Cranioplasty for large-sized calvarial defects in the pediatric population: a review

Safety and Efficacy of Autologous Calvarial Graft Reconstruction for Large Cranial Defects in Pediatric Patients

Reconstruction of cranial defects using autologous calvarial grafts offers long-term advantages over alloplastic alternatives, especially in pediatric patients. However, the effectiveness of this method has been questioned for larger defects. This study evaluates outcomes after cranial reconstructions with fresh autologous calvarial grafts in pediatric patients. Medical records of pediatric patients who underwent cranioplasty with fresh autologous calvarial grafts at our institution over 10 years (2012-2022) were reviewed. The area of the bone defect and degree of postoperative osseus healing was determined clinically or by using 3-dimensional computed tomography (CT) when available. Secondary outcomes, including complications, unanticipated readmissions, and reoperation rates, were assessed. Twenty-seven patients, with a median age of 9.8 years at the time of reconstruction, were included. There were no infections, cerebrospinal fluid leaks, readmissions, or reoperations reported. At a median of 51 months postoperatively, only one patient (3.7%) exhibited a clinically appreciable bone defect. Postoperative CT, obtained at a median of 24 months, was available for thirteen patients (48.1%). These patients had a median bone healing rate of 84.1%. Incomplete bone healing correlated with larger initial defects (median: 24; IQR: 20-40.6 cm2 vs. 260.4; IQR: 198-302 cm2; P=0.002] and a higher number of previous craniofacial procedures (P=0.032). Cranioplasty using fresh autologous bone graft is safe and effective, with a median clinical bone healing rate of 96.3% and radiographic bone healing rate of 84.1%. Patients with a higher number of previous cranial procedures and a larger initial defect size are at higher risk of incomplete bone healing.

The Approach to Cranioorbital Gunshot Wounds

Gunshot wounds to the head result in significant morbidity with a low rate of survival. Current treatment recommendations for penetrating traumatic brain injury (pTBI), established in 2001, are based off techniques used in recent Middle Eastern conflicts. However, many advancements in care have been made and updates in official pTBI treatment guidelines are being formulated. While some penetrating brain injury patients are managed nonoperatively due to poor prognosis, many undergo emergent interventions and delayed reconstruction by various surgical subspecialists. This article explores the management of pTBI and the collaborative roles of neurosurgeons, ophthalmologists, and plastic surgeons.

Pediatric Craniofacial Ballistic Injuries

Pediatric ballistic injuries are a public health crisis in the United States. Younger children are more likely to sustain craniofacial injuries, which are associated with higher mortality rates. An understanding of the timeline of craniofacial development and the variation in pediatric facial proportions over time is important to guide further treatment of these patients. Management of these patients includes initial stabilization according to the Advanced Trauma Life Support protocol followed by management of time-sensitive injuries. Ballistic injuries often result in soft tissue and bone defects, requiring fixation and coverage. As children experience faster rates of bone healing, fixation should be done promptly. Soft tissue coverage is dependent on the size of the defect; whereas smaller wounds can be closed with primary closure or local tissue rearrangement, larger wounds may require free tissue transfer.

Repeat Exchange Autologous Cranioplasty for Recurrent Benign Osteoma: Meta-analysis and Literature Review

Osteomas are benign bony lesions that can occur throughout the craniofacial skeleton. Surgical excision can be an effective treatment, as recurrence is relatively uncommon. Outside of incomplete resection, causes of recurrence are poorly documented, especially in the pediatric population. Exchange cranioplasty is an autologous reconstructive surgical option for patients of all ages, and it can be effective in the treatment of large calvarial osteomas. Recurrent lesions of the cranioplasty site have not been well described in the literature, with only 3 documented reports. In this study, we present a unique case of a recurrent osteoma at the site of a prior exchange cranioplasty. The authors also provide a systematic review of the literature for recurrent osteomas and highlight causes and conclusions for these lesions. Utilizing the PRISMA guidelines, a systematic review of articles published across databases was performed to identify accounts of recurrent osteomas at prior cranioplasty sites. Our systematic review illustrates that recurrent osteomas overlying different cranioplasty biomaterials is a rare entity and is due to incomplete resection of the galea and periosteum during the index procedure. Biomaterial selection for the pediatric population requires careful consideration before reconstruction. Though limited by 3 articles previously published and without a direct link to recurrence, long-term studies are needed to further guide biomaterial selection in the pediatric population to evaluate potential recurrences.

Biomaterials for Regenerative Cranioplasty: Current State of Clinical Application and Future Challenges

Acquired cranial defects are a prevalent condition in neurosurgery and call for cranioplasty, where the missing or defective cranium is replaced by an implant. Nevertheless, the biomaterials in current clinical applications are hardly exempt from long-term safety and comfort concerns. An appealing solution is regenerative cranioplasty, where biomaterials with/without cells and bioactive molecules are applied to induce the regeneration of the cranium and ultimately repair the cranial defects. This review examines the current state of research, development, and translational application of regenerative cranioplasty biomaterials and discusses the efforts required in future research. The first section briefly introduced the regenerative capacity of the cranium, including the spontaneous bone regeneration bioactivities and the presence of pluripotent skeletal stem cells in the cranial suture. Then, three major types of biomaterials for regenerative cranioplasty, namely the calcium phosphate/titanium (CaP/Ti) composites, mineralised collagen, and 3D-printed polycaprolactone (PCL) composites, are reviewed for their composition, material properties, and findings from clinical trials. The third part discusses perspectives on future research and development of regenerative cranioplasty biomaterials, with a considerable portion based on issues identified in clinical trials. This review aims to facilitate the development of biomaterials that ultimately contribute to a safer and more effective healing of cranial defects.

Enhanced bone regeneration in rat calvarial defects through BMP2 release from engineered poly(ethylene glycol) hydrogels

The clinical standard therapy for large bone defects, typically addressed through autograft or allograft donor tissue, faces significant limitations. Tissue engineering offers a promising alternative strategy for the regeneration of substantial bone lesions. In this study, we harnessed poly(ethylene glycol) (PEG)-based hydrogels, optimizing critical parameters including stiffness, incorporation of arginine-glycine-aspartic acid (RGD) cell adhesion motifs, degradability, and the release of BMP2 to promote bone formation. In vitro we demonstrated that human bone marrow derived stromal cell (hBMSC) proliferation and spreading strongly correlates with hydrogel stiffness and adhesion to RGD peptide motifs. Moreover, the incorporation of the osteogenic growth factor BMP2 into the hydrogels enabled sustained release, effectively inducing bone regeneration in encapsulated progenitor cells. When used in vivo to treat calvarial defects in rats, we showed that hydrogels of low and intermediate stiffness optimally facilitated cell migration, proliferation, and differentiation promoting the efficient repair of bone defects. Our comprehensive in vitro and in vivo findings collectively suggest that the developed hydrogels hold significant promise for clinical translation for bone repair and regeneration by delivering sustained and controlled stimuli from active signaling molecules.

Pathogenesis and treatment of a giant occipital bone defect with meningoencephalocele in an NF1 child: case report and review of the literature

Autosomal dominantly inherited neurofibromatosis type I (NF1) is a systemic disorder caused by a mutation of a gene on chromosome 17q11.2 and characterized by multiple café-au-lait spots, lentiginous macules, Lisch nodules of the iris, and tumors of the nervous system. Bony manifestations such as scoliosis, dysplasia of the greater sphenoidal wing, tibial pseudoarthrosis, short stature, and macrocephaly have been reported in approximately 50% of patients. However, calvarial bone defects are rare. After screening 324 articles, 23 cases (12 adult and 11 pediatric patients) of occipital bone defects in NF1 patients were selected. All patients had a single/multiple bone defect over the lambdoid suture. Adjacent benign plexiform neurofibromas were observed in 14 patients (60.8%, 7 adults and 7 children); one adult patient was diagnosed with neurofibrosarcoma. Meningoencephalocele over the occipital defect was noted in 8 cases (34.78%, all adults). Cranioplasty was performed in only 17.39% of patients. Histologic examination was performed in 7 of the 15 patients with associated neurofibromas/neurofibrosarcomas. Biopsy of the bone margins surrounding the defect was performed in only one case. Pathologic examination of the herniated parieto-occipital or cerebellar tissue was not performed in any of the patients studied. We report the case of a 9-year-old girl with NF1 and a significant occipital bone defect and performed a systematic review of the relevant literature to highlight the challenges in treating this condition and to investigate the underlying mechanisms contributing to bone defects or dysplasia in NF1.

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.

Accelerated reconstruction of rat calvaria bone defect using 3D-printed scaffolds coated with hydroxyapatite/bioglass

Self-healing and autologous bone graft of calvaraial defects can be challenging. Therefore, the fabrication of scaffolds for its rapid and effective repair is a promising field of research. This paper provided a comparative study on the ability of Three-dimensional (3D) printed polycaprolactone (PCL) scaffolds and PCL-modified with the hydroxyapatite (HA) and bioglasses (BG) bioceramics scaffolds in newly bone formed in calvaria defect area. The studied 3D-printed PCL scaffolds were fabricated by fused deposition layer-by-layer modeling. After the evaluation of cell adhesion on the surface of the scaffolds, they were implanted into a rat calvarial defect model. The rats were divided into four groups with scaffold graft including PCL, PCL/HA, PCL/BG, and PCL/HA/BG and a non-explant control group. The capacity of the 3D-printed scaffolds in calvarial bone regeneration was investigated using micro computed tomography scan, histological and immunohistochemistry analyses. Lastly, the expression levels of several bone related genes as well as the expression of miR-20a and miR-17-5p as positive regulators and miR-125a as a negative regulator in osteogenesis pathways were also investigated. The results of this comparative study have showed that PCL scaffolds with HA and BG bioceramics have a great range of potential applications in the field of calvaria defect treatment.

Pediatric Cranioplasty Patients With Hostile Reconstructive Environments: Split Calvarial Versus Prosthetic Implant

INTRODUCTION

Pediatric cranial defects can be preceded by prior infection, radiation therapy, failed prior cranioplasty, or cerebrospinal fluid leak, leading to a complex reconstructive environment. The primary aim of this study was to investigate differences in outcomes between pediatric patients with hostile reconstructive environments who received split-calvarial autologous grafts as opposed to prosthetic grafts in cranioplasty.

METHODS

We performed an institutional review board-approved retrospective chart review of 51 patients younger than 18 years who underwent cranioplasty with a hostile setting between 1998 and 2020. Patients were then stratified into prosthetic (45%) and autologous groups (54%). The primary outcome measured was postoperative complication, defined as requirement of a subsequent surgery or revision.

RESULTS

Overall, there were no significant differences in age, sex, type of hostile setting, etiology of cranial defect, or side of the cranial defect between the 2 groups. Complication rate among the 2 graft groups was 18%. However, there were no significant differences in complications, defined as infection, failure or resorption of the graft, wound breakdown or necrosis, resulting bone defect, or hematoma, between the 2 populations. There was a significant difference in etiology between patients with complications, with patients who required a cranioplasty due to previous hemicraniectomy being nearly 5 times as likely to face a complication ( P = 0.045).

CONCLUSIONS

In our study, there was no significant difference observed in complications between prosthetic and split-thickness autologous grafts in pediatric patients with hostile settings. It does, however, seem that patients who had a previous hemicraniectomy are more likely to face complications as a result of cranioplasty.

3D bioprinting of dECM/Gel/QCS/nHAp hybrid scaffolds laden with mesenchymal stem cell-derived exosomes to improve angiogenesis and osteogenesis

Craniofacial bone regeneration is a coupled process of angiogenesis and osteogenesis, which, associated with infection, still remains a challenge in bone defects after trauma or tumor resection. 3D tissue engineering scaffolds with multifunctional-therapeutic properties can offer many advantages for the angiogenesis and osteogenesis of infected bone defects. Hence, in the present study, a microchannel networks-enriched 3D hybrid scaffold composed of decellularized extracellular matrix (dECM), gelatin (Gel), quaterinized chitosan (QCS) and nano-hydroxyapatite (nHAp) (dGQH) was fabricated by an extrusion 3D bioprinting technology. And enlightened by the characteristics of natural bone microstructure and the demands of vascularized bone regeneration, the exosomes (Exos) isolated from human adipose derived stem cells as angiogenic and osteogenic factors were then co-loaded into the desired dGQH₂₀hybrid scaffold based on an electrostatic interaction. The results of the hybrid scaffolds performance characterization showed that these hybrid scaffolds exhibited an interconnected pore structure and appropriate degradability (>61% after 8 weeks of treatment), and the dGQH₂₀hybrid scaffold displayed the highest porosity (83.93 ± 7.38%) and mechanical properties (tensile modulus: 62.68 ± 10.29 MPa, compressive modulus: 16.22 ± 3.61 MPa) among the dGQH hybrid scaffolds. Moreover, the dGQH₂₀hybrid scaffold presented good antibacterial activities (against 94.90 ± 2.44% ofEscherichia coliand 95.41 ± 2.65% ofStaphylococcus aureus, respectively) as well as excellent hemocompatibility and biocompatibility. Furthermore, the results of applying the Exos to the dGQH₂₀hybrid scaffold showed that the Exo promoted the cell attachment and proliferation on the scaffold, and also showed a significant increase in osteogenesis and vascularity regeneration in the dGQH@Exo scaffoldsin vitroandin vivo. Overall, this novel dECM/Gel/QCS/nHAp hybrid scaffold laden with Exo has a considerable potential application in reservation of craniofacial bone defects.

Engineered 3D-Printed Polyvinyl Alcohol Scaffolds Incorporating β-Tricalcium Phosphate and Icariin Induce Bone Regeneration in Rat Skull Defect Model

The skull defects are challenging to self-heal, and autologous bone graft repair has numerous drawbacks. The scaffolds for the rapid and effective repair of skull defects have become an important research topic. In this study, polyvinyl alcohol (PVA)/β-tricalcium phosphate(β-TCP) composite scaffolds containing icariin (ICA) were prepared through direct-ink three-dimensional (3D) printing technology. β-TCP in the composite scaffold had osteoconductive capability, and the ICA molecule had osteoinductive capacity. The β-TCP and ICA components in the composite scaffold can enhance the capability to repair skull defects. We show that ICA exhibited a slow-release behaviour within 80 days. This behaviour helped the scaffold to continuously stimulate the formation of new bone. The results of in vitro cell compatibility experiments showed that the addition of ICA molecules contributed to the adhesion and proliferation of MC-3T3-E1 cells. The level of alkaline phosphatase secretion demonstrated that the slow release of ICA can promote the osteogenic differentiation of MC-3T3-E1 cells. The introduction of ICA molecules accelerated the in situ bone regeneration in in vivo. It is concluded that the 3D-printed PVA scaffold with β-TCP and ICA has a wide range of potential applications in the field of skull defect treatment.

A Hybrid Titanium-Softmaterial, High-Strength, Transparent Cranial Window for Transcranial Injection and Neuroimaging

A transparent and penetrable cranial window is essential for neuroimaging, transcranial injection and comprehensive understanding of cortical functions. For these applications, cranial windows made from glass coverslip, polydimethylsiloxane (PDMS), polymethylmethacrylate, crystal and silicone hydrogel have offered remarkable convenience. However, there is a lack of high-strength, high-transparency, penetrable cranial window with clinical application potential. We engineer high-strength hybrid Titanium-PDMS (Ti-PDMS) cranial windows, which allow large transparent area for in vivo two-photon imaging, and provide a soft window for transcranial injection. Laser scanning and 3D printing techniques are used to match the hybrid cranial window to different skull morphology. A multi-cycle degassing pouring process ensures a good combination of PDMS and Ti frame. Ti-PDMS cranial windows have a high fracture strength matching human skull bone, excellent light transmittance up to 94.4%, and refractive index close to biological tissue. Ti-PDMS cranial windows show excellent bio-compatibility during 21-week implantation in mice. Dye injection shows that the PDMS window has a "self-sealing" to keep liquid from leaking out. Two-photon imaging for brain tissues could be achieved up to 450 µm in z-depth. As a novel brain-computer-interface, this Ti-PDMS device offers an alternative choice for in vivo drug delivery, optical experiments, ultrasonic treatment and electrophysiology recording.

Pediatric Cranioplasty Using Hydroxyapatite Cement: A Retrospective Review and Preliminary Computational Model

INTRODUCTION

Cranioplasty is a standard technique for skull defect repair. Restoration of cranial defects is imperative for brain protection and allowing for homeostasis of cerebral spinal fluid within the cranial vault. Calcium phosphate hydroxyapatite (HA) is a synthetic-organic material that is commonly used in cranioplasty. We evaluate a patient series undergoing HA cement cranioplasty with underlying bioresorbable mesh for various cranial defects and propose a preliminary computational model for understanding skull osteointegration.

METHODS

A retrospective review was performed at the institution for all pediatric patients who underwent HA cement cranioplasty. Seventeen patients were identified, and success of cranioplasty was determined based on clinical and radiographic follow-up. A preliminary computational model was developed using bone growth and scaffold decay equations from previously published literature. The model was dependent on defect size and shape. Patient data were used to optimize the computational model.

RESULTS

Seventeen patients were identified with an average age of 6 ± 5.6 years. Average defect size was 11.7 ± 16.8 cm2. Average time to last follow-up computer tomography scan was 10 ± 6 months. Three patients had failure of cranioplasty, all with a defect size above 15 cm2. The computational model developed shows a constant decay rate of the scaffold, regardless of size or shape. The bone growth rate was dependent on the shape and number of edges within the defect. Thus, a star-shaped defect obtained a higher rate of growth than a circular defect because of faster growth rates at the edges. The computational simulations suggest that shape and size of defects may alter success of osteointegration.

CONCLUSION

Pediatric cranioplasty is a necessary procedure for cranial defects with a relatively higher rate of failure than adults. Here, we use HA cement to perform the procedure while creating a preliminary computational model to understand osteointegration. Based on the findings, cranioplasty shape may alter the rate of integration and lead to higher success rates.

Transforming the Degradation Rate of β-tricalcium Phosphate Bone Replacement Using 3-Dimensional Printing

BACKGROUND

β-Tricalcium phosphate (β-TCP) is one of the most common synthetic bone grafting materials utilized in craniofacial reconstruction; however, it is limited by a slow degradation rate. The aim of this study was to leverage 3-dimensional (3D) printing in an effort to accelerate the degradation kinetics of β-TCP.

METHODS

Twenty-two 1-month-old New Zealand white rabbits underwent creation of calvarial and alveolar defects, repaired with 3D-printed β-TCP scaffolds coated with 1000 μM of osteogenic agent dipyridamole. Rabbits were euthanized after 2, 6, and 18 months after surgical intervention. Bone regeneration, scaffold degradation, and bone mechanical properties were quantified.

RESULTS

Histological analysis confirmed the generation of vascularized and organized bone. Microcomputed tomography analysis from 2 to 18 months demonstrated decreased scaffold volume within calvarial (23.6% ± 2.5%, 5.1% ± 2.2%; P < 0.001) and alveolar (21.5% ± 2.2%, 0.2% ± 1.9%; P < 0.001) defects, with degradation rates of 54.6%/year and 90.5%/year, respectively. Scaffold-inducted bone generation within the defect was volumetrically similar to native bone in the calvarium (55.7% ± 6.9% vs 46.7% ± 6.8%; P = 0.064) and alveolus (31.4% ± 7.1% vs 33.8% ± 3.7%; P = 0.337). Mechanical properties between regenerated and native bone were similar.

CONCLUSIONS

Our study demonstrates an improved degradation profile and replacement of absorbed β-TCP with vascularized, organized bone through 3D printing and addition of an osteogenic agent. This novel additive manufacturing and tissue engineering protocol has implications to the future of craniofacial skeletal reconstruction as a safe and efficacious bone tissue engineering method.

Craniofacial Bone Tissue Engineering: Current Approaches and Potential Therapy

Craniofacial bone defects can result from various disorders, including congenital malformations, tumor resection, infection, severe trauma, and accidents. Successfully regenerating cranial defects is an integral step to restore craniofacial function. However, challenges managing and controlling new bone tissue formation remain. Current advances in tissue engineering and regenerative medicine use innovative techniques to address these challenges. The use of biomaterials, stromal cells, and growth factors have demonstrated promising outcomes in vitro and in vivo. Natural and synthetic bone grafts combined with Mesenchymal Stromal Cells (MSCs) and growth factors have shown encouraging results in regenerating critical-size cranial defects. One of prevalent growth factors is Bone Morphogenetic Protein-2 (BMP-2). BMP-2 is defined as a gold standard growth factor that enhances new bone formation in vitro and in vivo. Recently, emerging evidence suggested that Megakaryocytes (MKs), induced by Thrombopoietin (TPO), show an increase in osteoblast proliferation in vitro and bone mass in vivo. Furthermore, a co-culture study shows mature MKs enhance MSC survival rate while maintaining their phenotype. Therefore, MKs can provide an insight as a potential therapy offering a safe and effective approach to regenerating critical-size cranial defects.

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.

Pediatric Calvarial Tumors: 10 Years of Clinical Experience and Differences From the Literature

ABSTRACT

Very few studies have focused exclusively on pediatric calvarial tumors. These studies have primarily addressed the similarities of the cases with those reported in the literature, as opposed to their distinctive features. In contrast, the present study is the most detailed study conducted in the last 10 years that includes only pediatric calvarial tumors and highlights their differences according to the literature. A total of 31 patients with pediatric calvarial tumor surgically treated in our center between 2010 and 2020 were included in the study. The patients' files were analyzed retrospectively and 17 different preoperative, intraoperative, and postoperative parameters were determined and compared with previous studies. Except for the tumors causing lytic or sclerotic lesions, there was at least one distinguishing aspect of our series in all parameters. Despite the many distinctive features, the consensus in the treatment of calvarial tumors is to perform complete resection of the tumor and, if possible, remove some of the adjacent healthy bone. Considering the age factor, however, closure of the resulting bone defects with cranioplasty to address issues of cosmesis and intracranial pressure is yet another aspect of pediatric calvarial tumors, because pediatric cranioplasty has its own specific complications. Using intraoperative neuronavigation and performing tumor resection alone without additional craniectomy are also methods the authors use to prevent major bone defects.

Biomaterials with structural hierarchy and controlled 3D nanotopography guide endogenous bone regeneration

Biomaterials without exogenous cells or therapeutic agents often fail to achieve rapid endogenous bone regeneration with high quality. Here, we reported a class of three-dimensional (3D) nanofiber scaffolds with hierarchical structure and controlled alignment for effective endogenous cranial bone regeneration. 3D scaffolds consisting of radially aligned nanofibers guided and promoted the migration of bone marrow stem cells from the surrounding region to the center in vitro. These scaffolds showed the highest new bone volume, surface coverage, and mineral density among the tested groups in vivo. The regenerated bone exhibited a radially aligned fashion, closely recapitulating the scaffold's architecture. The organic phase in regenerated bone showed an aligned, layered, and densely packed structure, while the inorganic mineral phase showed a uniform distribution with smaller pore size and an even distribution of stress upon the simulated compression. We expect that this study will inspire the design of next-generation biomaterials for effective endogenous bone regeneration with desired quality.

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.

Endogenous Mechanisms of Craniomaxillofacial Repair: Toward Novel Regenerative Therapies

In the fields of oral and craniomaxillofacial surgery, regeneration of multiple tissue types-including bone, skin, teeth, and mucosal soft tissue-is often a desired outcome. However, limited endogenous capacity for regeneration, as well as predisposition of many tissues to fibrotic healing, may prevent recovery of normal form and function for patients. Recent basic science research has advanced our understanding of molecular and cellular pathways of repair in the oral/craniofacial region and how these are influenced by local microenvironment and embryonic origin. Here, we review the current state of knowledge in oral and craniomaxillofacial tissue repair/regeneration in four key areas: bone (in the context of calvarial defects and mandibular regeneration during distraction osteogenesis); skin (in the context of cleft lip/palate surgery); oral mucosa (in the context of minimally scarring repair of mucosal injuries); and teeth (in the context of dental disease/decay). These represent four distinct healing processes and outcomes. We will discuss both divergent and conserved pathways of repair in these contexts, with an eye toward fundamental mechanisms of regeneration vs. fibrosis as well as translational research directions. Ultimately, this knowledge can be leveraged to develop new cell-based and molecular treatment strategies to encourage bone and soft tissue regeneration in oral and craniomaxillofacial surgery.

Mesenchymal stem cells and three-dimensional-osteoconductive scaffold regenerate calvarial bone in critical size defects in swine

Craniofacial bones protect vital organs, perform important physiological functions, and shape facial identity. Critical‐size defects (CSDs) in calvarial bones, which will not heal spontaneously, are caused by trauma, congenital defects, or tumor resections. They pose a great challenge for patients and physicians, and significantly compromise quality of life. Currently, calvarial CSDs are treated either by allogenic or autologous grafts, metal or other synthetic plates that are associated with considerable complications. While previous studies have explored tissue regeneration for calvarial defects, most have been done in small animal models with limited translational value. Here we define a swine calvarial CSD model and show a novel approach to regenerate high‐quality bone in these defects by combining mesenchymal stem cells (MSCs) with a three‐dimensional (3D)‐printed osteoconductive HA/TCP scaffold. Specifically, we have compared the performance of dental pulp neural crest MSCs (DPNCCs) to bone marrow aspirate (BMA) combined with a 3D‐printed HA/TCP scaffold to regenerate bone in a calvarial CSD (>7.0 cm²). Both DPNCCs and BMA loaded onto the 3D‐printed osteoconductive scaffold support the regeneration of calvarial bone with density, compression strength, and trabecular structures similar to native bone. Our study demonstrates a novel application of an original scaffold design combined with DPNCCs or BMA to support regeneration of high‐quality bone in a newly defined and clinically relevant swine calvarial CSD model. This discovery may have important impact on bone regeneration beyond the craniofacial region and will ultimately benefit patients who suffer from debilitating CSDs.

OssDsign cranioplasty in children: a single-centre experience

INTRODUCTION

OssDsign have developed a new type of cranioplasty plate, consisting of calcium phosphate reinforced with titanium. Currently, there is little known about the cosmetic outcomes and infection rate when OssDsign cranioplasty plates are implanted into paediatric patients.

METHODS

A retrospective case series was performed to include all paediatric patients who received an OssDsign cranioplasty at a single centre, Sheffield Children's Hospital. The cosmetic outcomes were subjectively reported by the parents of the children.

RESULTS

We identified seven paediatric patients where OssDsign cranioplasty was performed. This included two bifrontal and five hemicranioplasties. However, there was failure to implant an OssDsign hemicranioplasty in one patient where a titanium plate was subsequently used. The median duration of follow-up was 15 months. The infection rate was zero. The parents of the patients who successfully received OssDsign cranioplasties were pleased with the cosmetic outcomes. There were cosmetic complaints from the parents of the one patient who received a titanium plate.

CONCLUSION

Our early experience with OssDsign cranioplasty in paediatric patients indicates that it may potentially be associated with a low rate of infection and good cosmetic outcomes.

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.

Dipyridamole-loaded 3D-printed bioceramic scaffolds stimulate pediatric bone regeneration in vivo without disruption of craniofacial growth through facial maturity

This study investigates a comprehensive model of bone regeneration capacity of dypiridamole-loaded 3D-printed bioceramic (DIPY-3DPBC) scaffolds composed of 100% beta-tricalcium phosphate (β -TCP) in an immature rabbit model through the time of facial maturity. The efficacy of this construct was compared to autologous bone graft, the clinical standard of care in pediatric craniofacial reconstruction, with attention paid to volume of regenerated bone by 3D reconstruction, histologic and mechanical properties of regenerated bone, and long-term safety regarding potential craniofacial growth restriction. Additionally, long-term degradation of scaffold constructs was evaluated. At 24 weeks in vivo, DIPY-3DPBC scaffolds demonstrated volumetrically significant osteogenic regeneration of calvarial and alveolar defects comparable to autogenous bone graft with favorable biodegradation of the bioactive ceramic component in vivo. Characterization of regenerated bone reveals osteogenesis of organized, vascularized bone with histologic and mechanical characteristics comparable to native bone. Radiographic and histologic analyses were consistent with patent craniofacial sutures. Lastly, through application of 3D morphometric facial surface analysis, our results support that DIPY-3DPBC scaffolds do not cause premature closure of sutures and preserve normal craniofacial growth. Based on this novel evaluation model, this DIPY-3DPBC scaffold strategy is a promising candidate as a safe, efficacious pediatric bone tissue engineering strategy.

Donor Site Changes in Bone Thickness, Volume, and Density Following Split Cranial Bone Graft Harvest

The calvarium can provide large amount of good quality corticocancellous autogenous bone graft. Although many studies have highlighted the advantages of the split cranial bone graft, there is no published work available in the literature about the fate of donor site of the split cranial bone graft. The present study was undertaken to assess the donor site as regards to the thickness, volume, and the density of the residual bone over a period of 12 months in the postoperative period. A total of 30 patients in the age group of 15 to 43 years were studied from January 2015 to January 2016. Postoperative computer tomography scans were taken at 2 weeks, 6 months, and 1 year postoperative to measure the bone thickness, volume, and density at the donor site of the split cranial bone graft harvest. The bone thickness at the donor site showed progressive increase in the thickness over the period of study and the average increase in thickness was about 12.4% at the end of 1 year. The average increase in volume at the donor site was of 2.65% after 12 months. Similarly, the average bone density increased by 3.7% at the end of 1 year. This prospective study conclusively proves that the residual bone at the donor site of the split cranial bone graft harvest site continues to grow in thickness and density over a period of 1 year.

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.

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.

Bone Transport Distraction Osteogenesis in the Reconstruction of Pediatric Posttraumatic Calvarial Defects

Supplemental Digital Content is available in the text.

Reconstruction of posttraumatic calvarial bone defects in pediatric patients is a challenge due to the growing brain and limited autogenous bone supply. Traditional techniques such as split calvarial and particulate bone grafts are associated with prolonged operative time and significant blood loss, which is a major concern in children under the age of 3 years. Bone transport distraction osteogenesis has proven efficacy and safety in the reconstruction of other craniofacial deformities. This procedure is less invasive and requires shorter operative times and hospital stay. We report our experience with 2 cases of bone transport distraction osteogenesis for the reconstruction of large posttraumatic calvarial defects in pediatric patients.

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.

Interleukin-10 Does Not Augment Osseous Regeneration in the Scarred Calvarial Defect Achieved with Low-Dose Biopatterned BMP2

BACKGROUND

Large calvarial defects represent a major reconstructive challenge, as they do not heal spontaneously. Infection causes inflammation and scarring, further reducing the healing capacity of the calvaria. Bone morphogenetic protein-2 (BMP2) has been shown to stimulate osteogenesis but has significant side effects in high doses. BMP2 has not been tested in combination with antiinflammatory cytokines such as interleukin-10.

METHODS

Sixteen New Zealand White rabbits underwent 15 × 15-mm flap calvarectomies. The flap was incubated in Staphylococcus aureus and replaced, and infection and scarring were allowed to develop. The flap was subsequently removed and the wound débrided. A 15 × 15-mm square of acellular dermal matrix biopatterned with low-dose BMP2, interleukin-10, or a combination was implanted. Computed tomographic scans were taken over 42 days. Rabbits were then killed and histology was performed.

RESULTS

Defects treated with BMP2 showed significantly (p < 0.05) greater osseous regeneration than untreated controls. Interleukin-10 did not significantly augment the healing achieved with BMP2, and interleukin-10 alone did not significantly increase healing compared with controls. Histology showed evidence of bone formation in defects treated with BMP2. Untreated controls and defects treated with interleukin-10 alone showed only fibrous tissue in the defect site.

CONCLUSIONS

Low-dose BMP2 delivered directly to the scarred calvarial defect augments bony healing. Interleukin-10 at the dose applied did not significantly augment healing alone or in combination with BMP2. Healing had not finished at 42 days and analysis at later time points or the use of higher doses of BMP2 may yield greater healing.

Reconstruction of a Calvarial Wound Complicated by Infection: Comparing the Effects of Biopatterned Bone Morphogenetic Protein 2 and Vascular Endothelial Growth Factor

Bone morphogenetic protein 2 (BMP2) bioprinted on biological matrix induces osseous regeneration in large calvarial defects in rabbits, both uncomplicated and scarred. Healing in unfavorable defects scarred from previous infection is decreased due in part to the lack of vascularity. This impedes the access of mesenchymal stem cells, key to osseous regeneration and the efficacy of BMP2, to the wound bed. The authors hypothesized that bioprinted vascular endothelial growth factor (VEGF) would augment the osseous regeneration achieved with low dose biopatterned BMP2 alone. Thirteen New Zealand white rabbits underwent subtotal calvariectomy using a dental cutting burr. Care was taken to preserve the underlying dura. A 15 mm × 15 mm flap of bone was cut away and incubated in a 1 × 108 cfu/mL planktonic solution of S aureus before reimplantation. After 2 weeks of subsequent infection the flap was removed and the surgical wound debrided followed by 10 days of antibiotic treatment. On postoperative day 42 the calvarial defects were treated with acellular dermal matrix bioprinted with nothing (control), VEGF, BMP2, BMP2/VEGF combined. Bone growth was analyzed with serial CT and postmortem histology. Defects treated with BMP2 (BMP2 alone and BMP2/VEGF combination) showed significantly greater healing than control and VEGF treated defect (P < 0.5). Vascular endothelial growth factor treated defect demonstrated less healing than control and VEGF/BMP2 combination treatments achieved less healing than BMP2 alone though these differences were nonsignificant. Low dose BMP2-patterned acellular dermal matrix improves healing of scarred calvarial defects. Vascular endothelial growth factor at the doses applied in this study failed to increase healing.

Quantitative and qualitative analysis of bone flap resorption in patients undergoing cranioplasty after decompressive craniectomy

OBJECTIVE: Autologous bone cranioplasty after decompressive craniectomy entails a notable burden of difficult postoperative complications, such as infection and bone flap resorption (BFR), leading to mechanical failure. The prevalence and significance of asymptomatic BFR is currently unclear. The aim of this study was to radiologically monitor the long-term bone flap survival and bone quality change in patients undergoing autologous cranioplasty. METHODS: The authors identified all 45 patients who underwent autologous cranioplasty at Oulu University Hospital, Finland, between January 2004 and December 2014. Using perioperative and follow-up CT scans, the volumes and radiodensities of the intact bone flap prior to surgery and at follow-up were calculated. Relative changes in bone flap volume and radiodensity were then determined to assess cranioplasty survival. Sufficient CT scans were obtainable from 41 (91.1%) of the 45 patients. RESULTS: The 41 patients were followed up for a median duration of 3.79 years (25th and 75th percentiles = 1.55 and 6.66). Thirty-seven (90.2%) of the 41 patients had some degree of BFR and 13 (31.7%) had a remaining bone flap volume of less than 80%. Patients younger than 30 years of age had a mean decrease of 15.8% in bone flap volume compared with the rest of the cohort. Bone flap volume was not found to decrease linearly with the passing of time, however. The effects of lifestyle factors and comorbidities on BFR were nonsignificant. CONCLUSIONS: In this study BFR was a very common phenomenon, occurring at least to some degree in 90% of the patients. Decreases in bone volume were especially prominent in patients younger than 30 years of age. Because the progression of resorption during follow-up was nonlinear, routine follow-up CT scans appear unnecessary in monitoring the progression of BFR; instead, clinical follow-up with mechanical stability assessment is advised. Partial resorption is most likely a normal physiological phenomenon during the bone revitalization process.

Custom-made hydroxyapatite for cranial repair in a specific pediatric age group (7-13 years old): a multicenter post-marketing surveillance study

BACKGROUND

CustomBone Service (CBS) is a patient-specific, biocompatible, and osteoconductive device made of porous hydroxyapatite, indicated for cranial reconstruction in adults and children. Adult literature data report a failure rate of about 8%. The aim of this Post-Marketing Surveillance study is to verify the hypothesis that CBS in children aged 7-13 years old shows a failure rate not superior to adults.

MATERIALS AND METHODS

Inclusion criteria were age at implantation ranging 7-13 years old, with at least 1 year elapsed from the date of surgery. The degree of satisfaction of surgeons and patients was assessed.

RESULTS

Data about 76 implants in 67 patients (M:F = 41:26) were obtained from 28 centers across 7 European countries. The mean age at surgery was 10.03 ± 1.72 years, with age stratification almost equally distributed. Fifty-nine subjects received one CBS, 7 subjects two and one subject received three CBS. Main etiologies were trauma (60.5%), malformation (11.8%), bone tumor (10.5%), and cerebral tumor (7.9%). Main indications to CBS were decompression (47.4%), autologous bone resorption (18.4%), tumor resection (11.8%), malformation (9.2%), comminuted fracture (5.3%), and other materials rejection (5.3%). Main implantation sites were fronto-parieto-temporal (26.3%), parietal (23.7%), frontal (11.8%), fronto-temporal (10.5%), and parieto-temporal (7.9%). CBS was chosen as first line of treatment in 63.1% of the cases. Mean follow-up was about 36 months. Eleven adverse events (14.5%) were reported in nine devices. Five CBS required explantation (three cases of infection, one fracture, and one mobilization). Failure rate was 6.58%, which is statistically not superior to the explantation rate recorded in adults (two-sided 95%, CI 2.2-14.7%). Satisfaction of surgeons and patients was of about 95%.

CONCLUSION

CBS is a safe and effective solution for cranial repair in pediatric patients. In particular, over the age of 7, CBS shows a rate of failure as low as in adults.

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.

Repair of Occipital Bone Defects in Neurofibromatosis Type 1 by Means of CAD/CAM Prefabricated Titanium Plates

Certain skeletal defects may develop in neurofibromatosis type 1 (NF1), a common tumor-suppressor syndrome, such as cranial lesions confined to the lambdoid suture region. Here, we report on the repair of osseous defects of occipital bone in a NF1 patient with history of skull trauma and tumorous hemorrhage. Computer-aided design and computer-aided manufacturing (CAD/CAM)-assisted devices were applied to safely close the bone defects. The variable phenotype of NF1 in the occipital skull region is discussed and a brief review is presented on NF1-related therapies for tumors and malformations of the occipitoparietal skull region.

A Growth-Accommodating Implant for Paediatric Applications

Medical implants of fixed size cannot accommodate normal tissue growth in children, and often require eventual replacement or in some cases removal, leading to repeated interventions, increased complication rates and worse outcomes. Implants that can correct anatomic deformities and accommodate tissue growth remain an unmet need. Here, we report the design and use of a growth-accommodating device for paediatric applications that consists of a biodegradable core and a tubular braided sleeve, with inversely related sleeve length and diameter. The biodegradable core constrains the diameter of the sleeve, and gradual core degradation following implantation enables sleeve and overall device elongation in order to accommodate tissue growth. By using mathematical modeling and ex vivo experiments using harvested swine hearts, we demonstrate the predictability and tunability of the behavior of the device for disease- and patient-specific needs. We also used the rat tibia and the piglet heart valve as two models of tissue growth to demonstrate that polymer degradation enables device expansion and growth accommodation in vivo.

* 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.

Osteointegration in cranial bone reconstruction: a goal to achieve

BACKGROUND

The number of cranioplasty procedures is steadily increasing, mainly due to growing indications for decompressive procedures following trauma, tumor or malformations. Although autologous bone is still considered the gold standard for bone replacement in skull, there is an urgent need for synthetic porous implants able to guide bone regeneration and stable reconstruction of the defect. In this respect, hydroxyapatite scaffolds with highly porous architecture are very promising materials, due to the excellent biocompatibility and intrinsic osteogenic and osteoconductive properties that enable deep bone penetration in the scaffold and excellent osteointegration. Osteointegration is here highlighted as a key aspect for the early recovery of bone-like biomechanical performance, for which custom-made porous hydroxyapatite scaffolds play a major role. There are still very few cases documenting the clinical performance of porous scaffolds following cranioplasty.

METHODS

This paper reports 2 clinical cases where large cranial defects were repaired by the aid of porous hydroxyapatite scaffolds with customized shapes and 3D profiles (Fin-Ceramica, Faenza, Italy).

RESULTS

In the long term (i.e., after 2 years), these scaffolds yielded extensive osteointegration through formation and penetration of new organized bone.

CONCLUSIONS

These results confirm that porous hydroxyapatite scaffolds, uniquely possessing chemico-physical and morphological/mechanical properties very close to those of bone, can be considered as a tool to provide effective bone regeneration in large cranial bone defects. Moreover, they may potentially prevent most of the postsurgical drawbacks related to the use of metal or plastic implants.