the last years as a risk factor for resorption of autologous bone flap that is still the most frequent complication in cranial repair after decompressive craniectomy.Age-related factors play a role also when alloplastic materials are used. In fact, the implantation of alloplastic materials is limited by skull growth under 7 years of age and is contraindicated in the first years if life. Thus, the absence of an ideal material for cranioplasty is even more evident in children with a steady risk of complications through the entire life of the patient that is usually much longer than surgical follow-up.As a result, specific techniques should be adopted according to the age of the patient and etiology of the defect, aiming to repair the skull and respect its residual growth.Thus, autologous bone still represents the best option for cranial repair, though limitations exist. As an alternative, biomimetic materials should ideally warrant the possibility to overcome the limits of other inert alloplastic materials by favoring osteointegration or osteoinduction or both.On these grounds, this paper aims to offer a thorough overview of techniques, materials, and peculiar issues of cranial repair in children.

Comparing the effects of Bone+B® xenograft and InterOss® xenograft bone material on rabbit calvaria bone defect regeneration.

BACKGROUND: The bone regeneration therapy is often used in patients with inadequate bone support for implants, particularly following tooth extractions. Xenografts derived from animal tissues are effective bone reconstructive options that resist resorption and pose a low risk of transmitting disease. Therefore, these implants may be a good option for enhancing and stabilizing maxillary sinuses. The purpose of this study was to compare two xenografts, Bone+B® and InterOss®, for the reconstruction of rabbit calvaria defects. METHODS AND MATERIALS: The study involved seven male New Zealand white rabbits. In the surgical procedure, 21 spots were created on both sides of the midline calvarium by creating three 8-millimeter defects. A control group was used, as well as two treatment groups utilizing Bone+B® Grafts and InterOss® Grafts. After 3 months, the rabbits were euthanized, followed by pathological evaluation. Analysis of these samples focused on bone formation, xenograft remaining material, and inflammation levels, using Adobe Photoshop CS 8.0 and SPSS version 24. RESULTS: With the application of Bone+B® graft, bone formation ranged from 32% to 45%, with a mean of 37.80% (±5.63), and the remaining material ranged from 28% to 37%, with a mean of 32.60% (±3.65). Using InterOss® grafts, bone formation was 61% to 75%, the mean was 65.83% (±4.75), and the remaining material was 9% to 18%, with a mean of 13.17% (±3.06). The bone formation in the control group ranged from 10% to 25%, with a mean of 17.17% (±6.11). InterOss® had lower inflammation levels than other groups, but the difference was not statistically significant (p > .05). CONCLUSION: InterOss® bone powder is the best option for maxillofacial surgery and bone reconstruction. This is due to more bone formation, less remaining material, and a lower inflammation level. Compared to the control group, Bone+B® improves healing and bone quality, thus making it an alternative to InterOss®.

Comparison of the Effect of Platelet-rich Plasma (PRP) and Fat Graft on Autologous Bone Grafting in a Randomized-controlled Experimental Skull Model.

Gold standard method for the treatment of critical-sized bone defects is the autogenous bone grafting procedure. A number of new and potentially useful adjuncts currently are being investigated to enhance the success of bone grafting. We propose to evaluate the effect of the most known and easily obtained 2 biological materials, fat graft and platelet-rich plasma (PRP), on bone graft healing. Twenty-seven New Zealand male rabbits were included in this randomized, controlled study. Two-sided 15-mm diameter bone defects were created in the parietal bones and the bones taken were replaced right-to-left and vice versa with 1 control group, 1 fat graft applied group, and the last one PRP applied group. Histologic evaluation and 3-dimensional maxillofacial computerized tomography were performed and bone density was calculated. In radiologic analysis, bone density was significantly different in the PRP group compared with the control and fat graft group in the 12th week ( P <0.05). In histologic scoring analysis, the PRP group had a better score than the control and fat graft group, while the fat graft group was worse than the control group in the 6th week ( P <0.05). The addition of PRP had a positive effect whereas fat graft had a negative effect on bone graft healing compared with the control group.

Back to the Roots: Reconstructing Large and Complex Cranial Defects using an Image-based Statistical Shape Model.

Designing implants for large and complex cranial defects is a challenging task, even for professional designers. Current efforts on automating the design process focused mainly on convolutional neural networks (CNN), which have produced state-of-the-art results on reconstructing synthetic defects. However, existing CNN-based methods have been difficult to translate to clinical practice in cranioplasty, as their performance on large and complex cranial defects remains unsatisfactory. In this paper, we present a statistical shape model (SSM) built directly on the segmentation masks of the skulls represented as binary voxel occupancy grids and evaluate it on several cranial implant design datasets. Results show that, while CNN-based approaches outperform the SSM on synthetic defects, they are inferior to SSM when it comes to large, complex and real-world defects. Experienced neurosurgeons evaluate the implants generated by the SSM to be feasible for clinical use after minor manual corrections. Datasets and the SSM model are publicly available at https://github.com/Jianningli/ssm .

Transcriptomic and cellular decoding of scaffolds-induced suture mesenchyme regeneration.

Precise orchestration of cell fate determination underlies the success of scaffold-based skeletal regeneration. Despite extensive studies on mineralized parenchymal tissue rebuilding, regenerating and maintaining undifferentiated mesenchyme within calvarial bone remain very challenging with limited advances yet. Current knowledge has evidenced the indispensability of rebuilding suture mesenchymal stem cell niches to avoid severe brain or even systematic damage. But to date, the absence of promising therapeutic biomaterials/scaffolds remains. The reason lies in the shortage of fundamental knowledge and methodological evidence to understand the cellular fate regulations of scaffolds. To address these issues, in this study, we systematically investigated the cellular fate determinations and transcriptomic mechanisms by distinct types of commonly used calvarial scaffolds. Our data elucidated the natural processes without scaffold transplantation and demonstrated how different scaffolds altered in vivo cellular responses. A feasible scaffold, polylactic acid electrospinning membrane (PLA), was next identified to precisely control mesenchymal ingrowth and self-renewal to rebuild non-osteogenic suture-like tissue at the defect center, meanwhile supporting proper osteointegration with defect bony edges. Especially, transcriptome analysis and cellular mechanisms underlying the well-orchestrated cell fate determination of PLA were deciphered. This study for the first time cellularly decoded the fate regulations of scaffolds in suture-bony composite defect healing, offering clinicians potential choices for regenerating such complicated injuries.

Cognitive Outcomes of Children With Sagittal Craniosynostosis Treated With Either Endoscopic or Open Calvarial Vault Surgery.

Importance: Several studies have reported a higher incidence of neurodevelopmental delays and cognitive deficits in patients with single-suture craniosynostosis; however, there are few studies examining the associations of repair type with cognitive outcomes. Objective: To measure differences in neuropsychological outcomes between school-age children who were treated for sagittal craniosynostosis and unaffected controls and explore differences in cognitive function among children with sagittal craniosynostosis who were previously treated with either endoscopic strip craniectomy or open calvarial vault surgery. Design, Setting, and Participants: This cohort study was performed between 2018 and 2022. Eligible participants included patients aged 5 to 17 years who had previously been seen as infants or toddlers (<3 years) at 1 of 3 surgical centers for craniosynostosis repair with either endoscopic surgery or open calvarial vault surgery. A separate cohort of unaffected controls were included for comparison. Data analysis was conducted from November 2023 to February 2024. Exposures: Open calvarial vault surgery or endoscopic repair for single-suture craniosynostosis. Main Outcomes and Measures: The primary outcome was the Differential Ability Scales-II (DAS-II) General Conceptual Ability (GCA) score, an index for overall intellectual ability. Secondary outcomes included DAS-II subscale scores (Verbal Ability, Nonverbal Reasoning, Spatial Ability, Working Memory, and Processing Speed), and Patient-Reported Outcomes Measurement Information System (PROMIS) cognitive function scores. Results: A total of 81 patients with sagittal craniosynostosis (59 male [73%]; 22 female [27%]) and 141 controls (81 male [57%]; 60 female [43%]) were included. Of the 81 participants with sagittal craniosynostosis, 46 underwent endoscopic repair and 35 underwent open repair. Median (range) age at time of follow-up assessment was 7.7 (5.0-14.8) years for children with sagittal craniosynostosis and median age at assessment was 8.5 (7.7-10.5) years for controls. After controlling for age at assessment, sex, and socioeconomic status, there was no statistically significant or clinically meaningful difference in GCA scores between children who underwent endoscopic repair (adjusted mean score, 100; 95% CI, 96-104) and open repair (adjusted mean score, 103; 95% CI, 98-108) (P > .99). We found no significant difference in PROMIS scores between repair types (median [range] for endoscopic repair 54 [31-68] vs median [range] for open repair 50 [32-63]; P = .14). When comparing the treatment groups with the unaffected controls, differences in subscale scores for GCA and working memory were observed but were within normal range. Conclusions and Relevance: In this cohort study, there were no statistically or clinically significant differences in cognitive outcomes among school-age children by and type of surgical procedure used to repair nonsyndromic sagittal craniosynostosis. These findings suggest primary care clinicians should be educated about different options for craniosynostosis surgery to ensure early referral of these patients so that all treatment options remain viable.

Evaluation of skull bone viability and effect of early surgical intervention in electrical contact burns using 18 F-Sodium Fluoride PET-CT imaging.

OBJECTIVE: Electrical contact burns of the scalp cause serious morbidity and mortality. Early necrotic bone debridement and flap cover are crucial for successful wound closure. 18 F Sodium Fluoride (NaF), with high bone-to-soft tissue activity ratio, is useful for bone viability assessment. This study evaluated the role of 18 F NaF PET-computed tomography (CT) in objectively defining the extent and depth of nonviable calvarial bone, to guide adequate bone debridement. METHOD: Of 20 patients referred to our institute with electrical contact burns of the scalp during a 2-year period, 15 were enrolled in the study. Two weeks after the initial management, tracer uptake pattern was noted on 18 F NaF PET-CT of the head and exposed bone measured. Surgical bone debridement was based on scan findings, followed by wound closure. All patients underwent clinical evaluation and follow-up scan 3 months after surgery. RESULTS: Eight patients showed a central photopenic area in the exposed bone (maximum standardized uptake value [SUVmax] of 0.76 ± 0.14 with mean maximum dimensions 4.10 ± 1.76/2.67 ± 1.54 cm). High tracer uptake (SUVmax, 9.66 ± 6.03) was seen peripheral to the exposed bone (mean maximum dimensions, 8.14 ± 3.03/4.75 ± 1.61 cm). Postoperatively, there was no significant change in tracer uptake in the central debrided region or peri-debridement bone area under the flap. Clinically all patients showed a well-healed flap. CONCLUSION: 18 F NaF PET-CT appears useful for objective evaluation of skull bone viability and planning necrotic bone debridement in patients with electrical contact burns. However, additional studies with longer patient follow-up are required to validate these results.

How to Safely Use the Perforator-based Keystone Island Flap in the Scalp: Basal Cell Carcinoma of the Scalp With Local Invasion to Calvarium.

Scalp reconstruction has always been a challenging problem for even the most experienced surgeon to provide good aesthetic and functional results. This is mainly because the scalp is less mobile and tight, requiring a much larger dissection for the size of the original defect. We hypothesized that the omega variant perforator-based keystone island flap at the subgaleal plane provides a versatile and easily reproducible reconstructive option for scalp reconstruction after wide skin cancer excision. We reviewed all patients who underwent reconstruction with the keystone flap or its modification to repair scalp defects following wide resection of skin cancer in the scalp abutting calvarium from May 2021 to July 2023. We designed the flap width 50% wider than original keystone flap design first introduced by Dr. Behan. We reconstructed medium- to large-sized scalp defects ranging from 2×2 to 5×5 cm 2 using an omega variant perforator-based keystone island flap. All patients were satisfied with the aesthetic outcomes without complications. Keystone flaps are a versatile option for reconstructing the scalp after cancer resection. This strategy obviates the need for skin grafting, myocutaneous flap or free flap after cancer removal in the scalp.

High-Density Porous Polyethylene Implant Cranioplasty: A Systematic Review of Outcomes.

Porous polyethylene has been widely used in craniofacial reconstruction due to its biomechanical properties and ease of handling. The objective of this study was to perform a systematic review of the literature to summarize outcomes utilizing high-density porous polyethylene (HDPP) implants in cranioplasty. A literature search of PubMed, Cochrane Library, and Scopus databases was conducted to identify original studies with HDPP cranioplasty from inception to March 2023. Non-English articles, commentaries, absent indications or outcomes, and nonclinical studies were excluded. Data on patient demographics, indications, defect size and location, outcomes, and patient satisfaction were extracted. Summary statistics were calculated using weighted averages based on the available reported data. A total of 1089 patients involving 1104 cranioplasty procedures with HDPP were identified. Patients' mean age was 44.0 years (range 2 to 83 y). The mean follow-up duration was 32.0 months (range 2 wk to 8 y). Two studies comprising 17 patients (1.6%) included only pediatric patients. Alloplastic cranioplasty was required after treatment of cerebrovascular diseases (50.9%), tumor excision (32.0%), trauma (11.4%), trigeminal neuralgia/epilepsy (3.4%), and others such as abscesses/cysts (1.4%). The size of the defect ranged from 3 to 340 cm 2 . An overall postoperative complication rate of 2.3% was identified, especially in patients who had previously undergone surgery at the same site. When data were available, contour improvement and high patient satisfaction were reported in 98.8% and 98.3% of the patients. HDPP implants exhibit favorable outcomes for reconstruction of skull defects. Higher complication rates may be anticipated in secondary cranioplasty cases.

Cranioplasty is not required in the reconstruction of small combined scalp and calvarial defects.

BACKGROUND: Treatment of scalp malignancies may include the need for craniectomy. The decision to perform cranioplasty is not straightforward and is frequently subjective. The purpose of this study was to assess the clinical outcomes after reconstruction of complex scalp and calvarial defects by comparing patients with and without cranioplasty. METHODS: Retrospective review of the clinical records of a consecutive series of patients who underwent scalp soft tissue reconstruction after craniectomy for malignancy or osteoradionecrosis between 2014 and 2022 at Royal Melbourne Hospital was conducted. Demographics, previous treatments, surgical details, and post-operative complications were assessed. Traumatic injuries and decompressive craniectomies were excluded. Minimum follow-up of 6 months. RESULTS: Thirty-seven patients were included in the study. Indications for surgery included skin malignancies, osteoradionecrosis, or both. There was one reconstructive failure (in the non-cranioplasty group). Infection and metalware exposure were common complications in patients who underwent cranioplasty (38.5%). No patient developed neurological symptoms subsequent to craniectomy. One patient needed revision surgery due to esthetic reasons (cranioplasty group). Transposition flaps were associated with more complications and revision procedures. CONCLUSION: Combined scalp and calvarial defects pose a difficult reconstructive challenge. Stable soft tissue coverage is more reliably achieved with free flap reconstruction. Cranioplasty is not always mandatory and should be reserved for cases with a very large bony defect or when the defect is located in a cosmetically sensitive area.

Customised pre-operative cranioplasty to achieve maximal surgical resection of tumours with osseous involvement-a case series.

PURPOSE: Surgical resection with bony margins would be the treatment of choice for tumours with osseous involvement such as meningiomas and metastasis. By developing and designing pre-operative customised 3D modelled implants, the patient can undergo resection of meningioma and repair of bone defect in the same operation. We present a generalisable method for designing pre-operative cranioplasty in patients to repair the bone defect after the resection of tumours. MATERIALS AND METHODS: We included six patients who presented with a tumour that was associated with overlying bone involvement. They underwent placement of customised cranioplasty in the same setting. A customised implant using a pre-operative imaging was designed with a 2-cm margin to allow for any intra-operative requirements for extending the craniectomy. RESULTS: Six patients were evaluated in this case series. Four patients had meningiomas, 1 patient had metastatic breast cancer on final histology, and 1 patient was found to have an intra-osseous arteriovenous malformation. Craniectomy based on margins provided by a cutting guide was fashioned. After tumour removal and haemostasis, the cranioplasty was then placed. All patients recovered well post-operatively with satisfactory cosmetic results. No wound infection was reported in our series. CONCLUSION: Our series demonstrate the feasibility of utilising pre-designed cranioplasty for meningiomas and other tumours with osseous involvement. Following strict infection protocols, minimal intra-operative handling/modification of the implant, and close follow-up has resulted in good cosmetic outcomes with no implant-related infections.

Subcutaneous preservation versus cryopreservation of autologous bone grafts for cranioplasty: A systematic review and meta-analysis.

BACKGROUND: Cranioplasty corrects cranial bone defects using various bone substitutes or autologous bone flaps created during a previous craniectomy surgery. These autologous bone flaps can be preserved through subcutaneous preservation (SP) or cryopreservation (CP). AIM: We aim to compare outcomes and complications for both SP and CP techniques to enhance the current evidence about autologous bone flap preservation. METHODS: Five electronic databases were searched to collect all relevant studies. Records were screened for eligibility. Data were extracted from the included studies independently. We categorized surgical site infection (SSI) as either due to Traumatic brain injury (TBI) or not to reveal potential variations in SSI incidence. The double-arm meta-analysis utilized risk ratios (RR) and mean differences (MD) with corresponding confidence intervals (CI) to pool categorical and continuous outcomes, respectively. Proportions with their respective 95% CIs were pooled for single-arm meta-analyses to determine outcomes related to SP technique. RESULTS: Seventeen studies involving 1169 patients were analyzed. No significant difference in SSI rates was observed between SP and CP methods in patients with or without TBI. SP was linked to shorter hospital stays in two studies (194 patients). Single-arm analysis showed a 17% revision surgery rate across five studies (375 patients) and infection rates in 17 studies for SP. New bone formation occurred in 13.2% of patients, with 19.9% showing resorption. CONCLUSION: SP and CP methods showed similar SSI rates post-craniectomy in TBI and non-TBI patients. SP was associated with reduced hospitalization time, low infection rates, and a moderate need for revision surgery.

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

PURPOSE: 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. METHODS: 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. RESULTS: The average thickness of the clinically used implants was 6.0 ± 0.5 mm, which approximates the thickness on the contra-lateral side of the skull (relative difference of -0.3 ± 1.4 mm). The average thickness of the MUG500+ implants was 2.9 ± 1.0 mm, significantly thinner than the intact skull thickness (relative difference of 2.9 ± 1.2 mm). Rim transitions in the clinical implants (average width of 8.3 ± 3.4 mm) were used to cap and create a smooth boundary with the skull. CONCLUSIONS: 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.

Predicting the optimal concentration of remifentanil for skull pin fixation with hemodynamic and analgesia nociception index monitoring.

Inadequate antinociception during skull pin fixation may cause hemodynamic instability in intracranial surgery. The optimal concentration of remifentanil to provide adequate antinociception and stable hemodynamics during skull pin fixation under analgesia nociception index monitoring is unknown. This study is to assess the 90% effective concentration of remifentanil for skull pin fixation under hemodynamic and analgesia nociception index monitoring. Twenty-six patients were enrolled for intracranial surgery, anesthesia was induced and maintained under total intravenous anesthesia using target-controlled infusion for remifentanil and propofol under analgesia nociception index and bispectral index monitoring. Skull pin fixation was performed at different effect-site concentrations of remifentanil required for Dixon's up-and-down method with a step size of 0.5 ng/ml under bispectral index 40-60. Inadequate antinociception is defined when either ANI < 30 or > 20% in hemodynamic changes from baseline (e.g. heart rate > 100 beats/min, or blood pressure > 180/100 mmHg) and the effect-site concentration of remifentanil is considered as failure. It is considered success as ANI > 30 and < 20% hemodynamic changes from baseline simultaneously. Seven pairs of failure/success were used for probit analysis. The 90% effective concentration of remifentanil for skull pin fixation with adequate antinociception and hemodynamic stability was 4.7 ng/ml.

A reduction method for anterior opening displacement in thoracolumbarvertebral fractures with diffuse idiopathic skeletal hyperostosis using the skull clamp-assisted position.

Diffuse idiopathic skeletal hyperostosis (DISH) frequently occurs in the spine, resulting in unstable fractures. Treating thoracolumbar fractures in patients with DISH is often difficult because the anterior opening of the vertebral body is exacerbated by dislocation in the prone position, making reduction difficult. In this study, we introduced a novel skull clamp-assisted positioning (SAP) technique. The patient is placed in a supine position with a skull clamp used in cervical spine surgery before surgery to prevent the progression of dislocation and to restore the patient's position. Using this method, the mean difference in local kyphosis angle improved from -2.9 (±8.4)° preoperatively to 10.9 (±7.7)° postoperatively. Furthermore, posterior displacement decreased from a preoperative mean of 5.5 (±4.3) mm to 0.3 (±0.7) mm postoperatively. Complications such as neurological sequelae, implant fracture, and surgical site infection were not observed through one year of postoperative follow-up. SAP may decrease invasiveness and complications. Longer-term studies and larger sample sizes are needed to establish long-term efficacy and benefits.