Incomplete reossification after craniosynostosis surgery-incidence and analysis of risk factors: a clinical-radiological assessment study

Optimal untwisting of the orbital bandeau in unicoronal craniosynostosis correction: A finite element analysis

BACKGROUND

Surgical correction of unicoronal craniosynostosis (UCS) is highly complex due to its asymmetric appearance. Although fronto-orbital advancement (FOA) is a versatile technique for craniosynostosis correction, harmonization of the orbital bandeau in UCS is difficult to predict. This study evaluates the biomechanics of the orbital bandeau using different patterns and varying characteristics of inner cortical bone layer osteotomies in a finite element (FE) analysis.

METHOD

An FE model was created using the computed tomography (CT) scan of a 6.5-month-old male infant with a right-sided UCS. The unaffected side of the orbital bandeau was virtually mirrored, and anatomical correction of the orbital bandeau was simulated. Different combinations of osteotomy patterns, numbers, depths, and widths were examined (n = 48) and compared to an uncut model.

RESULTS

Reaction forces and maximum stress values differed significantly (p < 0.01) among osteotomy patterns and between each osteotomy characteristic. Regardless of the osteotomy pattern, higher numbers of osteotomies significantly (p < 0.05) correlated with reductions in reaction force and maximum stress. An X-shaped configuration with three osteotomies deep and wide to the bone was biomechanically the most favorable model.

CONCLUSION

Inner cortical bone layer osteotomy might be an effective modification to the conventional FOA approach in terms of predictable shaping of the orbital bandeau.

Autologous Cranioplasty Using a Dental SafeScraper Device

SUMMARY

Conventional methods to reconstruct cortical bone defects introduced by pediatric cranial vault remodeling (CVR) procedures have shortcomings. Use of bone burr shavings as graft material leads to variable ossification, and harvesting split-thickness cortical grafts is time-intensive and often not possible in thin infant calvaria. Since 2013, the authors' team has used the SafeScraper, originally developed as a dental instrument, to harvest cortical and cancellous bone grafts during CVR. The authors assessed the effectiveness of this technique by analyzing postoperative ossification using computed tomography scans of 52 patients, comparing cohorts treated with the SafeScraper versus those who received conventional methods of cranioplasty during fronto-orbital advancement. The SafeScraper cohort had a greater reduction in total surface area of all defects (-83.1% ± 14.9 versus -68.9% ± 29.8; P = 0.034), demonstrating a greater and more consistent degree of cranial defect ossification compared with conventional methods of cranioplasty, suggesting potential adaptability of this tool. This is the first study that describes the technique and efficacy of the SafeScraper in reducing cranial defects in CVR.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Reossification of Bone Defects After Surgical Correction of Nonsyndromic Craniosynostosis: A Review and An Original Study

BACKGROUND AND OBJECTIVES

Surgical correction of nonsyndromic craniosynostosis (NSC) aims to restore cranial shape. Reossification of bone defects is paramount for the best aesthetic prognosis. However, the literature on the quantitative evaluation of bone defects after NSC surgery is scarce. This study aimed to quantify and analyze the surface area of bone defects after NSC surgery and establish a threshold value for predicting persistent defects.

METHODS

We conducted a systematic review and a prospective study of 28 children undergoing surgical treatment for NSC. We analyzed 426 defects on the first computed tomography scan (1 year postoperative) and 132 defects on the second computed tomography scan (4.6 years postoperative). Statistical analysis was performed using Spearman's rank correlation coefficient, Mann-Whitney-Wilcoxon rank-sum test, and Youden's J statistic.

RESULTS

Our systematic review identified three studies reporting on bone defects' surface area and reossification rate. In our study, we found no statistically significant differences in the number or size of defects between sex or type of NSC. The threshold value for the surface area of bone defects above which there was a higher probability of persistent defects was 0.19 cm2 (Youden point), with an 89.47 % probability of persistence. Defects with a surface area below 0.19 cm2 had a considerably lower probability, only 15.07%, of persistence over time.

CONCLUSION

Our study provides valuable quantitative data for managing bone defects after NSC surgery. Defects with a surface area above 0.19 cm2 should be monitored with radiological imaging because of the risk of persistence. Our findings highlight the importance of developing robust and reproducible methods for the quantitative analysis of bone defects after NSC surgery.

Spontaneous Reossification Following Craniectomy in a Pediatric Patient

Spontaneous reossification following a cranial defect is described by only a few case reports. A 6-month-old male with epidural hematoma underwent decompressive craniotomy, subsequently complicated by scalp abscess requiring removal of the bone flap. On serial outpatient follow-up, the patient demonstrated near-complete resolution of cranial defect over the course of 18 months, thus deferring the need for future cranioplasty. Prior articles have identified this occurrence in children and young adults; however, the present case is the first to report of this phenomenon in an infant less than 1 year of age. A brief review of the literature is provided with the proposed physiologic underpinning for the spontaneous reossification observed. While prior studies propose that recranialization is mediated by contact with the dura mater and pericranium, new investigations suggest that calvarial bone repair is also mediated by stem cells from the suture mesenchyme.

Early bone reformation after cranial vault remodelling for sagittal craniosynostosis: A retrospective 3D analysis

This study aims to measure postoperative bone reformation percentage, rates and patterns after cranial vault remodelling (CVR) in isolated non-syndromic sagittal craniosynostosis. Volumetric bone measurements were performed starting from the DICOM files of previously available postoperative CT scans. The 3D images were then resampled into the master box, and 'Skull 3D models' were derived. The percentage of bone reformation was investigated using automated 3D analysis software. The intra-rater reliability analysis revealed high reliability (Intraclass correlation coefficient = 0.99, p < 0.001). The median bone reformation volume and rate were 11.2 ml and 1.98 ml/week, respectively. The median percentage of bone reformation was 56.7% when the median postoperative CT timing was 6.1 weeks. As a statistic model, the linear plateau showed the highest Pseudo R² in both volume and percentage of bone reformation predicting patterns. By using the calculated model at 9 weeks postoperatively, the re-osteogenesis reaches 80% of the total cranial defect. After CVR, the early bone reformation pattern was demonstrated as a linear plateau model rather than logarithmic. This study gives a better understanding of the pattern and quantity of re-osteogenesis at cranial defects after CVR. The statistic model can facilitate healthcare practitioners to predict bone reformation and improve postoperative care protocol in sagittal craniosynostosis management.

Persistent Cranial Defects After Endoscopic Sagittal Synostosis Surgery

INTRODUCTION

Incomplete cranial ossification is a rare complication of calvarial-vault remodeling for sagittal synostosis often requiring reoperation. Studies show an incidence ranging from 0.5% to 18%.

METHODS

Infants with sagittal synostosis who underwent endoscopic sagittal synostectomy and barrel stave osteotomies with postoperative orthotic helmeting between 2003 and 2021 were included with minimum follow-up until the completion of helmeting.

RESULTS

Of 90 patients, 86 met inclusion; 3 had defects (3.5%). Patients with and without cranial defects had no difference in age of surgery (113 versus 131 d), duration helmeting (6.6 versus 7.0 mo), or perioperative/postoperative complications. Two underwent reoperation for recurrence. Patients with cranial defects manifested the evidence of developmental concerns more than patients without (100% versus 16.9%).The average cranial defect size was 19.33 cm 2 and age at surgery 4.29 years. All were managed with cranial particulate bone grafting with addition of bone matrix and SonicWeld plate. The first had 6×6 cm posterior defect requiring cranioplasty at 4.86 years with excellent healing. The second had a 3×6 cm posterior and 1×1 cm anterior defect, underwent cranioplasty at 4.14 years with persistent 4×6 defect, requiring repeat cranioplasty at 5.3 years. The third had a 3×5 cm posterior defect and underwent cranioplasty at 3.88 years with continued defect, planning for repeat intervention.

CONCLUSIONS

This is the largest documented series of reoperations for incomplete ossification after endoscopic sagittal synostectomy with postoperative helmet treatment. The authors report a 3.5% rate of cranial defects, managed with bone grafting, bone matrix, and absorbable plates. Patients with poor ossification may have a propensity toward developmental concerns.

A preliminary analysis of replicating the biomechanics of helmet therapy for sagittal craniosynostosis

PURPOSE

The aim of this study was to investigate the biomechanics of endoscopically assisted strip craniectomy treatment for the management of sagittal craniosynostosis while undergoing three different durations of postoperative helmet therapy using a computational approach.

METHODS

A previously developed 3D model of a 4-month-old sagittal craniosynostosis patient was used. The strip craniectomy incisions were replicated across the segmented parietal bones. Areas across the calvarial were selected and constrained to represent the helmet placement after surgery. Skull growth was modelled and three variations of helmet therapy were investigated, where the timings of helmet removal alternated between 2, 5, and 8 months after surgery.

RESULTS

The predicted outcomes suggest that the prolonging of helmet placement has perhaps a beneficial impact on the postoperative long-term morphology of the skull. No considerable difference was found on the pattern of contact pressure at the interface of growing intracranial volume and the skull between the considered helmeting durations.

CONCLUSION

Although the validation of these simulations could not be performed, these simulations showed that the duration of helmet therapy after endoscopically assisted strip craniectomy influenced the cephalic index at 36 months. Further studies require to validate these preliminary findings yet this study can lay the foundations for further studies to advance our fundamental understanding of mechanics of helmet therapy.

Modified endoscopic strip craniectomy technique for sagittal craniosynostosis: provides comparable results and avoids bony defects

PURPOSE

This study describes a modified technique addressing bony defects and incomplete ossification after endoscopic strip craniectomy (ESC) for SC followed by postoperative helmet therapy (PHT). The study aims to delineate quantitative and qualitative outcomes of this modified ESC technique followed by PHT and discern the optimal duration of PHT following ESC. A secondary aim is to address the effects of the technique on bony defects.

METHODS

Patients undergoing ESC followed by PHT between 2017 and 2021 were included. Patient sex, age at surgery, duration of surgery, red blood cell transfusion, length of hospital stay, PHT duration, cephalic index (CI) at multiple time points, and bony defect information were collected. Descriptive and correlative analysis was done.

RESULTS

Thirty-one patients (25 male, 6 female) were operated in study period. Mean age at surgery was 12.81 weeks, mean duration of surgery was 57.50 min, average transfused RBC volume was 32 cc, mean length of hospital stay was 1.84 days, mean PHT duration was 33.16 weeks, and mean follow-up time was 63.42 weeks. Mean preoperative CI was 70.6, and mean CI at the end of PHT was significantly higher, being 77.1. Maximum improvement in CI (CI_max) took place at week 22.97. PHT duration did not have a correlation with CI at last follow up. There were no bony defects.

CONCLUSION

Modified ESC technique is effective in successful correction of sagittal craniosynostosis. CI_max already takes place, while PHT is continuing, but there is no certain time point for dishelmeting. The technique avoided bony defects and incomplete ossification.

The Dura Split Technique in the Treatment of Craniosynostosis: Is It Still an Option?

BACKGROUND

The aim of this study was to report the outcome and the complications for patients operated on for craniosynostosis using the dura split technique. Specifically, the authors aimed to evaluate the safety of this technique, which is currently not in use, and to determine whether it is still useable.

METHODS

The data was collected from the hospital patient records of all children surgically treated for craniosynostosis using the dura split technique in Turku University Hospital during the period 1975 to 2015. The data was analyzed to determine the clinical and radiological outcomes of the surgical procedure, the need for reoperations, and the rate of complications.

RESULTS

During the study period, the dura split technique was used in the surgery of 65 patients. The outcome was either good or acceptable in most patients and reoperation was needed in only 2 patients (3.1%). Surgical complications included significant blood loss (26.2%), lesions on the inner layer of the dura (21.5%), leakage of cerebrospinal fluid (13.8%), and persistent bone defects (15.4% on palpation and 63.1% radiologically).

CONCLUSIONS

Although the outcome of surgery for craniosynostosis using the dura split technique was mostly acceptable and the need for reoperations rare, the technique cannot, however, be recommended in the future due to high rates of bone defects, frequent problems with lesions on the inner layer of the dura, and consequent perioperative leakage of cerebrospinal fluid.

Pediatric Cranial Defects: What Size Warrants Repair?

PURPOSE

Identifying which cranial defects among children warrant surgical repair is integral to providing adequate protection of the skull whereas minimizing exposure to surgical complications. This review examines the available evidence regarding the role of defect size in determining the appropriateness of nonsurgical versus surgical management.

METHODS

An electronic literature review was performed using PubMed and Google Scholar to identify publications that provided rationales for nonsurgical management of cranial defects in the pediatric population based on size. Titles and abstracts were reviewed by the authors to determine eligibility for full-text analysis. Ineligible studies were categorized and relevant data from fully analyzed texts were recorded.

RESULTS

Of the 523 articles that were reviewed, 500 were ineligible for full-text analysis due to the following most common reasons: no cranial defect described (227, 45%), did not discuss management of cranial defects (68, 14%), or surgery was performed on all defects in evaluation of a technique or protocol (86, 17%). Ten publications provided relevant data. The suggested size below which surgery was not recommended varied widely between articles. Beyond the age of 1 to 2 years, no general agreement on recommended management in children was found. Craniofacial surgeons had divergent views on the minimum diameter for a "critical" defect and the size for which surgical repair is necessary.

CONCLUSIONS

Little guidance or consensus exists regarding the indications for surgical correction of cranial defects based on the size of the defect. Objective data is needed to classify "clinically critical defects" in the pediatric population.

Does Coronal Suturectomies and Occipital Barrel Staves Make a Difference in Early Reconstruction for Sagittal Craniosynostosis?

BACKGROUND

Various surgical methods are used for early treatment of nonsyndromic sagittal craniosynostosis. The craniofacial centers in Uppsala and Helsinki fundamentally both use the H-Craniectomy: Renier's technique. However, the Helsinki group systematically adds coronal suturectomies to prevent secondary coronal synostosis and posterior barrel staves to address posterior bulleting. The effects of these additions in early treatment of sagittal craniosynostosis are currently unknown.

METHODS

Thirty-six patients from Uppsala and 27 patients from Helsinki were included in the study. Clinical data and computed tomography scans were retrieved for all patients.

RESULTS

The Helsinki patients had a smaller preoperative Cranial index (CI) (65 vs 72) and a smaller preoperative width (10.1 vs 11.2). There was no difference in postoperative CI, corresponding to a difference in change in CI. Regression analysis indicated that the larger change in CI in the Helsinki group was mainly due to a lower preoperative CI allowing for a larger normalization. The Helsinki patients had less growth in length (1.5 vs 2.1 cm) and more growth in width (2.3 vs 1.9 cm). There were no differences in head circumference or surgical complications. Secondary coronal synostosis was present in 43% of the Uppsala group at 3 years of age, while calvarial defects located at sites of previous coronal suturectomies and posterior barrel staving were seen in the Helsinki group 1 year postoperatively.

CONCLUSIONS

Lower preoperative CI appears to be the main factor in determining the amount of normalization in CI. Prophylactic coronal suturectomies do not seem to benefit preservation of coronal growth function since the modification correlates to less sagittal growth and more growth in width.

Using Sensitivity Analysis to Develop a Validated Computational Model of Post-operative Calvarial Growth in Sagittal Craniosynostosis

Craniosynostosis is the premature fusion of one or more sutures across the calvaria, resulting in morphological and health complications that require invasive corrective surgery. Finite element (FE) method is a powerful tool that can aid with preoperative planning and post-operative predictions of craniosynostosis outcomes. However, input factors can influence the prediction of skull growth and the pressure on the growing brain using this approach. Therefore, the aim of this study was to carry out a series of sensitivity studies to understand the effect of various input parameters on predicting the skull morphology of a sagittal synostosis patient post-operatively. Preoperative CT images of a 4-month old patient were used to develop a 3D model of the skull, in which calvarial bones, sutures, cerebrospinal fluid (CSF), and brain were segmented. Calvarial reconstructive surgery was virtually modeled and two intracranial content scenarios labeled “CSF present” and “CSF absent,” were then developed. FE method was used to predict the calvarial morphology up to 76 months of age with intracranial volume-bone contact parameters being established across the models. Sensitivity tests with regards to the choice of material properties, methods of simulating bone formation and the rate of bone formation across the sutures were undertaken. Results were compared to the in vivo data from the same patient. Sensitivity tests to the choice of various material properties highlighted that the defined elastic modulus for the craniotomies appears to have the greatest influence on the predicted overall skull morphology. The bone formation modeling approach across the sutures/craniotomies had a considerable impact on the level of contact pressure across the brain with minimum impact on the overall predicated morphology of the skull. Including the effect of CSF (based on the approach adopted here) displayed only a slight reduction in brain pressure outcomes. The sensitivity tests performed in this study set the foundation for future comparative studies using FE method to compare outcomes of different reconstruction techniques for the management of craniosynostosis.

Ultra-early synostectomy and cranial remodeling orthoses in the management of craniosynostoses

OBJECTIVE

The advent of endoscopic synostectomy has enabled early surgery for infants with craniosynostosis. Even though diagnosis is often made at birth, endoscopic synostectomy has traditionally been delayed until the infant is 3 months of age. There have been very few published reports of this procedure being performed in the early neonatal period. The authors discuss their experience with ultra-early endoscopic synostectomy, defined as an operation for infants aged 8 weeks or younger.

METHODS

A retrospective analysis of infants who underwent operations at or before 8 weeks of age between 2011 and 2020 was done.

RESULTS

Twenty-five infants underwent operations: 11 were 2 weeks of age or younger, 8 were between 3 and 4 weeks of age, and 6 were between 5 and 8 weeks of age. The infants weighed between 2.25 and 4.8 kg. Eighteen had single-suture synostosis, and 7 had multiple sutures involved. Of these 7, 4 had syndromic craniosynostosis. The average operative time was 35 minutes, and it was less than 40 minutes in 19 cases. The estimated operative blood loss was 25 ml or less in 19 cases; 5 infants required an intraoperative blood transfusion. In 1 child with syndromic multisuture craniosynostosis, the surgery was staged due to blood loss. Two children experienced complications related to the procedure: one had an incidental durotomy with skin infection, and the other had postoperative kernicterus. All infants were fitted for cranial remodeling orthoses following surgery. Three of the 25 infants required reoperations, with 2 patients with syndromic craniosynostosis needing repeat surgery for cranial volume expansion and cosmetic appearance. Another child with syndromic craniosynostosis is awaiting cranial expansion surgery. Follow-up varied between 6 months and 8 years.

CONCLUSIONS

The data show that ultra-early synostectomy is safe and not associated with increased complications compared with surgery performed between 3 and 6 months of age. Infants with multisuture synostosis had increased operative time, required blood transfusion, and were more likely to require a second operation.

Novel Suturectomy Using Absorbable Plates in Early Surgery for Craniosynostosis

BACKGROUND

In craniosynostosis patients under 3 months of age, suturectomy is a valuable early treatment improving their outcomes. However, conventional suturectomy might not be in severe patients. The efficacy of our developed suturectomy using absorbable plates was examined.

METHODS

Our method was indicated for craniosynostosis patients under 3 months old who had severe intracranial hypertension, scaphocephaly, plagiocephaly, or trigonocephaly between September 2011 and March 2018. All patients underwent suturectomy, and the bone edges on both sides of the cuts were covered with absorbable plates. Evaluation was conducted with 3-dimensional computed tomography and photographs, and cephalic index, distance from dorsum sellae to forehead on computed tomography were analyzed.

RESULTS

Twenty-one of the 25 patients were evaluated. The preoperative cranial shapes were 4 brachycephaly, 6 scaphocephaly, 5 oxycephaly, 2 clover-leaf deformity, and 4 plagiocephaly. There were 9 syndromic and 12 nonsyndromic patients. The mean age at the time of surgery was 52.3 days (7-89), and the mean follow-up period was 3.5 years (1-8).The cephalic index and cranial definition improved in 18 patients. The secondary surgery was not required in four syndromic and none of the 12 nonsyndromic patients. There were no major complications.

CONCLUSION

Placement of absorbable plates was able to prevent bone formation during the early postoperative period, and yet also promote bone formation after plate absorption. The authors believe syndromic craniosynostosis patients with severe deformities and nonsyndromic ones with scaphocephaly or plagiocephaly, successfully avoided secondary surgeries. This approach is less invasive for craniosynostosis and is expected to be highly effective.

A Comparison of Subgaleal Versus Subperiosteal Dissection in Open Cranial Vault Expansion for Sagittal Craniosynostosis

BACKGROUND

The aim of this study was to evaluate surgical outcomes for patients with sagittal craniosynostosis undergoing open cranial vault remodeling with a modified pi procedure comparing subgaleal versus subperiosteal dissection.

METHODS

A retrospective chart review was performed for children between the ages of 3 and 7 months with sagittal craniosynostosis undergoing open cranial vault expansion at Seattle Children's Hospital. Patient demographics, operative variables, and postoperative outcomes including the surface area of bony cranial defects at 2-year follow-up were evaluated.

RESULTS

Over a 3-year period, 35 patients between the ages of 3 and 7 months underwent surgical correction of sagittal craniosynostosis using our institutional adaptation of the modified pi technique. Twenty-five patients underwent exposure via a subgaleal (SG) approach, 10 patients had a subpericranial (SP) exposure. Compared with the SP group, the SG group had significant lower estimated blood loss and a shorter operating time (P < 0.05). There were no significant differences with regard to hospital length of stay or postoperative complications (P ≥ 0.48). At 2 years postoperatively, there were no significant differences in the size of the largest cranial defects (SG: 1.1 ± 0.1 cm² versus 3.7 ± 0.1 cm², P = 0.40); no patients required a secondary cranioplasty.

CONCLUSIONS

Open posterior and middle cranial vault expansion is a safe and efficient method of open cranial vault expansion in sagittal craniosynostosis regardless of the plane of dissection. Elevation of the scalp flaps in the SG plane is a minor technical modification that can reduce blood loss and operative times.

Exchange Cranioplasty Using Bioabsorbable Hydroxyapatite and Collagen Complex After Removal of an Extensive Frontal Bone Tumor in an Infant

BACKGROUND

Forehead reconstruction is challenging. Reconstruction of the innate curvature of the forehead is difficult, and the forehead is an esthetically important part of the face. Although synthetic implants and autologous split bone grafts are useful, these cannot be used in infants.

CASE DESCRIPTION

A 4-month-old girl was presented with a right frontal bone Ewing sarcoma. The tumor was removed, and the defect was reconstructed with an autologous contralateral parietal bone graft. The parietal bone defect was repaired with a bioabsorbable hydroxyapatite and collagen complex. Good reconstruction of the forehead and ossification of the donor site was achieved within 3 years after surgery.

CONCLUSIONS

After removal of an extensive frontal bone tumor in an infant, exchange cranioplasty with an autograft using a bioabsorbable hydroxyapatite and collagen complex at the donor site yielded good results.

Long-term 3D CT follow-up after endoscopic sagittal craniosynostosis repair

OBJECTIVE

Surgical treatment of sagittal synostosis involves various surgical modalities. Long-term follow-up issues include increased intracranial pressure, secondary sutural fusion, incomplete reossification, and suboptimal cosmetic appearance. The authors' objective in this study was to review their long-term endoscopic surgical results in children with sagittal synostosis using 3D CT.

METHODS

The authors reviewed the long-term results of their first 38 patients who underwent endoscopic sagittal synostosis repair at age 16 weeks or younger. A standard vertex craniectomy with biparietal wedges was done in each case. After surgery, the children were fitted with a helmet, which they wore until 8 months of age. Patients were followed up for 5 years or longer, at which point a 3D CT scan was obtained. The authors examined data on the cranial index, area of bony defect, presence or absence of secondary sutural fusion, neosuture formation, and scalloping of the inner table of the skull.

RESULTS

Thirty-two of 38 children met inclusion criteria. There was a small but significant recession of the cranial index after the completion of helmeting (from 0.772 after completion of helmeting to 0.755 at 5 years). Of 32 children, 14 had a bony defect area > 4 cm2. Three children had secondary sutural fusion (two unilateral coronal, one bicoronal). Ten of 32 patients had partial neosuture formation.

CONCLUSIONS

The authors report their experience with 32 of their first 38 children who underwent endoscopic sagittal synostosis repair at 16 weeks of age or younger. With a minimum duration of 5 years, this is the longest clinicoradiological follow-up utilizing 3D CT to date in children with sagittal synostosis treated with endoscopic surgery. The authors report detailed measurements of bony loss, adjacent sutural fusion, and neosuture formation.