Mixed reality guided advancement osteotomies in congenital craniofacial malformations.

This paper describes our experience with mixed reality (MR) intra-operative guides in patients with congenital craniofacial malformations. The first case was a patient with bilateral hemifacial microsomia. He underwent bilateral mandibular distraction osteogenesis. Pre-operative virtual planning determined the sites of osteotomy. Standard Tessellation Language (STL) files of mandibular 3D models with osteotomy sites were uploaded onto the HoloLens 2® MR glasses (Microsoft®, Washington, USA). The superimposed hologram denoted the osteotomy line. This was validated with a physical cutting guide. The second case was a patient with Crouzon's syndrome. A modified Lefort 2 advancement was performed to correct his midfacial deficiency. Pre-operative virtual planning was performed to determine the sites of osteotomies. Superimposed hologram using the Hololens 2® denoted the osteotomy sites. These were validated with a conventional intra-operative navigation system. The advantages of using MR include its immediate availability for use; saving time and costs. MR allows surgeons to maintain continuous line-of-sight within the operative field. A robust registration system is required to anchor the hologram onto the patient's skull without variations in hologram position from different angles of gaze. MR has the potential to function as an adjunct and possible replacement for conventional cutting guides and intra-operative navigation. LAY SUMMARY: We describe the use of mixed reality intra-operative guides in patients with congenital craniofacial malformations. Our experience shows the potential MR has as an adjunct and possible replacement for conventional cutting guides and intra-operative navigation.

The Use of E-Learning in Peyton's 4-Step Approach: Evaluation of Facial Computed Tomography Scans.

Imparting procedural skills is challenging. Peyton's approach is an effective face-to-face teaching technique increasingly used in complex skills training. Institutions are beginning to incorporate online training as part of their procedural curriculum. We developed E-Peyton's to employ Peyton's approach through an electronic learning platform. The efficacy of E-Peyton's approach in teaching the interpretation of facial computed tomography (CT) scans is evaluated in this study. Naïve learners (n=41) were randomized into 2 groups based on teaching techniques employed: E-Peyton's (n=20) and Peyton's (n=21) approaches. The distance between the infraorbital margin and the posterior ledge was measured using a 3-part standardized measuring protocol on OsiriX. Twenty measurements were assessed for accuracy against the benchmark (±2 mm) at week 0 and week 1. Training durations were compared. Questionnaires were administered before and after the study to identify learners' acceptance of teaching techniques and their confidence in interpreting facial CT scans. Learners in both teaching techniques had comparable skills retention. Gap scores indicate significant improvement in learner's confidence levels regardless of teaching technique (P<0.05). Both teaching techniques were well-accepted by learners. E-Peyton's and Peyton's approaches required a similar training duration. The COVID-19 pandemic highlights the importance of effective remote learning platforms. E-Peyton's approach is comparable to that of Peyton's in all areas of assessment. E-Peyton's approach effectively automates Peyton's approach, allowing for standardized, high-quality procedural skills training while reducing manpower burden.

Postoperative Scar Management Protocol for Asian Patients.

BACKGROUND: Postoperative scar formation remains a morbidity for patients even with the advent of minimally invasive techniques. Furthermore, the significant difference between the Asian and Caucasian skin results in poorer postoperative scar outcomes in Asians, supporting the need for an evidence-based scar management protocol. METHODS: Following a literature review of the PubMed and the Cochrane databases over the past 10 years, we constructed a novel postoperative scar management protocol for the Asian skin, utilized in a Singaporean tertiary healthcare institution. RESULTS: We describe a timeline-based scar protocol from the point of skin closure to a minimum of 1 year of follow-up. We support the use of intraoperative botulinum toxin for selected high-risk individuals upon skin closure with a follow-up regimen in the postoperative setting. For recalcitrant keloids, we have described a multimodal therapy comprising elements of intralesional steroids, botulinum toxin, lasers, surgery, and radiotherapy. CONCLUSIONS: A consolidated postoperative scar management protocol provides the necessary guidance for improved scar outcomes in the Asian skin. There is inherent potential in expanding the protocol to include post-traumatic and burn wounds or support other skin types including the Caucasian skin. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Straight-segment mandibulectomy: a reproducible porcine mandibular critical-size defect model.

Porcine mandibular defect models are commonly used for the preclinical evaluation of reconstruction techniques. Existing studies vary in technique, complexity, and postoperative outcomes. The procedures are complex and often described without sufficient detail. We describe in detail a simple and reproducible method for creating a critical-size mandibular defect in a porcine model. Seven hemimandibular critical size defects were created in five male Yorkshire-Landrace pigs, three with unilateral defects and two with bilateral defects. A transverse incision was made over the mandibular body. Periosteum was incised and elevated to expose the mandibular body and a critical-size defect of 30 × 20 mm created using an oscillating saw. The implant was inserted and fixed with a titanium reconstruction plate and bicortical locking screws, and the wound closed in layers with resorbable sutures. Intraoral contamination was avoided. Dentition was retained and the mental nerve and its branches preserved. The marginal mandibular nerve was not encountered during dissection. All pigs retained normal masticatory function, and there were no cases of infection, wound breakdown, haematoma, salivary leak, or implant-related complications. The procedure can be performed bilaterally on both hemimandibles without affecting load-bearing function. All pigs survived until the end point of three months. Postoperative computed tomographic scans and histology showed new bone formation, and a three-point bend test showed the restoration of biomechanical strength. Straight-segment mandibulectomy is a simple and reproducible method for the creation of critical-size mandibular defects in a porcine model, simulating a load-bearing situation.

Prophylactic Intraoperative Nasolacrimal Duct Intubation in Surgical Treatment of Facial Fractures-Is There a Role?

Nasolacrimal duct (NLD) damage is associated in the majority of type II and III naso-orbito-ethmoid (NOE) fractures. 1 Our study aims to investigate the efficacy and safety of prophylactic NLD intubation in the setting of facial fractures, by comparing incidence of postoperative epiphora and wound infection. A retrospective matched control study was conducted on all patients with surgically treated facial fractures from 2008 to 2013 ( n = 280) (IRB ref number: DSRB 2013/01198). Patients with the following fracture types were included: NOE ( n = 16), frontal sinus ( n = 2), Le Fort II/III ( n = 8), and > 1 type ( n = 48). All patients in this study were included with the intention to treat. The study group comprised patients who were intubated, while the control group patients were not intubated. Each group had 37 patients matched for age, gender, fracture type, and injury type. A single oculoplastic surgeon skilled in lacrimal surgery performed the procedure for all intubated patients. Patients with more severe and complex facial fractures were intubated with bicanalicular Crawford stents. Postoperative epiphora and infective complications (both facial wound and dacryocystitis) were assessed at 1, 3, 6, and 12 months. There was no significant difference in incidence of either postoperative epiphora ( p = 0.152) or wound infection ( p = 0.556) comparing both groups. Reduced incidence of postoperative epiphora in the study group is statistically not significant and does not support the need for prophylactic intubation. If radiographic evidence of NLD disruption or regurgitation seen on syringing on the NLD intraoperatively is present, intubation is safe and efficacious only if performed by an expert.

The superior lateral genicular artery flap for reconstruction of knee and proximal leg defects.

Reconstruction of defects around the knee region requires thin and pliable skin. The superior lateral genicular artery (SLGA) flap provides an excellent alternative to muscle-based flaps. The anatomy and the surgical techniques of the SLGA flap were reviewed and the results of cases using the SLGA flap for coverage of knee and proximal leg defects were analyzed. SLGA flaps were performed in two cases and followed up for at least 6 months. Twelve articles on the use of the SLGA flap were also identified. A review of 39 cases showed that the mean diameter of the perforator supplying the skin of the flap was 1.04 mm, while the mean diameter of the SLGA at its origin was 1.78 mm. The mean length of the pedicle measured from the origin of the popliteal artery was 7.44 cm. The average dimensions of the flap were 14.8×6.6 cm with primary closure of the donor site in 61.5% of cases. Of these cases, 38.5% were due to trauma, 23.1% were post-burn complications, 12.8% were defects after resection of tumors, and 10.3% were for ulcers post-bursectomy. The most common complication was flap tip necrosis. All studies reported favorable outcomes with complete wound healing.

Use of Intraoperative Frozen Section in the Surgical Management of Patients with Nonmelanoma Skin Cancer.

BACKGROUND: Intraoperative frozen section (IFS) is often utilised in the surgical treatment of nonmelanocytic skin cancer (NMSC) in sensitive facial regions when Mohs micrographic surgery (MMS) is not available. OBJECTIVE: To compare the outcome of NMSC patients with excision performed with and without IFS. MATERIALS AND METHODS: A retrospective, single-centre study was performed on all patients who had undergone resection of NMSC with and without IFS control at the National University Hospital (NUH) from 2010 to 2015. RESULTS: 116 patients were recruited, of which 86 had IFS and 30 did not. The complete excision rate of patients with IFS was higher at 87.2% (p=0.0194), need for secondary operation was lower at 1.2% (p=0.005), and need for postsurgery radiotherapy or chemotherapy was lower at 1.2% (p=0.001). The average duration of surgery in patients who underwent IFS was 95.4 minutes compared to 70.1 minutes in cases which did not undergo IFS. CONCLUSION: Our study showed an increased complete excision rate and reduced need for secondary surgeries and adjuvant therapy in patients with IFS. However, a longer operative duration was required. Use of IFS may be useful in patients with NMSC lesions in sensitive regions requiring complex reconstruction after tumour excision.

The Polyamine Regulator AMD1 Upregulates Spermine Levels to Drive Epidermal Differentiation.

Maintaining tissue homeostasis depends on a balance between cell proliferation, differentiation, and apoptosis. Within the epidermis, the levels of the polyamines putrescine, spermidine, and spermine are altered in many different skin conditions, yet their role in epidermal tissue homeostasis is poorly understood. We identify the polyamine regulator, Adenosylmethionine decarboxylase 1 (AMD1), as a crucial regulator of keratinocyte (KC) differentiation. AMD1 protein is upregulated on differentiation and is highly expressed in the suprabasal layers of the human epidermis. During KC differentiation, elevated AMD1 promotes decreased putrescine and increased spermine levels. Knockdown or inhibition of AMD1 results in reduced spermine levels and inhibition of KC differentiation. Supplementing AMD1-knockdown KCs with exogenous spermidine or spermine rescued aberrant differentiation. We show that the polyamine shift is critical for the regulation of key transcription factors and signaling proteins that drive KC differentiation, including KLF4 and ZNF750. These findings show that human KCs use controlled changes in polyamine levels to modulate gene expression to drive cellular behavior changes. Modulation of polyamine levels during epidermal differentiation could impact skin barrier formation or can be used in the treatment of hyperproliferative skin disorders.

Comparative Craniofacial Bone Regeneration Capacities of Mesenchymal Stem Cells Derived from Human Neural Crest Stem Cells and Bone Marrow.

Most craniofacial bones are derived from the ectodermal germ layer via neural crest stem cells, which are distinct from mesoderm-derived long bones. However, current craniofacial bone tissue engineering approaches do not account for this difference and utilize mesoderm-derived bone marrow mesenchymal stem cells (BM-MSCs) as a paradigm cell source. The effect of the embryonic origin (ontogeny) of an MSC population on its osteogenic differentiation potential and regenerative ability still remains unresolved. To clarify the effects of MSC ontogeny on bone regenerative ability, we directly compared the craniofacial bone regenerative abilities of an ecto-mesenchymal stem cell (eMSC) population, which is derived from human embryonic stem cells via a neural crest intermediate, with mesodermal adult BM-MSCs. eMSCs showed comparable osteogenic and chondrogenic ability to BM-MSCs in 2-D in vitro culture, but lower adipogenic ability. They exhibited greater proliferation than BM-MSCs and comparable construct mineralization in a well-established 3-D polycaprolactone-tricalcium phosphate (PCL-TCP) scaffold system in vitro. eMSC-derived 3D osteogenic constructs were maintained for longer in a proliferative osteoblast state and exhibited differential levels of genes related to fibroblast growth factor (FGF) signaling compared to BM-MSCs. Although both eMSC and BM-MSC-seeded scaffold constructs could promote bone regeneration in a rat calvarial defect model, eMSC-derived osseous constructs had significantly higher cellularity due to increased number of proliferative (Ki67+) cells than those seeded with BM-MSCs, and exhibited enhanced new bone formation in the defect area as compared to untreated controls. Overall, our study demonstrates the potential of human eMSCs for future clinical use in craniofacial regeneration applications and indicates the importance of considering MSC origin when selecting an MSC source for regenerative applications.

Planes of Reference for Orbital Fractures: A Technique for Reproducible Measurements of the Orbit on Computed Tomography Scans.

PURPOSE: Planes of reference for orbital fractures (PROF) was developed to standardize measurements made on orbital computed tomography scans. This study describes the use of PROF in determining the location along the orbital floor where the posterior ledge (PL) most commonly occurs. The transverse inclination and anterior-posterior inclination of the orbital floor will also be measured. METHODS: This study evaluates 104 patients with unilateral orbital fracture. Fifty-two patients had intact infra-orbital margin (IM) and 52 had fractured IM. Facial computed tomography scans were analyzed using Osirix Lite Digital Imaging and Communications in Medicine Viewer version 7.0.1 (Geneva, Switzerland). All skull positions were standardized by orientation according to Frankfurt and mid-sagittal planes. Measurements of distance of PL from IM were determined in the sagittal view. Measurements of the inclination of the orbital floor in the transverse and anterior-posterior sections were done on the coronal and sagittal views respectively. RESULTS: For patients with intact and fractured IM, the mean distances of PL from IM were 22.1 mm (95% CI: 21.2-23.0) and 21.1 mm (95% CI: 20.2-21.9) respectively. Mean transverse inclination was 19.4° (95% CI: 18.3-20.5). Mean anterior-posterior inclination was 15.5° (95% CI: 14.5-16.5). CONCLUSION: Planes of reference for orbital fractures is a simple and effective method to acquire standardized measurements of the orbital cavity on computed tomography scans. Understanding the commonest location of PL and the orientation of the orbital floor in 3-dimensional space allows surgeons to perform dissection with greater precision.

Backward Planning a Craniomaxillofacial Trauma Curriculum for the Surgical Workforce in Low-Resource Settings.

BACKGROUND: Trauma is a significant contributor to global disease, and low-income countries disproportionately shoulder this burden. Education and training are critical components in the effort to address the surgical workforce shortage. Educators can tailor training to a diverse background of health professionals in low-resource settings using competency-based curricula. We present a process for the development of a competency-based curriculum for low-resource settings in the context of craniomaxillofacial (CMF) trauma education. METHODS: CMF trauma surgeons representing 7 low-, middle-, and high-income countries conducted a standardized educational curriculum development program. Patient problems related to facial injuries were identified and ranked from highest to lowest morbidity. Higher morbidity problems were categorized into 4 modules with agreed upon competencies. Methods of delivery (lectures, case discussions, and practical exercises) were selected to optimize learning of each competency. RESULTS: A facial injuries educational curriculum (1.5 days event) was tailored to health professionals with diverse training backgrounds who care for CMF trauma patients in low-resource settings. A backward planned, competency-based curriculum was organized into four modules titled: acute (emergent), eye (periorbital injuries and sight preserving measures), mouth (dental injuries and fracture care), and soft tissue injury treatments. Four courses have been completed with pre- and post-course assessments completed. CONCLUSIONS: Surgeons and educators from a diverse geographic background found the backward planning curriculum development method effective in creating a competency-based facial injuries (trauma) course for health professionals in low-resource settings, where contextual aspects of shortages of surgical capacity, equipment, and emergency transportation must be considered.

Polyamine Regulator AMD1 Promotes Cell Migration in Epidermal Wound Healing.

Wound healing is a dynamic process involving gene-expression changes that drive re-epithelialization. Here, we describe an essential role for polyamine regulator AMD1 in driving cell migration at the wound edge. The polyamines, putrescine, spermidine, and spermine are small cationic molecules that play essential roles in many cellular processes. We demonstrate that AMD1 is rapidly upregulated following wounding in human skin biopsies. Knockdown of AMD1 with small hairpin RNAs causes a delay in cell migration that is rescued by the addition of spermine. We further show that spermine can promote cell migration in keratinocytes and in human ex vivo wounds, where it significantly increases epithelial tongue migration. Knockdown of AMD1 prevents the upregulation of urokinase-type plasminogen activator/urokinase-type plasminogen activator receptor on wounding and results in a failure in actin cytoskeletal reorganization at the wound edge. We demonstrate that keratinocytes respond to wounding by modulating polyamine regulator AMD1 in order to regulate downstream gene expression and promote cell migration. This article highlights a previously unreported role for the regulation of polyamine levels and ratios in cellular behavior and fate.

Flip-avoiding interpolating surface registration for skull reconstruction.

Skull reconstruction is an important and challenging task in craniofacial surgery planning, forensic investigation and anthropological studies. Existing methods typically reconstruct approximating surfaces that regard corresponding points on the target skull as soft constraints, thus incurring non-zero error even for non-defective parts and high overall reconstruction error. This paper proposes a novel geometric reconstruction method that non-rigidly registers an interpolating reference surface that regards corresponding target points as hard constraints, thus achieving low reconstruction error. To overcome the shortcoming of interpolating a surface, a flip-avoiding method is used to detect and exclude conflicting hard constraints that would otherwise cause surface patches to flip and self-intersect. Comprehensive test results show that our method is more accurate and robust than existing skull reconstruction methods. By incorporating symmetry constraints, it can produce more symmetric and normal results than other methods in reconstructing defective skulls with a large number of defects. It is robust against severe outliers such as radiation artifacts in computed tomography due to dental implants. In addition, test results also show that our method outperforms thin-plate spline for model resampling, which enables the active shape model to yield more accurate reconstruction results. As the reconstruction accuracy of defective parts varies with the use of different reference models, we also study the implication of reference model selection for skull reconstruction.

Permanent Versus Bioresorbable Implants in Orbital Floor Blowout Fractures.

PURPOSE: To compare the outcomes of bioresorbable and permanent implants in the reconstruction of isolated orbital floor blowout fractures. METHODS: Retrospective series of all patients who had orbital floor fracture repair in a single tertiary trauma center from January 2005 to December 2014. The authors reviewed the case notes and CT scans of patients with orbital floor fracture repair with either bioresorbable or permanent implants. Main outcome measures were enophthalmos, diplopia, and ocular motility restriction 1.5 years after fracture repair. Implant-related complications were collected for analysis. RESULTS: There were a total of 88 patients in our study. Bioresorbable implants were used in 48 patients (54.5%) while 40 patients had permanent implants (45.5%). The authors analyzed the implants used in various sizes of orbital fractures: small (<13.3 mm), medium (13.3-20 mm), and large (>20 mm). One and a half years after fracture repair, both groups had comparable clinical outcomes (n = 2 and n = 0 for diplopia for permanent and bioresorbable implant groups, respectively, n = 0 for enophthalmos for both groups and n = 1 for ocular motility limitation for both groups) overall and across all fracture sizes. CONCLUSION: Bioresorbable implants degrade after fracture healing through hydrolysis and promote the gradual transfer of functional forces to healing bone during its disintegration. The clinical outcomes of diplopia, enophthalmos, and ocular motility restriction associated with the use of resorbable implants are comparable to that of permanent implants for all fracture sizes. Their study shows that bioresorbable and permanent implants are equally safe and effective for the treatment of patients with isolated orbital floor blowout fractures.