Deciphering silver nanoparticles perturbation effects and risks for soil enzymes worldwide: Insights from machine learning and soil property integration.

Globally extensive research into how silver nanoparticles (AgNPs) affect enzyme activity in soils with differing properties has been limited by cost-prohibitive sampling. In this study, customized machine learning (ML) was used to extract data patterns from complex research, with a hit rate of Random Forest > Multiple Imputation by Chained Equations > Decision Tree > K-Nearest Neighbors. Results showed that soil properties played a pivotal role in determining AgNPs' effect on soil enzymes, with the order being pH > organic matter (OM) > soil texture ≈ cation exchange capacity (CEC). Notably, soil enzyme activity was more sensitive to AgNPs in acidic soil (pH < 5.5), while elevated OM content (>1.9 %) attenuated AgNPs toxicity. Compared to soil acidification, reducing soil OM content is more detrimental in exacerbating AgNPs' toxicity and it emerged that clay particles were deemed effective in curbing their toxicity. Meanwhile sand particles played a very different role, and a sandy soil sample at > 40 % of the water holding capacity (WHC), amplified the toxicity of AgNPs. Perturbation mapping of how soil texture alters enzyme activity under AgNPs exposure was generated, where soils with sand (45-65 %), silt (< 22 %), and clay (35-55 %) exhibited even higher probability of positive effects of AgNPs. The average calculation results indicate the sandy clay loam (75.6 %), clay (74.8 %), silt clay (65.8 %), and sandy clay (55.9 %) texture soil demonstrate less AgNPs inhibition effect. The results herein advance the prediction of the effect of AgNPs on soil enzymes globally and determine the soil types that are more sensitive to AgNPs worldwide.

High fatigue resistance in a titanium alloy via near-void-free 3D printing.

The advantage of 3D printing-that is, additive manufacturing (AM) of structural materials-has been severely compromised by their disappointing fatigue properties1,2. Commonly, poor fatigue properties appear to result from the presence of microvoids induced by current printing process procedures3,4. Accordingly, the question that we pose is whether the elimination of such microvoids can provide a feasible solution for marked enhancement of the fatigue resistance of void-free AM (Net-AM) alloys. Here we successfully rebuild an approximate void-free AM microstructure in Ti-6Al-4V titanium alloy by development of a Net-AM processing technique through an understanding of the asynchronism of phase transformation and grain growth. We identify the fatigue resistance of such AM microstructures and show that they lead to a high fatigue limit of around 1 GPa, exceeding the fatigue resistance of all AM and forged titanium alloys as well as that of other metallic materials. We confirm the high fatigue resistance of Net-AM microstructures and the potential advantages of AM processing in the production of structural components with maximum fatigue strength, which is beneficial for further application of AM technologies in engineering fields.

Predicting the effect of silver nanoparticles on soil enzyme activity using the machine learning method: type, size, dose and exposure time.

In this study, machine learning models predicted the impact of silver nanoparticles (AgNPs) on soil enzymes. Artificial neural network (ANN) optimized with genetic algorithm (GA) (MAE = 0.1174) was more suitable for simulating overall trends, while the gradient boosting machine (GBM) and random forest (RF) were ideal for small-scale analysis. According to partial dependency profile (PDP) analysis, polyvinylpyrrolidone coated AgNPs (PVP-AgNPs) had the most inhibitory effect (average of 49.5%) on soil enzyme activity among the three types of AgNPs at the same dose (0.02-50 mg/kg). The ANN model predicted that enzyme activity first declined and then rose when AgNPs increased in size. Based on predictions from the ANN and RF models, when exposed to uncoated AgNPs, soil enzyme activities continued to decrease before 30 d, but gradually rose from 30 to 90 d, and fell slightly after 90 d. The ANN model indicated the importance order of four factors: dose > type > size > exposure time. The RF model suggested the enzyme was more sensitive when experiments were conducted at doses, sizes, and exposure times of 0.01-1 mg/kg, 50-100 nm, and 30-90 d, respectively. This study presents new insights on the regularity of soil enzyme responses to AgNPs.

CircRANBP17 modulated KDM1A to regulate neuroblastoma progression by sponging miR-27b-3p.

Neuroblastoma (NB) is a common childhood cancer. Circular RNA RAN binding protein 17 (circRANBP17) has been identified to participate in diverse tumor progression. This study aims to explore the function and mechanism of circRANBP17 in NB. The levels of circRANBP17, miR-27b-3p and KDM1A in NB tissues and cells were measured by qRT-PCR. Mouse model assay was performed to investigate the effect of circRANBP17 knockdown on tumor formation in vivo. The levels of circRANBP17 and KDM1A were significantly up-regulated, and the level of miR-27b-3p was strikingly down-regulated in NB tissues and cells (SK-N-SH and SK-N-AS). Functional studies indicated that miR-27b-3p inhibitor mitigated the inhibitory effects on cell proliferation, migration, invasion and the promoting effect on cell apoptosis in SK-N-SH and SK-N-AS cells induced by circRANBP17 knockdown. Also, miR-27b-3p regulated NB cell malignancy by targeting KDM1A. Further studies revealed that miR-27b-3p inhibitor reversed the low expression of KDM1A induced by circRANBP17 knockdown. In support, circRANBP17 knockdown led to inhibition of tumor formation in vivo. In conclusion, circRANBP17 modulated KDM1A to promote cell proliferation, migration, invasion and restrain cell apoptosis in NB by sponging miR-27b-3p, and the new regulatory network may provide a theoretical basis for the further study of NB.

Polymorphisms of adiponectin gene and gene-lipid interaction with hypertension risk in Chinese coal miners: A matched case-control study.

OBJECTIVE: Low serum adiponectin level can predict hypertension development, and adiponectin gene (ADIPOQ) polymorphisms have been reported to be linked with hypertension risk. Whereas, the interaction between ADIPOQ polymorphisms and environmental factors on the susceptibility of hypertension remained unclear. The purpose of this study was to explore the relationship of ADIPOQ polymorphisms with hypertension risk and their interaction with lipid levels in coal miners. METHODS: A matched case-control study with 296 case-control pairs was performed in a large coal mining group located in North China. The participants were questioned by trained interviewers, and their ADIPOQ genotype and lipid levels were determined. Logistic regression, stratified analysis, and crossover analysis were applied to evaluate the effects of rs2241766, rs1501299, and rs266729 genotypes and gene-lipid interaction on hypertension risk. RESULTS: In this matched case-control study, the genotypes of rs2241766 TG+GG, rs1501299 GT+TT, and rs266729 CG+GG were marginally related to hypertension risk. Individuals with high total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) level were susceptible to hypertension (TC: odds ratio [OR] = 1.807, 95% confidence intervals [95%CI] = 1.266-2.581; LDL-C: OR = 1.981, 95%CI = 1.400-2.803; HDL-C: OR = 1.559, 95%CI = 1.093-2.223). Antagonistic interactions were detected between rs2241766 and TC, rs1501299 and TC, rs2241766 and LDL-C, and rs1501299 and HDL-C (rs2241766 and TC: OR = 0.393, 95%CI = 0.191-0.806; rs1501299 and TC: OR = 0.445, 95%CI = 0.216-0.918; rs2241766 and LDL-C: OR = 0.440, 95%CI = 0.221-0.877; rs1501299 and HDL-C: OR = 0.479, 95%CI = 0.237-0.967). Stratified analysis showed that hypertension risk was high for the subjects with rs2241766 TG+GG or rs1501299 GG under the low lipid level but low for those under the high lipid level. In the case group, the TC and LDL-C levels for rs2241766 TG+GG were lower than those for rs2241766 GG, and the TC and HDL-C levels for rs1501299 GT+TT were higher than those for rs1501299 GG. CONCLUSIONS: Although the effects of ADIPOQ polymorphisms alone were not remarkable, an antagonistic interaction was observed between ADIPOQ polymorphisms and lipid levels.

Discriminative Multi-View Dynamic Image Fusion for Cross-View 3-D Action Recognition.

Dramatic imaging viewpoint variation is the critical challenge toward action recognition for depth video. To address this, one feasible way is to enhance view-tolerance of visual feature, while still maintaining strong discriminative capacity. Multi-view dynamic image (MVDI) is the most recently proposed 3-D action representation manner that is able to compactly encode human motion information and 3-D visual clue well. However, it is still view-sensitive. To leverage its performance, a discriminative MVDI fusion method is proposed by us via multi-instance learning (MIL). Specifically, the dynamic images (DIs) from different observation viewpoints are regarded as the instances for 3-D action characterization. After being encoded using Fisher vector (FV), they are then aggregated by sum-pooling to yield the representative 3-D action signature. Our insight is that viewpoint aggregation helps to enhance view-tolerance. And, FV can map the raw DI feature to the higher dimensional feature space to promote the discriminative power. Meanwhile, a discriminative viewpoint instance discovery method is also proposed to discard the viewpoint instances unfavorable for action characterization. The wide-range experiments on five data sets demonstrate that our proposition can significantly enhance the performance of cross-view 3-D action recognition. And, it is also applicable to cross-view 3-D object recognition. The source code is available at https://github.com/3huo/ActionView.

MicroRNA-519d-3p antagonizes osteosarcoma resistance against cisplatin by targeting PD-L1.

Accumulating evidence indicates that a ligand of programmed cell death receptor-1 (PD-L1) participates in the progression and recurrence of multiple malignancies, including osteosarcoma. Nevertheless, the role of PD-L1 in chemoresistance development is not fully understood. In the current study, we aim to clarify the interaction of miR-519d-3p and PD-L1 in the development of cisplatin resistance. Immunohistochemistry, quantitative reverse-transcription polymerase reaction, and Western blot were used to evaluate PD-L1 expression. MTT and transwell migration assays were used to measure cell growth and motility, respectively. ENCORI, miRCode, and miRDB databases were recruited to predict candidate miRNAs targeting PD-L1. The binding sequences of miR-519d-3p and PD-L1 3' untranslated region were identified by dual-luciferase reporter and RNA immunoprecipitation assays. Flow cytometric analysis was conducted to measure the cycle distribution and cell apoptosis. Metastatic mouse models were generated with cisplatin-resistant sublines by intravenous injection. We found that PD-L1 expression was positively correlated to cisplatin resistance and metastasis, whereas miR-519d-3p expression was reduced in cisplatin-resistant specimens and was negatively correlated to cisplatin resistance and metastasis of osteosarcoma. We demonstrated that miR-519d-3p overexpression reversed cisplatin resistance, induced G1/S phase arrest and apoptosis. In addition, we proved that miR-519d-3p inhibited lung metastasis by establishing cisplatin-resistant MG63 metastatic xenograft models. The present findings suggest that miR-519d-3p/PD-L1 axis is a novel signaling pathway contributing to cisplatin resistance. Our study provides new clues for curing refractory osteosarcoma beyond immune checkpoint inhibitors.

LncRNA NEAT1 Acts as an miR-148b-3p Sponge to Regulate ROCK1 Inhibition of Retinoblastoma Growth.

BACKGROUND: It is reported that long non-coding RNA nuclear paraspeckle assembly transcript 1 (LncRNA NEAT1) is involved in the occurrence and development of various cancers. However, the detailed biological function and mechanism of LncRNA NEAT1 in retinoblastoma are still unclear. So we will explore the biological function and possible mechanism of LncRNA NEAT1 in retinoblastoma. MATERIALS AND METHODS: Quantitative real-time PCR (qRT-PCR) was used to detect LncRNA NEAT1 in retinoblastoma tissues and cell lines. Cell counting kit 8, Transwell and flow cytometry were applied to explore cell proliferation, invasion and apoptosis. The target miRNAs (miR) of LncRNA NEAT1 and miR and downstream target genes were predicted using Starbase3.0 software and confirmed by double luciferase reporting test and RNA binding protein immunoprecipitation (RIP). Western Blot was applied to explore ROCK1 in cells, and tumor allogeneic experiment was applied to study the role of LncRNA NEAT1 on tumor growth. RESULTS: It was found that LncRNA NEAT1 was up-regulated in retinoblastoma tissues, cells and serum, and the prognosis of patients with high expression of LNC RNA NEAT 1 was poor. Functional analysis showed that knocking down LncRNA NEAT1 could weaken proliferation and invasion, and accelerate apoptosis. Tumor allogeneic experiment showed that sh-NEAT1 injection can inhibit tumor growth. In addition, LncRNA NEAT1 inhibited proliferation and invasion, and promoted apoptosis through miR-148b-3p/ROCK1 axis. CONCLUSION: LncRNA NEAT1 can mediate miR-148b-3p/ROCK1 axis to weaken the proliferation and invasion of retinoblastoma.

Silencing of the Long Non-Coding RNA TTN-AS1 Attenuates the Malignant Progression of Osteosarcoma Cells by Regulating the miR-16-1-3p/TFAP4 Axis.

OBJECTIVES: Osteosarcoma (OS) is a type of bone malignancy. This study attempted to explore the effect of long non-coding RNA TTN-AS1 (TTN-AS1) on OS and to determine its molecular mechanisms. METHODS: The expression of TTN-AS1, microRNA-16-1-3p (miR-16-1-3p), and transcription factor activating enhancer binding protein 4 (TFAP4) in OS was assessed using qRT-PCR. The OS cell proliferation, migration, and invasion were measured using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), wound-healing, and transwell assays. N-cadherin and MMP-2 protein level was determined with western blot. Interactions between TTN-AS1 and miR-16-1-3p or TFAP4 and miR-16-1-3p were confirmed using the dual-luciferase reporter assay. Additionally, an OS xenograft tumor model was constructed to assess the effect of TTN-AS1 on tumor growth. RESULTS: TTN-AS1 and TFAP4 expression was increased in OS, while miR-16-1-3p expression was decreased. TTN-AS1 silencing restrained OS cell proliferation, migration, invasion, N-cadherin and MMP-2 protein expression, and hindered tumor growth. MiR-16-1-3p overexpression retarded the malignant behavior of OS cells. TTN-AS1 played a carcinostatic role by down-regulating miR-16-1-3p in the OS cells. Moreover, miR-16-1-3p inhibition or TFAP4 elevation weakened the suppressive effect of TTN-AS1 silencing on OS cell tumor progression. CONCLUSION: TTN-AS1 promoted the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of OS cells via mediating the miR-16-1-3p/TFAP4 axis. TTN-AS1 may be a critical target for improving OS.

Study on fracture of tungsten wire induced by acoustic cavitation at different hydrostatic pressures and driving electric powers.

The near-solid wall multi-bubble cavitation is an extremely complex phenomenon, and cavitation has strong erosiveness. The melting point (about 3410 °C) of tungsten is highest among all pure metals, and its hardness is also very high (its yield strength is greater than 1 GPa). What would happen to pure tungsten wire under extreme conditions caused by collapsing cavitation bubbles at high hydrostatic pressure? In this paper, we have studied the fracture process of pure tungsten wire with diameter of 0.2 mm mounted at the focus of a standing acoustic wave produced by a spherical cavity transducer with two open ends placed in a near spherical pressure container, and also studied the macro and micro morphological characteristics of the fracture and the surface damage at different fracture stages of tungsten wire under various hydrostatic pressures and driving electric powers. The results have shown that the fracture time of tungsten wire is inversely proportional to avitation intensity with hydrostatic pressure and driving electric power, the higher the acoustic pressure caused by higher electric power, the shorter the fracture time. The possible fracture mechanisms of tungsten wire in this situation we found mainly contributed to asymmetrically bubbles collapse near the surface of tungsten wire, leading to tearing the surface apart; consequently cracks along the radial and axial directions of a tungsten wire extend simultaneously, classified as trans-granular fracture and inter-granular fracture, respectively. With the increase of cavitation intensity, the cracks tend to extend more radially and the axial crack propagation path becomes shorter, that is, mainly for trans-granular fracture; with the decrease of cavitation intensity, intergranular fracture becomes more obvious. When the hydrostatic pressure was 10 MPa and the driving electric power was 2 kW, the fibers became softener due to the fracture of the tungsten wire. The fracture caused by acoustic cavitation was different from conventional mechanical fracture, such as tensile, shear, fatigue fracture, on macro and micro morphology.

[Effect of bilateral superior cervical sympathetic ganglion occlusion on pathological process of aortic dissection and its mechanism].

OBJECTIVE: To investigate the effect of bilateral superior cervical sympathetic ganglion occlusion (SCG) on aortic dissection and its possible mechanism. METHODS: Forty-five SD rats were randomly divided into three groups with 15 in each:blank control group, sham operation group and SCG group. ß-aminopropione (666 mg·kg-1·d-1) was given by subcutaneous injection for 4 weeks to establish the aortic dissection model. Rats in SCG group were given SCG before the injection of ß-aminopropione. Blood pressure and heart rate of the rats were monitored using noninvasive tail artery blood pressure measuring instrument; sympathetic activity was monitored using drug block method; the structure of aortic wall was observed using HE staining; collagen fibers in aortic wall was observed using Sirius red staining; protein expression of Apelin was detected by immunohistochemistry; and the protein expression of matrix metalloproteinase (MMP)-2, 9 was detected by Western blotting. RESULTS: During the experiment, the body mass of the sham operation group and SCG group was smaller than that of the blank control group (all P<0.05), and the body mass of the SCG group was larger than that of the sham operation group (all P<0.05). The heart rate and sympathetic activity of the sham operation group were higher than those of the blank control group (all P<0.05), while the SCG group were lower (all P<0.05). Compared with the blank control group, the aortic wall in the sham operation group was thickening, while that in the SCG group was improved. A large number of collagen-1 in the aortic wall of the blank control group was stained brown by Sirius red, which was lighter in SCG group, and the staining in the sham operation group was the lightest. Compared with the blank control group, the expression of Apelin, MMP-2 and MMP-9 protein in the sham operation group increased (all P<0.05), while those in the SCG group decreased (all P<0.05). CONCLUSIONS: SCG can effectively reduce the incidence and mortality of aortic dissection in rats, which may be related to the inhibition of sympathetic activity and the decrease of collagen-1, Apelin, MMP-2 and MMP-9 expression.

Contribution of biomarkers for pancreatic cancer-associated new-onset diabetes to pancreatic cancer screening.

BACKGROUND: Pancreatic cancer (PaC) is one of the deadliest types of tumor, and it is regarded as a fatal disease, with a 5-year survival rate less than 10%. Most clinical diagnoses for PaC are made at an advanced stage because of the insidious onset of the disease, which leads to an extremely poor prognosis. RECENT FINDINGS: The relationship between diabetes mellitus (DM) and PaC has been established by several decades of research, and the prevalence of DM in patients with PaC has been reported to be 40%, with half of the patients having developed new-onset DM within 2 years or less. Increasing evidence suggests that new-onset DM is associated with a high prevalence of PaC, and PaC resection ameliorates DM. Therefore, screening for PaC may be needed in patients with newly developed DM. PURPOSE: The objective of this review was to present our current understanding of biomarkers for PaC-associated new-onset DM (PCAND), to offer a perspective on the prospects and problems of using this strategy for early screening to differentiate PCAND from new-onset type 2 DM not associated with PaC and to suggest candidate biomarkers to use for PaC screening in patients with new-onset DM. Finding sensitive and specific biomarkers to manage these patients constitutes a challenge for the research community and for public health policies.

Biomechanical evaluation of four surgical scenarios of lumbar fusion with hyperlordotic interbody cage: A finite element study.

BACKGROUND: Lumbar spinal fusion in the interbody space is augmented with interbody fusion cages to provide structural support while arthrodesis occurs. Subsidence is a serious complication of interbody fusion. However, the biomechanical influence of anterior longitudinal ligament (ALL) and pedicle screws on subsidence has not been fully understood. OBJECTIVE: To investigate biomechanical effects of the hyperlordotic cages in different surgical conditions using finite element analysis. METHODS: Four surgical finite element (FE) models were constructed by inserting 15 degree lordosis cage at the L3-L4 disc space. The four surgical conditions were ALL intact (M1), ALL resected (M2), ALL intact and bilateral pedicle screws (M3), and ALL resected and bilateral pedicle screws (M4). Follow loads were applied at the L2 vertebral body while the inferior surface of L5 was fixed. FEA was implemented to simulate the four motion modes and biomechanical properties of four fusion scenarios with hyperlordotic interbody cage were compared. RESULTS: The range of motion (ROM) and facet joint force (FJF) at L3-L4 decreased significantly after fusion during all the motion modes. The cage stress and endplate stress at L3-L4 increased significantly after fusion during all the motion modes. The cage stress and endplate stress at L3-L4 for M3 and M4 were smaller than that for M1 and M2 during all the motion modes. The FJF at L3-L4 for M3 and M4 were smaller than that for M1 and M2 during extension, bending, and rotation. CONCLUSIONS: ALL has little effect on the biomechanics after lumbar fusion with hyperlordotic interbody cage. The bilateral pedicle screws significantly decreased the stress in cage, stress in endplate at L3-L4, and lowered facet contact force except for flexion mode. The implication is that the supplemental bilateral pedicle screws are recommended whether or not the ALL is resected.

Hydration-induced nano- to micro-scale self-recovery of the tooth enamel of the giant panda.

The tooth enamel of vertebrates comprises a hyper-mineralized bioceramic, but is distinguished by an exceptional durability to resist impact and wear throughout the lifetime of organisms; however, enamels exhibit a low resistance to the initiation of large-scale cracks comparable to that of geological minerals based on fracture mechanics. Here we reveal that the tooth enamel, specifically from the giant panda, is capable of developing durability through counteracting the early stage of damage by partially recovering its innate geometry and structure at nano- to micro- length-scales autonomously. Such an attribute results essentially from the unique architecture of tooth enamel, specifically the vertical alignment of nano-scale mineral fibers and micro-scale prisms within a water-responsive organic-rich matrix, and can lead to a decrease in the dimension of indent damage in enamel introduced by indentation. Hydration plays an effective role in promoting the recovery process and improving the indentation fracture toughness of enamel (by ∼73%), at a minor cost of micro-hardness (by ∼5%), as compared to the dehydrated state. The nano-scale mechanisms that are responsible for the recovery deformation, specifically the reorientation and rearrangement of mineral fragments and the inter- and intra-prismatic sliding between constituents that are closely related to the viscoelasticity of organic matrix, are examined and analyzed with respect to the structure of tooth enamel. Our study sheds new light on the strategies underlying Nature's design of durable ceramics which could be translated into man-made systems in developing high-performance ceramic materials. STATEMENT OF SIGNIFICANCE: Tooth enamel plays a critical role in the function of teeth by providing a hard surface layer to resist wear/impact throughout the lifetime of organisms; however, such enamel exhibits a remarkably low resistance to the initiation of large-scale cracks, of hundreds of micrometers or more, comparable to that of geological minerals. Here we reveal that tooth enamel, specifically that of the giant panda, is capable of partially recovering its geometry and structure to counteract the early stages of damage at nano- to micro-scale dimensions autonomously. Such an attribute results essentially from the architecture of enamel but is markedly enhanced by hydration. Our work discerns a series of mechanisms that lead to the deformation and recovery of enamel and identifies a unique source of durability in the enamel to accomplish this function. The ingenious design of tooth enamel may inspire the development of new durable ceramic materials in man-made systems.

Hybrid Constructs for Performing Three-level Hybrid Surgery: A Finite Element Study.

OBJECTIVE: To systematically investigate the effect of 3-level hybrid constructs on the cervical spine biomechanics based on a validated model of the C3-C7 segments. METHODS: Three hybrid constructs with 2 U-shaped dynamic cervical implants and 1 cage were simulated. The 3 constructs were 1) Cage-U-U (cage implanted at the C3-C4 level and U-shaped dynamic cervical implants implanted at the C4-C5 and C5-C6 levels), 2) U-Cage-U, and 3) U-U-Cage. Biomechanical parameters including moments, cervical motions, and stresses in the facet and implants were analyzed in flexion and extension. RESULTS: The flexion and extension motions at artificial cervical disc replacement levels increased for all hybrid constructs when compared with those of intact model. However, the maximum increase was 52% with U-U-Cage model. At the unoperated adjacent level, the maximum motion increase in extension was 23% with the U-U-Cage model. Also, the U-U-Cage and U-Cage-U model generated more than 40% increase in terms of flexion motion at the adjacent level. The facet stress at the adjacent level increased by 28%, 20%, and 39% with the Cage-U-U, U-Cage-U, and U-U-Cage models, respectively. The moments required to reach the same motion as the intact model were significantly increased. CONCLUSIONS: The study showed that the U-U-Cage model lead to more compensation in terms of motion and facet stress. Furthermore, the present results imply that when conducting the hybrid surgery, the segmental motions should be taken into account. Performing anterior cervical discectomy and fusion at the level whose motion is relatively small may decrease the compensation required at the adjacent level.

Biomechanical Analysis of Lateral Lumbar Interbody Fusion Constructs with Various Fixation Options: Based on a Validated Finite Element Model.

BACKGROUND: Lateral lumbar interbody fusion using cage supplemented with fixation has been used widely in the treatment of lumbar disease. A combined fixation (CF) of lateral plate and spinous process plate may provide multiplanar stability similar to that of bilateral pedicle screws (BPS) and may reduce morbidity. The biomechanical influence of the CF on cage subsidence and facet joint stress has not been well described. The aim of this study was to compare biomechanics of various fixation options and to verify biomechanical effects of the CF. METHODS: The surgical finite element models with various fixation options were constructed based on computed tomography images. The lateral plate and posterior spinous process plate were applied (CF). The 6 motion modes were simulated. Range of motion (ROM), cage stress, endplate stress, and facet joint stress were compared. RESULTS: For the CF model, ROM, cage stress, and endplate stress were the minimum in almost all motion modes. Compared with BPS, the CF reduced ROM, cage stress, and endplate stress in all motion modes. The ROM was reduced by more than 10% in all motion modes except for flexion; cage stress and endplate stress were reduced more than 10% in all motion modes except for rotation-left. After interbody fusion, facet joint stress was reduced substantially compared with the intact conditions in all motion modes except for flexion. CONCLUSIONS: The combined plate fixation may offer an alternative to BPS fixation in lateral lumbar interbody fusion.

Biomechanical analysis of lumbar interbody fusion cages with various lordotic angles: a finite element study.

Inappropriate lordotic angle of lumbar fusion cage could be associated with cage damage or subsidence. The biomechanical influence of cage lordotic angle on lumbar spine has not been fully investigated. Four surgical finite element models were constructed by inserting cages with various lordotic angles at L3-L4 disc space. The four motion modes were simulated. The range of motion (ROM) decreased with increased lordotic angle of cage in flexion, extension, and rotation, whereas it was not substantially changed in bending. The maximum stress in cage decreased with increased lordotic angle of cage in all motion modes. The maximum stress in endplate at surgical level increased with increased lordotic angle of cage in flexion and rotation, whereas it was not substantially changed in extension and bending. The facet joint force (FJF) was much smaller than that for the intact conditions in extension, bending, and rotation, while it was not substantially changed in flexion. In conclusion, the ROM, stresses in the cage and endplate at surgical level are sensitive to the lordotic angle of cage. The increased cage lordotic angle may provide better stability and reduce the risk of cage damage, whereas it may increase the risk of subsidence in flexion and rotation.

Finite element model predicts the biomechanical performance of transforaminal lumbar interbody fusion with various porous additive manufactured cages.

In lumbar interbody fusion, a porous additive manufactured (AM) cage can provide more desirable stiffness, and may be beneficial to bone ingrowth. The biomechanical influence of porous cages on stability, subsidence, and facet contact force has not been fully described. The aim of this study was to verify biomechanical effects of porous cages. A surgical finite element (FE) model of transforaminal lumbar interbody fusion (TLIF) was constructed. Partially porous (PP) cages and fully porous (FP) cages were applied. Mechanical tests were performed to obtain the mechanical parameters of porous materials. The porous cages were compared to solid titanium (TI) cage and solid PEEK cage. Four motion modes were simulated. Range of motion (ROM), cage stress, endplate stress, and facet joint force (FJF) were compared. After interbody fusion, ROM decreased by more than 90% in flexion, bending and rotation. Compared with TI and PP cages, PEEK and FP cages substantially reduced the maximum stresses in cage and endplate in all motion modes. Compared with PEEK cages, the stresses in cage and endplate for FP cages decreased, whereas the ROM increased. Compared among three FP cages, the stresses in cage and endplate decreased with increasing porosity, whereas ROM increased with increasing porosity. FJF for various cages was substantially reduced compared to the intact model in all motion modes except for flexion. In summary, fully porous cages with a porosity of between 65% and 80% may offer an alternative to solid PEEK cages in TLIF.

Biomechanical Analysis of Porous Additive Manufactured Cages for Lateral Lumbar Interbody Fusion: A Finite Element Analysis.

BACKGROUND: A porous additive manufactured (AM) cage may provide stability similar to that of traditional solid cages and may be beneficial to bone ingrowth. The biomechanical influence of various porous cages on stability, subsidence, stresses in cage, and facet contact force has not been fully described. The purpose of this study was to verify biomechanical effects of porous AM cages. METHODS: The surgical finite element models with various cages were constructed. The partially porous titanium (PPT) cages and fully porous titanium (FPT) cages were applied. The mechanical parameters of porous materials were obtained by mechanical test. Then the porous AM cages were compared with solid titanium (TI) cage and solid polyetheretherketone (PEEK) cage. The 4 motion modes were simulated. Range of motion (ROM), cage stress, end plate stress, and facet joint force (FJF) were compared. RESULTS: For all the surgical models, ROM decreased by >90%. Compared with TI and PPT cages, PEEK and FPT cages substantially reduced the maximum stresses in cage and end plate in all motion modes. Compared with PEEK cages, the stresses in cage and end plate for FPT cages decreased, whereas the ROM increased. Comparing FPT cages, the stresses in cage and end plate decreased with increasing porosity, whereas ROM increased with increasing porosity. After interbody fusion, FJF was substantially reduced in all motion modes except for flexion. CONCLUSIONS: Fully porous cages may offer an alternative to solid PEEK cages in lateral lumbar interbody fusion. However, it may be prudent to further increase the porosity of the cage.