Outcomes of cranioplasty following decompressive craniectomy in the pediatric population

Decompressive craniotomy in split-technique (DCST) for TBI in infants: introducing a new surgical technique to prevent long-term complications

INTRODUCTION

Decompressive craniectomy (DC) is rarely required in infants. These youngest patients are vulnerable to blood loss, and cranial reconstruction can be challenging due to skull growth and bone flap resorption. On the other hand, infants have thin and flexible bone and osteogenic potential. MATERIAL AND METHODS: We propose a new technique called DCST, which makes use of these unique aspects by achieving decompression using the circumstance of the thin and flexible bone. We describe the surgical technique and the follow-up course over a period of 13 months.

RESULTS AND CONCLUSION

In our study, DCST achieved adequate decompression and no  further repeated surgeries in accordance with decompressive craniectomy were needed afterwards.

The potential role of mechanotransduction in the management of pediatric calvarial bone flap repair

Pediatric patients suffering traumatic brain injuries may require a decompressive craniectomy to accommodate brain swelling by removing a portion of the skull. Once the brain swelling subsides, the preserved calvarial bone flap is ideally replaced as an autograft during a cranioplasty to restore protection of the brain, as it can reintegrate and grow with the patient during immature skeletal development. However, pediatric patients exhibit a high prevalence of calvarial bone flap resorption post-cranioplasty, causing functional and cosmetic morbidity. This review examines possible solutions for mitigating pediatric calvarial bone flap resorption by delineating methods of stimulating mechanosensitive cell populations with mechanical forces. Mechanotransduction plays a critical role in three main cell types involved with calvarial bone repair, including mesenchymal stem cells, osteoblasts, and dural cells, through mechanisms that could be exploited to promote osteogenesis. In particular, physiologically relevant mechanical forces, including substrate deformation, external forces, and ultrasound, can be used as tools to stimulate bone repair in both in vitro and in vivo systems. Ultimately, combating pediatric calvarial flap resorption may require a combinatorial approach using both cell therapy and bioengineering strategies.

Pediatric Cranial Vault and Skull Base Fractures

Cranial vault and skull base fractures in children are distinctly different from those seen in adults. Pediatric skull fractures have the benefit of greater capacity to remodel; however, the developing pediatric brain and craniofacial skeleton present unique challenges to diagnosis, natural history, and management. This article discusses the role of surgical treatment of these fractures, its indications, and techniques.

Analysis of the timing and the usage of drains following cranioplasty on outcomes and the incidence of bone resorption

Background

Pediatric cranioplasty is associated with a high rate of complications, including bone resorption (BR) in 20-50% of cases. We aimed to evaluate factors contributing to BR, including the effect of the timing of cranioplasty and the use of post-surgical drains.

Methods

This is a dual institution retrospective review of all patients under 18 years old who underwent a cranioplasty following a decompressive craniectomy (DC) for the treatment of traumatic brain injury between 2011 and 2021. Early cranioplasty was defined as within 30 days after DC and late cranioplasty as >30 days. Patients were grouped by BR and separately by timing to cranioplasty. Groups were compared based on the Glasgow Outcome Scale (GOS) and postoperative drain usage.

Results

A total of 30 patients were included in the study. The mean age was 7.39 (standard deviation = 6.52) and 60% were male. The median time to cranioplasty was 13 days (interquartile range = 10-17). BR was present in 16.7% of cases. A subgaleal drain was utilized in 93.3% and an external ventricular drain (EVD) in 63.3% of patients following cranioplasty. Drain usage was not associated with BR and timing to cranioplasty was not associated with discharge or 6-month GOS.

Conclusion

This study demonstrates that early cranioplasty following DC may have similar outcomes to late cranioplasty. Post-surgical EVDs and subgaleal drains did not increase the incidence of BR, suggesting their importance in the postoperative management of these patients.

Inverted gull-wing hinge decompressive craniotomy for infantile acute subdural hematoma: A case report

Infantile severe acute subdural hematomas (ASDHs) usually require a decompressive craniotomy. However, these infantile patients often suffer surgical site infection and aseptic bone-flap resorption after external decompression. In this report, we showed a case of a simplified hinge decompressive craniotomy in an infant with severe ASDH. A 2-month-old girl suffered from status epilepticus, impaired consciousness, multiple rib fractures, bilateral fundus hemorrhage, and a right ASDH. We performed a simplified hinge decompressive craniotomy, making a vascularized bone flap with a hinge using the partial temporal bone and temporal muscle and not fixing the bone flap like an inverted gull wing. Cranioplasty was performed 4 weeks after the decompression craniotomy with replaced resorbable substitute dura. Six months after the transfer, her development was generally in line with her age. The decompressive craniotomy with an inverted gull-wing hinge has shown a good outcome.

Severe Traumatic Brain Injury in children-paradigm of decompressive craniectomy compared to a historic cohort

PURPOSE

Traumatic brain injury (TBI) is one of the leading causes of death and disability in children. Medical therapy remains limited, and decompressive craniectomy (DC) is an established rescue therapy in case of elevated intracranial pressure (ICP). Much discussion deals with clinical outcome after severe TBI treated with DC, while data on the pediatric population is rare. We report our experience of treating severe TBI in two different treatment setups at the same academic institution.

METHODS

Forty-eight patients (≤ 16 years) were hospitalized with severe TBI (GCS ≤ 8 points) between 2008 and 2018 in a pediatric intensive care unit (ICU) at a specialized tertiary pediatric care center. Data on treatment, clinical status, and outcome was retrospectively analyzed. Outcome data included Glasgow Outcome Scale (GOS) at 3-, 12-, and 36-month follow-up. Data was compared to a historic cohort with 53 pediatric severe TBI patients treated at the same institution in a neurointensive care unit between 1996 and 2007. Ethical approval was granted (EA2/076/21).

RESULTS

Between 2008 and 2018, 11 patients were treated with DC. Compared to the historic cohort, patients were younger and GCS was worse, while in-hospital mortality and clinical outcome remained similar. A trend towards more aggressive EVD placement and the internal paradigm change for treatment in a specialized pediatric ICU was observed.

CONCLUSIONS

In children with severe TBI treated over two decades, clinical outcome was comparable and mostly favorable in two different treatment setups. Consequent therapy is warranted to maintain the positive potential for favorable outcome in children with severe TBI.

Favourable long-term recovery after decompressive craniectomy: the Northern Finland experience with a predominantly adolescent patient cohort

PURPOSE

Decompressive craniectomy (DC) is an effective treatment of intracranial hypertension. Correspondingly, the procedure is increasingly utilised worldwide. The number of patients rendered vegetative following surgery has been a concern-a matter especially important in children, due to long anticipated lifetime. Here, we report the long-term outcomes of all paediatric DC patients from an 11-year period in a tertiary-level centre that geographically serves half of Finland.

METHODS

We identified all patients younger than 18 years who underwent DC in the Oulu University Hospital between the years 2009 and 2019. Outcomes and clinicoradiological variables were extracted from the patient records.

RESULTS

Mean yearly prevalence of brain injury requiring DC was 1.34/100 000 children-twenty-four patients underwent DC during the study period and 21 (88%) survived. The median age of the patients was 16.0 years, and the median preoperative GCS was 5.0 (IQR 5.0). Fifteen patients (63%) had made a good recovery (Extended Glasgow Outcome Scale ≥ 7). Of the surviving patients, two (9.5%) had not returned to school. After traumatic brain injury (n = 20), the Rotterdam CT score (mean 3.0, range 1 to 5) was not associated with mortality, poor recovery or inability to continue school (p = 0.13, p = 0.41, p = 0.43, respectively). Absent basal cisterns were associated with mortality (p = 0.005), but not with poor recovery if the patient survived DC (p = 0.81). Hydrocephalus was associated with poor recovery and inability to continue school (p = 0.01 and p = 0.03, respectively).

CONCLUSION

Most of our patients made a favourable recovery and were able to continue school. No late mortality was observed. Thus, even in clinically and radiologically severely brain-injured children, decompressive craniectomy appears to yield favourable outcomes.

Two-center validation of the Oulu resorption score for bone flap resorption after autologous cranioplasty

OBJECTIVE

Autologous bone has been the gold standard of cranioplasty materials for decades. Unique to autologous cranioplasty, bone flap resorption is a poorly understood and unclearly defined complication. Even further, it has been unclear, whether the resorption process eventually stabilizes over time. Thus, the sufficient follow-up period after autologous cranioplasty is unknown. The Oulu Resorption Score (ORS) is a straight-forward classification system for the radiological interpretation of bone flap resorption. The aims of the present study were to evaluate the reliability of the ORS using intra-class correlation coefficient (ICC) and to assess the temporal progression of the resorption process.

METHODS

We identified 108 consecutive autologous cranioplasty patients treated between 2005 and 2018 in two tertiary referral centers. All 365 head CT scans the patients had undergone were evaluated using the ORS in a blinded, independent two-center setting. Intra- and inter-observer reliabilities were calculated. The ORS was applied to study the temporal progression of the resorption process.

RESULTS

The intra-observer reliability of the ORS was excellent (ICC 0.94, 95%CI 0.93-0.95). Inter-observer reliability was good-to-excellent (ICCs 0.87 and 0.89, 95%CIs 0.84-0.89 and 0.87-0.91, respectively). In scatterplot smoothing analyses, the progression of bone flap resorption appeared to stabilize 12-24 months after cranioplasty.

CONCLUSIONS

ORS is the only validated radiological tool for the standardized analysis of bone flap resorption after autologous cranioplasty. Evaluated using the ORS, the resorption process seemed to stabilize during the first two postoperative years after cranioplasty, suggesting that the sufficient follow-up time after autologous cranioplasty is two years.

ADSC-Based Cell Therapies for Musculoskeletal Disorders: A Review of Recent Clinical Trials

Recently published clinical trials involving the use of adipose-derived stem cells (ADSCs) indicated that approximately one-third of the studies were conducted on musculoskeletal disorders (MSD). MSD refers to a wide range of degenerative conditions of joints, bones, and muscles, and these conditions are the most common causes of chronic disability worldwide, being a major burden to the society. Conventional treatment modalities for MSD are not sufficient to correct the underlying structural abnormalities. Hence, ADSC-based cell therapies are being tested as a form of alternative, yet more effective, therapies in the management of MSDs. Therefore, in this review, MSDs subjected to the ADSC-based therapy were further categorized as arthritis, craniomaxillofacial defects, tendon/ligament related disorders, and spine disorders, and their brief characterization as well as the corresponding conventional therapeutic approaches with possible mechanisms with which ADSCs produce regenerative effects in disease-specific microenvironments were discussed to provide an overview of under which circumstances and on what bases the ADSC-based cell therapy was implemented. Providing an overview of the current status of ADSC-based cell therapy on MSDs can help to develop better and optimized strategies of ADSC-based therapeutics for MSDs as well as help to find novel clinical applications of ADSCs in the near future.

Cranioplasty

Calvarial defects are commonly encountered after neurosurgical procedures, trauma, and ablative procedures of advanced head neck cancers. The goals of cranioplasty are to provide a protective barrier for the intracranial contents, to restore form, and prevent syndrome of the trephined. Autologous and alloplastic techniques are available, each with their advantages and drawbacks. A multitude of materials are available for cranioplasty, and proper timing of reconstruction with attention to the overlying skin envelope is important in minimizing complications.

The Materials Utilized in Cranial Reconstruction: Past, Current, and Future

BACKGROUND

Cranioplasty (CP) is associated with high complication rates compared to other common neurosurgical procedures. Several graft materials are used for CP, which may contribute to the high complication rates, but data in the literature regarding the influence of graft material on post-CP outcomes are inconsistent making it difficult to determine if, when, and to what extent the graft material impacts the rate of perioperative complications. There is an increased demand to identify and develop superior graft materials.

OBJECTIVE

To review and compare the indications, risks, complications, and patient results associated with the use of different graft materials for cranial reconstructions.

DESIGN

A search through EBSCOhost was conducted using the keywords "craniectomy" or "decompressive craniectomy," "cranioplasty," and "materials." The search was limited to literature published in the English language from 2005 until the present. Ultimately, 69 articles were included in this review. Due to the heterogeneity of the study populations, results, statistical analyses, and collecting methods, no statistical analyses could be performed.

CONCLUSIONS

Several graft materials have been adapted for use in cranial reconstructions with inconsistent results making it unclear if or when one material may be indicated over others. Advances in computer-aided design have led to improved patient-specific implants, but the ideal graft material is still being sought after in ongoing research efforts. Reviewing materials currently available, as well as those in clinical trials, is important to identify the limitations associated with different implants and to guide future research.

Bone Flap Resorption in Pediatric Patients Following Autologous Cranioplasty

Following a decompressive craniectomy, the autologous bone flap is generally considered the reconstructive material of choice in pediatric patients. Replacement of the original bone flap takes advantage of its natural biocompatibility and the associated low risk of rejection, as well as the potential to reintegrate with the adjacent bone and subsequently grow with the patient. However, despite these advantages and unlike adult patients, the replaced calvarial bone is more likely to undergo delayed bone resorption in pediatric patients, ultimately requiring revision surgery. In this review, we describe the materials that are currently available for pediatric cranioplasty, the advantages and disadvantages of autologous calvarial replacement, the incidence and classification of bone resorption, and the clinical risk factors for bone flap resorption that have been identified to date.

Hinge and floating decompressive craniotomy for infantile acute subdural hematoma: technical note

Cranioplasty complications after decompressive craniectomy (DC) in infants are not fully recognized. We aimed to devise and assess the efficacy of a hinge and floating DC (HFDC) technique for treating infantile acute subdural hematoma. Five infants, aged 2-20 months, were included. Intracranial pressure was controlled below 20 mmHg, no additional surgery was required, and there was no incidence of surgical site infection or bone graft resorption.

Comparison of complications in cranioplasty with various materials: a systematic review and meta-analysis

Objective: Meta-analysis to evaluate complications in the use of autogenous bone and bone substitutes and to compare bone substitutes, specifically HA, polyetheretherketone (PEEK) and titanium materials.Methods: Search of PubMed, Cochrane, Embase and Google scholar to identify all citations from 2010 to 2019 reporting complications regarding materials used in cranioplasty.Results: 20 of 2266 articles met the inclusion criteria, including a total of 2913 patients. The odds of overall complication were significantly higher in the autogenous bone group (n = 214/644 procedures, 33.2%) than the bone substitute groups (n = 116/436 procedures, 26.7%, CI 1.29-2.35, p < 0.05). In bone substitutes groups, there was no significant difference in overall complication rate between HA and Ti (OR, 1.2; 95% CI, 0.47-3.14, p = 0.69). PEEK has lower overall complication rates (OR, 0.51; 95% CI, 0.30-0.87, p = 0.01) and lower implant exposure rates (OR, 0.17; 95% CI, 0.06-0.53, p = 0.002) than Ti, but there was no significant difference in infection rates and postoperative hematoma rates.Conclusions: Cranioplasty is associated with high overall complication rates with the use of autologous bone grafts compared with bone substitutes. PEEK has a relatively low overall complication rates in substitutes groups, but still high infection rates and postoperative hematoma rates. Thus, autologous bone grafts should only be used selectively, and prospective long-term studies are needed to further refine a better material in cranioplasty.

Cranial Reconstruction with Titanium Mesh for Open Depressed Skull Fracture in Children: Reports of Two Cases with Long-term Observation

In the treatment of open depressed skull fracture in pediatric cases, it is preferable to use the patient's own bone material rather than artificial material. However, there are occasions when self-material reconstruction may be impossible. In such cases the safe option is to leave the defect until future replacement of the skull becomes possible, however this often causes such children to experience severe limitations to school life. We present two thought-provoking cases in which we solved such issues by early stage cranioplasty using a titanium mesh. The first case involved a 9-year-old boy who sustained a depressed fracture in the right temporal region after falling down a riverbank. Although he underwent surgical repair, bacterial infection forced removal of the bone flap postoperatively. His school life was severely restricted and sports activities were prohibited due to the residual regional bone defect. Cranial reconstruction with a titanium mesh made it possible for him to enjoy a more active lifestyle. The second case involved a 7-year-old boy who sustained a right frontal depressed fracture in a traffic accident. The fractured skull was promptly replaced by a titanium mesh at the initial surgery due to the extreme degree of bone fragmentation. Both boys returned to school life enjoying normal activities and without any complications for up to 8 years now. The cases presented here indicate that early cranioplasty even using artificial material is not only safe but enables school age patients to participate in physical activities. From the standpoint of physical and psychological development, early stage cranioplasty with titanium mesh may be a valuable treatment option for pediatric open depressed skull fracture.

Massive Ossification with Hematopoietic Marrow on Both Surfaces of the Expanded Polytetrafluoroethylene Artificial Dura Mater

BACKGROUND

Artificial dural substitute made from an expanded polytetrafluoroethylene (ePTFE) sheet has been widely used in surgical application.

CASE DESCRIPTION

We describe a 19-year-old woman in whom massive ossification with hematopoietic marrow was noted on both surfaces of an ePTFE sheet during epilepsy surgery. At age 8, she underwent decompressive craniectomy for a ruptured arteriovenous malformation in the right frontal lobe, followed by duraplasty with an ePTFE sheet and autologous cranioplasty fixed with titanium miniplates.

CONCLUSIONS

Since the ossification was prominent in the wrinkle dents of the ePTFE sheet and fibrotic membrane with repetitive hemorrhagic events was noted under the ePTFE sheet, the most plausible mechanism of ossification development is the organization of epiartificial and subartificial dural hematoma. Surgeons should be aware of the possibility of ossification development when working with ePTFE sheets for duraplasty.

Hydroxyapatite ceramic implants for cranioplasty in children: a retrospective evaluation of clinical outcome and osteointegration

INTRODUCTION

Cranioplasty in children is a controversial and challenging issue, since there is still no consensus on the ideal material. Main problems in paediatric age are represented by the child's growing skull, the lower bone thickness and the high incidence of cerebrospinal fluid (CSF) disorders or brain swelling. Autologous bone is still considered the "gold standard". When it is not available, a wide range of alloplastic materials have been proposed. Hydroxyapatite, a ceramic-based derivative, bears a chemical composition very similar to the human natural bone, making this material a valuable alternative to other cranioplasty solutions.

METHODS

All patients implanted with a custom-made porous hydroxyapatite device at Santobono-Pausilipon Hospital in Naples were retrospectively reviewed. A follow-up CT scan of the skull was performed from 1 up to 48 months postoperatively to document the bone ingrowth as well as the osteointegration process. The bone density was measured as according to the Hounsfield scale at the bone-implant interface.

RESULTS

Between 2014 and 2018, 11 patients (7 males, 4 females) underwent cranioplasty with hydroxyapatite ceramic implants (HAP). Patients' age ranged between 3 and 16 years old. Initial aetiology was trauma in most cases. Two subjects were implanted with HAP as primary cranioplasty, 9 as revision surgery following previous cranioplasty failure. Sites of the cranial defect were unilateral fronto-temporo-parietal (N = 8), unilateral frontal (N = 1) and bifrontal (N = 2). Two patients with large bilateral defects received two prostheses. In one of these, the two prostheses were explanted and replaced with two back-up implants (accounting for a total of 15 implants in 11 patients). Osteointegration was measurable for 12 out of 15 implanted devices. The mean percentage was about 51%. There were six asymptomatic prosthesis fractures (40%), all occurring within 6 months from implant. In one case, the bifrontal prostheses were explanted and replaced. This was the only patient who underwent revision surgery.

CONCLUSION

Hydroxyapatite ceramic implants represent a valid alternative to other cranioplasty solutions. Where coaptation occurs correctly, with good osteointegration, implant mechanical resistance increases over time.

Cranioplasty Using Autoclaved Autologous Skull Bone Flaps Preserved at Ambient Temperature

Context

Decompressive craniectomy followed by cranioplasty (CP) uses autologous craniectomy flaps or synthetic materials like titanium. Sterilization and preservation methods for the autologous bone flaps continue to be the surgeon's choice.

Aim

This study aimed to assess the short-term as well as long-term clinical outcomes of CP using autoclaved autologous bone grafts.

Settings and Design

This retrospective observational study was performed on patients admitted in a tertiary care teaching neurosurgery department.

Patients and Methods

Seventy-two patients who underwent CP with autoclaved autologous skull flaps preserved under ambient conditions with strict aseptic precautions were included in the study.

Statistical Analysis Used

Frequencies and percentages of the various characteristics before and after the surgery were tabulated. Continuous variables were summarized as means and standard deviations.

Results

The primary CP had a satisfactory clinical outcome in 62 cases (86.11%). Osteomyelitis was observed in four patients (5.56%) nearly 2 months after the surgery. Radiologically significant bone resorption was noted in a single patient (1.39%) after 1 year. Five patients (6.94%) developed bone fragmentation or fracture, and the mean time taken for this was about 36 months. In all these ten cases, secondary CP was successfully done using a prefabricated, patient-specific titanium mesh.

Conclusions

The efficacy and safety of the studied craniectomy flaps used for cranial reconstruction showed a good patient outcome. Further retrospective studies with larger cohorts and prospective case-control studies are essential so as to issue standard guidelines for sterilization and preservation of autologous bone flaps.

Cranioplasty after craniectomy in pediatric patients-a systematic review

INTRODUCTION

Complications following cranioplasty with either autografts or cranial implants are commonly reported in pediatric patients. However, data regarding cranioplasty strategies, complications and long-term outcomes are not well described. This study systematically reviews the literature for an overview of current cranioplasty practice in children.

METHODS

A systematic review of articles published from inception to July 2018 was performed. Studies were included if they reported the specific use of cranioplasty materials following craniectomy in patients younger than 18 years of age, and had a minimum follow-up of at least 1 year.

RESULTS

Twenty-four manuscripts, describing a total of 864 cranioplasty procedures, met the inclusion criteria. The age of patients in this aggregate ranged from 1 month to 20 years and the weighted average was 8.0 years. The follow-up ranged from 0.4 months to 18 years and had a weighted average of 40.4 months. Autologous bone grafts were used in 484 cases (56.0%). Resorption, infection and/or hydrocephalus were the most frequently mentioned complications. In this aggregate group, 61 patients needed a revision cranioplasty. However, in 6/13 (46%) papers studying autologous cranioplasties, no data was provided on resorption, infection and revision cranioplasty rates. Cranial implants were used in 380 cases (44.0%), with custom-made porous hydroxyapatite being the most commonly used material (100/380, 26.3%). Infection and migration/fracturing/loosening were the most frequently documented complications. Eleven revision cranioplasties were reported. Again, no data was reported on infection and revision cranioplasty rates, in 7/16 (44%) and 9/16 (56%) of papers, respectively.

CONCLUSION

Our systematic review illuminates that whether autografts or cranial implants are used, postcranioplasty complications are quite common. Beyond this, the existing literature does not contain well documented and comparable outcome parameters, suggesting that prospective, long-term multicenter cohort studies are needed to be able to optimize cranioplasty strategies in children who will undergo cranioplasty following craniectomy.

Greenstick fracture-hinge decompressive craniotomy in infants: illustrative case and literature review of techniques for decompressive craniotomy without bone removal

PURPOSE

We present the potential usefulness of a greenstick fracture-hinge decompressive craniotomy, a variant of a hinge-craniotomy, as an alternative technique for use with a decompressive craniectomy (DC) in infants. A literature review of hinge-craniotomy procedures and technical variants is also provided, with a focus on complications associated with a DC peculiar to infants and children.

METHODS

Illustrative case presentation along with literature review.

RESULT

Significant rates of complications associated with a DC and subsequent cranioplasty have been reported, such as bone flap resorption, hydrocephalus, cerebrospinal fluid collection, and infection, especially in infants. A hinge-craniotomy is an older technique reported to have potential usefulness with some modifications, though concerns have been raised about adequate decompression and definitive indications.

CONCLUSION

A DC procedure performed in children, especially infants, includes a significantly high risk of various complications; thus, a hinge-craniotomy technique is worthwhile for consideration to avoid such complications. Additional studies are required to clarify whether this technique may contribute to reduce complications related to a DC in infants and children.

Cranioplasties following craniectomies in children-a multicenter, retrospective cohort study

OBJECTIVE

Complications following pediatric cranioplasty after craniectomy with either autologous bone flaps or cranial implants are reported to be common, particularly bone flap resorption. However, only sparse data are available regarding cranioplasty strategies, complications, and outcomes. This manuscript describes a Canadian-Dutch multicenter pediatric cohort study with autografts and cranial implant cranioplasties following craniectomies for a variety of indications.

METHODS

The study included all children (< 18 years) who underwent craniectomy and subsequent cranioplasty surgeries from 2008 to 2014 (with a minimum of 1-year follow-up) at four academic hospitals with a dedicated pediatric neurosurgical service. Data were collected regarding initial diagnosis, age, time interval between craniectomy and cranioplasty, bone flap storage method, type of cranioplasty for initial procedure (and redo if applicable), and the postoperative outcome including surgical site infection, wound breakdowns, bone flap resorption, and inadequate fit/disfigurement.

RESULTS

Sixty-four patients (46 males, average age 9.7 ± 5.5 years) were eligible for inclusion, with mean follow-up of 82.3 ± 31.2 months after craniectomy. Forty cranioplasties (62.5%) used autologous bone re-implant, 23 (57.5%) of which showed resorption. On average, resorption was documented at 434 days (range 62-2796 days) after reimplantation. In 20 cases, a revision cranioplasty was needed. In 24 of the post-craniectomy cases (37.5%), a cranial implant was used with one of ten different implant types. Implant loosening prompted a complete revision cranioplasty in 2 cases (8.3%). Cranial implants were associated with low morbidity and lower reoperation dates compared to the autologous cranioplasties.

CONCLUSION

The most prominent finding in this multicenter cohort study was that bone flap resorption in children remains a common and widespread problem following craniectomy. Cranioplasty strategies varied between centers and evolved over time within centers. Cranial implants were associated with low morbidity and low reoperation rates. Still, longer term and prospective multicenter cohort studies are needed to optimize cranioplasty strategies in children after craniectomies.

Cranioplasty in Infants Less Than 24 Months of Age: A Retrospective Case Review of Pitfalls, Outcomes, and Complications

BACKGROUND

Management of pediatric skull defects after decompressive craniectomy (DC) poses unique problems, particularly in children younger than 24 months. These problems include complications such as resorption and infection as well as difficulties with plagiocephaly and reconstruction. The goal of this study was to evaluate bone resorption complications after cranioplasty in patients <24 months.

METHODS

A single-center retrospective case study was performed of all patients younger than 24 months who underwent cranioplasty after DC between 2011 and 2018. The following variables were assessed: injury cause, age at craniotomy, time to cranioplasty, craniectomy size, mode of fixation, drain use, shunt use, subdural fluid collection, resorption, need for synthetic graft revision, and plagiocephaly.

RESULTS

A total of 10 patients were identified who met inclusion criteria; 3 patients were excluded for insufficient follow-up. Ages ranged from <1 day to 19 months, with a mean of 10.7 months. Overall rate of cranioplasty resorption was 85.7%, 57.1% of which required revision with synthetic graft. There were univariate trends toward more frequent implant resorption with subdural fluid collection (P = 0.1071) and without shunt placement (P = 0.1429). These effects persisted through multivariable analysis and even reached statistical significance in the case of subdural collection when controlling for operative and demographic characteristics (P = 0.01138, P = 0.0694). In addition, univariate analysis showed a trend toward more frequent neurologic complications with greater craniotomy-to-cranioplasty intervals (P = 0.1043), which reached significance on multivariable analysis (P = 0.00518).

CONCLUSIONS

In patients younger than 24 months undergoing cranioplasty subdural collection, a lack of shunt placement and increased time to cranioplasty were associated with increased rates of resorption.

Use of Vacuum-Assisted Wound Closure and Tissue Expansion in Revision Cranioplasty for a Large-Sized Composite Defect in a Child

Cranioplasty is generally defined as the procedure to reconstruct cranial bone defect arising from congenital or acquired process. As a surgical remedy, it can restore the function of original anatomical structure and produce a satisfactory cosmetic outcome. Although with available options for treating pediatric cranioplasty, large format (ie, >25 cm) cranioplasty of the aborted one with a composite defect is still a challenging procedure for plastic surgeons. The authors herein present a case of child who suffered failed cranioplasty with polyetheretherketone caused by postoperative infection, leading to skin ulcer and exposure of the polyetheretherketone. The treatments of the patient are performed sequentially. After thorough debridement of the wound, vacuum-assisted wound closure and autologous split-thickness skins are successively used to cover the defect following finally adopted strategy of tissue expansion of the scalp with a 3-dimensional-printed epoxide acrylate maleic composite material to repair the large-sized cranial defect.

Titanium mesh cranioplasty in pediatric patients after decompressive craniectomy: Appropriate timing for pre-schoolers and early school age children

PURPOSE

There is little knowledge on the growth of cranial defects, appropriate timing and outcomes of application of titanium mesh for cranioplasty in the pediatric population, especially pre-school age (2-5 years old) and school age (6-12 years old) children. We hypothesised that cranioplasty for pre-schoolers could be delayed to school age due to the expected cranium growth, whereas, for the school age group, it is better to perform routine cranioplasty (3-6 months) to protect the brain and therefore ensure their timely return to school life.

MATERIALS AND METHODS

A retrospective review of pediatric patients (2-12 years old) who underwent titanium mesh cranioplasty for cranial defects from 2006 to 2012 was performed. Patient demographic data, radiological data, and clinical information were collected. Specifically, cranial defect sizes were evaluated by three-dimensional (3D) reconstruction of computed tomography data after craniectomy, before cranioplasty and 2-years after cranioplasty. Patients were routinely followed up at an outpatient clinic for complications and school attendance.

RESULTS

A total of 18 titanium mesh cranioplasties were performed in 18 patients. The average interval between craniectomy and cranioplasty was 3 years for pre-schoolers and 4 months for the school age group. Patients in the pre-schooler group showed significant enlargements in cranial defects during the interval as compared with the school age group (26% vs. 4%, P < 0.05). There were no surgery-related complications except in one patient, who had titanium mesh exposure 11 months later. Two years after cranioplasty, there was no significant difference in mild cranial defect enlargements between the two groups (11% vs. 6%, P > 0.05). Patients were followed for an average of 5 (range, 2-8) years. All patients had satisfactory recovery of cranial contour, sufficient protection of the brain and active participation in school study. All patients had satisfactory recovery of cranial contour, sufficient protection of the brain and active participation in school.

CONCLUSION

Timing of titanium mesh cranioplasty after decompressive craniectomy based on their age is a workable solution for school-age pediatric patients. The enlargement of cranium defects in pre-schoolers supports a delayed repair until school age. The long-term outcomes for these patients with titanium mesh cranioplasty are favourable.

Cosmetic Outcome of Cranioplasty After Decompressive Craniectomy-An Overlooked Aspect

BACKGROUND

Cranioplasty (CP) is an obligatory surgery after decompressive craniectomy (DC). The primary objective is to protect the brain from external injury and prevent syndrome of trephined. In a government hospital, such cases pose a significant burden to a trauma center. Because of this reason, cosmetic outcome is never taken into account for the CP. We present results of CP performed at our hospital.

METHODS

This is a retrospective review of the cases of CP performed over the past 3 years at our hospital. The cosmetic outcome was divided into 3 grades: 1-good symmetrical, 2-irregularities, 2a-elevated and 2b depressed, and 3-bad cosmetic outcome requiring reoperation.

RESULTS

A total of 133 patients with acute brain injury underwent CP during the study period. The outcome was good in 74 (55.6%) and bad, requiring reoperation, in 2 (1.5%) cases. Various types of the CP materials like autologous bone flap, titanium mesh, and customized titanium plates were used. Methods of fixation were threads or miniplates and screws. In univariate analysis, cerebral venous thrombosis as an indication for DC, use of autologous bone flap, and fixation with thread were associated with poor outcome. However, in multivariate analysis only the method of implant fixation was associated with poor outcome. It was found that if screws and plates are used for fixation of bone flap, the chances of bad outcome are reduced by 74.6%.

CONCLUSIONS

The cosmetic outcome is overlooked for CP. The bone flap fixation has to be rigid for a good outcome.

Long-Term Complications of Cranioplasty Using Stored Autologous Bone Graft, Three-Dimensional Polymethyl Methacrylate, or Titanium Mesh After Decompressive Craniectomy: A Single-Center Experience After 596 Procedures

OBJECTIVE

Cranioplasty is a technically simple procedure intended to repair defects of the skull to provide protection after craniectomy, improve functional outcomes, and restore cosmesis. Several materials have been used for the restoration of skull defects, including autologous bone grafts (AGs), polymethyl methacrylate (PMMA) flaps, and titanium mesh (T-mesh). However, the long-term results of cranioplasty after use of these materials are controversial.

METHODS

Medical records of 596 patients who underwent cranioplasty at our medical center between 2009 and 2015 with at least 2.5 years of follow-up were retrospectively reviewed. Patients were classified into 3 groups according to the materials used: AG, three-dimensional PMMA, and T-mesh. Demographic and clinical characteristics and postoperative complications were analyzed.

RESULTS

Cranioplasty with AG had the highest bone flap depression rate (4.9%; P = 0.02) and was associated with a 26% long-term bone flap resorption. Younger age was a risk factor for bone flap resorption. T-mesh had a higher risk of postoperative skin erosion and bone exposure (17%; P = 0.004). Patients with diabetes, previous craniotomy, or hydrocephalus showed a higher risk of postoperative skin erosion. PMMA was associated with the highest rate of postoperative infection (14.4% <3 months, 28.1% >3 months; P < 0.05), and previous craniotomy may increase the infection risk after cranioplasty with PMMA.

CONCLUSIONS

Complications after cranioplasty are high, and the various types of cranioplasty materials used are associated with different complications. Surgeons need to be aware of these potential complications and should choose the appropriate material for each individual patient.

Classification of bone flap resorption after cranioplasty: a proposal for a computed tomography-based scoring system

Background

Bone flap resorption (BFR) is the most prevalent complication resulting in autologous cranioplasty failure, but no consensus on the definition of BFR or between the radiological signs and relevance of BFR has been established. We set out to develop an easy-to-use scoring system intended to standardize the interpretation of radiological BFR findings.

Methods

All 45 autologous cranioplasty patients operated on at Oulu University Hospital from 2004 to 2014 were identified, and the bone flap status of all the available patients was evaluated using the new scoring system. Derived from previous literature, a three-variable score for the detection of BFR changes is proposed. The variables “Extent” (estimated remaining bone volume), “Severity” (possible perforations and their measured diameter), and “Focus” (the number of BFR foci within the flap) are scored from 0 to 3 individually. Using the sum of these scores, a score of 0–9 is assigned to describe the degree of BFR. Additionally, independent neurosurgeons assessed the presence and relevance of BFR from the same data set. These assessments were compared to the BFR scores in order to find a score limit for relevant BFR.

Results

BFR was considered relevant by the neurosurgeons in 11 (26.8%) cases. The agreement on the relevance of BFR demonstrated substantial strength (κ 0.64, 95%CI 0.36 to 0.91). The minimum resorption score in cases of relevant BFR was 5. Thus, BFR with a resorption score ≥ 5 was defined relevant (grades II and III). With this definition, grade II or III BFR was found in 15 (36.6%) of our patients. No risk factors were found to predict relevant BFR.

Conclusions

The score was proven to be easy to use and we recommend that only cases with grades II and III BFR undergo neurosurgical consultation. However, general applicability can only be claimed after validation in independent cohorts.

Factors related to failure of autologous cranial reconstructions after decompressive craniectomy

PURPOSE

Cranioplasty is customary after decompressive craniectomy. Many different materials have been developed and used for this procedure. The ideal material does not yet exist, while complication rates in cranioplasties remain high. This study aimed to determine factors related to autologous bone flap failure.

MATERIALS AND METHODS

In this two-center retrospective cohort study, 276 patients underwent autologous bone cranioplasty after initial decompressive craniectomy between 2004 and 2014. Medical records were reviewed regarding patient characteristics and factors potentially related to bone flap failure. Data were analyzed using univariable and multivariable regression analysis.

RESULTS

Independent factors related to overall bone flap failure were: duration of hospitalization after decompressive craniectomy [OR: 1.012 (95%CI: 1.003-1.022); p = 0.012], time interval between decompressive craniectomy and cranioplasty [OR: 1.018 (95%CI: 1.004-1.032); p = 0.013], and follow-up duration [OR: 1.034 (95%CI: 1.020-1.047); p < 0.001]. In patients with bone flap infection, neoplasm as initial diagnosis occurred significantly more often (29.2% vs. 7.8%; RD 21.3%; 95%CI 8.4 -38.3%; NNH 5; 95%CI 3 -12) and duration of hospitalization after decompressive craniectomy tended to be longer (means 54 vs. 28 days, MD 26.2 days, 95%CI -8.6 to 60.9 days). Patients with bone flap resorption were significantly younger (35 vs. 43 years, MD 7.7 years, 95%CI 0.8-14.6 years) and their cranial defect size tended to be wider than in patients without bone flap resorption (mean circumference 39 vs. 37 cm; MD 2.4 cm, 95% CI -0.43-5.2 cm) and follow-up duration was significantly longer (44 vs. 14 months, MD 29 months, 95%CI 17-42 months).

CONCLUSION

A neoplasm as initial diagnosis, longer hospitalization after decompressive craniectomy, larger time interval between decompressive craniectomy and cranioplasty, and longer follow-up duration are associated with a higher risk of failure of autologous bone flaps for cranioplasty. Patients with these risk factors may be better served with an early recovery program after decompressive surgery or an alloplastic material for cranioplasty.

Transplant of Adult Bone for Reconstruction of a Large Post-Traumatic Cranial Defect in a Very Young Baby

Large cranial defects in very young patients are challenging. The ideal material for cranioplasty in this age group has not yet been identified. Cryopreserved autologous bone presents very high rates of failures, acrylic resins pose a number of compatibility problems, bioceramics may be contraindicated, and autografts may be not adequate for repair of large defects. We present an 18-month-old baby with a large post-traumatic cranial defect which was repaired by assembling a new bone flap on a sterile stereolithographic 3-D model. This customized newly assembled flap consisted of a scaffold of autologous bone (from vault duplication) sustaining 2 large grafts of homologous cadaveric bone. It was adequately modeled and contoured on the 3-D model using metallic plates and screws. Immediately after implantation on the skull, the metallic devices were progressively replaced by reabsorbable material, thus maintaining the previously obtained flap profile. In this paper we detail this original technique which was developed to manage this specific patient.

Outcome of Primary Bone Fragment Replacement in Pediatric Patients with Depressed Skull Fracture

OBJECTIVE

To evaluate pediatric patients who were operated with the diagnosis of depressed skull fracture.

METHODS

The records of pediatric patients who presented with traumatic head injury to multicenter neurosurgery clinics between 2002 and 2018 and who were operated with a diagnosis of depressed skull fracture were retrospectively reviewed. All of the patients underwent primary bone fragment replacement operation, and the patients' own bone flaps were used to repair depressed skull fractures in all of them.

RESULTS

A total of 78 patients were included in the study. Of the study group, 20 patients presented with mild head injury, 37 had moderate head injury, and 21 had severe head injury. Dural injury was present in 67 patients (86%) and the dura was intact in 11 patients (14%). After surgery, 63 patients (81%) had good outcome, 8 patients (10%) had moderate disability, and 5 patients (6.5%) had severe disability. Two patients with multiple accompanying cranial pathologies died and the mortality rate was 2.5%. Infection was detected in only 2 of the 78 patients who were treated within the first 72 h after trauma. One of them had meningitis and the other skin infection. Both patients were treated with appropriate antibiotherapy. None of the patients in the study group had an infection involving the bone, such as osteomyelitis, or the tissues under the bone, such as subdural-epidu-ral empyema or abscess. None of the patients required reoperation and removal of the bone.

CONCLUSION

In the present study, as the pathologies accompanying the depressed skull fractures of the patients increased, Glasgow Coma Scale scores at arrival and Glasgow Outcome Scale scores at discharge decreased. Regardless of whether the depressed fracture is simple or compound, primary bone fragment replacement with appropriate decontamination of the fractured bone and operation area via single-session intervention gives good results. It is important to perform the surgery as soon as possible to reduce the risk of contamination. Primary bone fragment replacement seems to be an appropriate treatment option for depressed skull fractures.

Complications following pediatric cranioplasty after decompressive craniectomy: a multicenter retrospective study

OBJECTIVE In children, the repair of skull defects arising from decompressive craniectomy presents a unique set of challenges. Single-center studies have identified different risk factors for the common complications of cranioplasty resorption and infection. The goal of the present study was to determine the risk factors for bone resorption and infection after pediatric cranioplasty. METHODS The authors conducted a multicenter retrospective case study that included all patients who underwent cranioplasty to correct a skull defect arising from a decompressive craniectomy at 13 centers between 2000 and 2011 and were less than 19 years old at the time of cranioplasty. Prior systematic review of the literature along with expert opinion guided the selection of variables to be collected. These included: indication for craniectomy; history of abusive head trauma; method of bone storage; method of bone fixation; use of drains; size of bone graft; presence of other implants, including ventriculoperitoneal (VP) shunt; presence of fluid collections; age at craniectomy; and time between craniectomy and cranioplasty. RESULTS A total of 359 patients met the inclusion criteria. The patients' mean age was 8.4 years, and 51.5% were female. Thirty-eight cases (10.5%) were complicated by infection. In multivariate analysis, presence of a cranial implant (primarily VP shunt) (OR 2.41, 95% CI 1.17-4.98), presence of gastrostomy (OR 2.44, 95% CI 1.03-5.79), and ventilator dependence (OR 8.45, 95% CI 1.10-65.08) were significant risk factors for cranioplasty infection. No other variable was associated with infection. Of the 240 patients who underwent a cranioplasty with bone graft, 21.7% showed bone resorption significant enough to warrant repeat surgical intervention. The most important predictor of cranioplasty bone resorption was age at the time of cranioplasty. For every month of increased age the risk of bone flap resorption decreased by 1% (OR 0.99, 95% CI 0.98-0.99, p < 0.001). Other risk factors for resorption in multivariate models were the use of external ventricular drains and lumbar shunts. CONCLUSIONS This is the largest study of pediatric cranioplasty outcomes performed to date. Analysis included variables found to be significant in previous retrospective reports. Presence of a cranial implant such as VP shunt is the most significant risk factor for cranioplasty infection, whereas younger age at cranioplasty is the dominant risk factor for bone resorption.

Efficacy of immediate replacement of cranial bone graft following drainage of intracranial empyema

OBJECTIVE Intracranial empyema is a life-threatening condition associated with a high mortality rate and residual deleterious neurological effects if not diagnosed and managed promptly. The authors present their institutional experience with immediate reimplantation of the craniotomy flap and clarify the success of this method in terms of cranial integrity, risk of recurrent infection, and need for secondary procedures. METHODS A retrospective analysis of patients admitted for management of intracranial empyema during a 19-year period (1997-2016) identified 33 patients who underwent emergency drainage and decompression with a follow-up duration longer than 6 months, 23 of whom received immediate bone replacement. Medical records were analyzed for demographic information, extent and location of the infection, bone flap size, fixation method, need for further operative intervention, and duration of intravenous antibiotics. RESULTS The mean patient age at surgery was 8.7 ± 5.7 years and the infections were largely secondary to sinusitis (52.8%), with the most common location being the frontal/temporal region (61.3%). Operative intervention involved removal of a total of 31 bone flaps with a mean surface area of 22.8 ± 26.9 cm². Nearly all (96.8%) of the bone flaps replaced at the time of the initial surgery were viable over the long term. Eighteen patients (78.3%) required a single craniotomy in conjunction with antibiotic therapy to address the infection, whereas the remaining 21.7% required more than 1 surgery. Partial bone flap resorption was noted in only 1 (3.2%) of the 31 successfully replaced bone flaps. This patient eventually had his bone flap removed and received a split-calvaria bone graft. Twenty-one patients (91.3%) received postoperative CT scans to evaluate bone integrity. The mean follow-up duration of the cohort was 43.9 ± 54.0 months. CONCLUSIONS The results of our investigation suggest that immediate replacement and stabilization of the bone flap after craniectomy for drainage of intracranial empyemas has a low risk of recurrent infection and is a safe and effective way to restore bone integrity in most patients.

Cranial autologous bone flap resorption after a cranioplasty: A case report

BACKGROUND

Craniectomies and cranioplasty are common neurosurgical procedures performed after brain trauma, ischemia, tumor resection, or infection. Post-cranioplasty autologous bone flap resorption may occur in patients after delayed cranial reconstruction. The occurrence is usually low when bone flaps are stored in subcutaneous abdominal tissue. We report a unique case of post-cranioplasty cranial bone flap.

CASE DESCRIPTION

We report a total autologous bone flap resorption in a 28-year-old man with a history of alcohol abuse. He was found unconscious in his bedroom with a head trauma of unknown mechanism. After an emergency room assessment, he was diagnosed with an acute subdural hematoma and underwent to emergency surgical drainage and a craniectomy. Three months later, a cranioplasty was performed and he exhibited exceptional outcomes. During a follow-up assessment, 7 months post-cranioplasty, total bone flap resorption was observed on computerized tomography image.

CONCLUSION

This case described an abnormal accelerated resorption of an autologous bone flap cranioplasty inserted after 3 months. Thus, to avoid bone flap resorption, an as early as possibly strategy may prevent this. Still, the exact mechanisms underlying bone resorption are poorly understood.

The Role of Skeletal Stem Cells in the Reconstruction of Bone Defects

Craniofacial surgery, since its inauguration, has been the culmination of collaborative efforts to solve complex congenital, dysplastic, oncological, and traumatic cranial bone defects. Now, 50 years on from the first craniofacial meeting, the collaborative efforts between surgeons, scientists, and bioengineers are further advancing craniofacial surgery with new discoveries in tissue regeneration. Recent advances in regenerative medicine and stem cell biology have transformed the authors' understanding of bone healing, the role of stem cells governing bone healing, and the effects of the niche environment and extracellular matrix on stem cell fate. This review aims at summarizing the advances within each of these fields.

How Early Can We Perform Cranioplasty for Traumatic Brain injury After Decompressive Craniectomy? A Retrospective Multicenter Study

OBJECTIVE

Decompressive craniectomy (DC) is used to treat intractable intracranial hypertension after severe traumatic brain injury (TBI). Cranioplasty (CP) is typically performed weeks or months later. However, the optimal timing for CP is unknown. We aimed to determine the earliest possible time point for CP.

METHODS

We retrospectively reviewed brain computed tomography images from 159 patients who underwent CP after DC for TBI at 3 hospitals. We determined the earliest possible day for CP by reviewing the resolution of intracranial pressure in serial brain computed tomography images between DC and CP. The early CP group was defined as the group within the earliest possible timing of CP; other cases constituted the late CP group. We compared complications and the Glasgow Outcome Scale scores at 6 months between groups.

RESULTS

The mean initial Glasgow Coma Scale score was 8.33 ± 3.46. The time interval between DC and CP was 94.75 ± 143.98 days. The earliest possible timing for CP was determined to be 34.60 ± 34.36 days after DC. The incidence of complications did not differ significantly between groups, except for ventriculomegaly, which occurred more frequently in the late CP group (P = 0.026). Predictors of good outcome were revision because of infection, preoperative epidural hematoma, early cranioplasty, and no ventriculomegaly after DC.

CONCLUSIONS

CP can be performed at around 34 days after DC for TBI. Ventriculomegaly occurred less frequently and the 6-month Glasgow Outcome Scale score was better in the early CP group than in the late CP group.

Bone Flap Resorption Following Cranioplasty with Autologous Bone: Quantitative Measurement of Bone Flap Resorption and Predictive Factors

Objective

To quantitatively measure the degree of bone flap resorption (BFR) following autologous bone cranioplasty and to investigate factors associated with BFR.

Methods

We retrospectively reviewed 29 patients who underwent decompressive craniectomy and subsequent autologous bone cranioplasty between April 2005 and October 2014. BFR was defined as: 1) decrement ratio ([the ratio of initial BF size/craniectomy size]-[the ratio of last BF/craniectomy size]) >0.1; and 2) bone flap thinning or geometrical irregularity of bone flap shape on computed tomographic scan or skull plain X-ray. The minimal interval between craniectomy and cranioplasty was one month and the minimal follow-up period was one year. Clinical factors were compared between the BFR and no-BFR groups.

Results

The time interval between craniectomy and cranioplasty was 175.7±258.2 days and the mean period of follow up was 1364±886.8 days. Among the 29 patients (mean age 48.1 years, male: female ratio 20: 9), BFR occurred in 8 patients (27.6%). In one patient, removal of the bone flap was carried out due to severe BFR. The overall rate of BFR was 0.10±0.11 over 3.7 years. Following univariate analysis, younger age (30.5±23.2 vs. 54.9±13.4) and longer follow-up period (2204.5±897.3 vs. 1044.1±655.1) were significantly associated with BFR (p=0.008 and 0.003, respectively).

Conclusion

The degree of BFR following autologous bone cranioplasty was 2.7%/year and was associated with younger age and longer follow-up period.

* Calvarial Defects: Cell-Based Reconstructive Strategies in the Murine Model

Calvarial defects pose a continued clinical dilemma for reconstruction. Advancements within the fields of stem cell biology and tissue engineering have enabled researchers to develop reconstructive strategies using animal models. We review the utility of various animal models and focus on the mouse, which has aided investigators in understanding cranial development and calvarial bone healing. The murine model has also been used to study regenerative approaches to critical-sized calvarial defects, and we discuss the application of stem cells such as bone marrow-derived mesenchymal stromal cells, adipose-derived stromal cells, muscle-derived stem cells, and pluripotent stem cells to address deficient bone in this animal. Finally, we highlight strategies to manipulate stem cells using various growth factors and inhibitors and ultimately how these factors may prove crucial in future advancements within calvarial reconstruction using native skeletal stem cells.

Decompressive craniectomy and CSF disorders in children

INTRODUCTION

Decompressive craniectomy (DC) is a lifesaving procedure but is associated to several post-operative complications, namely cerebrospinal fluid (CSF) dynamics impairment. The aim of this multicentric study was to evaluate the incidence of such CSF alterations after DC and review their impact on the overall outcome.

MATERIAL AND METHODS

We performed a retrospective multicentric study to analyze the CSF disorders occurring in children aged from 0 to 17 years who had undergone a DC for traumatic brain injury (TBI) in the major Departments of Pediatric Neurosurgery of France between January 2006 and August 2016.

RESULTS

Out of 150 children, ranging in age between 7 months and 17 years, mean 10.75 years, who underwent a DC for TBI in 10 French pediatric neurosurgical centers. Sixteen (6 males, 10 females) (10.67%) developed CSF disorders following the surgical procedure and required an extrathecal CSF shunting. External ventricular drainage increased the risk of further complications, especially cranioplasty infection (p = 0.008).

CONCLUSION

CSF disorders affect a minority of children after DC for TBI. They may develop early after the DC but they may develop several months after the cranioplasty (8 months), consequently indicating the necessity of clinical and radiological close follow-up after discharge from the neurosurgical unit. External ventricular drainage and permanent CSF shunt placement increase significantly the risk of cranioplasty infection.

Problems of reconstructive cranioplasty after traumatic brain injury in children

Cranial repair after traumatic brain injury in children is still burdened by unsolved problems and controversial issues, mainly due to the high rate of resorption of autologous bone as well as the absence of valid alternative material to replace the autologous bone. Indeed, inert biomaterials are associated to satisfactory results in the short period but bear the continuous risk of complications related to the lack of osteointegration capacity. Biomimetic materials claiming osteoconductive properties that could balance their mechanical limits seem to allow good cranial bone reconstruction. However, these results should be confirmed in the long term and in larger series. Further complicating factors that may affect cranial reconstruction after head injury should be identified in the possible associated alterations of CSF dynamics and in difficulties to manage the traumatic skin lesion and the surgical wound, which also might impact on the cranioplasty outcome. All the abovementioned considerations should be taken into account when dealing with the cranial reconstruction after decompressive craniectomy in children.

Bioinspired Collagen Scaffolds in Cranial Bone Regeneration: From Bedside to Bench

Calvarial defects are common reconstructive dilemmas secondary to a variety of etiologies including traumatic brain injury, cerebrovascular disease, oncologic resection, and congenital anomalies. Reconstruction of the calvarium is generally undertaken for the purposes of cerebral protection, contour restoration for psychosocial well-being, and normalization of neurological dysfunction frequently found in patients with massive cranial defects. Current methods for reconstruction using autologous grafts, allogeneic grafts, or alloplastic materials have significant drawbacks that are unique to each material. The combination of wide medical relevance and the need for a better clinical solution render defects of the cranial skeleton an ideal target for development of regenerative strategies focused on calvarial bone. With the improved understanding of the instructive properties of tissue-specific extracellular matrices and the advent of precise nanoscale modulation in materials science, strategies in regenerative medicine have shifted in paradigm. Previously considered to be simple carriers of stem cells and growth factors, increasing evidence exists for differential materials directing lineage specific differentiation of progenitor cells and tissue regeneration. In this work, we review the clinical challenges for calvarial reconstruction, the anatomy and physiology of bone, and extracellular matrix-inspired, collagen-based materials that have been tested for in vivo cranial defect healing.

An Outcomes Comparison Between Autologous and Alloplastic Cranioplasty in the Pediatric Population

BACKGROUND

The use of alloplastic material in cranial reconstruction has been well described in the adult population, especially when a paucity of autologous tissue exists. In children it is unknown how long-term growth, however, may be affected by the implantation of nonexpansible alloplastic material. Therefore, the authors sought to compare the outcomes of pediatric patients undergoing alloplastic versus autologous cranial reconstruction.

METHODS

To assess the safety and long-term outcomes of alloplastic cranioplasty in children, an institutional review board-approved, retrospective, single institution review of pediatric patients undergoing cranioplasty was performed from 2000 to 2014. The age at surgery, cause of the cranial defect, defect size, time since initial surgery to reconstruction, implant type, and complications were assessed. Postreconstruction imaging was reviewed if available.

RESULTS

A reconstructive cranioplasty was performed in 41 pediatric patients (ages 1-19 years, average 7.35 years). Thirty patients underwent alloplastic reconstruction (age 4.37 ± 5.57 years), and 11 underwent autologous reconstruction (age 2.00 ± 3.74 years). The size of the cranial defects was 144.01 ± 393.04 cm for autologous and 405.31 ± 572.96 cm for alloplastic reconstructions. Follow-up for all patients was an average of 2.33 ± 2.76 years (0.1-9 years). No patients in either group showed evidence of elevated intracranial pressure after cranioplasty. In long-term follow-up, none of the implants were exposed or lost because of infection. Computed tomography and physical examination demonstrated that there was no skull growth restriction in either group.

CONCLUSIONS

Our data show that alloplastic cranioplasty in the pediatric population is a safe alternative, when autologous cranial bone is not available.

Hydroxyapatite ceramic implants for cranioplasty in children: a single-center experience

PURPOSE

The use of hydroxyapatite ceramic (HAC) implants for the treatment of skull defects in pediatric patients started 2010 at our institution. Ceramic implants facilitate osteoblast migration and therefore optimize osteointegration with the host bone. The purpose of this study is to report a single-center experience with this treatment modality.

METHODS

A retrospective review of all patients from July 2010 through June 2014 undergoing a cranioplasty using hydroxyapatite ceramic implant and managed at a single institution was performed. Indication for cranioplasty, the hospital course, and follow-up were reviewed. Bone density was measured in Hounsfield Units (HU) and osteointegration was calculated using Mimics Software® (Mimics Innovation Suite v17.0 Medical, Materialize, Leuven, Belgium).

RESULTS

Over the 4-year period, six patients met criteria for the study. Five patients had an osteointegration of nearly 100%. One patient had an incomplete osteointegration with a total bone-implant contact area of 69%. The mean bone density was 2800 HU (2300-3000 HU). Bone density alone is estimated to have a Hounsfield value between 400 and 2000 HU depending on the body region and bone quality. There were no major complications, and the patients were highly satisfied with the esthetical result.

CONCLUSION

Hydroxyapatite ceramic implants for cranioplasty in pediatric patients are a good choice for different indications. The implants show excellent osteointegration and esthetical results.