The Science Behind the Springs: Using Biomechanics and Finite Element Modeling to Predict Outcomes in Spring-Assisted Sagittal Synostosis Surgery

Spring-assisted surgery for the correction of scaphocephaly has gained popularity over the past 2 decades. Our unit utilizes standardized torsional springs with a central helix for spring-assisted surgery. This design allows a high degree of accuracy and reproducibility of the force vectors and force distance curves. In this manuscript, we expand on the biomechanical testing and properties of these springs. Standardization of design has enabled us to study the springs on bench and in vivo and a comprehensive repository of calvarial remodeling and spring dynamics has been acquired and analyzed. Finite element modeling is a technique utilized to predict the outcomes of spring-assisted surgery. We have found this to be a useful tool, in planning our surgical strategy and improving outcomes. This technique has also contributed significantly to the process of informed consent preoperatively. In this article, we expand on our spring design and dynamics as well as the finite element modeling used to predict and improve outcomes. In our unit, this practice has led to a significant improvement in patient outcomes and parental satisfaction and we hope to make our techniques available to a wider audience

Sporting activity after craniosynostosis surgery in children: a source of parental anxiety

Purpose: Craniosynostosis correction involves major skull surgery in infancy—a potential source of worry for parents when their treated children begin involvement in sports. Methods: Electronic multiple choice survey of parents of children who had undergone craniosynostosis surgery in infancy using 5-point Likert scales. Results: Fifty-nine completed surveys were obtained from parents of children who had undergone previous craniosynostosis surgery. Mean age of children was 7.8 years (range 3 months to 22 years), with 36 non-syndromic and 23 syndromic cases. The most common surgery was fronto-orbital remodelling (18). Fifty-two of 59 were involved in athletic activity. The most intense sport type was non-contact in 23, light contact in 20, heavy contact in 4 and combat in 5. Participation level was school mandatory in 12, school club in 17, non-school sport club in 21 and regional representative in 2. One child had been advised to avoid sport by an external physician. Mean anxiety (1–5 Likert) increased with sport intensity: non-contact 1.7, light contact 2.2, heavy contact 3.5 and combat 3.6. Twenty-nine of 59 parents had been given specific advice by the Craniofacial Team regarding athletic activity, 28 of which found useful. Three sport-related head injuries were reported, none of which required hospitalisation. Conclusion: Little information exists regarding sports for children after craniosynostosis surgery. This study suggests that parental anxiety remains high, particularly for high impact/combat sports, and that parents would like more information from clinicians about the safety of post-operative sporting activities

Computational modelling of patient specific spring assisted lambdoid craniosynostosis correction

Lambdoid craniosynostosis (LC) is a rare non-syndromic craniosynostosis characterised by fusion of the lambdoid sutures at the back of the head. Surgical correction including the spring assisted cranioplasty is the only option to correct the asymmetry at the skull in LC. However, the aesthetic outcome from spring assisted cranioplasty may remain suboptimal. The aim of this study is to develop a parametric finite element (FE) model of the LC skulls that could be used in the future to optimise spring surgery. The skull geometries from three different LC patients who underwent spring correction were reconstructed from the pre-operative computed tomography (CT) in Simpleware ScanIP. Initially, the skull growth between the pre-operative CT imaging and surgical intervention was simulated using MSC Marc. The osteotomies and spring implantation were performed to simulate the skull expansion due to the spring forces and skull growth between surgery and post-operative CT imaging in MSC Marc. Surface deviation between the FE models and post-operative skull models reconstructed from CT images changed between ± 5 mm over the skull geometries. Replicating spring assisted cranioplasty in LC patients allow to tune the parameters for surgical planning, which may help to improve outcomes in LC surgeries in the future

Enhanced neuro-ophthalmologic evaluation to support separation of craniopagus twins

Craniopagus conjoined twins are extraordinarily rare and present unique challenges to the multidisciplinary team. There is a paucity of literature on optimizing neuro-ophthalmologic evaluation in craniopagus twins. Herein, we present our enhanced neuro-ophthalmologic evaluation and management in 17-month-old male craniopagus twins, uniquely using handheld optical coherence tomography (OCT) plus portable slit-lamp biomicroscopy, indirect ophthalmoscopy and modified forced-choice preferential looking assessment. Staged surgical separation was supported by enhanced neuro-ophthalmologic evaluation, detailed radiology, three-dimensional printing and virtual reality simulation. This represents the fourth separation of craniopagus twins by our unit

Finite element method for the design of implants for temporal hollowing

Temporal indentations are the most impacting craniofacial complication after coronal flap dissection. It is mainly due to a temporal fat pad or temporalis muscle dissection. Because of the great improvements achieved recently in CAD-CAM-aided surgery and the possibility of performing accurate pre-surgical virtual planning, it is now possible to correct it with a customised virtual approach. Furthermore, advancements in material science have allowed surgeons to rely on biocompatible materials like PEEK (showing a low complication and recurrence rate) for the manufacturing of patient-specific implants. We hereby describe our experience on a case of secondary and corrective surgery after a fronto-orbital remodelling, in which we used PEEK implants designed by CAD and optimized by finite element modelling

The Esthetic Perception of Morphological Severity in Scaphocephalic Patients is Correlated With Specific Head Geometrical Features

OBJECTIVE: To investigate the relationship between perception of craniofacial deformity, geometric head features, and 3D head shape analyzed by statistical shape modeling (SSM). PATIENTS: A total of 18 unoperated patients with scaphocephaly (age  =  5.2  ±  1.1m)-6 were followed-up after spring-assisted cranioplasty (SAC) (age  =  9.6  ±  1.5m)-and 6 controls (age  =  6.7  ±  2.5m). MAIN OUTCOME MEASURES: 3D head shapes were retrieved from 3D scans or computed tomography (CTs). Various geometrical features were measured: anterior and posterior prominence, take-off angle, average anterior and posterior lateral and horizontal curvatures, cranial index (CI) (cranial width over length), and turricephaly index (TI) (cranial height over length). SSM and principal component analysis (PCA) described shape variability. All models were 3D printed; the perception of deformity was blindly scored by 9 surgeons and 1 radiologist in terms of frontal bossing (FB), occipital bulleting (OB), biparietal narrowing (BN), low posterior vertex (LPV), and overall head shape (OHS). RESULTS: A moderate correlation was found between FB and anterior prominence (r  =  0.56, P < .01) and take-off angle (r  =  - 0.57, P < .01). OB correlated with average posterior lateral curvature (r  =  0.43, P < 0.01) similarly to BPN (r  =  0.55, P < .01) and LPV (r  =  0.43, P < .01). OHS showed strong correlation with CI (r  =   - 0.68, P < .01) and TI (r  =  0.63, P< .01). SSM Mode 1 correlated with OHS (r  =  0.66, p < .01) while Mode 3 correlated with FB (r  =   - 0.58, P < .01). CONCLUSIONS: Esthetic cranial appearance in craniofacial patients is correlated to specific geometric parameters and could be estimated using automated methods such as SSM

Craniopharyngioma in children: trends from a third consecutive single-center cohort study

OBJECTIVE: The management of children with craniopharyngioma has evolved over time, with a trend toward less invasive neurosurgical approaches as surgeons have sought to balance oncological control and treatment-related morbidity. To this end, the aim of this study was to evaluate the safety and effectiveness of the current management of children with craniopharyngioma compared to the previous management methods used at the authors’ treatment center. METHODS: A prospectively maintained database was searched over a 14-year period between January 1, 2005, and December 31, 2018, to identify all children 17 years of age or younger with a new diagnosis of craniopharyngioma. A retrospective case note review was performed for each child to extract data on the presentation, investigation, treatment, and outcome of their illness. Morbidity was assessed in the same fashion as in previous cohorts, according to the following categories: visual loss, pituitary dysfunction, hypothalamic dysfunction, neurological deficits, and cognitive impairment. RESULTS: In total, 59 children were identified with craniopharyngioma during the study period. A total of 92 operations were performed, including cyst drainage (35/92; 38.0%), craniotomy and resection (30/92; 32.6%), and transsphenoidal resection (16/92; 17.4%). Approximately two-thirds of all operations were performed using image guidance (66/92; 71.7%) and one-third were performed using endoscopy (27/92; 29.3%). The majority of children had adjuvant therapy comprising proton beam therapy (18/59; 30.5%) or conventional radiotherapy (16/59; 27.1%). The median follow-up duration was 44 months (range 1–142 months), and approximately one-half of the children had no evidence of residual disease on MRI studies (28/59; 47.5%). Of the remaining 31 children, there was a reduction in the volume of residual disease in 8 patients (8/59; 13.6%), stable residual disease in 18 (18/59; 30.5%), and tumor growth in 5 patients (5/59; 8.5%). There was significantly reduced morbidity (p < 0.05) in all categories in the current cohort compared with our last cohort (1996–2004). CONCLUSIONS: The authors’ institutional experience of pediatric craniopharyngioma confirms a trend toward less invasive neurosurgical procedures, most of which are now performed with the benefit of image guidance or endoscopy. Moreover, the authors have identified an expanding role for more targeted radiotherapy for children with residual disease. These advances have allowed for tumor control comparable to that achieved in previous cohorts, but with significantly reduced morbidity and mortality

Lack of association of cranial lacunae with intracranial hypertension in children with Crouzon syndrome and Apert syndrome: a 3D morphometric quantitative analysis

Purpose Cranial lacunae (foci of attenuated calvarial bone) are CT equivalents of “copper beating” seen on plain skull radiographs in children with craniosynostosis. The qualitative presence of copper beating has not been found to be useful for the diagnosis of intracranial hypertension (IH) in these patients. 3D morphometric analysis (3DMA) allows a more systematic and quantitative assessment of calvarial attenuation. We used 3DMA to examine the relationship between cranial lacunae and IH in children with Crouzon and Apert syndromic craniosynostosis. Methods Patients were divided into IH and non-IH groups defined on an intention-to-treat basis. Pre-operative CT scans were converted into 3D skull models and processed to quantify lacunae as a percentage of calvarium surface area (LCP). This was done on individual bone and whole skull basis. Results Eighteen consecutive children with Crouzon’s syndrome and 17 with Apert syndrome were identified. Median age at CT scan was 135 days (range 6–1778). Of the 35 children, 21 required surgery for IH at median age of 364 days (range 38–1710). Of these 21 children, 14 had lacunae with mean LCP of 3% (0–28%). Of the 14 non-IH children, 8 had lacunae with mean LCP of 2% (0–8%). LCP was not significantly different between IH and non-IH groups. Parietal bones were most likely to show lacunae (IH 14/21, non-IH 9/14), followed by occipital (IH 8/21, non-IH 3/14), and frontal (IH 6/21, non-IH 2/14). Conclusion Results suggest that cranial lacunae, measured using quantitative 3DMA, do not correlate with IH, in agreement with evidence from qualitative plain skull radiograph studies