Are There Correlations Between Facet Joint Parameters and Lumbar Disk Herniation Laterality in Young Adults?

Background: We aimed to determine whether there is an association, in young adults, between the occurrence of lumbar disk herniation（LDH）at a given segment and the segment’s facet joint parameters [facet orientation (FO) and tropism (FT)]. In addition, associations between facet joint parameters in the corresponding segment and LDH laterality were also investigated.Methods: We retrospectively analyzed data from 529 patients who were between 18 and 35 years old, who had experienced single-level LDH (L4–5 or L5–S1) between June 2017 and December 2019, and with less than 2 years of clinical history. We included an additional 122 patients with no history of LDH as an age-matched control group. LDH were classified by laterality (left-sided, right-sided, or central herniation). At each level (L4–L5 or L5–S1 segments), we investigated the relationship between facet joint parameters and herniation laterality. Results: FOA values at the L4–L5 level and the L5–S1 level were significantly lower and FT was higher for the LDH group compared with those for the control group. The level at which LDH occurred, FOL, FOR, and FT differed significantly among the three groups. There was a significant association between herniation laterality and FO at the L4–L5 level but not at the L5–S1 level.Conclusions: Abnormal facet joint parameters are significantly associated with LDH. Young adults with higher FT should be paid more attention, to prevent the occurrence of LDH. At the L4–L5 level, intervertebral disk herniation tended to occur ipsilateral to the side with a lower facet joint angle when FT was present.

The Correlation Between Facet Joint Parameters and the Location of Lumbar Disc Herniation in the Young Population

Background: Facet joint parameters have been discussed as substantial factors in the development of LDH. However, the correlation between facet joint parameters and the location of LDH in the corresponding segment is still unclear. The objective of this study was to demonstrate a clearly relationship between facet orientation (FO), facet tropism (FT) and lumbar disc herniation (LDH) in young individuals.Methods: Between June 2017 and December 2019, 529 patients having single-level LDH (L4-5 or L5-S1) between 18 and 35 years old with a less than 2 years clinical history were included. Another 122 age-matched patients with no LDH were enrolled as the control group (N-LDH group). Based on the location of herniation, cases in LDH group were divided into three groups (LDHL, LDHR, and LDHM). We investigated the correlation between facet joint parameters and the location of LDH.Results: The FOA in L4-5 and L5-S1 level were significantly lower while FT were higher in LDH group than N-LDH group respectively. In terms of the correlation between the facet joint parameters and the location of LDH, the level of LDH, the FOL, FOR, and FT were significantly varied among the three groups. There is a significant association between the different location of LDH and different FO of bilateral facet joints in L4-5 while not in L5-S1 level.Conclusion: The facet joint parameters abnormality have an significant association with the development of LDH. Young individuals with higher FT and/or lower FO should be paid more attention to preventing the occurrence of LDH. There was more location of IVD herniated on the ipsilateral location with lower FO of facet joint when FT existed in L4-5 level.

Are Facet Orientation and Tropism Risk Factors for Cervical Spondylotic Radiculopathy? A Retrospective Study in a Chinese Population

Background Facet parameters, such as facet orientation (FO) and tropism (FT) are thought to be predisposing factors for pathological changes in the lumbar spine. This study aimed to explore the association between facet parameters and cervical spondylotic radiculopathy (CSR) on 3-dimentional views. Methods A total of 226 patients with single-level CSR and 182 normal control participants were included. FO, FT and the incidence of FT (defined as FT ≥ 7) based on reconstructed CT images were measured. Univariate and multiple logistic regression analysis were used to investigate the association between facet joint parameters and the incidence of CSR. The Pearson Chi-square test was used to find out the relationship between the side of herniation and facet joint parameters in CSR patients. Results Axial FT of CSR group was significantly larger compared to control group at each spinal level, while sagittal except C5/6 and coronal FT shown not. The differences of incidence of axial FT at all levels between groups were statistically significant, as well as incidence of sagittal FT at C4/5 and C5/6. Incidence of axial FT with respect to all levels was significantly associated with CSR, and incidence of sagittal FT only at C4/5 and C5/6 was associated with CSR. The proportion between the left and right side of greater FO was significantly different on axial view. Conclusion Axial and sagittal FT but not FO were associated with CSR, and axial FT might exert more dominant function on the development of CSR. Moreover, CSR might be more vulnerable to more severe axial FT, which should be paid more attention. The side of herniation might prefer the side of greater axial FO.

Tensile behavior of a Brazilian Disk Containing non-persistent Joint Sets Subjected to Diametral Loading: An Experimental Investigation

Structural defects are part of the inherent characteristics of rock masses. They can be found in the form of fishers, joints, and beddings and can be divided into persistent or non-persistent one. The coalescence of non-persistent cracks may lead to the formation of persistent joints under the tensile stress field, leading to instability of rock mass. The mechanical behavior of non-persistent jointed disks under tensile stress has essential implications for rock engineering structures. In this paper, concrete Brazilian disks containing open non-persistent joints were constructed and subjected to diametral loading to investigate the effect of this kind of joint parameters on the tensile strength and stiffness of disks. The effect of some parameters, such as joint continuity factor (the relationship between joint length and rock bridge length), bridge angle, joint spacing, and loading direction with respect to joint angle were investigated to estimate the tensile strength and stiffness as well as failure pattern. The results of experiments revealed that the tensile strength, stiffness, and failure pattern of Brazilian disks are highly affected by non-persistent pre-existing crack parameters. The increase of joint continuity factor and loading direction leads to an increase in tensile strength and a decrease in stiffness. However, when bridge angle and spacing increase tensile strength rises, and the former decreases stiffness while the latter results in its reduction. Finally, all the parameters significantly affect the failure pattern, and some failure patterns such as step-path failure, splitting, or sliding may occur as a function of non-persistent joint parameters.

3D Linear Identification of Mechanical Joint Using FRF Decoupling and Inverse Structural Modification Methods

Mechanical connections such as bolts and rivets are inevitable in most engineering structures and may significantly affect the dynamic behavior of the structures. Therefore, modeling a joint simply and accurately is essential for assembled structures. On the other hand, the most important step is the determination of these joint model parameters which will be used in the calculation of dynamic response of assembled structures. For this purpose, in this paper, FRF Decoupling Method (FRF-DM), proposed in an earlier study for bolted beam connections is extended in two ways: Firstly, the bolt model proposed for 2D beam elements is extended to 3D finite element models of structural systems, and thus the dynamics of a bolted connection is modeled as an equivalent 6 × 6 complex stiffness matrix including linear and torsional stiffnesses. Secondly, FRF-DM is extended to include measurements at connection degrees of freedoms, which improves the accuracy in identification. Several equations for the identification of joint parameters are derived utilizing FRF-DM. Joint parameters are calculated by using developed FRF decoupling relations, as well as by employing a recently developed method called Inverse Structural Modification Method (ISMM) in a case study consisting of two beams connected by a 6 × 6 stiffness and viscous damping matrices. The accuracy and the advantages of each method/formulation are discussed by using the case study based on simulated experiments.

ANALYSIS AND DESIGN OF STRUCTURAL STEEL JOINTS AND CONNECTION: SOFTWARE IMPLEMENTATION

The paper presents COMET software which enables to design steel structural joints widely used in civil and industrial engineering. Algorithm for designing each joint prototype has been presented as a set of operations implementing the rules for determining the interrelated values of the joint parameters. Each prototype is developed as an independent program that performs a full cycle of designing the joint and verification of the joint parameters according to the specified design codes. Searching of unknown joint parameters has been transformed to a decision making problem based on analysis of the joint mathematical model. Automatic searching of unknown joint parameters has been implemented as a multiple targeted improvement of a certain initial joint design in order to satisfy load-carrying capacity constraints taking into account the structural and assortment-based constraints. Multiple improvement of current joint design is performed on the basis of sensitivity analysis relative to variation of governing joint parameters.

Low Infiltration of CD8+ PD-L1+ T Cells and M2 Macrophages Predicts Improved Clinical Outcomes After Immune Checkpoint Inhibitor Therapy in Non-Small Cell Lung Carcinoma

BackgroundMany clinical studies have shown that patients with non-small cell lung carcinoma (NSCLC) can benefit from immune checkpoint inhibitor (ICI) therapy; however, PD-L1 and tumor mutation burden (TMB), which are recommended by the NCCN guidelines, are still insufficient in predicting the response to and prognosis of immunotherapy. Given the widespread use of ICIs, it is important to find biomarkers that can predict immunotherapy outcomes in NSCLC patients, and the exploration of additional effective biomarkers for ICI therapy is urgently needed.MethodsA total of 33 stage II-IV NSCLC patients were included in this study. We analyzed immune markers in biopsy and surgical tissue resected from these patients before treatment with ICIs. We examined the infiltration of immune cells and expression of PD-L1 in immune cells using fluorescent multiplex immunohistochemistry (mIHC) stained with CD8/CD68/CD163/PD-L1 antibodies.ResultsIn this cohort, we observed that the levels of CD8+ T cells, CD8+PD-L1+ T cells, and CD68+CD163+ M2 macrophages in the total region were independent prognostic factors for progression-free survival (PFS) in NSCLC patients treated with ICIs (HR=0.04, P=0.013; HR=17.70, P=0.026; and HR=17.88, P=0.011, respectively). High infiltration of CD8+ T cells and low infiltration of CD8+PD-L1+ T cells throughout the region were correlated with prolonged PFS (P=0.016 and P=0.02, respectively). No statistically significant difference was observed for CD68+CD163+ M2 macrophages. The joint parameters CD8+ high/CD8+PD-L1+ low, CD8+ high/CD68+CD163+ low and CD8+PD-L1+ low/CD68+CD163+ low predicted better PFS than other joint parameters (P<0.01, P<0.01, and P<0.001, respectively), and they also demonstrated stronger stratification than single biomarkers. The response rate of patients with high infiltration of CD8+ T cells was significantly higher than that of those with low infiltration (P<0.01), and the joint parameters CD8+/CD8+PD-L1+ and CD8+/CD68+CD163+ also demonstrated stronger stratification than single biomarkers.ConclusionsThis retrospective study identified the predictive value of CD8+PD-L1+ T cells, CD8+ T cells, and CD68+CD163+ M2 macrophages in NSCLC patients who received ICIs. Interestingly, our results indicate that the evaluation of joint parameters has certain significance in guiding ICI treatment in NSCLC patients.

Influence of the Rivet Coating on the Friction during Self-Piercing Riveting

The number of multi-material joints is increasing as a result of lightweight design. Self-piercing riveting (SPR) is an important mechanical joining technique for multi-material structures. Rivets for SPR are coated to prevent corrosion, but this coating also influences the friction that prevails during the joining process. The aim of the present investigation is to evaluate this influence. The investigation focuses on the common rivet coatings Almac® and zinc-nickel with topcoat as well as on uncoated rivet surfaces. First of all, the coating thickness and the uniformity of the coating distribution are analysed. Friction tests facilitate the classification of the surface properties. The influence of the friction on the characteristic joint parameters and the force-stroke curves is analysed by means of experimental joining tests. More in-depth knowledge of the effects that occur is achieved through the use of numerical simulation. Overall, it is shown that the surface condition of the rivet has an impact on the friction during the joining process and on the resulting joint. However, the detected deviations between different surface conditions do not restrict the operational capability of SPR and the properties of uncoated rivet surfaces, in particular, are similar to those of Almac®-coated rivets. It can thus be assumed that SPR with respect to the joining process is also possible without rivet coating in principle.