Faculty Bibliography

BACKGROUND/PURPOSE/OBJECTIVE:This paper describes the changes in maxillary arch morphology in infants with bilateral cleft lip and palate (BCLP) following nasoalveolar molding (NAM) and with follow up to assess the need for secondary alveolar bone grafting (ABG) and premaxillary repositioning surgery at preadolescence. METHODS/DESCRIPTION/UNASSIGNED:Treatment records of infants with BCLP treated with NAM between 2003 and 2013 were reviewed. Patients with complete BCLP who underwent NAM and had complete sets of maxillary casts at T 0 pre-NAM (mean = 27 days), T 1 post-NAM (mean = 6 months and 5 days), and T 2 before palate surgery (mean = 11 months and 15 days) were included. The sample comprised 23 infants (18 male, 5 female). Casts were digitized and analyzed using three dimensional software. The need for secondary ABG and premaxillary repositioning surgery was assessed at preadolescent follow-up (mean = 8.3 years). RESULTS:Cleft width was reduced on average by 4.73 mm (SD ± 3.15 mm) and 6.56 mm (SD ± 4.65) on the right and left sides, respectively. At T 1, 13 (56.52%) patients underwent bilateral gingivoperiosteoplasty (GPP), 8 (34.78%) patients unilateral GPP, and 2 patients (8.7%) did not undergo GPP. 34/46 clefts sites (73.91%) underwent GPP while 12 (26.08%) did not. At preadolescent follow-up of 19 patients, 7 patients (36.84%) did not need ABG on either side, 8 (42.10%) needed ABG on 1 side, and 4 (21.05%) needed ABG on both sides. None of the patients needed premaxillary repositioning surgery. CONCLUSIONS:Nasoalveolar molding treatment significantly improves the position of the premaxilla before primary repair, and there is a significant reduction in the need for secondary ABG and premaxillary repositioning surgery at preadolescence.

Agnathia-otocephaly complex (AOC), a first branchial arch defect, is characterized by mandibular hypoplasia or aplasia, ear abnormalities, microstomia, and macroglossia and is a rare and often fatal diagnosis. Herein, the technical considerations and details of mandibular reconstruction using virtual surgical planning (VSP) and a vascularized free fibula flap for further mandibular reconstruction in a 10-year-old boy are presented. The patient's preoperative examination was consistent with agnathia (absence of mandibular symphysis, bilateral mandibular bodies, condyles, coronoids, rami, and temporomandibular joint), severe microstomia, and a Tessier # 30 cleft (maintained to allow oral access until later in treatment). Virtual surgical planning was utilized to plan a 3-segment fibula for the reconstruction of the mandibular symphysis and bilateral body segments, and bilateral costochondral grafts were planned for the rami. To the authors' knowledge, this represents the first application of virtual surgical planning for mandibular reconstruction with a vascularized free fibula flap in a pediatric patient with severe agnathia-otocephaly complex.

Sphenoorbital meningiomas are a challenge to access and reconstruct. Although there is much neurosurgical literature on resection of such tumors, there is little discussion on the best methods for the reconstruction of consequent defects, which are often extensive due to large areas of hyperostosis requiring resection. We performed a retrospective analysis of patients who underwent resection and reconstruction of a sphenoorbital meningioma by the senior authors (C.S. and D.A.S.) between 2010 and 2020. Surgical access in all cases included an orbitozygomatic osteotomy. The study cohort consisted of 23 patients (20 female, 3 male) with an average age of 50 (range: 37-72) years at the time of surgery. Most patients had progressive proptosis before the ablative operation. Orbital reconstruction was with a combined titanium-Medpor implant in 18 patients, split calvarial bone graft in 3 patients, and a Medpor implant in 2 patients. Calvarial reconstruction was performed with titanium mesh in 21 patients, split calvarial bone graft and titanium mesh in 1 patient, and craniotomy bone and titanium plate in 1 patient. Reoperation was required in 7 patients due to hypoglobus or enophthalmos (N=2), orbital implant malposition (N=1), abscess (N=1), pain (N=1), intracranial fat graft modification (N=1), and soft tissue deformities (N=2). Our experience demonstrates that sphenoorbital meningiomas can require broad areas of resection of the skull base and calvarium and necessitate comprehensive reconstruction of the anterior cranial fossa, orbital walls, and cranium. Collaboration between craniofacial surgeons and neurosurgeons can achieve optimal results.

Lambdoid craniosynostosis (CS) is a congenital anomaly resulting from premature fusion of the cranial suture between the parietal and occipital bones. Predominantly sporadic, it is the rarest form of CS and its genetic etiology is largely unexplored. Exome sequencing of 25 kindreds, including 18 parent-offspring trios with sporadic lambdoid CS, revealed a marked excess of damaging (predominantly missense) de novo mutations that account for ~ 40% of sporadic cases. These mutations clustered in the BMP signaling cascade (P = 1.6 × 10^-7), including mutations in genes encoding BMP receptors (ACVRL1 and ACVR2A), transcription factors (SOX11, FOXO1) and a transcriptional co-repressor (IFRD1), none of which have been implicated in other forms of CS. These missense mutations are at residues critical for substrate or target sequence recognition and many are inferred to cause genetic gain-of-function. Additionally, mutations in transcription factor NFIX were implicated in syndromic craniosynostosis affecting diverse sutures. Single cell RNA sequencing analysis of the mouse lambdoid suture identified enrichment of mutations in osteoblast precursors (P = 1.6 × 10^-6), implicating perturbations in the balance between proliferation and differentiation of osteoprogenitor cells in lambdoid CS. The results contribute to the growing knowledge of the genetics of CS, have implications for genetic counseling, and further elucidate the molecular etiology of premature suture fusion.

The calvaria (top part of the skull) is made of pieces of bone as well as multiple soft tissue joints called sutures. The latter is crucial to the growth and morphogenesis of the skull, and thus a loss of calvarial sutures can lead to severe congenital defects in humans. During embryogenesis, the calvaria develops from the cranial mesenchyme covering the brain, which contains cells originating from the neural crest and the mesoderm. While the mechanism that patterns the cranial mesenchyme into bone and sutures is not well understood, function of Lmx1b, a gene encoding a LIM-domain homeodomain transcription factor, plays a key role in this process. In the current study, we investigated a difference in the function of Lmx1b in different parts of the calvaria using neural crest-specific and mesoderm-specific Lmx1b mutants. We found that Lmx1b was obligatory for development of the interfrontal suture and the anterior fontanel along the dorsal midline of the skull, but not for the posterior fontanel over the midbrain. Also, Lmx1b mutation in the neural crest-derived mesenchyme, but not the mesoderm-derived mesenchyme, had a non-cell autonomous effect on coronal suture development. Furthermore, overexpression of Lmx1b in the neural crest lineage had different effects on the position of the coronal suture on the apical part and the basal part. Other unexpected phenotypes of Lmx1b mutants led to an additional finding that the coronal suture and the sagittal suture are of dual embryonic origin. Together, our data reveal a remarkable level of regional specificity in regulation of calvarial development.

BACKGROUND:The bulk metallic glass (BMG), Pd79Ag3.5P6Si9.5Ge2, has a high fracture toughness and has been found to accommodate post-yield stress, unlike most other BMG. Moreover, due to its greater noble gas composition it has a intrinsic corrosion resistance, ideal for dental and orthopedic implants. OBJECTIVE:This present study aimed to evaluate the in vivo application of Pd79Ag3.5P6Si9.5Ge2 in a large translational sheep model to assess its efficacy to be utilized as an endosteal device. METHODS:Twelve implants in the form of cylindrical rods (3 mm in diameter) were produced through rapid quenching. Each sheep (n = 12) received one osteotomy in the mandibular region using rotary instrumentation, which was subsequently filled with Pd79Ag3.5P6Si9.5Ge2. After 6- and 24-weeks the animals were euthanized, and samples collected en bloc to conduct histomorphometric analysis. The level/degrees of osseointegration were assessed through bone-to-implant contact (BIC). RESULTS:Favorable BIC was observed with fibrous connective tissue layers at both 6- and 24-weeks. Bone along with interfacial remodeling was observed in proximity with the metallic glass surface at 6 weeks with higher degrees of bone organization being observed at the later healing time, 24 weeks. CONCLUSIONS:The introduced BMG revealed potential to serve as an alternative biomaterial to commonly used Ti alloys given its unique combination of toughness and strength.

BACKGROUND:While autografts to date remain the "gold standard" for bone void fillers, synthetic bone grafts have garnered attention due to their advantages such as ability to be tailored in terms of its physical and chemical properties. Bioactive glass (BG), an inorganic material, has the capacity to form a strong bond with bone by forming a bone-like apatite surface, enhancing osteogenesis. Coupled with three-dimensional printing it is possible to maximize bone regenerative properties of the BG. OBJECTIVE:The objective of this study was to synthesize and characterize 3D printed mesoporous bioactive glass (MBG), BG 45S5, and compare to β-Tricalcium phosphate (β-TCP) based scaffolds; test cell viability and osteogenic differentiation on human osteoprogenitor cells in vitro. METHODS:MBG, BG 45S5, and β-TCP were fabricated into colloidal gel suspensions, tested with a rheometer, and manufactured into scaffolds using a 3D direct-write micro-printer. The materials were characterized in terms of microstructure and composition with Thermogravimetric Analyzer/Differential Scanning Calorimeter (TGA/DSC), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Micro-Computed Tomography (μ-CT), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and Mattauch-Herzog-Inductively Coupled Plasma-Mass Spectrometry (MH-ICP-MS). RESULTS:Scaffolds were tested for cell proliferation and osteogenic differentiation using human osteoprogenitor cells. Osteogenic media was used for differentiation, and immunocytochemistry for osteogenic markers Runx-2, Collagen-I, and Osteocalcin. The cell viability results after 7 days of culture yielded significantly higher (p < 0.05) results in β-TCP scaffolds compared to BG 45S5 and MBG groups. CONCLUSION/CONCLUSIONS:All materials expressed osteogenic markers after 21 days of culture in expansion and osteogenic media.

A 3-year-old patient sustained a tripartite mandibular fracture, including bilateral condylar fractures with lateral dislocation of the left condyle and symphyseal fracture. Staged lower jaw reconstruction with closed reduction of the laterally dislocated condyle, transfacial pinning between the mandibular angles, MMF using circummandibular wiring and intermaxillary fixation screws was performed.