The mechanism of selenium regulating the permeability of vascular endothelial cells through selenoprotein O.

Vascular diseases, a leading cause of death in human, are strongly associated with pathological damage to blood vessels. The selenoprotein (Sel) have been reported to play important roles in vascular disease. However, the role of SelO in vascular disease has not been conclusively investigated. The present experiment was to investigate the regulatory mechanism of the effect of SelO on the permeability of vascular endothelial. The H.E staining, FITC-Dextran staining, Dil-AC-LDL staining and FITC-WGA staining showed that vascular structure was damaged, and intercellular junctions were disrupted with selenium (Se)-deficient. Immunohistochemistry, qPCR and Western blot revealed decreased expression of the adhesion plaque proteins vinculin, talin and paxillin, decreased expression of the vascular connectivity effector molecules connexin, claudin-1 and E-cadherin and increased expression of JAM-A and N-cadherin, as well as decreased expression of the ZO-1 signaling pathways ZO-1, Rock, rhoGEF, cingulin and MLC-2. In a screening of 24 Sel present in mice, SelO showed the most pronounced changes in vascular tissues, and a possible association between SelO and vascular intercellular junction effectors was determined using IBM SPSS Statistics 25. Silencing of SelO, vascular endothelial intercellular junction adverse effects present. The regulatory relationship between SelO and vascular endothelial intercellular junctions was determined. The results showed that Se deficiency lead to increased vascular endothelial permeability and vascular tissue damage by decreasing SelO expression, suggesting a possible role for SelO in regulating vascular endothelial permeability.

Polyethylene microplastics induced inflammation via the miR-21/IRAK4/NF-κB axis resulting to endoplasmic reticulum stress and apoptosis in muscle of carp.

As a widespread environmental pollutant, microplastics pose a great threat to the tissues and organs of aquatic animals. The carp's muscles are necessary for movement and survival. However, the mechanism of injury of polyethylene microplastics (PE-MPs) to carp muscle remains unclear. Therefore, in this study, PE-MPs with the diameter of 8 µm and the concentration of 1000 ng/L were used to feed carp for 21 days, and polyethylene microplastic treatment groups was established. The results showed that PE-MPs could cause structural abnormalities and disarrangement of muscle fibers, and aggravate oxidative stress in muscles. Exposure to PE-MPs reduced microRNA (miR-21) in muscle tissue, negatively regulated Interleukin-1 Receptor Associated Kinase 4 (IRAK4), activated Nuclear Factor Kappa-B (NF-κB) pathway, induced inflammation, and led to endoplasmic reticulum stress and apoptosis. The present study provides different targets for the prevention of muscle injury induced by polyethylene microplastics.

More than nutrition: Therapeutic potential and mechanism of human milk oligosaccharides against necrotizing enterocolitis.

Human milk is the most valuable source of nutrition for infants. The structure and function of human milk oligosaccharides (HMOs), which are key components of human milk, have long been attracting particular research interest. Several recent studies have found HMOs to be efficacious in the prevention and treatment of necrotizing enterocolitis (NEC). Additionally, they could be developed in the future as non-invasive predictive markers for NEC. Based on previous findings and the well-defined functions of HMOs, we summarize potential protective mechanisms of HMOs against neonatal NEC, which include: modulating signal receptor function, promoting intestinal epithelial cell proliferation, reducing apoptosis, restoring intestinal blood perfusion, regulating microbial prosperity, and alleviating intestinal inflammation. HMOs supplementation has been demonstrated to be protective against NEC in both animal studies and clinical observations. This calls for mass production and use of HMOs in infant formula, necessitating more research into the safety of industrially produced HMOs and the appropriate dosage in infant formula.

Potential role of bile acids in the pathogenesis of necrotizing enterocolitis.

Necrotizing enterocolitis (NEC) is one of the most common acute gastrointestinal diseases in preterm infants. Recent studies have found that NEC is not only caused by changes in the intestinal environment but also by the failure of multiple systems and organs, including the liver. The accumulation of bile acids (BAs) in the ileum and the disorder of ileal BA transporters are related to the ileum injury of NEC. Inflammatory factors such as tumor necrosis factor (TNF)-α and interleukin (IL)-18 secreted by NEC also play an important role in regulating intrahepatic BA transporters. As an important link connecting the liver and intestinal circulation, the bile acid metabolic pathway plays an important role in the regulation of intestinal microbiota, cell proliferation, and barrier protection. In this review, we focus on how bile acids explore the dynamic changes of bile acid metabolism in necrotizing enterocolitis and the potential therapeutic value of targeting the bile acid signaling pathways.

Treatment of preterm brain injury via gut-microbiota-metabolite-brain axis.

BACKGROUND: Brain injury in preterm infants potentially disrupts critical structural and functional connective networks in the brain. It is a major cause of neurological sequelae and developmental deficits in preterm infants. Interesting findings suggest that the gut microbiota (GM) and their metabolites contribute to the programming of the central nervous system (CNS) during developmental stages and may exert structural and functional effects throughout the lifespan. AIM: To summarize the existing knowledge of the potential mechanisms related to immune, endocrine, neural, and blood-brain barrier (BBB) mediated by GM and its metabolites in neural development and function. METHODS: We review the recent literature and included 150 articles to summarize the mechanisms through which GM and their metabolites work on the nervous system. Potential health benefits and challenges of relevant treatments are also discussed. RESULTS: This review discusses the direct and indirect ways through which the GM may act on the nervous system. Treatment of preterm brain injury with GM or related derivatives, including probiotics, prebiotics, synbiotics, dietary interventions, and fecal transplants are also included. CONCLUSION: This review summarizes mechanisms underlying microbiota-gut-brain axis and novel therapeutic opportunities for neurological sequelae in preterm infants. Optimizing the initial colonization and microbiota development in preterm infants may represent a novel therapy to promote brain development and reduce long-term sequelae.

Role of the gut-microbiota-metabolite-brain axis in the pathogenesis of preterm brain injury.

Brain injury, a common complication in preterm infants, includes the destruction of the key structural and functional connections of the brain and causes neurodevelopmental disorders; it has high morbidity and mortality rates. The exact mechanism underlying brain injury in preterm infants is unclear. Intestinal flora plays a vital role in brain development and the maturation of the immune system in infants; however, detailed understanding of the gut microbiota-metabolite-brain axis in preterm infants is lacking. In this review, we summarise the key mechanisms by which the intestinal microbiota contribute to neurodevelopment and brain injury in preterm infants, with special emphasis on the influence of microorganisms and their metabolites on the regulation of neurocognitive development and neurodevelopmental risks related to preterm birth, infection and neonatal necrotising enterocolitis (NEC). This review provides support for the development and application of novel therapeutic strategies, including probiotics, prebiotics, synbiotics, and faecal bacteria transplantation targeting at brain injury in preterm infants.

Selenium deficiency induced inflammation and apoptosis via NF-κB and MAPKs pathways in muscle of common carp (Cyprinus carpio L.).

Selenium (Se), one of the essential trace elements of fish, regulates immune system function and maintains immune homeostasis. Muscle is the important tissue that generate movement and maintain posture. At present, there are few studies on the effects of Se deficiency on carp muscle. In this experiment, carps were fed with dietary with different Se content to successfully establish a Se deficiency model. Low-Se dietary led to the decrease of Se content in muscle. Histological analysis showed that Se deficiency resulted in muscle fiber fragmentation, dissolution, disarrangement and increased myocyte apoptosis. Transcriptome revealed a total of 367 differentially expressed genes (DEGs) were screened, including 213 up-regulated DEGs and 154 down-regulated DEGs. Bioinformatics analysis showed that DEGs were concentrated in oxidation-reduction process, inflammation and apoptosis, and were related to NF-κB and MAPKs pathways. Further exploration of the mechanism showed that Se deficiency led to excessive accumulation of ROS, decreased the activity of antioxidant enzymes, and also resulted in increased expression of the NF-κB and MAPKs pathways. In addition, Se deficiency significantly increased the expressions of TNF-α, IL-1ß and IL-6, and the pro-apoptotic factors BAX, p53, caspase-7 and caspase-3, while decreased the expressions of anti-apoptotic factors Bcl-2 and Bcl-xl. In conclusion, Se deficiency reduced the activities of antioxidant enzymes and led to excessive accumulation of ROS, which caused oxidative stress and affected the immune function of carp, leading to muscle inflammation and apoptosis.

Assessment of Instant Loss of Elbow Flexion in Children with Untreated Gartland IIA Humeral Supracondylar Fractures-A Simulation Study with Lateral Elbow Radiographs.

OBJECTIVE: The suitability of in situ cast fixation for treating Gartland IIA humeral supracondylar fractures has remained controversial due to concerns regarding loss of elbow flexion. This study aimed to assess the instant loss of elbow flexion after Gartland IIA humeral supracondylar fractures based on the relationship between the anterior marginal line of the humerus and capitellum in the lateral view. METHODS: This simulation study was conducted with normal radiographs using Adobe Photoshop 14.0, followed by verification using clinical cases. Standard lateral views of normal elbows of children were collected from January 2008 to February 2020. Adobe Photoshop was used to simulate Gartland IIA supracondylar fractures with different degrees of angulation in the sagittal plane. A formula was deduced to assess flexion loss, and this method was verified in three cases. The data were grouped by age, and the relationship between elbow flexion loss and age, as well as the angulation of the fracture, was analyzed using a one-way or multivariate ANOVA. RESULTS: There was a flexion loss of 19° (11-30°) when the anterior margin line of the humerus was tangential to the capitellum. This loss increased with age at injury (r = 0.731, P = 0.000). Moreover, the difference in angulation in the sagittal plane also influenced the extent of elbow flexion loss (r = -0.739, P = 0.000). The more horizontal the fracture line in the lateral view, the greater the loss of elbow flexion. CONCLUSION: Instant elbow flexion loss after Gartland IIA humeral supracondylar fractures increases with age at the time of injury and decreases with angulation in the sagittal plane. When the anterior margin of the humerus is tangential to the capitellum, there will be an average loss of 19° in elbow flexion. These findings provide a quantitative reference for clinical decision-making in the treatment of Gartland IIA supracondylar fractures.

Effect of powdered vancomycin on stopping surgical site wound infections in neurosurgery: A meta-analysis.

We performed a meta-analysis to evaluate the effect of powdered vancomycin on stopping surgical site wound infections in neurosurgery. A systematic literature search up to July 2022 was performed and 24 137 subjects with neurosurgery at the baseline of the studies; 10 496 of them were using the powdered vancomycin, and 13 641 were not using the powdered vancomycin as a control. Odds ratio (OR) with 95% confidence intervals (CIs) were calculated to assess the effect of powdered vancomycin on stopping surgical site wound infections in neurosurgery using dichotomous methods with a random or fixed-effect model. The powdered vancomycin had significantly lower surgical site wound infections after spinal surgery (OR, 0.53; 95% CI, 0.41-0.70, P < .001), deep surgical site wound infections after spinal surgery (OR, 0.45; 95% CI, 0.35-0.57, P < .001), superficial surgical site wound infections after spinal surgery (OR, 0.60; 95% CI, 0.43-0.83, P = .002), and surgical site wound infections after cranial surgery (OR, 0.37; 95% CI, 0.22-0.61, P < .001) compared to control in subjects with neurosurgery. The powdered vancomycin had significantly lower surgical site wound infections after spinal surgery, deep surgical site wound infections after spinal surgery, superficial surgical site wound infections after spinal surgery, and surgical site wound infections after cranial surgery compared to control in subjects with neurosurgery. The analysis of outcomes should be done with caution even though the low number of studies with low sample size, 3 out of the 42 studies, in the meta-analysis, and a low number of studies in certain comparisons.

Rotation of both X- and Y-axes is a predictive confounder of ulnar nerve injury and open reduction in pediatric lateral flexion supracondylar humeral fractures: A retrospective cohort study.

Background: Rotation of the distal fragment often occurs in flexion-type supracondylar humerus fractures (SCHFs), potentially leading to ulnar nerve injury (UNI) and open reduction. We analyzed the correlation between the rotations and UNI or open reduction and then assessed the risk factors associated with these rotations. Methods: Data of Wilkins type III lateral flexion SCHFs were collected over a 10-year time period (1 January 2012 to 31 December 2021) in Children's Hospital of Fudan University Anhui Hospital. We defined the rotation of the distal fragment on the coordinate axis as two types, IIIA (X-axis rotation) and IIIB (the rotation of both X- and Y-axes) on X-ray radiography. Demographic data, the incidence of the two-type rotation, odds ratios (ORs) of UNI and open reduction, and risk factors of the rotation of both X- and Y-axes were analyzed. Results: Totally, 152 patients were found (50 with IIIA vs. 102 IIIB). The UNI rate was 13%, and the open reduction rate was 22%. The UNI rate of the IIIB was five-fold higher than that of the IIIA [OR, 5.143; 95% confidence interval (CI), 1.414-23.125; p = 0.019], and the open reduction rate of the IIIB was nearly five-fold higher than that of the IIIA (OR, 4.729, 95%CI, 1.584-14.495; p = 0.003). In these two types, patients with UNI had a higher risk of open reduction than those without UNI (OR, 9.816; 95%CI, 3.503-27.508; p = 0.001). In the multiple regression analysis, a high level of fracture was identified as a risk factor for the rotation of both X- and Y-axes. Conclusion: Type IIIB lateral flexion-type SCHFs have higher rates of UNI and open reduction, and a high level of fracture is a risk factor associated with this type.

Emerging prediction methods for early diagnosis of necrotizing enterocolitis.

Necrotizing enterocolitis (NEC) is a life-threatening disease of the digestive system that occurs in the neonatal period. NEC is difficult to diagnose early and the prognosis is poor. Previous studies have reported that abnormalities can be detected before the presentation of clinical symptoms. Based on an analysis of literature related to the early prediction of NEC, we provide a detailed review on the early prediction and diagnosis methods of NEC, including ultrasound, near-infrared spectroscopy, biomarkers, and intestinal microbiota. This review aimed to provide a reference for further research and clinical practice.

Stem cell therapy as a promising strategy in necrotizing enterocolitis.

Necrotizing enterocolitis (NEC) is a devastating gastrointestinal disease that affects newborns, particularly preterm infants, and is associated with high morbidity and mortality. No effective therapeutic strategies to decrease the incidence and severity of NEC have been developed to date. Stem cell therapy has been explored and even applied in various diseases, including gastrointestinal disorders. Animal studies on stem cell therapy have made great progress, and the anti-inflammatory, anti-apoptotic, and intestinal barrier enhancing effects of stem cells may be protective against NEC clinically. In this review, we discuss the therapeutic mechanisms through which stem cells may function in the treatment of NEC.

Predictive factors for open reduction of flexion-type supracondylar fracture of humerus in children.

OBJECTIVE: The incidence of open reduction and internal fixation (ORIF) in flexion-type supracondylar humerus fractures (SCHF) in children is significantly higher than that of extension-type fractures. This study aimed to identify risk factors for ORIF in flexion-type SCHF. METHODS: One hundred seventy-one patients with Wilkins type III flexion-type SCHF from January 2012 to December 2021 were retrospectively enrolled in a tertiary paediatric hospital. Patients were divided into ORIF group versus closed reduction and internal fixation (CRIF) group. Then, patients data of age, sex, injury side, obesity, deviation of displacement, fracture level, rotation, nerve injury, and delay from injury to surgery were reviewed. Univariate analysis and multivariate logistic regression were used to identify independent risk factors and odds ratios (OR) of ORIF. RESULTS: Overall, 171 children with type III flexion-type SCHF were analyzed (average aged 7.9 ± 2.8 years). Displacement was lateral in 151 cases, medial in 20. 20 cases had combined ulnar nerve injury. The failed closed reduction rate was 20%. Univariate analysis indicated age, distal fracture fragment rotation, and ulnar nerve injury were significantly associated with ORIF. (P = 0.047, P = 0.009, and P = 0.001, respectively). Multivariate logistic regression analysis showed that distal fracture fragment rotation (OR, 3.3; 95%CI:1.1-9.5; P = 0.028) and ulnar nerve injury (OR, 6.4; 95%CI:2.3-18.3; P = 0.001) were independent risk factors; however, the age was not an independent one (OR, 1.5; 95%CI:0.6-3.5; P = 0.397) for ORIF in the Wilkins type III flexion-type SCHF. CONCLUSION: Distal fracture fragment malrotation on initial x-rays and ulnar nerve injury were significant risk factors for ORIF in Wilkins type III flexion-type SCHF. Surgeons should prepare tourniquets or other open reduction instruments when treating these types of fractures. LEVEL OF EVIDENCE: Level IV.

The Integrity of Cartilage Hinge in Song 2/3 Lateral Humeral Condylar Fractures in Children: A Retrospective Radiological Study in Two Centers.

OBJECTIVE: For pediatric lateral condylar fractures (LCFs) of the humerus, it is often hard to determine the stability of the fracture based on the Song classification, especially for those categorized as Song stages 2 and 3. This study aims to define the characteristics of cartilage injury and assess the stability of LCFs classified as Song stages 2 and 3 on post-traumatic magnetic resonance imaging (MRI). METHODS: This was a retrospective study based on imaging data, conducted with a short follow-up period. From January 2016 to May 2019, data of all patients with Song 2 and Song 3 LCFs treated at two institutions were collected. Based on the inclusion criteria, a total of 62 patients with Song stage 2/3 LCF were included. All radiographs were selected for observation and classification for comparison by two observers, both experienced pediatric orthopedic surgeons. MRIs scans for comparison were analyzed in three consecutive coronal sections and cross-sections. Patients were treated conservatively with casting or surgically with closed reduction and percutaneous pinning (CRPP). RESULTS: Altogether 62 cases between 1.5 to 9 years old were included. Reliability analysis revealed poor, moderate, or good agreement between the two observers (range, 0.149-0.633). Both observers showed moderate or good consistency (range, 0.413-0.611). Among the 62 patients diagnosed with Song stages 2 and 3 fractures on initial radiographs, only two patients (3%) had complete fractures with complete disruption of the cartilage hinge as seen on MRI. The hinge was generally located in the posterior-inferior region of the distal humeral cartilage as indicated on MRI. There was no significant difference between Song stages 2 and 3 with regard to ratio of hinge to total values in any cross-sections, nor was there any significant difference in the completeness of the coronal sections (P > 0.05). Of the 62 patients treated, 50 were managed conservatively with casting and 12 underwent CRPP. Forty-nine of the remaining 60 patients (97%) with incomplete fractures were managed conservatively, while the remaining 11 patients were managed with CRPP. All patients with incomplete fractures showed bone healing and no evidence of lateral condyle displacement on follow-up radiographs. CONCLUSIONS: The Song stage 2 or 3 classification is not entirely accurate and is inadequate at guiding treatment outcomes. The cartilage hinge was most likely located posteroinferiorly within the distal humeral epiphysis. According to our findings, conservative treatment with an effective cast or splint may be sufficient for bone healing in case of incomplete cartilage fractures.

Analysis of the location and trajectory of the Kirschner wires in the fixation of extension-type supracondylar fracture of the humerus by 3D computational simulation.

BACKGROUND: Closed reduction and percutaneous pinning is still a preference for the treatment of supracondylar humerus fractures in children. However, no reports have shown the pin trajectory and the characteristics of the entry point so far. So we established a computational simulation model of the elbow to observe the trajectory of pinning for supracondylar humerus fractures. METHODS: We reconstructed an adult elbow computationally and simulated pin placement through lateral and medial pinning. Pin trajectories were traced after placement and after the addition of the skin profile; the relative entry points of the pins were determined. We used the center of the dorsal olecranon inflection as an anatomic reference for the entry points of lateral pinning. Four quadrants were established based on the center of the dorsal olecranon inflection: upper medial quadrant, upper lateral quadrant, lower medial quadrant, and lower lateral quadrant (LLQ). RESULTS: The maximum angle of pinning through the lateral column was 64° ± 3°. The minimum angles of pinning through the lateral column and middle column were 37° ± 3° and 20° ± 2°, respectively. The range of safe angle pinning through the medial column was between 18° ± 2° and 57° ± 3° to avoid penetration of the olecranon fossa and the cortex of the medial column. The entry points of lateral pinning were within the lateral half of the LLQ, and the lateral one-third of the LLQ contained all entry points of the pins through the lateral column and minor points of the pins through the middle column. The exit points of the medial pinning were within the lateral fringe of the metaphyseal-diaphyseal junction region; entering from the inferior two-thirds of the medial epicondyle could lead to the exit points in the proximal half of the metaphyseal-diaphyseal junction region laterally. DISCUSSION: For lateral pinning, the entry points would be within the lateral half of the LLQ. For the pins through the lateral column, the entry points should be within the lateral one-third of the LLQ. For medial pinning, entering from the inferior two-thirds of the medial epicondyle would lead to a more proximal exit.

Toll-like receptor 4-mediated necroptosis in the development of necrotizing enterocolitis.

BACKGROUND: Dramatic intestinal epithelial cell death leading to barrier dysfunction is one of the mechanism of neonatal necrotizing enterocolitis (NEC), in which Toll-like receptor 4 (TLR4) plays a pivotal role. This study explored the role of necroptosis, a drastic way of cell death in NEC. METHODS: The expression of necroptotic proteins was tested in NEC intestinal tissue and compared with controls. NEC was induced in neonatal wild-type mice and a necroptosis inhibitor was given to investigate whether NEC could be relieved. The general condition, macroscopic scoring, and histological evaluations were performed. The expression of tight junction proteins, inflammatory cytokines, and necroptosis-related proteins was measured, and barrier function was examined. Then, NEC was induced in TLR4-knockout pups to confirm the role of TLR4 in necroptosis. RESULTS: Necroptotic proteins were significantly upregulated in both NEC patient and animal models, together with the expression of TLR4. NEC could be relieved and inflammatory infiltration was decreased by necrostatin-1s. TLR4-knockout mice showed milder tissue degradation and less necroptosis after NEC induction. CONCLUSIONS: Necroptosis is an essential pathological process of NEC. TLR4 may be one stimulator of necroptosis in NEC. Inhibiting the intestinal cell necroptosis might be a useful strategy in the treatment of NEC. IMPACT: Necroptosis is a key pathological process in NEC, which appears to involve TLR4. Anti-necroptosis treatment is a promising strategy that could significantly relieve the symptoms of NEC.

Bridging Myositis Ossificans After Supracondylar Humeral Fracture in a Child: A Case Report.

Background: Myositis ossificans is an uncommon complication of trauma and surgery, defined as ossifying changes in a non-osseous tissue such as muscles. It happens after tissue injury, with or without fractures. When myositis ossificans occurs around a joint, it can cause ankylosis, leading to complete dysfunction of the joint. Though it has been described in most parts of the body, bridging myositis ossificans involving the elbow joint were scarcely reported. Case Presentation: We report a severe case of myositis ossificans after a supracondylar humerus fracture in a 9-year-old child. In this case a palpable painless mass appeared following the fracture and surgical trauma. Ultrasound or X-ray is of significant diagnostic value. The brachialis was completely ossified and formed a bony bridge around the elbow, causing complete ankylosis. The bone mass was surgically removed through a bilateral less-invasive approach with less surgical trauma 9 months after initial presentation. we applied bone wax to the fresh bone wounds to prevent the formation of hematocele. Indomethacin, a non-steroidal anti-inflammatory drug, was administered after the operation to suppress bone proliferation in our case. Our patient had the best possible functional status and no recurrence at 2 years' follow-up. Conclusion: Elbow myositis ossificans in children may mainly affects the brachialis. A bilateral less-invasive approach is sufficient to remove the bone mass with less surgical trauma. This case also provides a new reference for the treatment of myositis ossificans after the elbow injuries.

The most stable pinning configurations in transverse supracondylar humerus fracture fixation in children: A novel three-dimensional finite element analysis of a pediatric bone model.

PURPOSE: This study aimed at finding out the effect of exit height, trajectory and number of pins on the stability of cross and divergent-lateral pins used in the fixation of extension-type, transverse supracondylar humerus fracture (SHF) in children, based on finite element analysis. METHODS: Distal humerus model consisting of the ossific nucleus of the capitellum (ONC) and distal cartilage of a 6-year-old boy was developed via three-dimensional finite modeling. Various cross and divergent-lateral pinning models with either two or three pins were simulated on an extension-type, transverse SHF and tested in six loading directions. RESULTS: Two-cross pins and 2-divergent-lateral pins were more stable against torsional and translation forces respectively, while 3-cross pins were the most stable against all forces. The cross pins exiting at the upper border of the distal metaphyseal-diaphyseal junction (MDJ) had the best stiffness among the 2-cross pins, while the lateral pins with a middle third ONC distal pin provided the best stiffness among the 2-lateral pins. A third olecranon fossa pin greatly enhanced stability of the 2-lateral pins. CONCLUSION: For typical transverse fractures, 2-cross pins are found to be superior to 2-divergent lateral pins only against torsional forces. Pins exiting at the upper border of the MDJ provides the best mechanical stability with 2-cross pins. Two-divergent-lateral pins with a distal pin going through the middle third of the ONC provides the best mechanical stability against translation forces for these transverse fractures. Three-cross pins however offer the best mechanical stability against both translation and torsional forces. This study offers important clues in the preoperative evaluation and management of extension-type supracondylar fractures in children.

[Three-dimensional finite element analysis of Kirschner wire fixation configuration for supracondylar fracture of humerus fracture in children].

OBJECTIVE: To establish a new mechanical model of distal humerus in children with epiphysial cartilage, stimulate supracondylar humerus fracture and perform three dimensional finite elements, and study effect of pins numbers, pin tract, outlet height and pin configurations on stability of fixation. METHODS: Three dimensional computed tomography (CT) data of 6-year-old boy with distal humerus was downloaded from picture archiving and communications systems software (PACS), the data of picture was imported into Simpleware and SolidWorks 2016 software to establish distal humerus fracture in children contained ossific nucleus of the capitellum (ONC) and distal cartilage. Normal extense supracondylar humerus fracture model was established to stimulate configurations of crossed and lateral pinning fixation, 30 N was added on the direction of flexion extension and varus valgus, while 50 N was added on the direction of internal and external turning. Stability was analyzed by displacement degree of distal fracture. RESULTS: Among 2-pin configurations, 2-crossed pins were more stable against rotation forces which could resist rotation stress over 2 585 Nmm/ °, while low position through ONC of 2-divergent lateral pins were more stable, which could resist stress of 45 N /mm and 190 N /mm during the test of resistant strains and varus-valgus stress. The third pins was added into the more stable lateral 2-pins, the stability in all directions were increased obviously, and 3 crossed pins is the most stable, stress of flexion-extension, varus-valgus and internal-external turning were 198 N /mm, 395 N /mm and 6 251 Nmm/ °. CONCLUSION: Two-divergent lateral pins could provide enough stability for supracondylar humerus fracture in children. In two-crossed pins, the upper border of MDJ could provide the best stability. Three-crossed pins could offer the best stability against both translation and rotation forces.