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OBJECTIVES: Primary sclerosing cholangitis is an autoimmune illness affecting the intrahepatic and/or extrahepatic bile ducts that has a varying clinical history and no clear therapy. Recurrence of primary sclerosing cholangitis after transplantation can cause recurring liver failure, decreased survival, and the necessity for retransplant. Here, we explored the incidence of recurrence while also identifying the risk factors of primary sclerosing cholangitis. MATERIALS AND METHODS: In this retrospective cohort study, we collected demographic and clinical data from patients with a history of primary sclerosing cholangitis after liver transplant between 2011 and 2021. With SPSS software, we compared results in 2 groups of patients (with and without recurrent sclerosing biliary cholangitis) in terms of demographic and clinical variables. RESULTS: The study included 408 patients. Lower donor age and the occurrence of acute cellularrejection were shown to be key risk factors for recurrence of primary sclerosing cholangitis. Acute cellularrejection showed the best likelihood of predicting primary sclerosing cholangitis recurrence. As the number of acute cellular rejection episodes increased, so did the chance of primary sclerosing cholangitis. Death rate of patients with recurrence of primary sclerosing cholangitis was 40.8% (n = 20 patients) compared with 18.9% (n = 68 patients) in those without recurrence (significant at P < .001). CONCLUSIONS: The recurrence of primary sclerosing cholangitis had a detrimental effect on survival after liver transplant. Modifiable risk variables have the potentialto affecttherapies on care and prevention of primary sclerosing cholangitis recurrence. Donor age and acute cellular rejection were risk factors for decreased survival and higher primary sclerosing cholangitis recurrence. The use of mycophenolate (Cellcept) increased recurrence, but tacrolimus reduced mortality.

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Colangitis Esclerosante , Inmunosupresores , Trasplante de Hígado , Recurrencia , Humanos , Colangitis Esclerosante/cirugía , Colangitis Esclerosante/mortalidad , Colangitis Esclerosante/diagnóstico , Trasplante de Hígado/efectos adversos , Trasplante de Hígado/mortalidad , Factores de Riesgo , Estudios Retrospectivos , Masculino , Femenino , Adulto , Persona de Mediana Edad , Resultado del Tratamiento , Inmunosupresores/efectos adversos , Factores de Tiempo , Medición de Riesgo , Irán/epidemiología , Adulto Joven , Incidencia , Factores de Edad , Adolescente , Rechazo de Injerto/mortalidad , Rechazo de Injerto/prevención & control , Rechazo de Injerto/diagnóstico , Rechazo de Injerto/inmunología

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Background: Hepatitis A is a widespread viral infection with significant public health implications. Assessing glucose 6-phosphate dehydrogenase (G6PD) deficiency in hepatitis A patients is essential for various reasons, including prognosis, disease severity evaluation, encephalopathy risk identification, tailored management, and advancing scientific understanding. This study aimed to investigate the prevalence and clinical implications of G6PD impairment in individuals with fulminant hepatitis A. Methods: A cross-sectional descriptive analysis was conducted, involving hospitalized patients with fulminant hepatitis A. Demographic data, prevalence rates, and clinical findings were recorded in a database. The diagnosis of hepatitis A infection was confirmed using an anti-HAV IgM antibody test, and G6PD enzyme activity was measured with a fluorescent spot assay. Results: Out of 81 patients with hepatitis A, 57 (70.4%) were males, and 24 (29.5%) were females, with an average age of 24.6 years. Dark yellow urine and anorexia were the most common clinical symptoms. Notably, 30 (37%) patients lacked G6PD. The group with G6PD deficiency showed significantly higher rates of encephalopathy and mortality (P<0.01), along with elevated bilirubin (P=0.00), abnormal coagulation parameters, and low hemoglobin levels (P=0.00). Conclusion: In light of these findings, the present study proposes the implementation of routine G6PD level assessments and the evaluation of other relevant markers in regions where hepatitis A is endemic. Furthermore, the study underscores the need for vigilant monitoring of hemolysis and encephalopathy in affected patients to optimize clinical management and reduce morbidity and mortality associated with this condition.

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Metal matrix composites (MMCs) combine metal with ceramic reinforcement, offering high strength, stiffness, corrosion resistance, and low weight for diverse applications. Al-SiC, a common MMC, consists of an aluminum matrix reinforced with silicon carbide, making it ideal for the aerospace and automotive industries. In this work, molecular dynamics simulations are performed to investigate the mechanical properties of the complex-shaped models of Al-SiC. Three different volume fractions of SiC particles, precisely 10%, 15%, and 25%, are investigated in a composite under uniaxial tensile loading. The tensile behavior of Al-SiC composites is evaluated under two loading directions, considering both cases with and without diffusion effects. The results show that diffusion increases the ultimate tensile strength of the Al-SiC composite, particularly for the 15% SiC volume fraction. Regarding the shape of the SiC particles considered in this research, the strength of the composite varies in different directions. Specifically, the ultimate strength of the Al-SiC composite with 25% SiC reached 11.29 GPa in one direction, and 6.63 GPa in another, demonstrating the material's anisotropic mechanical behavior when diffusion effects are considered. Young's modulus shows negligible change in the presence of diffusion. Furthermore, diffusion improves toughness in Al-SiC composites, resulting in higher values compared to those without diffusion, as evidenced by the 25% SiC volume fraction composite (2.086 GPa) versus 15% (0.863 GPa) and 10% (1.296 GPa) SiC volume fractions.

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OBJECTIVES: Acetaminophen is the most widely antipyretic analgesic medicine used in adults and children worldwide. Rectal acetaminophen is widely used in children who resist or cannot take oral medications. This study was designed to compare the efficacy of rectal and IV acetaminophen in children with fever and mild to moderate pain. PATIENTS AND METHODS: Total 60 children aged six months to 6 years, with fever and pain, that were treated with rectal or intravenous acetaminophen were selected and assigned in two groups. The IV group received 10mg/kg paracetamol as an IV infusion, and the rectal group received a 15mg/kg dose immediately after admission. Pain score was calculated using the FLACC method, and the axillary temperature was recorded at baseline and then 0.5, 1, 2, 4, and 6hours after drug administration. Blood samples were collected at baseline and then at 30min-intervals for the first 90minutes. RESULTS: The trend of changes in mean pain score at different time intervals was significantly different between the two groups. Body temperature decrease was more prominent in the IV group. The plasma concentration increased in both groups significantly with time. This increase was sharper in the IV group, just in the first 60minutes after drug administration. CONCLUSIONS: IV acetaminophen has more rapid onset of action, while rectal dosage form control fever and pain for longer duration. Considering its favorable effects with ease of administration and lower cost, rectal acetaminophen can be a reasonable option in selected patients with pain or fever.

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Acetaminofén , Administración Rectal , Analgésicos no Narcóticos , Antipiréticos , Fiebre , Dolor , Humanos , Acetaminofén/administración & dosificación , Acetaminofén/uso terapéutico , Acetaminofén/sangre , Masculino , Preescolar , Femenino , Niño , Lactante , Antipiréticos/administración & dosificación , Antipiréticos/uso terapéutico , Irán , Fiebre/tratamiento farmacológico , Analgésicos no Narcóticos/administración & dosificación , Analgésicos no Narcóticos/uso terapéutico , Dolor/tratamiento farmacológico , Administración Intravenosa , Dimensión del Dolor , Temperatura Corporal/efectos de los fármacos , Infusiones Intravenosas

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This study comprehensively investigates Al2O3's mechanical properties, focusing on fracture toughness, surface energy, Young's modulus, and crack propagation. The density functional theory (DFT) is employed to model the vacancies in Al2O3, providing essential insights into this material's structural stability and defect formation. The DFT simulations reveal a deep understanding of vacancy-related properties and their impact on mechanical behavior. In conjunction with molecular dynamics (MD) simulations, the fracture toughness and crack propagation in Al2O3 are explored, offering valuable information on material strength and durability. The surface energy of Al2O3 is also assessed using DFT, shedding light on its interactions with the surrounding environment. The results of this investigation highlight the significant impact of oxygen vacancies on mechanical characteristics such as ultimate strength and fracture toughness, drawing comparisons with the effects observed in the presence of aluminum vacancies. Additionally, the research underscores the validation of fracture toughness outcomes derived from both DFT and MD simulations, which align well with findings from established experimental studies. Additionally, the research underscores the validation of fracture toughness outcomes derived from DFT and MD simulations, aligning well with findings from established experimental studies. The combination of DFT and MD simulations provides a robust framework for a comprehensive understanding of Al2O3's mechanical properties, with implications for material science and engineering applications.

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INTRODUCTION: Biliary complications (BCs) are a well-documented post-liver transplantation concern with potential implications for patient survival. This study aims at identifying risk factors associated with the development of BCs in recipients after liver transplantation (LT) and exploring strategies for their management. METHODS: We conducted a retrospective analysis of 1595 adult patients (age > 18 years) who underwent LT surgery between 2019 and 2021. The study assessed the incidence of BCs in this cohort. RESULTS: Of 1595 patients, 178 (11.1%) experienced BCs, while 1417 (88.8%) did not exhibit any signs of such complications. Patients who developed BCs were found to have a significantly lower average age (p < 0.001) and longer cold ischemic times (p < 0.001) compared to those without BCs. Variables such as sex, body mass index (BMI), model for end-stage liver disease (MELD) score, primary diagnosis, type of anastomosis, hepatectomy technique, type of transplanted liver and mortality did not demonstrate statistically significant differences between the two groups (p > 0.05). Univariate logistic regression analysis revealed that a cold ischemic time exceeding 12 hours and duct-to-duct anastomosis were positive predictors for BC development (odds ratios of 6.23 [CI 4.29-9.02] and 1.47 [CI 0.94-2.30], respectively). Conversely, increasing age was associated with a protective effect against BC development, with an odds ratio of 0.64 (CI 0.46-0.89). CONCLUSION: Our multi-variate analysis identified cold ischemia time (CIT) as the sole significant predictor of post-liver transplantation biliary complications. Additionally, this study observed that advancing patient age had a protective influence in this context. Notably, no significant disparities were detected between hepatectomy techniques and the etiology of liver disease types in the two study groups.

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Enfermedades de las Vías Biliares , Trasplante de Hígado , Complicaciones Posoperatorias , Humanos , Trasplante de Hígado/efectos adversos , Factores de Riesgo , Masculino , Femenino , Estudios Retrospectivos , Persona de Mediana Edad , Complicaciones Posoperatorias/etiología , Complicaciones Posoperatorias/epidemiología , Adulto , Enfermedades de las Vías Biliares/etiología , Enfermedades de las Vías Biliares/epidemiología , Isquemia Fría/efectos adversos , Estudios de Cohortes , Factores de Edad , Incidencia

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OBJECTIVES: Prolonged tracheal intubation and mechanical ventilation after liver transplant increase postoperative complications. Hence, timely extubation should be considered; however, a standard clinical criteria set or scoring system to select patients has not been established for early extubation after livertransplant.We investigated the factors that affect early extubation to design a predictive scoring system for early extubation. MATERIALS AND METHODS: This study is a case-control study of adult liver transplant patients. Preoperative, intraoperative, and postoperative clinical data were collected. Early extubation was defined as tracheal extubation immediately or up to 6 hours posttransplant. The variables were compared between the early extubation group and the delayed extubation (>6 hours) group. RESULTS: Our study enrolled 237 patients; among them, 57 patients (24%) were in the early extubation group, and 180 (76%) were in the delayed extubation group. Multiple logistic regression analysis showed that postoperative base excess level at admission to the intensive care unit, number of units of packed red blood cells transfused during surgery, urine volume, and excess base level 6 hours after surgery were the main predictors of successful early extubation. CONCLUSIONS: The initial base excess level at the entrance to the intensive care unit(postsurgery) and 6 hours after surgery, packed red blood cell volume transfused during surgery, and urine volume 6 hours after surgery are the main predictors for a successful early tracheal extubation.These factors are considered for the Shiraz Extubation Predictor formula.

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Extubación Traqueal , Trasplante de Hígado , Adulto , Humanos , Estudios de Casos y Controles , Extubación Traqueal/efectos adversos , Trasplante de Hígado/efectos adversos , Factores de Tiempo , Respiración Artificial

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Modeling metal matrix composites in finite element software requires incorporating a cohesive zone model (CZM) to represent the interface between the constituent materials. The CZM determines the behavior of traction-separation (T-S) in this region. Specifically, when a diffusion zone is formed due to heat treatment, it becomes challenging to determine experimentally the equivalent mechanical properties of the interface. Additionally, understanding the influence of heat treatment and the creation of a diffusion zone on the T-S law is crucial. In this study, the molecular dynamics approach was employed to investigate the effect of the diffusion region formation, resulting from heat treatment, on the T-S law at the interface of a SiC/Al composite in tensile, shear, and mixed-mode loadings. It was found that the formation of a diffusion layer led to an increase in tensile and shear strengths and work of separation compared with the interfaces without heat treatment. However, the elastic and shear moduli were not significantly affected by the creation of the diffusion layer. Moreover, the numerical findings indicated that the shear strength in the diffusion region was higher when compared with the shear strength of the {111} slip plane within the fcc aluminum component of the composite material. Therefore, in the diffusion region, crack propagation did not occur in the pure shear loading case; however, shear sliding was observed at the aluminum atomic layers.

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The equivalent characteristics of the materials' interfaces are known to impact the overall mechanical properties of ceramic-metal composites significantly. One technological method that has been suggested is raising the temperature of the liquid metal to improve the weak wettability of ceramic particles with liquid metals. Therefore, as the first step, it is necessary to produce the diffusion zone at the interface by heating the system and maintaining it at a preset temperature to develop the cohesive zone model of the interface using mode I and mode II fracture tests. This study uses the molecular dynamics method to study the interdiffusion at the interface of α-Al2O3/AlSi12. The hexagonal crystal structure of aluminum oxide with the Al- and O-terminated interfaces with AlSi12 are considered. A single diffusion couple is used for each system to determine the average main and cross ternary interdiffusion coefficients. In addition, the effect of temperature and the termination type on the interdiffusion coefficients is examined. The results demonstrate that the thickness of the interdiffusion zone is proportional to the annealing temperature and time, and Al- and O-terminated interfaces exhibit similar interdiffusion properties.

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The mechanical properties of ceramic-metal nanocomposites are greatly affected by the equivalent properties of the interface of materials. In this study, the effect of vacancy in SiC on the interdiffusion of SiC/Al interfaces is investigated using the molecular dynamics method. The SiC reinforcements exist in the whisker and particulate forms. To this end, cubic and hexagonal SiC lattice polytypes with the Si- and C-terminated interfaces with Al are considered as two samples of metal matrix nanocomposites. The average main and cross-interdiffusion coefficients are determined using a single diffusion couple for each system. The interdiffusion coefficients of the defective SiC/Al are compared with the defect-free SiC/Al system. The effects of temperature, annealing time, and vacancy on the self- and interdiffusion coefficients are investigated. It is found that the interdiffusion of Al in SiC increases with the increase in temperature, annealing time, and vacancy.

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<b>Introduction:</b> The Burden of Colorectal cancer (CRC) as one of the most common malignancies is considerable worldwide, with 1.8 million diagnoses each year. Although it is well established that most CRCs arise from colonic polyps, guidelines and recommendations indicate different ages as starting points for endoscopic examination of the colon, either as cancer screening programs or in symptomatic patients. Most standard guidelines adapt the cut-off age of 50. However, this has been challenged by the results of recent studies. This multicentric prospective study aimed to investigate the frequency, distribution, and histopathological findings of colonic polyps in patients who underwent colonoscopy with special attention to the age group of 40-49-year-olds compared with 50-59 in the population.</br></br> <b>Material and methods:</b> This multicentric, prospective study was designed to enroll adult patients referred to three universityaffiliated endoscopy units. As many as 723 patients met all the inclusion criteria. Data analysis was performed on endoscopic and histopathological characteristics of all detected lesions, including colonic polyps and neoplastic lesions.</br></br> <b>Results:</b> A total of 723 patients with a mean age of 46.03 (16.8) years were included in this study. Rectal bleeding was the most frequent symptom (40.9%). One hundred and thirteen patients (15.6%) were found to have colonic polyps, and 11 cases (1.52%) of CRC were detected. Most polyps were located in the left colon (67.5%). There was no statistical difference in the prevalence of adenomatous polyps between the age group of 40-49 years and 50-59 years (P = 0.77). Detailed examination of data using receiver operating characteristic (ROC) curve analysis not only showed age is a risk factor for the presence of colonic polyps but also revealed the cut-off age of 42.5 for the presence of all types of colonic polyps (44.5 years for adenomatous polyps).</br></br> <b>Conclusion:</b> This study has showed a similar polyp prevalence in the age group of 40-49 years as compared to 50-59. Our study suggests that appropriate colon examination should be performed at a younger age to achieve early detection of colonic polyps, specifically in patients with red flag symptoms.

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Pólipos Adenomatosos , Pólipos del Colon , Adulto , Humanos , Persona de Mediana Edad , Pólipos del Colon/diagnóstico , Pólipos del Colon/epidemiología , Estudios Prospectivos , Prevalencia , Estudios Retrospectivos , Colonoscopía , Pólipos Adenomatosos/patología

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INTRODUCTION: In the early stage of fracture fixation, the aim of a unilateral external fixator (UEF) to stimulate healing and maintain stability may be suppressed by using inadequate number of pins. Cortical thinning due to age or osteoporosis endangers a successful fracture fixation. MATERIALS AND METHODS: This study evaluates the initial strength and stability of the fracture fixation and tissue differentiation under the influences of variable cortical thickness (5 mm to 1 mm) and variable number of pins (1 to 4 in each bone fragment). A finite element program was utilised to develop 20 three-dimensional models of simplified diaphyseal tibia with fracture callus fixed with UEF. A mechano-regulation code based on the deviatoric strain theory was written and applied to simulate tissue differentiation. The values of von Mises stress, interfragmentary strain (IFS), and fibrocartilage index (FCI) were evaluated. RESULTS: Cortical thinning from 5 mm to 1 mm increased IFS and FCI by an average of 30.3% and 18.7%, respectively, and resulted in higher stresses in the UEF and bone. Using 1 pin in each bone fragment produced excessive IFS in the models with 1 mm, 2 mm and 3 mm cortical thickness. Inserting the second pin into the bone fragment could considerably reduce the IFS and fibrocartilaginous tissue formation in the fracture site and improve load transmission to the fixator. Whereas inserting the fourth pin could minimally affect the mechano-biological environment of healing. CONCLUSIONS: This study suggests that initial instability due to cortical thinning can be efficiently alleviated by adding the number of pins up to 3 in a UEF; additionally, it may improve the knowledge about applying UEFs adequately stable, whilst promoting inclination toward endochondral ossification, simultaneously.

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Tibia , Fracturas de la Tibia , Callo Óseo , Adelgazamiento de la Corteza Cerebral , Fijadores Externos , Análisis de Elementos Finitos , Fijación de Fractura , Humanos , Tibia/diagnóstico por imagen , Tibia/cirugía , Fracturas de la Tibia/diagnóstico por imagen , Fracturas de la Tibia/cirugía

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Purpose: Children with celiac disease (CD) are at an increased risk of low bone mineral density (BMD) owing to malabsorption of fat-soluble vitamins, inflammation, and malnutrition. This study aimed to determine the prevalence and risk factors for low BMD in Iranian children with CD. Methods: This prospective cohort study examined 149 Iranian children with CD between 2011 and 2018 at Zabol University of Medical Sciences. BMD was measured using dual-energy X-ray absorptiometry. Demographic, clinical, and laboratory data were collected from patients' medical records. Logistic regression analysis was performed to identify the factors associated with low areal BMD (BMD-Z <-2) in the lumbar spine and femoral neck. Descriptive data were analyzed using the mean, standard deviation, and relative frequency. Data were analyzed using the chi-square test, t-test, and analysis of variance. Results: Of the 149 children with CD, 27.5% had osteoporosis. The mean body mass index (BMI) Z score was -1.28±1.2. Lower BMI was associated with a higher likelihood of BMD-Z (odds ratio 2.17; p≤0.05). Conclusion: Overall, the findings of this study showed that there was no correlation among Marsh classification, presence of specific human leukocyte antigens, and low BMD in Iranian children with CD. BMI can be a predictor of bone density in children with CD and may be applied clinically in early screenings to evaluate the bone health status in these children.

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This comparative study simulates bone remodeling outcome around titanium dental implants and compares the final bone configuration with the one around novel implants composed of radial functionally graded materials (FGMs) and the titanium implants with hydroxyapatite (HA) coating. A dental implant system embedded in 3D mandibular bone with masticatory loading was simulated by the finite element method. A bone remodeling algorithm was applied to cancellous and cortical bones. Young's modulus and von Mises stress were obtained to ensure bone homeostasis and evaluate the final bone configuration. Local stress distribution in the bone-implant interface was analyzed before and after bone remodeling. The average final Young's modulus of cancellous bone reached 2.68, 2.49, and 2.32 GPa for the FGM, HA-coated, and the titanium models, respectively. These values for cortical bone were 17.75, 16.86, and 17.20 GPa in the same order. Radial FGM implants generated the highest remodeling stimulus and bone density. Their superiority over the HA-coated models was confirmed by four implant surface stiffness values (10, 20, 30, and 40 GPa). Remodeling increased bone density around the implant, consistent with clinical data and reduced stress concentration in the cortical neck. The stress values were in the safe zone regarding overload-induced bone resorption. The findings of this study were substantiated by clinical images and bone density values from previous literature.

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Implantes Dentales , Durapatita , Remodelación Ósea , Simulación por Computador , Análisis del Estrés Dental , Análisis de Elementos Finitos , Mandíbula , Estrés Mecánico , Titanio

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Peritendinous adhesion is considered a major postsurgical tendon complication in hand surgery. This complication could be mitigated partially through early tendon mobilization. However, development of new treatment modalities to guide tissue regeneration and to reduce postsurgical tendon adhesion has recently gained attentions. In this article, synthesis and characterization of electrospun nanofibrous membranes (NFMs) of polycaprolactone (PCL) and chitosan to form a physical barrier against cellular migration leading to tendon adhesion is presented. The mechanical properties of the NFMs are modulated to maintain high integrity during postsurgical tendon mobilization. The tensile strength of the NFMs is examined in wet and dry conditions after 1000 cyclic pull loadings. In addition, the mechanical strength of the NFMs is evaluated after a degradation period of 30 days. To obtain NFM with desired properties, concentrations of polymer solutions, operation parameters of electrospinning and the thickness of NFMs were optimized. Based on the biodegradation and mechanical evaluations, the optimum NFM was obtained for specified amounts of PCL (5 wt %) + chitosan (2 wt %) at an electrospinning drum speed of 400 rpm. The engineered NFM could withstand forces of 33 and 19 N before and after 1000 pull cycles that are sufficient during tendon healing process. The bonding of chitosan fibers over PCL nanofibers allowed for production of NFMs with appropriate mechanical integrity and degradation rate. In vitro cell culture tests demonstrated that PCL/chitosan could only have minor impact on decreasing fibroblast attachment over the membranes probably due to protonation of amine groups.

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Quitosano , Nanofibras , Humanos , Membranas Artificiales , Poliésteres , Tendones/patología , Tendones/cirugía , Adherencias Tisulares/patología , Adherencias Tisulares/prevención & control

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BACKGROUND: One of the most severe side effects of solid-organ transplantation is posttransplant lymphoproliferative disease (PTLD). People with human immunodeficiency virus infection (HIV), an immunosuppressive disease comparable to HIV, have a higher chance of developing lymphoma when their peripheral blood contains elevated levels of the immunoglobulins kappa and lambda free light chains (FLCs). METHODS: This systematic review's objective was to monitor associated B lymphoma cells in PTLD patients. In order to find relevant studies published between 1/1/2000 and 1/9/2022, two independent researchers conducted searches (MT, AJ). A literature search of English language publications was conducted using MEDLINE through PubMed, EMBASETM through Ovid, the Cochrane Library, and Trip. In addition to Magiran and SID, we searched KoreaMed and LILACS for literature published in other languages. sFLC or PTLD, transplant, or Electrophoresis are terms used in the search strategy. RESULTS: A total of 174 studies were selected. After analyzing their correspondence with the required criteria, a final review of five studies was conducted. The manuscript presents current findings on the potential benefits of the clinical applicability of sFLCs in PTLD. While the preliminary results appear promising, the only consistent result is that early-onset PTLD is predicted within the first two years after transplant, a biomarker that could be used to diagnose the condition. CONCLUSIONS: Therefore, PTLD has been predicted by using the sFLCs. There have been contradictory results to date. Future research could include assessing the quantity of sFLCs and their quality in transplant recipients. In addition to PTLD and complications after transplantation, sFLCs may provide insight into other diseases. To confirm the validity of sFLCs, more studies are needed.

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Infecciones por Virus de Epstein-Barr , Infecciones por VIH , Linfoma , Trastornos Linfoproliferativos , Humanos , Trastornos Linfoproliferativos/etiología , Trastornos Linfoproliferativos/diagnóstico , Trastornos Linfoproliferativos/patología , Linfoma/complicaciones , Biomarcadores

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Performance of the locking compression plate (LCP) is a multifactorial function. The control parameters of plating, such as geometries, material properties, and physical constraints of the LCP components, affect basic functions associated with the bone fixation, including the extent of stress shielding and subsequent bone remodeling, strength and stability of the bone-LCP construct, and performance of secondary bone healing. The main objectives of this research were as follows: (1) to find the appropriate values of control parameters of an LCP construct to achieve the optimized performance throughout bone healing; and (2) to unravel relationships between LCP parameters and the LCP's performance. Different values for the plate/screw modulus of elasticity (E), plate width (W), plate thickness (T), screw diameter (D), bone-plate offset (O), and screw configuration (C), as six control parameters, were considered at five different levels. Taguchi method was adopted to create trial combinations of control parameters and determining the best set of parameters, which can optimize the overall performance of the LCP. All design cases were analyzed using the finite element method. The optimal set of control parameters consisting of 150 GPa, 12 mm, 4 mm, 5.5 mm, 2 mm, and 123,678 were determined for E, W, T, D, O, and C, respectively. Furthermore, ANOVA was used to rank the most influential parameters on each function of the LCP fixation. In the overall performance of the LCP fixation, E, D, T, C, W, and O showed a contribution percentage of 46%, 22%, 10%, 11%, 8%, and 3%, respectively.

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Fijación Interna de Fracturas , Tibia , Análisis de Varianza , Fenómenos Biomecánicos , Placas Óseas , Tornillos Óseos , Fijación Interna de Fracturas/métodos , Tibia/cirugía

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The role of connecting rod in healing process of a fractured bone has always been of significant importance for surgeons. Adding a connecting rod to the fixator would be a secure option for increasing stability without increasing infection rate. The roles of 4 design parameters of the connecting rod (ie, connecting rod diameter, elevation, material, and configuration) were assessed by using finite element models to calculate axial stiffness and interfragmentary strain at the fracture gap. Taguchi method was used to achieve an optimal design set for maximizing stability with regard to connecting rod variables. Also, analysis of variance (ANOVA) approach was employed to determine contribution percentage of each design parameter on outputs. For optimizing connecting rod design parameters, an optimal set of variables consisting of 11 mm, 40 mm, 200 GPa, and Type 3 external fixator were determined by Taguchi for connecting rod diameter, elevation, modulus of elasticity, and configuration, respectively. However, as Type 3 external fixator stability is a little more than Type 2, it would be better if Type 3 external fixator in Taguchi suggestion be replaced by Type 2 external fixator to be as minimally invasive as possible. Furthermore, ANOVA results revealed that the connecting rod configuration is the most important parameter with 95% and 96% effectiveness on the interfragmentary strain and axial stiffness.

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Fijadores Externos , Fracturas Óseas , Fenómenos Biomecánicos , Elasticidad , Fijación de Fractura , Humanos

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This study aimed at finding the acceptable range, and the optimal value for the locking compression plate (LCP) thickness (THK), through simulating the osteogenic pathway of bone healing, and by checking bone-plate construct's strength and stability. To attain the goals of this research, a multi-objective approach was adopted, which should trade-off between some conflicting objectives. A finite element model of the long bone-plate construct was made first, and validated against an experimental study. The validated model was then employed to determine the initial strength and stability of the bone-plate construct, for the time right after surgery, for various thicknesses of the LCP. Afterward, coupling with a mechano-regulatory algorithm, the iterative process of bone healing was simulated, and follow up was made for each LCP thickness, over the first 16 post-operative weeks. Results of this study regarding the sequence of tissue evolution inside the fracture gap, showed a similar trend with the existing in-vivo data. For the material and structural properties assigned to the bone-plate construct, in this study, an optimal thickness for the LCP was found to be 4.7 mm, which provides an enduring fixation through secondary healing, whereas for an LCP with a smaller or greater thickness, either bone-implant failure, unstable fixation, impaired fracture consolidation, or primary healing may occur. This result is in agreement with a recent study, that has employed a comprehensive optimization approach to find the optimal thickness.

Asunto(s)

Fijación Interna de Fracturas , Fracturas Óseas , Fenómenos Biomecánicos , Placas Óseas , Análisis de Elementos Finitos , Humanos