Step Deformation Research Articles

Superficial Thinning of the DIEP Flap: A Safe Option to Achieve an Aesthetic Reconstructed Breast in the Obese Patient.

Abdominal flap-based breast reconstruction is challenging in the overweight and obese population not only because of increased donor-site complications, but also because excessive flap thickness makes inset cumbersome, requiring thinning and remodeling that frequently result in aesthetically poor outcomes. The authors started by studying 10 deep inferior epigastric artery perforator flaps with angiographic computed tomography. Then, they prospectively performed 21 breast reconstructions using a superficial thinning technique reliant on a constant suprafascial vessel as the pedicle for the remaining deep fat and compared the rate of complications with their previous experience using traditional flap thinning techniques. All samples studied showed a suprafascial division of the main perforator. Two constant branches were identified, one coursing over the Scarpa fascia and displaying a robust network of linking vessels with the subcutaneous and subdermal plexuses. That anatomical insight was used to develop a flap-thinning technique tested on 21 consecutive high-body mass index patients. A 7-year retrospective analysis (n = 164) showed no significant correlation between body mass index and incidence of complications except for a long-term upper pole step deformity that was associated with increasing body mass index (p = 0.001). No statistically significant difference in complications was found comparing high-body mass index patients from the retrospective group (n = 72) with the superficial thinning group, but a highly suggestive difference (p = 0.061) was found regarding the avoidance of the step deformity using the superficial thinning technique. The presence of a constant suprafascial perforator branch makes superficial DIEP thinning a safe technique that facilitates inset and improves the reconstructed breast contour of obese patients. Therapeutic, IV.

Management of mandibular parasymphysis fracture: a case report

Mandibular fractures are among the most common injuries to the facial skeleton. Mandibular parasymphysis fractures lead to the loss of occlusion with step deformity formation. Treatment of mandibular fractures aims to restore occlusion and function and facilitate direct bone healing by adequate reduction and immobilization on the fractured site. We report a mandibular parasymphysis fracture of 17 years old male patient due to the road traffic accidents. Patient reported severe jaw pain during movement and abundant intraoral bleeding was observed. A clinically computed tomography scan of the face with axial, coronal, and 3-D reconstruction was performed, which showed parasymphysis fracture. The following treatment done was the application Arch bar and open reduction internal fixation (ORIF) mini plate under general anesthesia. After access, mandibulomaxillary fixation was performed to ensure satisfactory occlusion after adequate fragment reduction. The fractures were properly fixed with 6 hole and 3 hole, screw 8mm for the left mandibular, and for the right mandibular used 5 hole and 3 hole, screw 8 mm. Mandibular fractures are the most common fractures of facial region and treatment options depend upon the type of fracture of mandible according to the anatomic variations.

Efficiency-Efficacy Assessment of External Lateral Osteotomy Technique Versus Internal One in the Rhinoplasty.

In this study we aimed to compare external lateral osteotomy technique vs. internal one in the rhinoplasty. In this before-after clinical trial study 30 patients who were candidates for rhinoplasty involved. In each patient, external lateral osteotomy was performed on one side and internal lateral osteotomy was performed on the other side randomly. Information, including patients' age, sex, grade of edema and ecchymosis 1, 3, and 7 days after the surgery, and the type of lateral osteotomy, the amount of step deformity, the need for the specialist intervention, nasal bone mobility, and flail nasal bone was recorded and analyzed. The incidence of edema and ecchymosis on the first and the third day was statistically lower in the external method (P value < 0.001). Although the incidence of edema and ecchymosis on the seventh day was lower in the external method, it was not statistically significant (P value > 0.05). Forty seven percent of patients in the internal method and 36% of patients in the external method had step deformity (p value < 0.001). Fifty percent of patients in the internal method and 41% of patients in the external method needed the specialist intervention (p value > 0.05). Seventy four of patients in the internal method and 83% of patients in the external method had nasal bone mobility (p value > 0.05). Out of 30 patients, only one had flail nasal bone. Based on our findings, the external technique is suggested as a more effective and convenient method with less complications for inexperienced surgeons.

Numerical Simulation of Stepped Spillways with Front Step Deformation

In order to solve the flood discharge problem of both small- and medium-sized warping dams in the Loess Plateau, a stepped spillway scheme, based on an ecological bag, to achieve full-section water flow and energy dissipation has been proposed in this paper. The hydraulic and energy dissipation characteristics of a stepped spillway layout scheme were studied using 3D numerical simulation. As the height of the dams is low and the spillways are short, the research has shown that the traditional single-step layout scheme leads to a low overall energy dissipation rate due to the small amount of energy dissipated in the initial steps. As a result of this, this paper has put forward two kinds of step layout schemes such as the shunt type and the staggered type for the initial steps. Through analysis of the flow state, the pressure distribution, and the total energy dissipation rate, the results have shown that shunt type and staggered type with front step deformation produced an obvious mixing of the water flow, fewer negative pressure areas, and a higher energy dissipation rate. The optimal energy dissipation rate of the staggered type reached 87.75%, and the maximum energy dissipation rate was increased by 27.97%.

Unilateral Zygomatic Complex Fracture - A Comparison Between Nonsurgical Treatment and Surgical Treatment.

Medical advances have enabled zygomatic complex (ZMC) fractures to be treated by various approaches. This study aims to analyze the demographics and treatment outcomes of unilateral ZMC fractures, treated nonsurgically or surgically. This 5-year nonrandomized prospective study had included 65 cases of unilateral ZMC fractures from October 2014 until December 2019. Patients were treated and divided into nonsurgical and surgically treated group. Treatment outcomes in terms of step deformities, malar depression, diplopia, infraorbital hypoaesthesia, and mouth opening were evaluated up to six months post-trauma/intervention. Road traffic accident (96.9%) was the main cause, with predominant male involvement (80%) and median age of 28 years. Significant improvements (P < 0.05) were observed for step deformities and malar depression among the surgically treated group at postoperative day 1 and week 1. Throughout the six months review, infraorbital hypoesthesia and diplopia showed no significant differences between both groups, (P > 0.05). Besides, all patients showed significant mouth opening improvement (P < 0.05) over six months period. The authors found that infraorbital hypoaesthesia and limited of mouth opening should not be the absolute indications for surgical treatment of ZMC fractures. Nonsurgical treatment that included early jaw exercise and symptomatic treatment had potential value for satisfactory functional gain.

Evaluation of stability and esthetic outcome following rigid fixation of a new sagittal genioplasty technique - A clinical study.

Background:Routine and popular conventional genioplasty procedure is often curvilinear, requires lower border extension below, and behind the mental foramen, which after advancement has a tendency to produce step deformity, butt contact, hence nonunion, instability, and increased relapse tendencies. The present technique is aimed to study the new sagittal genioplasty technique and its efficacy to overcome the above-mentioned drawbacks of conventional genioplasty. This technique also aids in correcting mild-to-moderate breathing irregularities.Materials and Methods:A total of 10 patients included in this study. The comparative analysis of the displacement of the chin in vertical and horizontal directions following surgery was evaluated by measuring the difference between preoperative, immediate postoperative, 3 and 6 months postoperative on lateral cephalometric radiographs.Results:The study of new sagittal chin advancement results showed an advantage over conventional technique in terms of esthetics outcome (no jowl), easy to perform without damaging the mental nerve, superior healing with less relapse, and better surface area contact.Conclusion:In this study, the new technique of sagittal genioplasty overcomes the disadvantages of conventional genioplasty. However, this technique is best suited for patients who require straight or moderately vertical augmentation advancement genioplasty and is not suitable for asymmetry corrections, i.e., centering genioplasty and double sliding genioplasty.

Determining the deformed state in the process of rolling conical shells with a flange

Obtaining conical shells by forging is an important and relevant task in energy and heavy engineering. Existing processes of their manufacture come down to simplifying the configuration of such billets. The result is the increased material’s consumption while the internal fiber is cut during machining, which also leads to a decrease in mechanical properties. A new forging technique necessitated a study into the shape change of the billet and the distribution of deformations in the process of rolling. A finite-element method was used to investigate the process of rolling out the step hollow billets. Based on the study results, the forging’s taper was established, obtained during the forging process. A research procedure involving the finite-element method was devised to study the operation of conical shells’ rolling, which made it possible to determine a change in the shape and size of a hollow forging when rolled out by a step tool. A parameter has been proposed to quantify the formation of taper in the process of rolling a billet with a flange. Based on the study results, a step-wise distribution of the intensity of logarithmic deformities in the body of a forging was established when conical shells were rolled out. It was found that the step deformation leads to an increase in the uneven distribution of deformations on the part of the protrusion and ledge. Maximum deformations of 1.0...1.2 occur at the inner and outer surfaces of the step billet’s protrusion. Dependences of the shape change in a step billet for the investigated ratios of sizes and rolling modes have been established. It was found that the maximum taper is obtained at a deformation degree of 15 %. It was determined that the degree of compression in the ledge and protrusion is leveled after 3 deformation runs of the step billet

Conservative management of pediatric mandibular distal fractures-A retrospective study.

Pediatric mandibular distal fractures present unique treatment challenges which are usually managed with open reduction and internal fixation (ORIF) with the risk of developing tooth bud injuries. Conservative management through maxillomandibular fixation (MMF) with orthodontic bracket-elastic as an out-patient department (OPD) service has been used for these fractures presenting with derangement of occlusion. The aim of this study was to retrospectively analyze MMF with orthodontic bracket-elastic as a treatment method and its outcome for management of pediatric mandibular distal fractures. Data of seventeen pediatric cases diagnosed with displaced mandibular distal fractures managed with MMF with orthodontic bracket-elastic over a period of 5years were analyzed. In this technique, two weeks of immobilization and one week for guiding elastics were used. The mean age of patients was 7.6±1.6years with a mean follow-up of 24months. All fractures healed uneventfully with satisfactory occlusion. The cases included 23.5% minimally displaced, and 64.7% moderately displaced and 11.8% significantly displaced fractures with step deformity with successful remodeling of the lower border contours over a duration of 18months±1month. The developing tooth buds in the fracture line showed no complications except for root dilacerations/malformation (n=3). MMF with orthodontic bracket-elastic is a viable and conservative technique for the management of pediatric mandibular distal fractures which need to be verified through randomized trials for generalization of the results.

Dorsal preservation septorhinoplasty

Nasal dorsum deprojection is avery important tool in functional and aesthetic rhinoplasty. In classic techniques, resection of dorsal bone and cartilage renders dorsal reconstruction necessary. The concept of dorsal preservation rhinoplasty has been known for more than acentury but has experienced arenaissance in recent years, with many critical technical modifications. We present the latest technique of piezo-assisted dorsal preservation rhinoplasty with subdorsal triangular resection and subdorsal Cottle modification based on clinical experience of 205cases. Furthermore, the advantages and disadvantages of this technique are discussed and several other current variations are presented. Piezo-assisted osteotomy enables avery precise fracture line and sparing of periosteum, with bone sculpting possible even after mobilization. Subdorsal septal height reduction always precedes completion of the osteotomy and nasal bone mobilization, to ensure patient safety with regard to skull base injury. Using the presented technical modifications, the risk of step deformities in the radix is minimized. In selected patients, dorsal preservation septorhinoplasty enables the surgeon to perform very conservative and precise deprojection of the nose with excellent outcomes, although the spectrum of possible complications is shifted in comparison to classic techniques. The preliminary experience of 205cases with arevision rate of less than 10% is promising. Afinal evaluation of the technique will only be possible after further studies and evaluation of long-term results.

Relationship between interfacial and foaming properties of a Porphyra dioica seaweed protein concentrate

Porphyra dioica macroalgae can be regarded as a food-grade protein source that can be used for the stability of dispersed food systems. This work is focused on the foaming properties of a seaweed protein concentrate (SWE) from Porphyra dioica . The characterisation of air-water (A/W) interfacial layers formed after the SWE adsorption was carried out by means of interfacial tension, interfacial viscoelastic measurements and step deformation tests. These results were related to those obtained for SWE stabilized foams. Interfacial shear measurements indicate that not extensive protein-protein interactions at the A/W interface were developed (G' s = 1.0 ± 0.1·10 −2 mPa m), whereas the dilatational response (E' s = 23.5 ± 0.5 mN/m) match with the formation of a rigid interface as a result of a densely packed structure. Even if the foaming properties obtained for SWE (overall foam capacity, OFC, = 0.74 ± 0.01 mL/s) are similar to those reported for other commercial protein systems, its lower stability (t 1/2 = 204 ± 4 s) would indicate the need of adding stabilizers for an adequate shelf life of the final food product. The suitability of combining dilatational and interfacial shear rheology to predict the dynamics of dispersed systems was proven to be relevant to acquire insights of complex interfaces. • Porphyra dioica algae could be a food-grade protein source for dispersed systems. • Dilatational response indicated the formation of a rigid interface. • The weak interfacial shear response suggested the formation of a densely packed structure. • Dilatational and interfacial shear rheology was combined to predict the dynamics of foams. • Foaming properties were similar to those reported for commercial protein systems.

Fabrication of step functionally graded NiTi by laser heating

This paper investigates the application of localized laser heating to produce a step pseudoelastic behavior of a cold worked Ni-rich Ti-50.9 at%Ni alloy. The localized heating was done using a custom-made laser heating apparatus. The aim is to create step graded martensitic phase transformation plateaus with large stress window and good recoverability. A cold-worked NiTi wire was locally heated using laser at 400 °C for 10 min, 475 °C for 30 min and 525 °C for 20 min along its length. These temperature and duration settings were carefully chosen based on isothermal heat treatment of the same Ti-50.9 at%Ni wire. Under tensile load, the wire exhibited deformation in a sequence of stress plateaus (step deformation), starting from the segment heated at the highest temperature and ending at the segment heated at the lowest temperature. The step gradient stress plateau produced 310 MPa and 270 MPa stress windows on the forward and reverse transformations, respectively. The residual strain on the recovery was about 1%. This novel heat treatment technique provides the possibility to produce a step pseudoelastic behavior of Ni-rich NiTi alloys to improve the mechanical responses of this smart material in actuator applications.

Sagittal Genioplasty: New Techniques.

The chin is a reflection of the entire face and, along with the nose, is one of the major determinants of facial profile balance. When it is appropriate in size, shape and position, the chin can enhance the normal harmony and symmetry of the face, even camouflaging less than ideal jaw relationships. Failure to perform a needed genioplasty can jeopardise the end product of many hours of otherwise successful major orthognathic or cosmetic surgery. Genioplasty procedure has been used for many years and has been modified in various ways, despite its original description by Trauner and Obwegeser. To overcome the disadvantages of older techniques such as step deformity, less bone contact and more chances of relapse. Type 1-Esthetic genioplasty: A curvilinear horizontal osteotomy can be performed at lower border as posteriorly as possible. After the osteotomy, the detached segment can be moved as per the requirement. Type 2-Functional genioplasty: A horizontal subapical cut was made through full thickness of the mandible involving the labial and lingual cortex, then vertical cuts were made bicortically and two oblique cuts were made at the end of vertical cuts monocortically. This modification has various advantages such as more bone contact, no step deformity, less chance of relapse and also most effective treatment for sleep apnoea patients.

Management of Palatal Fracture and Airway Challenge in A Child — A Red Flag

Airway managements in maxillofacial fracture patients are complex and crucial. Trauma to the maxillofacial region may cause hemorrhage, swelling which may lead to pulmonary aspiration and airway obstruction. Airway managements in maxillofacial fracture patients are complex and crucial. Besides being uncooperative, presence of fractures and soft tissue injuries posed challenges in managing pediatric patient who already have smaller airway opening. This condition is an important red flag which required extra caution from the treating clinicians. A 6-year-old boy was involved in a road traffic accident and presented with profuse bleeding from the oral cavity and nostrils. Physical examination showed oozing of blood with step deformity of the midpalate. Multiple attempts in intubation resulted in failure before succeeding with the aid of suction devices. After intubation was done, intraoral bleeding was successfully managed with transpalatal wiring and nasal packing. The patient was ventilated in the intensive care unit and was extubated two days later. He was discharged well from hospital after one week of admission. Airway management is a rush against time, particularly in a pediatric patient suffering from a palatal fracture. The need for helping hands for suction and child control must be emphasized to ensure the patient’s survival.

Effect of thick slurry and stepped deformation on mechanical properties of AA6061 alloy

Modification of aluminum (Al)-based components with low porosity is a basic requirement of aluminum industries for various applications. Furthermore, porosity and surface cracking are the most common problems with the components produced by the casting process alone. However, several modifications have been proposed to minimize these problems. A mounting component of motor brackets was produced with the influence of thick mushy-stage slurry as the primary process and stepped angular deformation (SAD) as the secondary process. SAD provides advantage of plastic deformation for the thick slurry cast (between 220 and 360°C) and as a result, a fine microstructure with excellent level density is achieved. The fabricated component was analyzed according to the microstructure pattern along the cross-section, microindentation hardness and wear behavior. The experimental results revealed a dense microstructure, whereas phase analysis confirmed the presence of aluminum oxide (Al2O3), magnesium oxide (MgO), Mg2Si3 and Al3FeO2 intermetallics.

Surface viscoelasticity in model polymer multilayers: From planar interfaces to rising bubbles

In the present work, a polymeric transient viscoelastic network is used as a model system to investigate several fundamentals of interfacial viscoelasticity and nonlinear behavior, in simple shear, compression, and for simple mixed deformations. A supramolecular polymer bilayer, characterized by long but finite relaxation times, is created at the water-air interface using a layer-by-layer assembly method. The possibility of studying the individual layers starting from an unstrained reference state enabled the independent quantification of the equilibrium thermodynamic properties, and the viscoelastic response of the bilayer could be studied separately for shear and compressional deformations. Time- and frequency-dependent material functions of the layer were determined in simple shear and uniform compression. Moreover, a quasilinear neo-Hookean model for elastic interfaces was adapted to describe step strain experiments on a viscoelastic system by allowing the material properties to be time-dependent. The use of this model made it possible to calculate the response of the system to step deformations. Within the linear response regime, both stress-strain proportionality and the superposition principle were investigated. Furthermore, the onset of nonlinear behavior of the extra stresses was characterized in shear and for the first time in pure compression. We conclude by investigating the multilayer system in a rising bubble setup and show that the neo-Hookean model is able to predict the extra and deviatoric surface stresses well up to moderate deformations.

Functional outcome of internal fixation for tibial plateau fracture

Being an intra-articular fracture of a major weight bearing joint-accurate anatomical alignment and reconstruction are essential. The treatment mandates on early mobilization to avoid stiffness and limitation of movements which are major handicaps in squatting and cross-legged sitting in our social life.The authors who have written extensively about this subject are generally in agreement that the result of treatment are dependent on the intra articular comminution and the presence or absence of step deformity on the weight bearing surface. If the step deformity can be eliminated by accurate anatomical reduction and if the reduction can be maintained, a good result can be usually anticipated. We have reported our experience in this study.

Hot deformation flow behavior of powder metallurgy based Al-SiC and Al-Al2O3 composite in a single step and two-step uni-axial compression

The material flow behavior of aluminium metal matrix composites at a high-temperature is required to manufacture the forged components for the lightweight application. In this study, four varieties of aluminium based composites such as Al/3 vol%SiC, Al/7 vol%SiC, Al/3 vol%Al2O3 and Al/7 vol%Al2O3 composites were synthesized using powder metallurgy route. Single step deformation was performed at 500 °C to get a true unity strain at strain rates of 10/s and 20/s. In two-step, the first deformation was at 500 °C followed by additional deformation at 430 °C at strain rates of 10/s and 20/s. The compression test results show the Al/7 vol% SiC composite exhibit comparatively higher value of peak true stress (46.36 MPa at a strain rate of 20/s) at a temperature of 500 °C in single step deformation. The interface coefficient of friction between anvils and specimen decreased with increase in strain rate. Electron backscatter diffraction (EBSD) maps revealed that, Al/7 vol% SiCp and Al/7 vol% Al2O3p shows partially dynamically recrystallized grains at the interface of aluminium and the particulate reinforcements (SiC and Al2O3) under a strain rate of 10/s. Subgrain boundaries with dynamic recovery grains were observed in aluminium when it was deformed at strain rates of 10/s and 20/s to a true strain of 0.6. In the view of flow stress and evolution of microstructures, this investigation provides insight into the implementation of the forging process for aluminium metal matrix composite.

Analysis and experimental study of low-stepped mirror in light FTIRS

The structural parameters of low-stepped mirror which is the core component of a light Fourier transform infrared spectrometer (FTIRS) have important influence on the performance of the instrument. A simple method of multiple deposition is proposed to fabricate a low-stepped mirror with step height of 625 nm, for its high precision, high efficiency and miniaturization. So the film stress will be introduced in the process of coating, which can lead to step deformation. We build a bending model of the low-stepped mirror and analyze the influence of its deformation. The light intensity and spectrum are changed by the step deformation. Therefore, the film stress should be reduced in order to ensure the accuracy of the spectral information. Increasing the thickness of substrate is proposed in this paper to reduce the step deformation, besides adjusting the coating temperature and adding sub-layer. Our results reveal that the basic requirements of the system are satisfied when the thickness of the substrate is 5 mm in the appropriate coating environment. An FTIRS based on stepped mirrors and grid beam splitter is assembled and corresponding experiment is carried out to obtain the spectrum curve of acetonitrile.

Study on the Enhanced Superplasticity of Mg-Li Based Alloy by a Stepped Deformation Method

A two-step deformation approach is proposed for the superplastic deformation (SPD) of Mg-9Li-1Al (LA91) alloy. This method has been successfully applied to titanium alloys and has induced enhanced superplasticity, and the feasibility of the method for the Mg-Li based alloy is explored. In a previous research, single-step SPD of LA91 alloy has been investigated, and the highest elongation of 563.7% was obtained by using the 8-pass equal channel angular extruded material, by the maximum strain rate sensitivity (Maxm) mode deformation. While in this research, the raw material in the as-extruded state is utilized. Constant velocity (Constv) and constant strain rate (CSR) modes are adopted for the first step of the deformation, respectively, with the elongation of the first step from 50% to 150%. The Maxm mode, in which the strain rate sensitivity m is always kept to be the maximum value, is applied to the second step. In addition, single-step tests by Constv, CSR and Maxm modes until fracture are conducted. The experimental temperature is 300°C, which was proved to be the optimum temperature for the SPD of this material in the previous research. The result shows that the 2-step method can greatly improve the superplasticity of the LA91 alloy, especially for the CSR mode deformation, and the maximum elongation obtained is 535.3%, by the CSR-Maxm mode, which is comparable to the optimum result in the previous research.

Does C-Arm Guidance Improve Reduction of Zygomatic Arch Fractures?—A Randomized Controlled Trial

Traditionally, in the assessment of the reduction of zygomatic arch fractures, the surgeon uses subjective measures such as palpation of a bony step deformity, the anecdotal "pop" sounds, and visual confirmation of symmetry. In the present study, we sought to objectively assess the accuracy of reduction and improvement in form and function after C-arm-guided reduction of isolated zygomatic arch fractures (IZAFs) and to compare these results with those obtained conventionally. A prospective, randomization of patients scheduled for surgical closed reduction of IZAF was performed. The test group underwent C-arm-guided reduction of the fracture until the arch contour was re-established and visualized on fluoroscopic images. In the control group, palpation, auditory cues, and visualization of symmetry determined the adequacy of the reduction. The patients and evaluator were both unaware of the treatment technique used. The primary outcome measures were the maximum interincisal distance (IID), standardized measurements on computed tomography (CT), and measures of symmetry on facial photographs. Variables such as intragroup differences and patient-evaluator agreement were also studied. The data were analyzed using SPSS software, version21. The study sample consisted of 20 patients (10 each in the test and control groups). Significant improvement in facial symmetry was observed in all 20 patients (P<.001) from preoperatively to 30days postoperatively. The CT measurements confirmed acceptable symmetry, with insignificant differences between the 2 groups (C-arm group, P<.001; vs control group, P=.004 for intragroup improvement in symmetry). The IID had improved significantly (P<.001) at the end of follow-up in both groups. Although significantly superior outcomes were not inferred in the symmetry-related and CT measurements, C-arm-guided reduction provided an opportunity to instantaneously confirm the accuracy of bony reduction. Thus, the need for postoperative imaging and secondary surgery can be overcome, enabling even inexperienced surgeons to attain precise and reproducible results.