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

IIntroduction 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. 17 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 was 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 CT 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 hydroxyapatite cement to perform the procedure while creating a preliminary computational model to understand osteointegration. Based on the findings, cranioplasty shape may alter rate of integration and lead to higher success rates.

Modification Of Reading Man Flap For Reconstruction Of Infraorbital Defects: a Case Report

Background: Reconstruction of the defect in the infraorbital area after wide excision can lead to problems such as distortion of the anatomical point and ectropion. A “reading man” flap is a recent local flap procedure, which has been used to treat this problem.Case Presentation: We report a case of keratotic basal cell carcinoma in the right infraorbital area. After wide excision, a defect of 40x35 mm was found, which was very close to the lid margin and close to the bottom of the eyebrow, which was reconstructed by reading man flap with slight modifications. Our modification is to extend the leg flap laterally, to avoid the lower part of the brow. So that the eyebrows are still protected from the flap incision.Conclusion: Reading man flap as a circular defect closure option is a useful addition to the plastic surgeon's mastery of techniques for performing round periorbital defect reconstruction. Reading man flap can be designed flexibly. It is a good option for the closure of round or elliptical-shaped defects.

The Dermal Nipple-Areola-Complex Flap Method in Female-to-Male Gender Affirming Surgery

Background:Subcutaneous mastectomy (SCM) plays a major role in female-to-male (FtM) gender affirming surgery, and obtaining a flattering chest contour remains a challenge to the surgeon. We present an operative method using a dermal nipple-areola-complex (NAC) flap with the aim to create a naturally masculine appearance, while reducing the risk of NAC complications by maintaining sufficient neurovascularization.Methods:Through a horizontal incision, a superior thoracic full skin flap was elevated at the dissection plane for mastectomy. The mastectomy was continued inferiorly, creating an inferior flap including the NAC. The surface of the inferior flap was deepithelialized, secluding the NAC, which allowed the inferior dermal flap to be inserted posterior to the superior flap. A circular defect was created in the superior flap, into which the NAC was sutured.Results:The surgery delivered satisfactory results with an aesthetically pleasing masculine appearance and a high level of patient satisfaction. We were able to place the horizontal scars inferiorly along the pectoral muscles, which enabled some camouflage. Additionally, the inferior flap provided a uniform filling effect to the chest, further contributing to the male aesthetic. There were no NAC complications.Conclusion:The dermal NAC flap method could be applied as an excellent alternative to the traditionally performed free nipple graft technique in FtM gender confirming surgery. The method is simple, provides an aesthetically appealing outcome, and poses a low risk of NAC complications. Intraoperatively, it allows for good exposure and a uniform removal of breast tissue, as well as repositioning and/or reduction of the NAC where required.

Structural Changes of Circularly Defected Monolayer Circular Graphene Nanosheets Upon Mechanical Vibrations

As the strongest and toughest material known, graphene has found numerous applications in various types of sensors. Due to the great influences of the graphene sheet’s geometry on resonance frequency, circular defects could effect on expected results of sensors. Circular holes in circular graphene sheets (CGSs) have been modeled with molecular dynamics (MD) simulation in the present work. Then the vibration behavior of intact circular plate and circular sheet with the circular defect has been investigated using frequency-domain analysis (FDD). Furthermore, for validating the used method, the obtained natural frequencies for different graphene sheets have been compared with acquired data in former research. The result of validation showed the accuracy of the used method in this study. The results indicated that by increasing the hole size, the natural frequency of a defected sheet with free edges will be diminished, and with simply-supported interior boundary conditions typically went up. Also, by increasing the hole’s eccentricity, the natural frequency of the defected graphene sheet will be diminished when the hole boundary was subjected to simply-support or free condition.

Oblique Deposition of Ti/Pt/Au Electrode on Photonic Crystal for Vertical Current Injection

We describe a device for inter-chip or intra-chip optical communications that contains the Circular Defect in photonic crystal (CirD) lasers array driven by vertical current injection. In order to improve the conductivity of the structure while also preventing current leakage, we introduce the oblique deposition of electrodes on a photonic crystal pattern by using an electron beam evaporation apparatus. The performance of an electrode is investigated by a transmission line method, and the CirD structure is fabricated with the electrode. We analyze the voltage-current relationship and confirm the CirD structure’s low resistance of under 1 kΩ.

Optical Textures and Orientational Structures in Cholesteric Droplets with Conical Boundary Conditions

Cholesteric droplets dispersed in polymer with conical boundary conditions have been studied. The director configurations are identified by the polarising microscopy technique. The axisymmetric twisted axial-bipolar configuration with the surface circular defect at the droplet’s equator is formed at the relative chirality parameter N 0 ≤ 2.9 . The intermediate director configuration with the deformed circular defect is realised at 2.9 < N 0 < 3.95 , and the layer-like structure with the twisted surface defect loop is observed at N 0 ≥ 3.95 . The cholesteric layers in the layer-like structure are slightly distorted although the cholesteric helix is untwisted.

Experimental Study on the Dynamic Behavior of Running Crack Affected by Defect Shape and Filling Material

Using the caustics method and the experimental system of digital laser dynamic caustics, the model experiment of drop hammer impact loading was carried out, and the effect of the defect shape (circular and rectangular) and the filling material (air, epoxy, and silicone rubber) on the propagation behavior of the running crack was investigated. The experimental results show that, under the impact loading, the running crack initiates at the end of precrack and propagates toward the defect. After the running crack connects to the defect, it accumulates energy within a certain period before initiating again at the upper edge of the defect. Subsequently, only one running crack is formed at the upper edge of the circular defect, but two running cracks are formed at the upper edge of the rectangular defect. The defect shape and the filling material have a significant effect not only on the energy accumulation time of the running crack at the defect but also on the stress intensity factor when initiating at the defect. The effect degree of the defect shape on the running crack propagation behavior is in the following order: circular defect > rectangular defect, whereas the effect degree of the filling material on the running crack propagation behavior follows this order: air > silicone rubber > epoxy.

An ultrasonic inverse scattering imaging technique for defect located at an arbitrary position in the cylindrical material

In order to meet the quantitative nondestructive evaluation requirements for a cylindrical material, an ultrasonic inverse scattering technique is proposed to reconstruct the defect located at an arbitrary position in the cylindrical material, which can obtain the quantitative geometrical information of a defect from the backscattering data. In order to overcome the problem of incident wave amplitude variation with the relative position between transducer and defect due to the diffraction effect of ultrasonic transducer, the backscattering signal is corrected before input to the defect reconstruction. Three aluminum cylindrical specimens with elliptical defect or circular defect are prepared for experiments, and the results proved the feasibility and validity of this method.