This study describes a computational analysis technique for evaluating the effect of screw spacing and angle on the pediatric hip locking plate system in proximal femoral osteotomy in pediatric patients having DDH with an aberrant femoral head and femoral angle. Under static compressive load conditions, the stresses of the screw and bone were examined as the screw spacing and angle changed. The spacing and angle of various screws were specifically considered as variables in this study based on the pile mechanism studied in civil engineering. As with the group pile mechanism, the tighter the screw spacing under static compressive loads, the more the overlapping effect between the bone stresses and the screws develops, increasing the risk of injuring the patient’s bone. Therefore, a series of simulations was performed to determine the optimal screw spacing and angles to minimize the overlapping effect of bone stress. In addition, a formula for determining the minimum screw spacing was proposed based on the computational simulation results. Finally, if the outcomes of this study are applied to pediatric patients with DDH in the pre-proximal femoral osteotomy stage, post-operative load-induced femur damage will be reduced. Developmental dysplasia of the hip (DDH) encompasses all malformations associated with growing hips, including frank dislocation, subluxation and instability, and dysplasia of the femoral head and acetabulum . The preFollowing these surgical procedures, it is routine to immobilize the lower body and determine surgical prognosis using computed tomography (CT). However, injuries to the femur around the screw caused by an external force can’t be quantified in this follow-up procedure. Furthermore, it is difficult to assess the risk of bone injury due to loading. Animal experiments or finite element analysis (FEA) can be used to detect and indirectly overcome these difficulties. For many years, in silico approaches based on FEA have been widely employed to examine disease mechanisms in other organs and have been widely used in femur-related research. From a biomechanical standpoint, Zhang et al. revealed the mechanical properties and theoretical foundation of a diaphyseal prosthesis with a tooth mechanism using an FEA approach . Coquim Despite these FEA studies on the fixation of various fractures, research on proximal femoral osteotomies for patients with DDH has been limited. Furthermore, in a clinical investigation of proximal femoral osteotomies in children, the absolute values for plate and screw standards have not been quantitatively established.Therefore, the finite element method was used in this study to investigate the variation of bone damage according to the screw specifications in pediatric hip locking plates with proximal femoral osteotomy. Bone damage assessments can assist in establishing the correct quantity, spacing, and angle of screws when setting up a treatment approach before surgery, which can aid in the post-operative management of young children. The spacing and angles of the screws addressed in this study were specifically introduced from the standpoint of civil engineering. In the case of screw spacing, various spacings have been investigated by applying the civil engineering principle of group piles to determine the ideal spacing , 23. It In this investigation, a CT image of a girl with advanced DDH  was used to extract a 3D model of the femur to replicate the femur of a patient with advanced DDH. For the patient’s right femur, the angle between the femoral head and the femur was measured to be approximately 137.2°. The study was conducted in accordance with the declaration of Helsinki and approved by the Institutional Review Board of Pusan National University Hospital (IRB No. 2008-010-094). The patient voluntarily provided written informed consent. Written authorization of participants to publish data, including personal identifying information, was also collected.Using 3D Slicer software, the previously obtained CT image data was transformed into a finite element model of the left femur. Osteotomy was used to cut and reshape the bone in this 3D virtual patient model, and the angle between the femoral head and femur was corrected to 126°, as shown in Fig. In addition, the pediatric hip locking plate , used in this 3D virtual patient model, was measured using a digital caliper and converted to a finite element model, as shown in Fig. Table In this study, an FEA scenario was established with the spacing and angle of the screw to investigate the behavior of the bone under stress and relate it to the spacing and angle of the screw. The screw distance was considered to range from 6 to 16 mm , whereas the angle was considered to range from 70° to 130° . When modifying the distance between the screws attached to the femur, the highest of the three screws was held in place in all finite element models, whereas the other two screws were moved according to the scenario. Only the lowest of the three screws was moved when setting the angle. In addition, because of the screw-to-screw overlap, the case for 70° of the most inferior screw with screw spacings of 6 and 7 mm was removed from the scenario. Because screws attached to a single cortical bone of the femoral shaft have a weak fixation force, connecting screws to both cortical bones is recommended. In addition, during the process of securing the screw to the cortical bone, if the screw protrudes excessively from the cortical bone on the opposite side, it may damage the soft tissue beyond the cortical bone [Under static compressive loading conditions, the series simulation results for the stress of the screw according to the spacing and angle of the screw are reported in this section for a patient who underwent proximal femoral osteotomy for DDH. The stress in a screw was investigated by separately distinguishing between screws inserted into the femoral head and screws inserted into the femur Figs.  and 6. FThe variation in stress due to spacing and angle could not be demonstrated in the screws placed in the femoral head. However, the stress varied depending on the screw location. The average stresses for screws 1 and 2 in Fig. Figure The stress in the bone surrounding the screw inserted into the femoral head is depicted in Fig. In the case of the bone stresses around the screw placed in the femur, it can be seen that the bone stresses around one screw have a different tendency than the bone stresses around the other screw, as shown in Fig. Figure Figures In this study, a computational simulation was performed to quantitatively evaluate the effectiveness of the existing pediatric hip locking plate system used in proximal femoral osteotomy in children with DDH who had an unstable femoral head and femur angle. The spacing or angle of the screws placed into the femur can help distribute the load stresses in the bone. As a result, the ideal pediatric hip locking plate system was determined in this study by examining the screw and the bone stress around it induced by different screw spacings and angles. In addition, we present a formula for determining screw spacing to derive the ideal pediatric hip locking plate system for the environmental parameters of DDH examined in this study.The insertion direction of the screw in the existing pediatric hip locking plate was separated into a screw placed into the femoral head and a screw inserted into the femur. In particular, it can be proven that there is no significant change in the stresses of a screw inserted into the femoral head owing to variations in the spacing and angle of the screws placed into the femur under a static compressive load. It should be emphasized that the function of the screw inserted into the femoral head is to strengthen the fixation force of the modified femoral head and pediatric hip locking plate to seat the patient’s femur in the optimal position. However, under static compressive load conditions, the stress distribution of the screws placed in the femoral head differed according to their insertion position. In the case of screws 1 and 2 in Fig. Furthermore, screws 4 and 5 placed into the femur did not result in significant outcomes in terms of screw spacing and angle. However, in the case of screw 6, which was placed in the femur, the screw stress increased as the angle increased. When the screw spacing was 9 and 11 mm, the variation in screw stress according to the angle increased only slightly. This is due to the fact that each position differs slightly in the process of determining the maximum stress from the screw. Moreover, a series of simulations for screw spacing indicated that the stress on screw 6 increased as the screw angle increased from 90° to 130°, with a maximum stress value of 94.27 MPa. Considering the material properties of the screw, it can be confirmed that the screw of the pediatric hip locking plate is not greatly influenced by the screw angle because a stress of 100 MPa or less is considered to be a very low value when compared to the yield stress.The bone stress around the screw placed into the femoral head did not alter significantly depending on the screw spacing and angle, although there was a modest variance depending on the screw location. In particular, the stress on screw 3 was significantly different compared to other screws in the stress analysis, whereas the bone stresses around screw 3 were overall higher than the stresses in other locations in the stress analysis. However, it can be seen that the difference in bone stresses around the screw inserted into the femoral head was not large. This indicates that the static compressive load has a greater effect on the screw than on the bone in the femoral head region.In addition, the results of the bone stress analysis demonstrated that only the bone stress surrounding screw 6 changed according to the screw angle. This means that as the screw angle increases, so does the contact area between the bone and the screw, reducing the stress that can occur in the bone owing to the static compressive load. Based on these results, it is hypothesized that, by reviewing the thickness of the lateral and medial femur in the CT-analysis stage of patients with DDH prior to surgery, the screw angle can be altered to reduce stress on the femur. For example, if the lateral cortical bone of the femur is thinner than the medial cortical bone, the angle is increased to reduce load damage because the lateral cortical bone is more susceptible to stress. Furthermore, to quantify the stress distribution generated in the bone around screws 4 and 5 inserted into the femur, this study was divided into sections A (A1 to A2) and B (B1 to B2), as shown in Fig. In proximal femoral osteotomy, it is important to comprehend how the stress on the screw increases and the stress on the bone decreases according to the angle or spacing of the screw. Stresses due to external forces, such as compressive and tensile loads, are typically localized in the screws of DDH patients who have undergone proximal femoral osteotomy . This phThe piles should be constructed such that the force exerted by one pile on another is as small as possible . BecauseFor single piles,For group piles,where S is the pile center-to-center spacing, r is the radius of the pile, and L is the length of the pile. Based on Eqs.  and 2),,2), the where n is the number of screws. This revised proposed formula was modified based on the results of a series of simulations in which the superposition effect of the stress generated in the bone decreased with a screw spacing of 11 mm or greater.However, this study has a number of limitations. First, when walking, the joint reaction force is typically calculated to be between 3.5 and 5 times the body weight . In addiSecond, the verification step of comparing the FEA results with the experimental results based on proximal femoral osteotomy was not performed in this study. Therefore, in this study, FEA was conducted considering the material properties of the actual bone to ensure the validity of the FEA results by referencing previous research –45. FurThird, in this study, the femoral-bone properties of adults, not children, were considered, as were the femoral bone properties of healthy individuals. Obtaining femur samples from actual children and femurs from DDH patients presents numerous challenges. Therefore, in this series of simulations, we focused on determining the optimal surgical method based on the trend of the screw spacing and angle values.As per journal instruction funding is mandatory hence we processed acknowledgment statement as funding statement. Kindly check.Yes, I checked, and the funding statement is fine.Fourth, this model only considered static compression, and other loading conditions may produce different results. In addition, because only one osteotomy technique was evaluated, different outcomes may be observed when similar load conditions are applied to other osteotomy techniques.To overcome these problems, we plan to conduct additional study on cyclic and dynamic loading, the development of an experimental system capable of motion analysis, and various material characteristics that can consider deformed and children’s bones. This study can be considered the first step in conducting these future studies. Particularly, the findings of this study can be applied to the design phase of the pediatric hip locking plate to create an improved plate with the capacity to control screw spacing. In addition, we believe that the fixation-force effects of each screw angle, as determined in the preceding analysis, and the results of future studies can be utilized to improve upon the proximal femoral osteotomy methodology. Therefore, the findings of this study are expected to provide surgeons with guidelines for improved proximal femoral osteotomy and facilitate improvements in other surgical techniques.


The corrosion inhibition process for mild steel was employed alongside various techniques, such as potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), temperature effect (TE), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and theoretical approaches . Further, the corrosion efficacies obtained at the optimum concentration (10−3 M of the TGP) were 85.5% (EIS) and 88.6% (PDP), respectively. The PDP results indicated that the TGP tetrafunctional epoxy resin acted the same as an anodic inhibitor type in 0.5 M H2SO4 solution. SEM and EDS analyses found that the protective layer formed on the MS electrode surface in the presence of TGP could prevent the attack of the sulfur ions. The DFT calculation provided more information regarding the reactivity, geometric properties and the active centers of the corrosion inhibitory efficiency of the tested epoxy resin. RDF, MC and MD simulations showed that the investigated inhibitory resin have a maximum inhibition efficiency in 0.5 M H2SO4 solution.In this work, a tetrafunctional epoxy resin entitled 2,3,4,5-tetraglycidyloxy pentanal (TGP) was tested and investigated as a potential corrosion inhibitor for mild steel (MS) in 0.5 M H Metallic steel is widely employed and investigated in various industrial fields of application, including aeronautics, automotives, railways, metal construction, etc., due to its advantageous availability and excellent mechanical resistance ,2. In adRecently, and based on the great advances made in supercomputers, quantum chemical methods, such as density functional theory (DFT), molecular dynamic simulation and Monte Carlo methods, have become very useful tools in the determination of the molecular structure, electronic structure and molecular reactivity of chemical compounds. Therefore it has become common practice to perform quantum chemistry calculations in order to predict the molecular corrosion inhibition performance and efficiency of different molecules and to understand their inhibitory mechanisms.2SO4, including when analyzed using different characterization techniques, such as potentiodynamic polarization, electrochemical impedance spectroscopy, temperature effect, scanning electron microscopy and X-ray energy-dispersive spectroscopy [In this potential study, an inhibitory resin entitled 2,3,4,5-tetraglycidyloxy pentanal was employed; it performed excellently in terms of providing anticorrosion protection to steel substrate electrodes in 0.5 M Htroscopy . To knowtroscopy . Additiotroscopy .−3 to 10−6 M in 0.5 M H2SO4 solution was maintained in order to obtain the potentiodynamic polarization curves (PDP) and electrochemical impedance spectroscopy (EIS) measurements. In addition, the electrochemical measurements were investigated using a Potentiostat/Galvanostat/ZRA (Gamry apparatus). Furthermore, the electrochemical cell was composed of the mild steel, which was used as the work electrode, the platinum, which was used as the counter electrode, and the saturated calomel electrode, which was used as the reference electrode. The open circuit potential (OCP) was maintained for 30 min in each assay after reaching the equilibrium state. Then, the PDP plots were measured at 0.3 mV/s when the potential range was between −900 and −100 mV. The EIS measurements were carried out when the OCP was in the frequency range of 100 KHz to 0.1 Hz with an AC voltage of 10 mV. In addition, the surfaces of the MS samples immersed in 0.5 M H2SO4 solution were uninhibited and inhibited with 10−3 M of TGP; this was performed using a scanning electron microscope and energy-dispersive X-ray spectroscopy. In addition, the SEM technique was investigated for its potential ability to create images of the uninhibited and inhibited mild steel surface in the presence of TGP at 10−3 M, using a JEOL-JSM-5500-type microscope. Moreover, EDS analysis was used in order to obtain the elemental chemical composition. Furthermore, the measurement conditions were as follows: the magnification was x2000, the process time was T4, the acceleration voltage was 20.00 kV, the measurement was first, the real time was 38.74 s, the live time was 30.00 s, the count rate was 29,643.00 CPS and the dead time was 22.00%. Additionally, the corrosion efficiencies for the potentiodynamic polarization curves and for electrochemical impedance spectroscopy were measured according to Equations (1) and (2), as follows:The inhibitory resin, namely 2,3,4,5-tetraglycidyloxy pentanal, was synthetized, identified and confirmed by Hsissou et al., according to the procedures illustrated several of the previously published studies in this area ,14. In aIn this work, density functional theory (DFT) was used in order to analyze the electronic behaviors of the investigated tetrafunctionnal epoxy resin (TGP) and its protonated form . OptimizEHOMO) and the LUMO (A = −ELUMO) were investigated in order to illustrate the energy gap (∆Egap) of the neutral and protonated species (∆Egap = ELUMO − EHOMO). Several quantum global reactivity descriptors of the investigated inhibitor, including electronegativity (χ), absolute hardness (η), the electrophilicity index (ω), softness (S) and the fraction of electrons transferred (∆N), were evaluated in terms of the vertical ionization potential (Iv) and vertical electron affinity (Av); these were calculated as functions of Equation (3), as follows [The minimum value of the potential energy areas of these samples was found using the absence of imaginary frequencies. The molecular modeling studies were carried out by using Gaussian 09 . Gaussvi follows ,20,21:(3E(N), E(N − 1) and E(N + 1), and FeΦ, ΔEb−d, are the total energy of the optimized structures, the cationic and anionic energies at the optimized neutral geometries, the work function (4.82 eV), the hardness of Fe(110) (0.0 eV) and the electronic back-donation energy, respectively [ΔEb−d < 0, the mechanism is energetically favored, otherwise the process is energetically unfavored [In the above set of equations, ectively . If ΔEb−nfavored .Fukui functions can give a useful indication of the local reactivity centers regarding nucleophilic and electrophilic attacks when using the investigated inhibitory resin . To compion (4)) :(4)fk+=qUsing the Material Studio package’s Forcite module, the ability of neutral and protonated inhibitory resins to adhere to the area of iron was studied via MC and MD simulations. This was performed in a simulation box (2.4823 nm × 2.4823 nm × 1.824 nm + 3.5 nm vacuum layer) with regular conditions at the edges. For the system being studied, the Fe(110) area with a slab of 15 was chosen; this is because it is the most stable of the three common iron areas . Details2SO4 solution at 298 K, PD was used and investigated, as illustrated in icorr decreases to lower values that ranging between 1850 and 211 µA cm−2 with as the TGP concentration increases (from 10−6 to 10−3 M) [2SO4 solution. Additionally, all the corrosion potential displacements (ΔEcorr) for MS uninhibited and inhibited with different concentrations of TGP (97 to 112 mV) are higher than ±85 mV, indicating that the TGP molecule acted as an anodic inhibitor type [In order to determine the interaction between the tetrafunctionnal inhibitory resin and the surface of the MS samples uninhibited and inhibited with TGP at different concentrations in 0.5 M H 10−3 M) . These dtor type . In additor type . Further2SO4 environment, uninhibited and inhibited with TGP at different concentrations. Further, a careful examination of the Nyquist plots reveals that the corrosion processes are the same for both the uninhibited and inhibited MS surfaces. According to the data displayed in 2SO4 solution, which indicates that the TGP can be adsorbed into the metallic substrates by forming a protective layer and by preventing the dissolution of the metal [Re), the constant-phase element (CPE(Cdl and ndl)), the charge transfer resistance (Rct) and the inductance element (RL and L), as illustrated in 2, and also that the inductive element values increase from 2.17 to 22.35 Ω cm2 for the MS surface uninhibited and inhibited with 10−3 M of TGP; this reflects the highest blockage of sulfur ions by using TGP at the MS/0.5 M H2SO4 interface [Q values and the anticorrosive inhibitory efficacy. For the mild steel electrode, the Q values decrease as the TGP concentration increases, but only when compared to the blank; this is due to an increase in the thickness of the protective layer and/or a decrease in the dielectric constant. This protective property is predominantly shown in the differences between the surface states of the metallic substrates in terms of the structure and roughness of the samples after anticorrosive protection. For the inhibitory resin investigated, a more pronounced effectiveness is achieved with 10−3 M of TGP, which is in excellent correlation with the data obtained using the potentiodynamic polarization technique. For all concentrations, the ndl values for the MS surfaces uninhibited and inhibited with inhibitory resin in 0.5 M H2SO4 solution are less than 1, resulting in the pseudo-capacitive system of the CPE. These data suggest that the inhibitory resin offers excellent anticorrosion protection compared to other epoxy resins that have been investigated for their potential anticorrosion protection [In order to determine and understand the corrosion inhibition of the metallic surface, TGP was employed and investigated. he metal . Accordinterface . These d2SO4, with inhibitory resin at a higher concentration (10−3 M). In addition, the surface of the MS electrode shows cracks, holes and a severe surface. However, the MS samples display the protective layer, and are smooth with fewer cracks and holes with 10−3 M of TGP, suggesting that the TGP is a good inhibitor and has a more significant protective effect [−3 M of TGP in 0.5 M H2SO4 are shown in −3 M of TGP (from 9.51 to 34.66% (for oxygen) and from 5.04 to 6.89% (for carbon)) due to the heteroatoms of oxygen and carbon that are present in the inhibitory resin studied; this suggests that the TGP reduces the density of the active sites on the surface of the metallic substrates by forming a protective layer, thus delaying the corrosion inhibition.In order to display and evaluate the adsorption phenomena between the surface of metallic substrates and the TGP employed, SEM and EDS characterization analyses were used and discussed further. e effect . Additio2SO4 solution, the experimental results obtained using the PDP technique were evaluated by applying the various adsorption isotherms equations and ascertaining the best fit, which in this case, was the Langmuir adsorption mechanism mode (2) is 1, which is in good agreement with the Langmuir adsorption mechanism. In addition, this information indicates that the inhibitory resin TGP could be adsorbed on the MS surface, due to the fact that the best mode could be used in order to develop a certain experience. Moreover, the Gibbs energy variation (ΔGads) values for adsorption offer more data concerning the adsorption mechanism performed by the inhibitory resin and the MS surface. Additionally, a ΔGads value that is higher than −40 KJ/mol indicates chemical adsorption. However, a ΔGads value that is less than −20 kJ/mol suggests the physical adsorption mode [ads, θ, Cinh, T and R are the adsorption equilibrium constant, the surface coverage degree, the inhibitory resin concentration, the employed temperature and the perfect gas constant, respectively.In order to determine and evaluate the adsorption mechanism mode that functions between the inhibitory resin and the MS surface in the 0.5 M Hism mode . Accordiion mode . Furtherion mode :(5)CinhθGads value is equal to −44.74 KJ mol−1, which suggests that the TGP inhibitory resin could be adsorbed on the MS area through the chemical adsorption isotherm model. Therefore, the chemical adsorption of the inhibitory resin studied could be due to the nature the bond between the Fe ions and the epoxy systems, and the methoxy function and the free electron of the oxygen heteroatoms present in the TGP inhibitory resin employed.A careful analysis of 2SO4 medium with an optimal concentration of TGP at different temperatures. In addition, in order to study the temperature effect on the inhibitory resin employed, potentiodynamic polarization analysis was carried out at varying temperatures, as follows: 298, 308, 318 and 328 K. −3 M of inhibitory resin and tested at different temperatures. The different electrochemical parameters obtained using the PDP curves for different temperatures are displayed in −3 M at a TGP concentration higher than 85 mV/SCE, for all the temperatures investigated. Further, it is evident that the cathodic slops within 10−3 M of TGP at different temperatures were higher compared to those of the acidic environment only; these data indicate that the TGP studied acted as an excellent anodic-type inhibitor. According to the data listed in In order to determine and evaluate the adsorption mechanism, the temperature effect of the system was one of the essential factors used to study the corrosion inhibition of an uninhibited and inhibited steel electrode in a 0.5 M H2SO4) at 10−3 M of employed inhibitory resin, the Arrhenius formula between the icorr values and the temperature applied was used and investigated according to Equation (7). Additionally, an alternative formula for the Arrhenius relationship was investigated in order to calculate the activation standard enthalpy (∆Ha) and the activation standard entropy (∆Sa), according to Equation (8), as follows [h, N, and R denote the Arrhenius constant , the Planck number, the Avogadro number and the perfect gas constant, respectively.In order to determine the activation energies of the corrosion process of the metallic electrode surface when it is plunged in an aggressive environment (0.5 M H follows :(7)icorricorr) as a function of 1000/T for MS uninhibited and inhibited with the investigated inhibitory resin at different concentrations. 2SO4, only (Ea) can be adsorbed on the electrode area of the metallic sample via electrostatic bonds (the physisorption mode). However, the activation energy of the inhibitory resin is lower than that of the 0.5 M H2SO4 alone (a), which could be adsorbed on the metallic sample area by the covalent bonds (the chemisorption mode). A careful analysis of the data illustrated in 2SO4 alone. These data indicate that the tested inhibitory resin could be adsorbed via the physico-chemical adsorption mode on the surface of the steel electrode. In addition, icorr/T) as a function of the 1000/T in an aggressive environment for MS uninhibited and inhibited with 10−3 M of the investigated inhibitory resin. In addition, the slopes of the straight lines were investigated in order to obtain the values of the activation standard enthalpy; meanwhile, the intercept allows us to determine the activation standard entropy. Furthermore, according to the results illustrated in Ha reflects the endothermic nature of the surface of the steel electrode and the dissolution of the corrosion inhibition process. In addition, the negative signs of ∆Sa in the aggressive environment for uninhibited MS mean that the activated TGP molecule was in a lower order state compared to the initial step. However, in the presence of 10−3 M of TGP inhibitory resin, the activation standard entropy (∆Sa) is positive; this result indicates that the activated molecule was in a higher order state compared to the initial step. Furthermore, according to the data listed in −3 M of TGP is higher than that of the uninhibited MS ; thus, there is an increase in the disorder during the adsorption process.Furthermore, the activation energy values were measured using the slopes of the lines. In addition, EHOMO, ELUMO, ∆Egap, χ, μ, S, ω, ΔN and ∆Eb−d, were calculated so as to study the inhibitory efficacy of the employed TGP inhibitory resin used to protect the mild steel electrode area from corrosion in the 0.5 M H2SO4 solution. For the sake of comparison, the neutral and protonated forms of the investigated resin were used in an aqueous environment. In order to confirm the data obtained during the experimental part, the DFT descriptors, namely The distribution of the HOMO surface of the neutral/protonated forms on all of the parts of the molecules, except the oxirane rings, implies that the carbonyl oxygen atoms and the oxygen ether group atoms are able to donate their electrons to the vacant d-orbital of the metal. However, the LUMO surface is mostly distributed on the carbonyl function and its neighboring carbon atoms, implying that this part of the epoxide resin has the ability to accept electrons from the occupied d-orbital of the metallic substrates area. These data are also supported by the electrostatic potential map.EHOMO is the most commonly used quantum chemical descriptor, and is associated with the tendency to donate electrons to the vacant d-orbitals of the metallic area. The high values of the EHOMO suggest the high propensity of electrons to transfer to the lowest virtual d-orbital of the acceptor [ELUMO indicates that inhibitors can accept electrons from the vacant d-orbital of the metallic area. It has been outlined that the lower that the ELUMO of the molecule is, the greater its tendency to accept electrons from the donor. Therefore, the adsorptive mechanism can be supported by the donation and acceptance competence to/from the inhibitor/metal and can also help to protect the metallic area from corrosion. The chemical reactivity of the inhibitors also depends on the energy gap between the EHOMO and ELUMO [ΔEb−d < 0, back-donation from the inhibitory resin to the metallic area is energetically favored [As is known, acceptor . On the nd ELUMO . The sma favored . The ant favored . The dipE1 and ΔE2) [E1  values are slightly lower than those of ΔE2 (6.861/6.843 eV). These results reveal that the electron’s transfer from the metal ion to the inhibitor is energetically favored.Since we are dealing with the donation/acceptance of electrons to/from metal, it is helpful to estimate two important parameters that explain the metal–inhibitor interaction (Δand ΔE2) . These dtes area . In thisectively . For theks and ΔC1, O18, C2 and C19), whereas the more reactive sites for the electrophilic attacks are the oxygen heteroatoms   .Eads [FeE, and inhibitorE are the total energy of the Fe(110) area and the corresponding free inhibitory resins, respectively.Starting with the Fe(110) area makes it easy to compute the system’s adsorption energies. Applying Equation (9) to a molecule yields its adsorption energy, or Eads :(9)EadsoAfter the MC approaches were successful , a consiThe adsorption of inhibitory resin onto the metallic substrates area offers data on the formation of the substantial Eads , which a2SO4. Data obtained using the PDP technique suggest that the employed epoxide resin can be adsorbed strongly in the metallic substrates area, as an anodic-type inhibitor. Additionally, the DFT calculation gives further data about the reactivity and energetic properties of the interaction between the inhibitory resin and the iron area. According to the data obtained using the MC and MD approaches, the inhibitory resin has a somewhat flat-adsorbed configuration on the side walls of the resin, which maximizes its contact with the oxygen heteroatoms. The concept that the inhibitory resin contains important negative adsorption energies is given further credence by the evidence that was gathered through experimental testing.The corrosion inhibition of the employed inhibitory resin has been investigated via electrochemical analyses, morphology and computational approaches. PDP and EIS techniques illustrated that the inhibitory resin possessed high inhibitory efficacies at its optimum concentrations, such as at 88.6% (PDP) and 85.6% (EIS). SEM/EDS analyses revealed the potential ability of inhibitory resin to protect a mild steel surface in 0.5 M H


However, the route of contamination remains elusive. To address this point, we determined the microbial contamination of refillable standard pump dispensers and nonrefillable press‐dispenser systems. Following the collection of 104 liquid soap dispensers from hotel rooms across Germany, bacterial counts were determined. Isolates of samples containing nonfastidious Gram‐negative(lac−) bacteria were further analyzed by the Vitek 2 system for the determination of species. 70.2% of the refillable pump dispensers  but only 10.6% of the nonrefillable press dispensers, were contaminated . Of samples containing nonfastidious Gram‐negative(lac−) bacteria, Pluralibacter gergoviae was present in 41.7%, Pseudomonads (Pseudomonas aeruginosa and Pseudomonas putida) in 25%, Serratia marcescens in 16.7%, and Klebsiella oxytoca and Pasteurella testudinis in 8.3%. After the initial assessment, we contaminated different dispensing systems with P. aeruginosa/P. gergoviae, to reveal the route of contamination and identied the pressure release of standard pump dispensers as the loophole for microbial contamination.Liquid soap dispensers are widely used in domestic and clinical settings. In previous studies, the risk of bacterial contamination of refillable systems was pointed out and a bacterial contamination rate of 25%, with values of up to 10 8 colony‐forming units/mL was reported. We contaminated different dispensing systems with Pseudomonas aeruginosa /Pluralibacter gergoviae biofilm, to reveal the route of contamination and identified the pressure release of standard pump dispensers as the loophole for microbial contamination.Liquid soap dispensers are widely used in domestic and clinical settings. In previous studies, the risk of bacterial contamination of refillable systems was pointed out and a bacterial contamination rate of 25%, with values of up to 10 To determine the effect of handwashing with contaminated liquid soap, they experimentally contaminated liquid soap with a high level (3.2 × 107 CFU/mL) or low level (3.2 × 104 CFU/mL) of Serratia marcescens and found postwash titers of 1.9 × 105 and 5.0 × 101 CFU/hand, respectively. They further confirmed these results in a follow‐up field study. Here the mean number (3.9 × 102 CFU/hand) of bacteria recovered from the hands, after handwashing with a contaminated soap, was significantly higher than the pre‐handwashing value of 1.5 × 101 CFU/hand  and 47 alternative press dispensers (nonrefillable) were collected from hotel rooms across Germany Figure . The disBecause liquid soap dispensers are touched daily with dirty hands, the exterior can be heavily contaminated. Thus, the dispenser nozzle was wiped down with a sterile cloth to remove superficial contamination before sampling. The liquid soap from the first three pump/press steps was discarded, to subsequently draw the liquid soap for further analysis.2.2−1 to 10−4 in neutralizing solution , 3% Tween 80, 0.3% lecithin, 0.1% histidine, and 0.01% thiosulfate) and spread‐plated by application of 100 µL to tryptic soy agar (TSA), malt extract agar, or MacConkey agar (Merck), for determination of total bacterial count, yeasts/molds, and nonfastidious Gram‐negatives, respectively. Plates were incubated for 24–48 h at 30°C. The lowest dilution of 10−1 also means that samples with CFU/mL values below 100 must be considered as ≤100 CFU/mL. Triplicate determinations were carried out.Because of the viscous nature of liquid soap, direct application of the sample to agar plates and determination of CFU/mL is not possible. Liquid soap samples were therefore diluted from 10(lac−) colonies (MacConkey agar) of each sample were classified based on colony morphology .Nonfastidious Gram‐negativeOf these groups, isolates were picked and subcultured on TSA. After sub‐cultivation for 24–48 h at 30°C, pure isolates were applied to the VITEK 2 System/VITEK 2 GN ID card (Biomerieux) for the determination of bacterial species.Acinetobacter baumannii, P. aeruginosa, and some Enterobacteriaceae . These pathogens exhibit intrinsic resistance to multiple antibiotics and can cause severe and often fatal infectious diseases such as bloodstream infections and pneumonia. Furthermore, some of these strains can use liquid soap ingredients as substrates and exhibit increased tolerance to common preservatives  such as P. aeruginosa isolate of sample 42 and P. gergoviae isolate of sample 26, were used for the in vitro/in situ experiments.2.3P. aeruginosa and P. gergoviae were incubated in 10% tryptic soy broth (TSB) at 30°C for 48 h. These cultures contain free planktonic cells, but also bacterial aggregates embedded in an extracellular matrix with biofilm properties. A 1/1 mixture of P. aeruginosa and P. gergoviae culture in tap water was prepared . Concentration was determined by spread plating on TSA after vigorous vortexing for 1 min.2.4During the second phase of this study, it became clear that the main route of microbial contamination is the pressure release of the pump dispensers. Liquid can accumulate and is aspirated into the pump head and further into the dispenser bottle through the pressure release when the pump is actuated. Based on this observation we developed the following sequence for a contamination model. Application of 200 µL bacterial suspension , can grow in standard liquid soap, we conducted a series of experiments. Liquid soap .The biofilm was transferred to a microscope glass slide and submerged in 250 µL of a staining solution (1 μL of SYTO® 9 stain and 1 μL of propidium iodide stain per 1 mL of 10 mM PBS pH 7.2). The glass slide was covered using a plastic Petri dish lid and incubated and protected from light (20 min at room temperature). After incubation, the staining solution was aspirated, leaving the biofilm attached to the surface of the glass slide. To remove access dye, the biofilm was rinsed with 500 µL of 10 mM PBS pH 7.2. After the staining procedure, the biofilms were analyzed using a Zeiss Axio Imager M2M Fluorescence Microscope and a water immersion objective .2.72O; Sigma Aldrich, St. Louise, USA) directly to the pump head, followed by three pump strokes. After 24–48 h the staining was complete.In situ staining of biofilms in liquid soap was carried out by application of 200 µL of resazurin solution (6 mg/mL in deionized distilled H2.8We used GraphPad Prism (Version 6.07) for statistical calculations. Determination of the statistical significance of the respective cell numbers between refillable pump‐ and nonrefillable press‐dispensers and the significance of the growth of bacteria in different concentrations of liquid soap was done by Dunn's multiple comparison test and Tukey's multiple comparison test, respectively.33.1Figure nonfastidious Gram‐negatives(lac+), the difference in mean values (CFU/mL) between the pump‐ and press‐dispensers is significant .Except for 5 CFU/mL; max. 7.7 × 106 CFU/mL). 31.6% of the pump dispensers (18/57) contained nonfastidious Gram‐negative(lac−) bacteria . Yeasts and molds were found in 13/57 of the pump dispensers .Of 57 standard pump dispensers, 70.2% (40/57) were contaminated with bacteria  and neither nonfastidious Gram‐negatives nor yeasts and molds were detected. The mean total viable counts were therefore close to the detection limit of the analytics used here, of ≤100 CFU/mL.In contrast to the results of the pump dispensers, the press dispensers exhibited a very low contamination rate of 10.6% (5/47) and only very low cell counts colonies. This pertains only to the standard pump dispensers, as shown in Figure P. gergoviae was detected in 5/12 (41.7%), pseudomonads (P. aeruginosa and Pseudomonas putida) in 3/12 (25%), S. marcescens in 2/12 (16.7%), and Klebsiella oxytoca and Pasteurella testudinis, respectively, in 1/12 (8.3%) of the tested samples.Individual bacterial species were isolated from plates with Interestingly, if liquid soaps from hotels were heavily contaminated, one or two bacterial species dominated.3.3In 100% liquid soap solution, no growth of bacteria was observed, and the bacterial count remained at the level of Day 0 Figures  and 4. TP. gergoviae and P. aeruginosa bacterial suspension in 10% TSB) but that the bacteria cannot use the soap solution as a substrate alone. In any case, significant growth in 100% liquid soap solution was not present. In addition, the liquid soap solution and its preservation system are likely to have an inhibitory effect. However, it is important to note that we found no decrease in cell number in 100% liquid soap over 28 days.When diluted in tap water, slight growth occurs with decreasing soap concentration but only by 1–2 log10 steps Figure . AlthougDiluted in 10% TSB, as the soap concentration decreases and the nutrient level increases, significant growth occurred by up to 3–4 log10 steps at 12.5%–75% liquid soap  as can be seen by propidium iodine staining  bacteria. For 12/18 of samples containing nonfastidious Gram‐negative(lac−) colonies, bacterial isolates could be picked and subcultured. P. gergoviae was found to be the most frequent (5/12) nonfastidious Gram‐negative(lac−) colonizer. Further isolates included the species P. aeruginosa, P. putida, S. marcescens, K. oxytoca, and P. testudinis.70.2% of standard refillable pump dispensers collected from hotel rooms across Germany were contaminated with bacterial biofilms but only 10.6% of the nonrefillable press dispensers. Furthermore, mean CFU/mL values were significantly lower in the press dispensers and close to the detection limit. 18/57 (31.6%) of pump‐dispensers were contained with (lac−) bacteria  with yeast and molds found in this study should not be overlooked. Especially considering an increase in fungal infections and antifungal resistance of Candida spp. and Aspergillus fumigatus , were less or not affected by microbial contamination. Liquid soap from nonrefillable press dispensers was scarcely contaminated and contamination rather originated from the transfer of bacteria, from the outer part of the dispenser, during sampling.P. aeruginosa/P. gergoviae biofilms rather persist and accumulate, than grow in an undiluted (100%) liquid soap solution. These persisting cells have the potential to shift back to a growth phase and become problematic if conditions are more favorable. However, if the liquid soap is diluted by an influx of liquid through the pump head and an aqueous phase forms on top of the liquid soap, these cell aggregates and biofilms can grow slowly especially with the simultaneous introduction of nutrients. This is also the case when the liquid soap contains a preservative system and is supported by other studies as well. P. aeruginosa and P. gergoviae can develop resistance to common preservatives and antibiotics and can use a wide range of different substrates  for energy production  as well as the Food and Drug Administration (FDA) and P. gergoviae as well as P. aeruginosa were found to be the main cause of microbial contamination of shower gels, shampoos, liquid soaps, and lotions ; methodology ; writing—original draft . Nicolevan Leuven: Investigation . Dirk Bockmühl: Project administration ; writing—review and editing .The authors declare no conflict of interest.None required.


BackgroundScrew fixation continues to be a commonly used treatment for syndesmotic disruption; however, screw breakage remains a complication post-fixation. Despite this complication, investigation on the variability of surgical placement in conjunction with syndesmotic screw characteristics affecting breakage has not been fully elucidated. The purpose of this study is to compare patients with syndesmotic screw breakage versus those with intact screws based on surgically controlled variables.MethodsA total of 176 patients and 260 syndesmotic screws were included in the study, 88 patients each with and without broken syndesmotic screws. A retrospective analysis of patients who underwent syndesmotic screw fixation was performed. Patients with syndesmotic screw breakage were compared to those with intact screws. Screw width and length, the number of screws used, fracture type, and the number of cortices for fixation were all collected. Further analysis included radiographic measurement of syndesmotic screw angle and height of placement above the tibial plafond.ResultsDecreased screw width, increased number of screws used, and younger age were all associated with increased rates of screw breakage . No statistical difference was appreciated between groups based on screw length, number of cortices used, or angle relative to the tibial plafond .ConclusionHigher placement of syndesmotic screws above the tibiotalar joint, specifically greater than 20 mm above the tibial plafond, increases the screw breakage rate. Decreased screw width, increasing numbers of screws used, and younger age were all also associated with increased rates of screw breakage. No difference was appreciated based on the screw angle relative to the tibial plafond. Screws are frequently used for the fixation of syndesmosis disruption. The fixation of syndesmosis disruption with screws remains a frequent and efficacious treatment modality ,2. WhileBreakage of screws is a well-known and common complication seen in many patients following syndesmotic fixation with metal screws. Although other complications, such as mal-reduction or the need for additional surgery, may occur, screw breakage remains the most commonly reported ,11,14. DFollowing institutional review board approval by the University of Toledo Human Research Protection Program Biomedical IRB, a retrospective analysis of patients who underwent syndesmotic screw fixation from 2008 to 2020 was performed. The majority of patients underwent syndesmotic fixation in conjunction with an ankle fracture resulting in syndesmotic disruption. Patients underwent syndesmotic fixation at either the time of primary open reduction and internal fixation (ORIF) surgery or shortly after in the case of severe trauma requiring periods of external fixation. Only a few patients underwent syndesmotic fixation for isolated syndesmotic diastasis secondary to ankle trauma without resulting fracture or a Maisonneuve fracture. A total of 176 patients and 260 syndesmotic screws were included in the study. Each group comprised 88 patients. Ninety-seven patients with skeletally mature bone were found to have syndesmotic screw breakage, of which 88 met the inclusion criteria. All patients received syndesmosis screw fixation as well as plate and screw fixation for distal fibular fractures. A clear postoperative radiograph demonstrating screw breakage within the tibia, fibula, or clear space was required for inclusion. All syndesmotic fixation using methods other than screw fixation were excluded.Following identification and complete data collection of the breakage group, an additional 88 patients without syndesmotic screw breakage were identified to serve as the control group. Patients in this group were chosen at random within the same time frame as the breakage group. Basic patient demographic data were collected, including age, gender, and body mass index (BMI). Screw variable analysis included screw width and length, the number of screws used, ankle fracture type, and the number of cortices used for fixation. The surgical variable analysis included radiographic measurement of the syndesmotic screw angle relative to the tibiotalar joint and height of placement above the tibiotalar joint. A series of radiographs and a demonstration of the measurement of screw placement above the tibiotalar joint from a patient with syndesmotic screw breakage is shown in Figures Postoperative management included non-weight-bearing status for six weeks with regular physical therapy. A gradual progression to full weight-bearing was then employed with full weight-bearing status occurring no earlier than 12 weeks. Patients were typically seen for clinical follow-up at two, four, six, and 12 weeks postoperatively. All operative decisions, including screw size, screw number, amount of cortices screws traversed, screw placement angle, and screw placement height, were made by our institutional surgeons, who are all well-equipped to treat ankle fractures, using their best clinical judgment. Diagnosis of syndesmotic disruption was made using radiographic evidence, including tibiofibular overlap, tibiofibular clear space talar tilt, and intraoperative stress testing.The breakage group had a total of 121 syndesmotic screws while the control group had 139. The breakage group was comprised of 45 males (51.1%) and 43 females (48.9%) with an average age of 38.88 (SD + 15.61). The control group consisted of 47 males (53.4%) and 41 females (46.6%) with an average age of 45.12 (SD + 16.69). Patients with broken screws were found to be significantly younger than those with intact screws (p = .0148). An average BMI of 33.55 (SD + 9.818) was seen in the breakage group and 31.58 (SD + 8.15) in the control group (p = .1346) . A nearly identical number of patients within each group used two syndesmotic screws  while more patients within the breakage group used > 2 syndesmosis screws when compared to the control group n = 12, n = 3). There was a significant association between screw breakage and an increased number of screws used (p = .019). The average screw width in the breakage group was 3.67 (SD =.38) and 4.06 (SD =0.04) in the intact group (p =< .001). No statistical difference was appreciated between groups based on screw length (p = .2432) or the number of cortices used (p = .4699)  in the breakage group and 16.75 mm (SD = 9.28) (p = .0033) in the control group. No statistical difference was appreciated between groups based on the angle relative to the tibial plafond (p = .9233) . A significant difference was appreciated when comparing screw placement p = .022). Fifty-two percent of patients within the breakage group had screws placed > 20 mm above the tibial plafond compared to 34.5% in the control group. Fracture type showed no difference between groups (p = .272)  and mortise view X-rays were available for analysis, limiting our analysis of screw angle to the coronal plane. Due to the nature of this retrospective study, the inability to examine other planes may have limited our ability to detect a significant association between the angle of screw placement and the risk of screw breakage.A recent study by Ibrahim et al. found that in patients with syndesmotic screw breakage, screws placed greater than 20 mm above the tibial plafond were at increased risk for breakage within an intraosseous location when compared to clear space breakage. However, no control group for comparison was included and conclusions were made comparing only broken screws based on breakage location .Many studies have presented conflicting conclusions on the optimal height of syndesmotic screw placement. Optimal placement height has been suggested as 30-40 mm, 20 mm, and 1 cm above the tibial plafond -19. KukrMany studies have examined screw failure based on screw width and the number of cortices used -26. The Notably, we did attempt to compare non-broken screws against broken screws in patients that had at least one broken screw and at least one intact screw. Although 39 patients with 48 broken and 40 intact screws met these criteria, we did not appreciate any significant findings similar to those found in our initial comparison.It is our opinion that surgeons should be mindful of the height of placement above the plafond when using syndesmotic screws. Further, younger patients should be counseled on the increased risk of screw breakage and counseled accordingly based on the surgeon’s experience as the clinical significance of screw breakage remains an active debate.While our data uncovers many meaningful findings, there are still limitations to this retrospective study. Particularly, many of the patients did not receive computerized tomography (CT), which made analyzing screw angles within the sagittal plane difficult. Ideally, we would have included the angle of screw placement relative to the sagittal plane in our comparison, especially since the well-accepted 25-30 degrees of angulation have recently been called into question . Future Higher placement of syndesmotic screws above the tibiotalar joint, specifically greater than 20 mm above the tibial plafond, increases the screw breakage rate. No difference was appreciated based on the screw angle relative to the tibial plafond in the coronal plane. In addition to placement, there are other factors that can contribute to an increased rate of screw breakage. For example, decreased screw width can make the screws more prone to breaking under stress. Using a higher number of screws to stabilize can also increase the likelihood of breakage. Finally, younger patients were also more prone to screw breakage. By taking these factors into account, there is a possibility of reduced risk of complications.


Patients with adult spinal deformity (ASD) may have risk factors for nonunion and subsequent instrumentation failure. This study reviews a novel surgical technique for a quad-rod construct to the pelvis using both S2 alar iliac (S2AI) screw fixation and medialized entry iliac screw fixation as described through three separate cases and a review of the literature.This technique facilitates alignment of the construct and rod insertion into the tulip heads. The medialized iliac screw technique also avoids the potential soft-tissue complications of the conventional iliac screw bolt given that it is deeper and has more soft-tissue coverage.Three cases performed by the most senior author (V.A.) in which this novel technique was used are presented in this report along with clinical and radiographic images to educate the reader on appropriate execution of this technique. A review of the existing literature regarding pelvic fixation techniques for ASD was also done.Quad-rod augmentation of long thoracolumbar spinal constructs with two independent SI anchoring points is potentially an effective technique to increase lumbar sacral construct rigidity, thereby promoting fusion rates and decreasing revision rates. The described technique provides spine surgeons with an additional tool in their armamentarium to treat patients with complex ASD. In addition, given the increasing amount of healthcare expenditure on ASD, minimizing rates of revision surgery would improve cost-effectiveness, which has become an increasing concern among insurers and policy makers.5With an increasing mean age of the general population, there has been a growing incidence of symptomatic adult spinal deformity (ASD) necessitating long fusion constructs.7 This was followed by insertion of two iliac screws bilaterally and four rods.8 In most cases, this technique required the insertion of an iliac screw on the inner iliac cortex just outside the sacroiliac (SI) joint  and another screw on the top of the iliac crest . One disadvantage of the conventional iliac bolt technique includes prominence, which may lead to wound healing issues, pain, and discomfort, particularly for thin patients.In 2006, the senior author published a novel method on using a four-rod technique for thoracolumbar reconstruction based on alternating between the Roy Camille screw trajectory (straight in) and Magerl screw trajectory  at each level in the lumbar spine.10In addition, the traditional iliac bolt is typically not in line with the cephalad pedicle screw construct which requires an offset connection, and the introduction of yet another interface decreases the strength of the inferior portion of the construct, which is essential for stability.111213141516 the senior author combined the medialized entry iliac (MEI) screw and the S2AI screw in patients who required pelvic fixation with four screws.With the advent of the S2 alar iliac (S2AI) screw technique,Considering that patients with ASD have risk factors for nonunion and subsequent instrumentation failure, this study aims to describe a novel surgical technique that can be used as a tool to increase lumbar sacral construct rigidity, with the objective of promoting fusion rates in the treatment of patients with complex ASD.Two authors conducted separate searches using the following medical databases on January 1, 2022: PubMed (1966-present), SCOPUS (1966-present), and Ovid MEDLINE (1946-present). A focused search strategy was done. Keywords including ‘pelvic fixation,’ ‘S2 alar,’ ‘medialized,’ and ‘long fusion’ were combined with Boolean operators and queried. The results were reviewed in order of relevance. A review of the included references of relevant studies was also done.8 Nonunion and associated rod fracture is a concern with long spinal deformity constructs. The present technique provides additional axial and torsional stability to minimize the risk of rod fracture, particularly in cases of three-column osteotomies.The surgical technique for a quad-rod construct to the pelvis using both S2AI screw fixation and MEI screw fixation is outlined below. This technique facilitates alignment of the construct and rod insertion into the tulip heads. The medialized iliac screw technique also avoids the potential soft-tissue complications of the conventional iliac screw bolt given that it is deeper and has more soft-tissue coverage. The technique allows versatility in selecting the location and direction of bone anchors into the pelvis.Three cases in which this novel technique was used are presented in this report Table –6. This Three cases from our practice demonstrating the described quad-rod technique being used in the care of patients are described Table –6. All c•Pars interarticularis at each level•Facet joints at each level•Transverse processes at each level•Upper 1/3 of the sacrum including the S1 and S2 sacral foramina•Sacroiliac joints bilaterally•Posterior superior iliac spine bilaterallyAnatomic bony landmarks to be exposed:Dissection is done in a standard subperiosteal fashion until the transverse processes and the upper 1/3 of the sacrum including the S1 and S2 dorsal foramina are exposed. The sacroiliac joints, posterior superior iliac spines, and the iliac crest adjacent to the S1 foramen should also be exposed. A Hohmann retractor can be positioned over the iliac crest to provide excellent exposure of the pelvic instrumentation starting points. To ensure patient safety during this technique, it is not advisable to begin instrumentation until all bony landmarks are clearly visualized given that this technique relies heavily on patient anatomy rather than imaging guidance to place instrumentation. Generally, the only form of imaging necessary to place instrumentation in this technique is preoperative AP and lateral radiographs and a preoperative CT scan . Preoperative CT is recommended because it assists the surgeon in using the anatomic technique to appropriately plan pedicle screw start point, trajectory, and size. CT scan also helps to plan appropriate start point, trajectory, and size of the S2AI and MEI screws because there is some variation in individual patient pelvic anatomy as well as between sexes which affects screw start point and trajectory during insertion. After all bony landmarks are exposed, pedicle instrumentation is begun at L4, followed by L5 and S1 in a caudal progression. Special attention should be paid to the insertion point of the L5 screw, ensuring that it falls on a line between L4 and the S1 pedicle screws. Pelvic instrumentation follows pedicle screw insertion.The S1 sacral screws are placed using the standard bony landmarks. A point midway between the medial aspect of the sacral ala and first sacral foramina is identified, which is typically within 1 mm of the superior articulating process of the S1 vertebra. After burring the pilot hole, the S1 pedicle is cannulated with a curved awl with a 30° to 40° medial trajectory aiming for the superior aspect of sacral promontory. The pedicular wall integrity is palpated and confirmed with a ball tip probe in the usual fashion, followed by the placement of the screw. The cannulated pedicle does not need to be tapped unless using larger screws measuring 8 mm or more.Pelvic instrumentation includes a MEI screw and a S2AI screw. The decision of which of the two screws is placed first depends on which starting point aligns with the main vertical rod of the construct. Typically, the MEI screw aligns with the main vertical rod and the S2AI screw aligns with the second rod, which would then be placed medial to the first rod. If the S2AI screw is aligned with the lumbar instrumentation, the second rod may run laterally into the MEI screws.For primary pelvic fixation, the conventional iliac screw starts at the posterior superior iliac spine. However, this insertion point is associated with prominence of the instrument, leading to pain and wound issues. Figure . To avoi17 After assessing its integrity with a ball tip probe, the cannulation is then tapped followed by placement of a long iliac screw typically measuring 80 to 100 millimeters with a diameter of 9 millimeters.For secondary rod fixation, a point between the S1 and S2 dorsal foramina is selected medial to the previously placed primary MEI screw, thereby allowing medial placement of the secondary rod. A standard S2AI screw trajectory is used, traversing the SI joint obliquely aiming toward the greater trochanter with an estimated angulation of 30 to 45 degree of pedicle finder with respect to dorsal sacral surface.18After completion of the foundation of the construct bilaterally, bilateral teardrop views are taken with fluoroscopy to check the positioning of the MEI and S2AI screws. The teardrop view is obtained by rolling the C-arm 30 to 40° over the table and then tilting the C-arm 30 to 40° toward the patient's head. The image obtained in this position shows the column of bone extending from the posterior superior iliac spine to the anterior inferior iliac spine, whereby the overlap of the inner and outer cortices of the ilium creates the shape of a teardrop. The contralateral side can then be obtained by rolling the C-arm back to neutral and then 30 to 40° away from the table while maintaining the same 30 to 40° tilt toward the patient's head. The instrumentation is then run cranially using standard landmarks and pedicular trajectories to the upper instrumented vertebrae. A freehand pedicle screw placement technique is used.19 In addition, triggered electromyography (EMG) is always done with each pedicle screw to assess for pedicle breach and confirm the safety of the neurologic structures.20After instrumentation is completed, either AP and lateral fluoroscopy or intraoperative CT can be done to assess for screw malposition and ensure appropriate placement of all pedicle screws and pelvis instrumentation after the freehand technique.This is followed by the preoperatively planned decompression and/or osteotomies with restoration of lordosis. After obtaining the desired lordosis, the rod is then contoured aiming to replicate the desired lordosis followed by dialing in of the appropriate thoracic kyphosis.Next, the secondary rod is placed by anchoring it into the S2AI screws bilaterally and then connecting with the primary rod using lateral connectors or connecting to medially placed screw in the case of Roy Camille trajectory screws. At least three side-to-side open connectors are generally used on each side to obtain the desired stiffness and stability of the construct. This is followed by final tightening of the set screws starting with the primary construct, followed by the connector-primary rod interface and finally the secondary rod. This sequence is maintained to ensure prevention of undue stress at the connector-primary rod interfaces because they are the weakest point in the construct. The secondary rods should cross to at least two levels above the highest osteotomy site or two levels above the thoracolumbar junction. Decortication is done, and bone graft is added during this procedure.A 57-year-old man with a history of Parkinson disease and prior involvement in a motor vehicle collision presented with progressive back pain, stiffness, and postural decline over several years. Full length, AP, and lateral radiographs are shown at the preoperative, 1 month postoperative, and 20 months postoperative time points , can result in flat back syndrome. Correction of the deformity may require a long construct and a lower lumbar spine osteotomy to restore the sagittal alignment. The goal is to achieve fusion of the spine in the corrected position,Instrumentation failure is routinely recognized as a surrogate marker for pseudarthrosis. The technique described in this report is used to augment long spinal constructs especially in elderly patients with high BMI, osteopenia, increased frailty scores, and other comorbidities who require long constructs because of sagittal malalignment. Furthermore, increasing sagittal decompensation in elderly population also requires increasing use of osteotomy techniques, including three-column osteotomy techniques. This results in higher incidence of pseudarthrosis leading to an increased risk of instrumentation failure in this population.25 in in vitro testing, thus promoting fusion across the lumbosacral junction and second to decrease rod fracture and thus potentially obviating the need for revision surgery, as demonstrated by Shen et al26 in a cohort of 32 patients with 8.3% rate of rod breakage, however, with none of the patients requiring revision surgery.Adult degenerative scoliosis can also be included in the abovementioned cohort with patients frequently requiring long spinal constructs and multiple osteotomies requiring sacroiliac (SI) anchoring. Formerly, SI fixation was obtained by traditional iliac screws and/or S2AI screws. These techniques can be used for good effect by running multiple screw rod constructs up along the length of construct. This requires careful planning preoperatively by using the available space for placement of a two large diameter screw heads on each side. The intended advantage of such instrumentation architecture is two-fold, first and foremost by increasing rigidity across the lumbosacral transition, suggested by Kelly et al28 A cadaveric study demonstrated greater stability when using a 4-rod technique compared with S1 or S1 plus iliac screws.29 A comparative study by Hyun et al30 showed superiority for multirod constructs with a three-column osteotomy compared with a dual-column approach.Construct augmentation with multiple rods has been increasingly used and described over the past one to 2 decades with varying architecture.31 also highlighted the reduction of rod fracture in multirod constructs in comparison with a dual-rod approach. Patients in the three-column approach showed notable reductions in rates of rod breakage and revision surgery for pseudarthroses versus two-column osteotomies. Most of these descriptions include secondary systems comprising rods and connectors which differ from our technique. Our described architecture involves individual SI anchoring, in the form of separate dedicated S2AI screw, thus promoting increasing rigidity across the construct foundation via stress distribution over two iliac bolts. This increased rigidity may have implications on fusion rates because a stiffer construct may decrease motion at the lumbosacral junction and lower the risk of mechanical failure, thereby promoting protective factors for fusion.25 Kelly at al. found increased stability and flexibility with the four-rod model compared with the conventional two-rod construct.32 A recent retrospective study by Villazón et al compared a pelvic fixation with a multirod construct to two-rod constructs in the setting of ASD and found no difference in complication rates in the use of additional rods.33 This study of 33 patients with multirod fixation and 33 patients with a dual-rod approach found a higher rate of rod breakage and revision surgery in the dual-rod cohort. A retrospective study by Merrill et al34 compared 15 patients in the dual-rod group and 16 in the multirod group and found that the dual-rod construct cohort exhibited a higher rate of pseudarthroses. Despite a limited sample size, the authors concluded that increasing construct rigidity with multiple rods has been associated with superior fusion outcomes.In a similar study, Yamato et al10 Therefore, this study aims to describe the technical nuances of the technique with recent clinical examples. This technique can also be used in short lumbosacral constructs if mechanical demands dictate the need for a more robust construct. The potential clinical non-ASD scenarios would be cases requiring extensive sacral osteotomy in neoplasm resection. Other cases would include high-grade spondylolistheses requiring surgical management and/or revision cases with lumbosacral junctional pseudo arthrosis, as well as traumatic case of unstable U/H-shaped sacral fractures with spinopelvic dissociation.This technique has been previously described by the senior author.The safety and complication profile, although outside the purview of this study, is comparable with the expected norm for such procedures. The abovementioned architecture relies on established instrumentation techniques. Additional work on the long-term clinical outcomes of the technique is warranted. Future work validating the rigidity of this construct could include biomechanical studies comparing the quad-rod technique with more traditional dual-rod constructs using either traditional iliac bolts or S2AI fixation alone. Furthermore, long-term follow-up of patients with ASD treated with the quad-rod construct will provide additional insight into rates of nonunion and/or instrumentation failure with this technique. Although the increased stiffness of the quad-rod construct may decrease rates of mechanical failure, the potential association between construct stiffness and bony fusion requires additional investigation. The quad-rod construct may improve fixation by providing alternative traversing of rods through the lumbosacral junction. The quad-rod construct described in this study specifically proposes a method involving four rods, each of which is independently anchored to its own dedicated pelvic bolt. Other multirod constructs use side-to-side connectors to attach a supplementary rod along the side of one or both main rods. The construct is anchored to the pelvis using one or two pelvic screws on each side. These other constructs rely on the two main rods, and their anchor points as the foundation of the construct. The supplementary rod is dependent on the cross connectors used near the pelvic bolts. Our method increases redundancy in pelvic fixation and relies less on the integrity of the two main rods. In addition, the supplementary rods are not functionally dependent on a single pair of cross connectors at the base of the construct. These three cases and a review of the literature support the implementation of the quad-rod augmentation technique as a potential surgical technique for thoracolumbar spinal constructs in patients with complex ASD.Quad-rod augmentation of long thoracolumbar spinal constructs with two independent SI anchoring points is potentially an effective technique, with the objective of increasing lumbar sacral construct rigidity, which may promote fusion rates and thereby decreasing revision. The described technique may serve as an effective tool to treat patients with ASD.


Aspergillus-specific immunoglobulin E as a key item, and regard IgG as an auxiliary method in diagnose. Nevertheless, there is no conclusive study in summarize the performance of IgG and IgE diagnosing ABPA.Hitherto, the bulk of diagnostic criteria regards  I2 statistic were used to test the heterogeneity.We conducted a systematic review to identify studies report results of IgE and IgG detection in diagnosing ABPA. QUADAS-2 tool was used to evaluate included studies, and we applied the HSROC model to calculate the pooled sensitivity and specificity. Deeks’ funnel was derived to evaluated the public bias of included studies, and Cochrane Q test andEleven studies were included in this study (1127 subjects and 215 for IgE and IgG). Deeks’s test for IgE and IgG were 0.10 and 0.19. The pooled sensitivity and specificity for IgE were 0.83  and 0.89 , and for IgG were 0.93  and 0.73 , with P value < 0.001. The PLR and NLR for IgE were 7.80  and 0.19 , while for IgG were 3.45  and 0.09 . The combined diagnostic odds ratio and diagnostic score were 41.49  and3.73  for IgE, respectively, and were 38.42  and 3.65  for IgG.The sensitivity for IgG diagnosing ABPA is higher than IgE, while the specificity for IgE is higher. IgG might be able to play a more important role in filtering ABPA patients.The online version contains supplementary material available at 10.1186/s12890-023-02620-3. Aspergillus, and it is a complex of various immune reactions that leads to immune disorder and it is most commonly combined with asthma and cystic fibrosis [Aspergillus fumigatus (Af), and a similar disease caused by fungus infection other than Aspergillus fumigatus is called allergic bronchopulmonary mycosis (ABPM) [Allergic bronchopulmonary aspergillosis (ABPA) is a bronchopulmonary allergic inflammatory disease caused by fibrosis . The pris (ABPM) , 3 The cs (ABPM) . The pats (ABPM) , 5. BronAspergillus-specific immunoglobulin E (IgE) and immunoglobulin G (IgG) antibodies or precipitated antibodies to detect type I and III allergic reactions [A. fumigatus, and the secondary features include raised specific IgG against A. fumigatus, eosinophilia, and radiological signs [Hitherto, the published diagnostic criteria for ABPA include Greenberger and Patterson , the Inteactions . The necal signs .A. fumigatus specific IgG and IgE are pivotal for diagnosing ABPA because they reflect type I and III allergic reactions to Aspergillus species [A. fumigatus allergen was not helpful in diagnosing ABPA or detecting sensitization to fungus.As mentioned above, the detection of  species , 5. Ther species , 11. How species . In cont species  showed tA. fumigatus-specific IgG and IgE performed concurrently in the same set of patients, we aimed to find whether detection of A. fumigatus specific IgG or IgE by immunoassay-methods would perform better in diagnosing ABPA in this systematic review.Considering that there is no conclusive study on the specificity and sensitivity of detection of We conducted this systematic review and meta-analysis according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses for diagnostic test accuracy (PRISMA-DTA) statement . Our stuTwo investigators (AL and WS) independently searched the EMBASE and PubMed databases for records (until July 30). The search strategy includes terms including “ABPA”, “IgG”, and “Immunoassay”, and the detailed strategy is shown in Supplementary Methods studies describing immunoassay methods for detecting both IgE  and A. fumigatus-specific IgG antibodies for diagnosing ABPA;studies reporting the diagnostic accuracy values of both techniques or allowing the calculation of sensitivity from the study observations;the studies had a control group and an experimental group.We included studies meeting the following criteria:studies including case reports, abstracts, comments, editorials, and reviews;studies only describing either the IgE or IgG for diagnosing ABPA;studies published in a language other than English.Studies that met the following criteria would be excluded:The primary outcome of our study is the sensitivity and specificity of detecting IgG and IgE with the immunoassay method in diagnosing ABPA. We used various methods to evaluate the diagnostic performance of IgG and IgE, including the HSROC model, random-effect model, and diagnostic odds ratios.A total of 3383 studies were obtained via PubMed and Embase, and unpublished data in our institution, which identify 510 possible studies in the first stage. All articles were imported into a file manager , then two authors (AL and WS) screened the files by reviewing the title and abstract after dropping the duplicates. Any disagreement would be handed to a third author (YQ) and reached consensus after discussion. In subsequent, authors (JL and YW) would conduct the second screening based on the full text, and the inclusion and exclusion criteria were applied. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) flow diagram of the search results and article exclusion details are shown in Fig. publication information ;study design ;the inclusion and exclusion criteria for the study and the number of studies;the type of control population included;the criteria for diagnosing ABPA;the detailed detecting methods .Two authors (AL and WC) independently extracted data using a preapproved electric form by all authors. Retrieved data included a few dimensions:Any difference would be submitted to another author, QY, to resolve. Studies with high quality and detailed sensitivity and specificity for both IgE and IgG would be selected.We use the QUADAS-2 to measure the quality of included studies, which brings more transparency to bias assessment and diagnostic laboratory evaluation . RevMan P < 0.10 denoting heterogeneity, while the I [P < 0.01 indicating significant public bias.The Rutter and Gatsonis hierarchical model has been proved to be effective in diagnostic meta-analysis, and has been widely used to provide a summary ROC curve, as different ranges of thresholds for immunoassay were used by different investigators . The maile the I  statistile the I , with P We used Stata17  to conducted all of the statistical analyses.After the initial search, we found 3383 articles . After screening the abstracts and titles and evaluating the eligibility for research based on the inclusion and exclusion criteria, eight manuscripts were included in our study, with 1127 subjects and 215 for IgE and IgG , 20–25, All included studies were case–control studies, among which 4 used ELISA –22, 4 usQuality assessment was conducted with the QUADAS-2 tool, and the detailed is showed in supplementary materials  and 0.19  , and 3.73(3.29–4.16) for IgE, respectively -4, IL-5, IL-13 and other cytokines, and inflammatory cells such as eosinophils would be also stimulated [Diagnostic meta-analysis requires careful assessment of included studies. As a widely acknowledged tool to evaluate the quality of diagnostic meta-analysis , we usedimulated . To diagimulated . Previouimulated . In thisA. fumigatus-specific IgE, which is regarded the most sensitivity investigation methods in diagnosing ABPA [A. fumigatus-specific IgE were found to be 100% and 70%, respectively, in the diagnosis of ABPA [IgE had been regarded as a crucial criterion in diagnosing ABPA, especially an elevated level of serum ing ABPA , 7, 28.  of ABPA . In cont of ABPA .A. fumigatus-specific IgG is valuable in diagnosing ABPA, whose sensitivity is 89% and specificity is 100% [A. fumigatus-specific IgG detected using double gel diffusion technique has a sensitivity of only 27% in the diagnosis of ABPA while the commercial enzyme immunoassay methods for measuring A. fumigatus-specific IgG have a sensitivity exceeding 90% [A. fumigatus-specific IgE, which strongly indicate possible active CPM [Meanwhile, the importance of IgG seemed to be underestimated. A cohort study suggested that  is 100% . In our ding 90% , 32. We tive CPM , 34. TheThough we found interesting results in our study, it is noteworthy that though serum tests of IgE and IgG is important in diagnosing ABPA, the diagnose requires a more comprehensive examination. For example, the level of serum total IgE may lower in different country , and putThis study suffers from serval limitations. First of all, as shown in Supplementary Fig. The sensitivity for IgG in diagnosing ABPA is higher than IgE, and the specificity of IgE is higher than IgG. The value of IgG in diagnosing ABPA should not be underestimated, and it may play a more important role in filtering possible ABPA patients.Additional file 1:Supplementary Table 1. Detailed information of included studies. Supplementary Table 2. Summary performance for IgE and IgG in diagnosing ABPA. Supplementary Figure 1. Risk of bias and applicability concerns summary. Supplementary Figure 2. Forest plot of pooled sensitivity and specificity of the included articles (n = 12). Supplementary Figure 3. Forest plot of positive likelihood ratio and negative likelihood ratio of the included articles (n = 12). Supplementary Figure 4. Forest plot of the diagnostic score and diagnostic odds ratio of the included articles (n = 12). Supplementary Figure 5. Forest plot of pooled sensitivity and specificity of the included articles (n = 12). Supplementary Figure 6. Forest plot of positive likelihood ratio and negative likelihood ratio of the included articles (n = 12). Supplementary Figure 7. Forest plot of the diagnostic score and diagnostic odds ratio of the included articles (n = 12). Supplementary Figure 8. Sensitivity analysis of IgE and IgG (n = 12).