Efficacy of Opportunistic Screening with Chest CT in Identifying Osteoporosis and Osteopenia in Patients with T2DM.

Purpose: To explore the validity of the thoracic spine Hounsfield Unit (HU) measured by chest computed tomography (CT) for opportunistic screening of diabetic osteoporosis. The current study attempted to establish a diagnostic threshold for thoracic spine HU in a type 2 diabetes mellitus (T2DM) population with osteoporosis. Patients and Methods: The current study retrospectively included 334 patients with T2DM. They underwent chest CT and Dual-energy X-ray (DXA) between August 2021 and January 2022 in our hospital. HU values were measured on the resulting chest CT images at thoracic spine 11 and 12 to construct regions of interest. All patients were grouped according to the lowest T-value of DXA examination: osteoporosis, osteopenia and normal bone density. HU values were compared with T-values in each group of patients, and receiver operating characteristics curves were plotted to calculate diagnostic thresholds as well as sensitivity and specificity. Results: There was a strong correlation between the HU values of chest CT and the T-values of DXA (p < 0.01). The sensitivity for osteoporosis was 88.7% for T11 attenuation≤ 98 HU and the specificity for osteoporosis was 87.5% for T12 attenuation ≤ 117HU; the specificity for normal BMD was 85.4% for T11 attenuation ≥ 147 HU and 82% for T12 attenuation ≥ 146 HU. Conclusion: Chest CT can be used to screen patients with T2DM for opportunistic osteoporosis and help determine if they need DXA screening. The current study suggests that when the HU threshold of T11 ≤ 98/T12 ≤ 117, patients may need further osteoporosis screening.

Space between bone cement and bony endplate can trigger higher incidence of augmented vertebral collapse: An in-silico study.

BACKGROUND: The pathogenesis of postoperative complications in patients with osteoporotic vertebral compressive fractures (OVCFs) undergoing percutaneous vertebroplasty (PVP) is multifaceted, with local biomechanical deterioration playing a pivotal role. Specifically, the disparity in stiffness between the bone cement and osteoporotic cancellous bone can precipitate interfacial stress concentrations, potentially leading to cement-augmented vertebral body collapse and clinical symptom recurrence. This study focuses on the biomechanical implications of the space between the bone cement and bony endplate (BEP), hypothesizing that this interface may be a critical locus for stress concentration and subsequent vertebral failure. METHODS: Leveraging a validated numerical model from our previous study, we examined the biomechanical impact of the cement-BEP interface in the L2 vertebral body post-PVP, simulated OVCF and PVP and constructed three distinct models: one with direct bone cement contact with both cranial and caudal BEPs, one with contact only with the caudal BEPs and one without contact with either BEP. Moreover, we assessed stress distribution across cranial and caudal BEPs under various loading conditions to describe the biomechanical outcomes associated with each model. RESULTS: A consistent trend was observed across all models: the interfaces between the bone cement and cancellous bone exhibited higher stress values under the majority of loading conditions compared to models with direct cement-BEP contact. The most significant difference was observed in the flexion loading condition compared to the mode with direct contact between BEP and cement. The maximum stress in models without direct contact increased by at least 30%. CONCLUSIONS: Our study reveals the biomechanical significance of interfacial stiffness differences at the cement-BEP junction, which can exacerbate local stress concentrations and predispose to augmented vertebral collapse. We recommend the strategic distribution of bone cement to encompass a broader contact area with the BEP for preventing biomechanical failure and subsequent vertebral collapse.

Opportunistic prediction of osteoporosis in patients with degenerative lumbar diseases: a simplified T12 vertebral bone quality approach.

BACKGROUND: Osteoporosis is one of the risk factors for screw loosening after lumbar fusion. However, the probability of preoperative osteoporosis screening in patients with lumbar degenerative disease is low. Therefore, the aim of this study was to investigate whether a simplified vertebral bone quality (VBQ) score based on T12 T1-MRI could opportunistically predict osteoporosis in patients with degenerative lumbar spine diseases. METHODS: We retrospectively analyzed cases treated for lumbar degenerative diseases at a single institution between August 2021 and June 2022. The patients were divided into three groups by the lowest T-score: osteoporosis group, osteopenia group, and normal bone mineral density (BMD) group. The signal intensity based on the T12 vertebral body divided by the signal intensity of the cerebrospinal fluid was calculated to obtain the simplified VBQ score, as well as the CT-based T12HU value and the traditional L1-4VBQ score. Various statistical analyses were used to compare VBQ, HU and DEXA, and the optimal T12VBQ threshold for predicting osteoporosis was obtained by plotting the receiver operating curve (ROC) analysis. RESULTS: Total of 166 patients were included in this study. There was a statistically significant difference in T12VBQ scores between the three groups (p < 0.001). Pearson correlation showed that there was a moderate correlation between T12VBQ and T-score (r=-0.406, p < 0.001). The AUC value of T12VBQ, which distinguishes between normal and low BMD, was 0.756, and the optimal diagnostic threshold was 2.94. The AUC value of T12VBQ, which distinguishes osteoporosis from non-osteoporosis, was 0.634, and the optimal diagnostic threshold was 3.18. CONCLUSION: T12VBQ can be used as an effective opportunistic screening method for osteoporosis in patients with lumbar degenerative diseases. It can be used as a supplement to the evaluation of DEXA and preoperative evaluation. TRIAL REGISTRATION: retrospectively registered number:1502-009-644; retrospectively registered number date:27 oct 2022.

The Sanbi Decoction alleviates intervertebral disc degeneration in rats through intestinal flora and serum metabolic homeostasis modulation.

BACKGROUND: Intervertebral disc degeneration (IVDD) is an essential cause of low back pain (LBP), the incidence of which has risen in recent years and is progressively younger, but treatment options are limited, placing a serious economic burden on society. Sanbi decoction (SBD) is an important classical formula for the treatment of IVDD, which can significantly improve patients' symptoms and is a promising alternative therapy. PURPOSE: The aim of this study is to investigate the safety and efficacy of SBD in the treatment of IVDD and to explore the underlying mechanisms by using an integrated analytical approach of microbiomics and serum metabolomics, as well as by using molecular biology. METHODS: A rat IVDD puncture model was established and treated by gavage with different concentrations of SBD, and clean faeces, serum, liver, kidney, and intervertebral disc (IVD) were collected after 4 weeks. We assessed the safety by liver and kidney weighing, functional tests and tissue staining, the expression of tumor necrosis factor-alpha (TNF-ɑ), interleukin 1ß (IL-1ß) and interleukin 6 (IL-6) inflammatory factors in serum was detected by ELISA kits, and X-ray test, magnetic resonance imaging (MRI) examination, immunohistochemistry (IHC), western blotting (WB), hematoxylin-eosin (HE) staining and safranin O-fast green (SO/FG) staining were used to assess the efficacy. Finally, we performed 16S rRNA sequencing analysis on the faeces of different groups and untargeted metabolomics on serum and analyzed the association between them. RESULTS: SBD can effectively reduce the inflammatory response, regulate the metabolic balance of extracellular matrix (ECM), improve symptoms, and restore IVD function. In addition, SBD can significantly improve the diversity of intestinal flora and maintain the balance. At the phylum level, SBD greatly increased the relative abundance of Patescibacteria and Actinobacteriota and decreased the relative abundance of Bacteroidota. At the genus level, SBD significantly increased the relative abundance of Clostridia_UCG-014, Enterorhabdus, and Adlercreutzia, and decreased the relative abundance of Ruminococcaceae_UCG-005 (p < 0.05). Untargeted metabolomics indicated that SBD significantly improved serum metabolites and altered serum expression of 4alpha-phorbol 12,13-didecanoate (4alphaPDD), euscaphic acid (EA), alpha-muricholic acid (α-MCA), 5-hydroxyindoleacetic acid (5-HIAA), and kynurenine (Kyn) (p < 0.05), and the metabolic pathways were mainly lipid metabolism and amino acid metabolism. CONCLUSIONS: This study demonstrated that SBD can extensively regulate intestinal flora and serum metabolic homeostasis to reduce inflammatory response, inhibit the degradation of ECM, restore IVD height and water content to achieve apparent therapeutic effect for IVDD.

Visualizing the bibliometrics of the inflammatory mechanisms in intervertebral disc degeneration.

OBJECTIVE: Intervertebral disc degeneration (IVDD) constitutes a crucial pathological foundation for spinal degenerative diseases (SDD) and stands as a primary contributor to both low back pain (LBP) and disability. The progression of IVDD is linked to structural and functional alterations in tissues, where an imbalance in the inflammatory microenvironment can induce extracellular matrix (ECM) degradation, senescence, and apoptosis. This imbalance is a key pathomechanism in the disease's development, gaining considerable attention in recent years. This study aims to conduct a bibliometric analysis of publications pertaining to the inflammatory mechanisms of IVDD to quantitatively assess current research hotspots and directions. METHODS: In this study, we queried the Web of Science Core Collection (WOSCC) database covering the period from January 1, 2001, to November 7, 2023. Content in this area was analyzed and visualized using software such as Citespace, Vosviewer, and the bibliometrix package. RESULTS: Findings indicate a consistent annual increase in the number of publications, highlighting the widespread attention garnered by research on the inflammatory mechanisms of IVDD. In terms of journal research, Spine emerged with the highest number of publications, along with significantly elevated total citations and average citations compared to other journals. Regarding country analysis, China led in the number of publications, while the USA claimed the highest number of citations and total link strength. Institutional analysis revealed Sun Yat-sen University as having the highest number of publications and total link strength, with Thomas Jefferson University securing the highest total citations. Author analysis identified Ohtori, S. with the highest number of publications, Risbud, M.V. with the highest number of citations, and Inoue, G. with the highest total link strength, all of whom have made significant contributions to the field's development. Citation and co-citation analyses indicated that highly cited documents primarily focused on classical studies exploring inflammatory mechanisms in IVDD pathogenesis. Keyword analysis showcased the ongoing research hotspot as the further investigation of mechanisms and treatment studies. Recent years have seen a shift towards exploring pyroptosis, necrotic apoptosis, autophagy, ferroptosis, oxidative stress, and bacterial infection, among other mechanisms. In terms of treatment, alongside traditional monomer, drug, and compound therapies for IVDD, research is increasingly concentrating on stem cell therapy, exosomes, hydrogels, and scaffolds. CONCLUSION: This bibliometric analysis of research on inflammatory mechanisms in IVDD provides insights into the current status, hotspots, and potential future trends. These findings can serve as a valuable reference and guide for researchers in the field.

IVD fibrosis and disc collapse comprehensively aggravate vertebral body disuse osteoporosis and zygapophyseal joint osteoarthritis by posteriorly shifting the load transmission pattern.

BACKGROUND: Disuse is a typical phenotype of osteoporosis, but the underlying mechanism has yet to be identified in elderly patients. Disc collapse and intervertebral disc (IVD) fibrosis are two main pathological changes in IVD degeneration (IDD) progression, given that these changes affect load transmission patterns, which may lead to disuse osteoporosis of vertebral bodies and zygapophyseal joint (ZJ) osteoarthritis (ZJOA) biomechanically. METHODS: Clinical data from 59 patients were collected retrospectively. Patient vertebral bony density, ZJOA grade, and disc collapse status were judged via CT. The IVD fibrosis grade was determined based on the FA measurements. Regression analyses identified potential independent risk factors for osteoporosis and ZJOA. L4-L5 numerical models with and without disc collapse and IVD fibrosis were constructed; stress distributions on the bony endplate (BEP) and zygapophyseal joint (ZJ) cartilages were computed in models with and without disc collapse and IVD fibrosis. RESULTS: A significantly lower disc height ratio and significantly greater FA were recorded in patients with ZJOA. A significant correlation was observed between lower HU values and two parameters related to IDD progression. These factors were also proven to be independent risk factors for both osteoporosis and ZJOA. Correspondingly, compared to the intact model without IDD. Lower stress on vertebral bodies and greater stress on ZJOA can be simultaneously recorded in models of disc collapse and IVD fibrosis. CONCLUSIONS: IVD fibrosis and disc collapse simultaneously aggravate vertebral body disuse osteoporosis and ZJOA by posteriorly shifting the load transmission pattern.

Zinc mitigates cadmium-induced sperm dysfunction through regulating Ca2+ and metallothionein expression in the freshwater crab Sinopotamon henanense.

Cadmium (Cd) is a highly toxic heavy metal element that might adversely affect sperm function such as the acrosome reaction (AR). Although it is widely recognized that zinc (Zn) plays a crucial role in sperm quality, the complete elucidation of how Zn ameliorates Cd-induced sperm dysfunction is still unclear. In this study, we aimed to explore the protective effects of Zn against the sperm dysfunction induced by Cd in the freshwater crab Sinopotamon henanense. The results demonstrated that Cd exposure not only impaired the sperm ultrastructure, but also caused sperm dysfunction by decreasing the AR induction rate, acrosome enzyme activity, and Ca2+ content in sperm while elevating the activity and transcription expression of key Ca2+ signaling pathway-related proteins Calmodulin (CAM) and Ca2+-ATPase. However, the administration of Zn was found to alleviate Cd-induced sperm morphological and functional disorders by increasing the activity and transcription levels of CaM and Ca2+-ATPase, thereby regulating intracellular Ca2+ homeostasis and reversing the decrease in Ca2+ contents caused by Cd. Furthermore, this study was the first to investigate the distribution of metallothionein (MT) in the AR of S. henanense, and it was found that Zn can reduce the elevated levels of MT in crabs caused by Cd, demonstrating the significance of Zn in inducing MT to participate in the AR process and in metal detoxification in S. henanense. These findings offer novel perspectives and substantiation regarding the utilization of Zn as a protective agent against Cd-induced toxicity and hold significant practical implications for mitigating Cd-induced sperm dysfunction.

Stepwise reduction of bony density in patients induces a higher risk of annular tears by deteriorating the local biomechanical environment.

BACKGROUND CONTEXT: The relationship between osteoporosis and intervertebral disc degeneration (IDD) remains unclear. Considering that annular tear is the primary phenotype of IDD in the lumbar spine, the deteriorating local biomechanical environment may be the main trigger for annular tears. PURPOSE: To investigate whether poor bone mineral density (BMD) in the vertebral bodies may increase the risk of annular tears via the degradation of the local biomechanical environment. STUDY DESIGN: This study was a retrospective investigation with relevant numerical mechanical simulations. PATIENT SAMPLE: A total of 64 patients with low back pain (LBP) and the most severe IDD in the L4-L5 motion segment were enrolled. OUTCOME MEASURES: Annulus integration status was assessed using diffusion tensor fibre tractography (DTT). Hounsfield unit (HU) values of adjacent vertebral bodies were employed to determine BMD. Numerical simulations were conducted to compute stress values in the annulus of models with different BMDs and body positions. METHODS: The clinical data of the 64 patients with low back pain were collected retrospectively. The BMD of the vertebral bodies was measured using the HU values, and the annulus integration status was determined according to DTT. The data of the patients with and without annular tears were compared, and regression analysis was used to identify the independent risk factors for annular tears. Furthermore, finite element models of the L4-L5 motion segment were constructed and validated, followed by estimating the maximum stress on the post and postlateral interfaces between the superior and inferior bony endplates (BEPs) and the annulus. RESULTS: Patients with lower HU values in their vertebral bodies had significantly higher incidence rates of annular tears, with decreased HU values being an independent risk factor for annular tears. Moreover, increased stress on the BEP-annulus interfaces was associated with a stepwise reduction of bony density (ie, elastic modulus) in the numerical models. CONCLUSIONS: The stepwise reduction of bony density in patients results in a higher risk of annular tears by deteriorating the local biomechanical environment. Thus, osteoporosis should be considered to be a potential risk factor for IDD biomechanically.

Analysis of global research hotspots and trends in immune cells in intervertebral disc degeneration: A bibliometric study.

Intervertebral disc degeneration is an important pathological basis for spinal degenerative diseases. The imbalance of the immune microenvironment and the involvement of immune cells has been shown to lead to nucleus pulposus cells death. This article presents a bibliometric analysis of studies on immune cells in IDD in order to clarify the current status and hotspots. We searched the WOSCC, Scopus and PubMed databases from 01/01/2001 to 08/03/2023. We analyzed and visualized the content using software such as Citespace, Vosviewer and the bibliometrix. This study found that the number of annual publications is increasing year on year. The journal study found that Spine had the highest number of articles and citations. The country/regions analysis showed that China had the highest number of publications, the USA had the highest number of citations and total link strength. The institutional analysis found that Shanghai Jiao Tong University and Huazhong University of Science Technology had the highest number of publications, Tokai University had the highest citations, and the University of Bern had the highest total link strength. Sakai D and Risbud MV had the highest number of publications. Sakai D had the highest total link strength, and Risbud MV had the highest number of citations. The results of the keyword analysis suggested that the current research hotspots and future directions continue to be the study of the mechanisms of immune cells in IDD, the therapeutic role of immune cells in IDD and the role of immune cells in tissue engineering for IDD.

The cranial vertebral body suffers a higher risk of adjacent vertebral fracture due to the poor biomechanical environment in patients with percutaneous vertebralplasty.

BACKGROUND CONTEXT: Adjacent vertebral fracture (AVF), a frequent complication of PVP, is influenced by factors such as osteoporosis progression, increased intervertebral cement leakage (ICL), and biomechanical deterioration. Notably, the risk of AVF is notably elevated in the cranial vertebral body compared with the caudal counterpart. Despite this knowledge, the underlying pathological mechanism remains elusive. PURPOSE: This study delves into the role of biomechanical deterioration as a pivotal factor in the heightened risk of AVF in the cranial vertebral body following PVP. By isolating this variable, we aim to unravel its prominence relative to other potential risk factors. STUDY DESIGN: A retrospective study and corresponding numerical mechanical simulations. PATIENT SAMPLE: Clinical data from 101 patients treated by PVP were reviewed in this study. OUTCOME MEASURES: Clinical assessments involved measuring Hounsfield unit (HU) values of adjacent vertebral bodies as a representation of patients' bone mineral density (BMD). Additionally, the rates of ICL were compared among these patients. Numerical simulations were conducted to compute stress values in the cranial and caudal vertebral bodies under various body positions. METHODS: In a retrospective analysis of PVP patients spanning July 2016 to August 2019, we scrutinized the HU values of adjacent vertebral bodies to discern disparities in BMD between cranial and caudal regions. Additionally, we compared ICL rates on both cranial and caudal sides. To augment our investigation, well-validated numerical models simulated the PVP procedure, enabling the computation of maximum stress values in cranial and caudal vertebral bodies across varying body positions. RESULTS: The incidence rate of cranial AVF was significantly higher than the caudal side. No notable distinctions in HU values or ICL rates were observed between the cranial and caudal sides. The incidence of AVF showed no significant elevation in patients with ICL in either region. However, numerical simulations unveiled heightened stress values in the cranial vertebral body. CONCLUSIONS: In patients postPVP, the cranial vertebral body faces a heightened risk of AVF, primarily attributed to biomechanical deterioration rather than lower BMD or an elevated ICL rate.

Research on Design Method of Multilayer Metamaterials Based on Stochastic Topology.

Metamaterials are usually designed using biomimetic technology based on natural biological characteristics or topology optimization based on prior knowledge. Although satisfactory results can be achieved to a certain extent, there are still many performance limitations. For overcoming the above limitations, this paper proposes a rapid metamaterials design method based on the generation of random topological patterns. This method realizes the combined big data simulation and structure optimization of structure-electromagnetic properties, which makes up for the shortcomings of traditional design methods. The electromagnetic properties of the proposed metamaterials are verified by experiments. The reflection coefficient of the designed absorbing metamaterial unit is all lower than -15 dB over 12-16 GHz. Compared with the metal floor, the radar cross section (RCS) of the designed metamaterial is reduced by a minimum of 14.5 dB and a maximum of 27.6 dB over the operating band. The performance parameters of metamaterial obtained based on the random topology design method are consistent with the simulation design results, which further verifies the reliability of the algorithm in this paper.

Current status and trends in quantitative MRI study of intervertebral disc degeneration: a bibliometric and clinical study analysis.

Background: Quantitative magnetic resonance imaging (MRI) has the function of noninvasive quantitative evaluation, providing unique advantages in intervertebral disc degeneration (IDD) assessment. Although studies exploring the field for domestic and international scholars are increasingly being published, there is a lack of systematic scientific measurement and clinical analysis of the literature in this field. Methods: Articles published from the respective database establishment to September 30, 2022, were obtained from the Web of Science core collection (WOSCC), PubMed database, and ClinicalTrials.gov. The scientometric software (VOSviewer 1.6.18, CiteSpace 6.1.R3, Scimago Graphica, and R software) were used for bibliometric and knowledge graph visualization analysis. Results: We included 651 articles from the WOSCC database and 3 clinical studies from ClinicalTrials.gov for literature analysis. With the passage of time, the number of articles in this field gradually increased. The United States and China were the top 2 countries in terms of the number of publications and citations, and Chinese publications lacked international cooperation and exchange. The author with the most publications was Schleich C, while the author with the most citations was Borthakur A, who have both made important contributions to research in this field. The journal publishing the most relevant articles was Spine, and the journal with the most mean times cited per study was Radiology, both of which are the authoritative journals in this field. Keyword co-occurrence, clustering, timeline view, and emergent analysis revealed that recent studies in this field have focused on quantifying the biochemical components of the degenerated intervertebral disc (IVD). There were few available clinical studies. The more recent clinical studies mainly used molecular imaging technology to explore the relationship between different quantitative MRI sequence values and the IVD biomechanical environment and biochemical components content. Conclusions: The study provided a knowledge map of quantitative MRI for IDD research in terms of countries, authors, journals, cited literature, and keywords through bibliometric analysis, and systematically sorted the current status, hotspots, and clinical research features in the field to provide a reference for future research.

Regional differences in bone mineral density biomechanically induce a higher risk of adjacent vertebral fracture after percutaneous vertebroplasty: a case-comparative study.

BACKGROUND: Adjacent vertebral fracture (AVF) is a frequently observed complication after percutaneous vertebroplasty (PVP) in patients with osteoporotic vertebral compressive fracture. Biomechanical deterioration initially induces a higher risk of AVF. Studies demonstrated that the aggravation of regional differences in the elastic modulus of different components might deteriorate the local biomechanical environment and increase the risk of structural failure. Considering the existence of intravertebral regional differences in bone mineral density (BMD) (i.e. elastic modulus), it was hypothesized in the present study that higher intravertebral BMD differences may induce a higher risk of AVF biomechanically. MATERIALS AND METHODS: The radiographic and demographic data of osteoporotic vertebral compressive fracture patients treated using PVP were reviewed in the present study. The patients were divided into two groups: those with AVF and those without AVF. The Hounsfield unit (HU) values of transverse planes from the superior to the inferior bony endplate were measured, and the differences between the highest and lowest HU values of these planes were considered the regional differences of the HU value. The data from patients with and without AVF were compared, and the independent risk factors were identified through regression analysis. PVP with different grades of regional differences in the elastic modulus of the adjacent vertebral body was simulated using a previously constructed and validated lumbar finite element model, and the biomechanical indicators related to AVF were computed and recorded in surgical models. RESULTS: Clinical data on 103 patients were collected in this study (with an average follow-up period of 24.1 months). The radiographic review revealed that AVF patients present a significantly higher regional difference in the HU value and that the increase in the regional difference of the HU value was an independent risk factor for AVF. In addition, numerical mechanical simulations recorded a stress concentration tendency (the higher maximum equivalent stress value) in the adjacent vertebral cancellous bone, with a stepwise aggravation of the adjacent cancellous bony regional stiffness differences. CONCLUSIONS: The aggravation of regional BMD differences induces a higher risk of AVF after PVP surgery through a deterioration of the local biomechanical environment. The maximum differences in the HU value of the adjacent cancellous bone should, therefore, be measured routinely to better predict the risk of AVF. Patients with noticeable regional BMD differences should be considered at high risk for AVF, and greater attention must be paid to these patients to reduce the risk of AVF. EVIDENCE GRADE: Level III b.

Safety and clinical efficacy of endoscopic procedures for the treatment of adjacent segmental disease after lumbar fusion: A systematic review and meta-analysis.

BACKGROUND: Adjacent segment disease (ASD) is a common complication after lumbar fusion and is still traditionally treated by open surgery. In recent years, with the development of minimally invasive techniques, percutaneous endoscopic surgery(PES) has been used for the treatment of ASD after lumbar fusion due to its unique benefits. Nevertheless, it remains unclear about its significant clinical efficacy and advantages over conventional open surgery. OBJECTIVES: To evaluate the clinical efficacy and safety of PES in the treatment of ASD after lumbar fusion. STUDY DESIGN: A systematic review and meta-analysis studies about the role of PES in managing ASD after lumbar fusion. METHODS: A systematic search review was conducted in PubMed, EMBASE, Cochrane Library, Web of Science, CNKI, VIP, WanFang, and SinoMed databases from the start of their construction to 15 November 2021. Eligible studies included references to clinical trials of PES for ASD after open lumbar fusion. Observations included pain relief, recovery of postoperative function, overall excellent rates, and indicators of the advantages of minimally invasive surgery compared to conventional surgery. Postoperative complications and recurrence rates were also recorded. RESULTS: A total of 24 studies, including 20 single-arm studies and 4 clinical control studies, all involving 928 patients were included. A total of 694 patients were included in the single-arm analysis. The results of the single-arm meta-analysis showed that PES could significantly reduce low back and leg pain and improve the functional status of the lumbar spine in patients with ASD after open lumbar fusion compared to preoperatively, and had good clinical efficacy after surgery. A total of 234 patients were included in the four clinically controlled studies, and the results of the meta-analysis showed that PES could clearly reduce pain and improve lumbar function, with no significant difference in efficacy between PES and open surgery. However, PES has a lower surgical incision, less intraoperative bleeding, and shorter operative time and length of hospital stay compared to open surgery. Moreover, it has a lower rate of postoperative recurrence as well as complications and a longer duration of efficacy. CONCLUSIONS: On the basis of the available clinical literature and the results of this study, PES could achieve satisfactory clinical effects in ASD treatment after lumbar fusion. Compared with conventional open surgery, PES can not only obtain similar clinical results, but also had the advantages of less trauma and faster recovery. Nevertheless, a randomized controlled study is still needed to validate the findings of this study. TRIAL REGISTRATION: Systematic review registration: https://www.crd.york.ac.uk/prospero/, identifier CRD42022298387.

Annulus Calibration Increases the Computational Accuracy of the Lumbar Finite Element Model.

STUDY DESIGN: Mechanical simulations. OBJECTIVE: Inadequate calibration of annuli negatively affects the computational accuracy of finite element (FE) models. Specifically, the definition of annulus average radius (AR) does not have uniformity standards. Differences between the elastic moduli in the different layers and parts of the annulus were not fully calibrated when a linear elastic material is used to define its material properties. This study aims to optimize the computational accuracy of the FE model by calibrating the annulus. METHODS: We calibrated the annulus AR and elastic modulus in our anterior-constructed lumbar model by eliminating the difference between the computed range of motion and that measured by in vitro studies under a flexion-extension loading condition. Multi-indicator validation was performed by comparing the computed indicators with those measured in in vitro studies. The computation time required for the different models has also been recorded to evaluate the computational efficiency. RESULTS: The difference between computed and measured ROMs was less than 1% when the annulus AR and elastic modulus were calibrated. In the model validation process, all the indicators computed by the calibrated FE model were within ±1 standard deviation of the average values obtained from in vitro studies. The maximum difference between the computed and measured values was less than 10% under nearly all loading conditions. There is no apparent variation tendency for the computational time associated with different models. CONCLUSION: The FE model with calibrated annulus AR and regional elastic modulus has higher computational accuracy and can be used in subsequent mechanical studies.

Incomplete insertion of pedicle screws triggers a higher biomechanical risk of screw loosening: mechanical tests and corresponding numerical simulations.

Screw loosening is a widely reported issue after spinal screw fixation and triggers several complications. Biomechanical deterioration initially causes screw loosening. Studies have shown that incomplete insertion of pedicle screws increases the risk of screw breakage by deteriorating the local mechanical environment. However, whether this change has a biomechanical effect on the risk of screw loosening has not been determined. This study conducted comprehensive biomechanical research using polyurethane foam mechanical tests and corresponding numerical simulations to verify this topic. Pedicle screw-fixed polyurethane foam models with screws with four different insertion depths were constructed, and the screw anchoring ability of different models was verified by toggle tests with alternating and constant loads. Moreover, the stress distribution of screw and bone-screw interfaces in different models was computed in corresponding numerical mechanical models. Mechanical tests presented better screw anchoring ability with deeper screw insertion, but parameters presented no significant difference between groups with complete thread insertion. Correspondingly, higher stress values can be recorded in the model without complete thread insertion; the difference in stress values between models with complete thread insertion was relatively slight. Therefore, incomplete thread insertion triggers local stress concentration and the corresponding risk of screw loosening; completely inserting threads could effectively alleviate local stress concentration and result in the prevention of screw loosening.

Nerve abnormalities in lumbar disc herniation: A systematic review and meta-analysis of diffusion tensor imaging.

PURPOSE: The purpose of this study was to examine the values of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) in diffusion tensor imaging (DTI) for diagnosing patients with nerve impairment due to lumbar disc herniation (LDH). METHODS: A literature search of databases (PubMed, Web of Science, Cochrane Library and Embase) was systematically performed to identify articles published before September 2021 that were relevant to this study. FA and ADC estimates of compressed nerve roots due to LDH and healthy controls in the same segment were compared, with either fixed or random effects models selected according to I2 heterogeneity. Additionally, subgroup analysis, sensitivity analysis, potential publication bias analysis and meta-regression analysis were also performed. RESULTS: A total of 369 patients with LDH from 11 publications were included in this meta-analysis. The results showed significantly lower FA values (Weighted Mean Difference (WMD): -0.08, 95% confidence interval (CI): -0.09 to -0.07, P ≤ 0.001, I2 = 87.6%) and significantly higher ADC values (WMD: 0.25, 95% CI: 0.20 to 0.30, P ≤ 0.001, I2 = 71.4%) of the nerve on the compressed side due to LDH compared to the healthy side. Subgroup analysis indicated that different countries and magnetic field strengths may be associated with higher heterogeneity. Furthermore, meta-regression analysis further revealed that segment and field strength did not have a significant effect on the results, regardless of the FA or ADC values. Contrastingly, in FA, the year of publication, country, b value and directions showed an effect on the results. CONCLUSIONS: This meta-analysis showed a significant decrease in FA and a significant increase in ADC in patients with nerve damage due to LDH. The results favourably support the presence of nerve impairment in patients with LDH.

Knowledge Areas and New Trends in Lumbar Disc Herniation Research: Bibliometrics and Knowledge Mapping Analysis.

Objective: To determine the coalitions and impact of authors, countries, institutions, and journals, evaluate the knowledge base, find the hotspot trends, and identify the emerging topics in lumbar disc herniation (LDH). Method: The articles related to LDH were obtained from the Web of Science Core Collection on August 21, 2021. Two scientometric software (CiteSpace 5.8.R.1 and VOSviewer 1.6.17) were used to perform bibliometric and knowledge-map analysis. Results: From the set parameters, 4642 articles were included in the literature. Although the total number of publications fluctuated between 2001 and 2020, a general trend toward increase was observed. Respectively, the most productive country and institution in the field were the United States and Wooridul Spine Hospital. The most active and cited authors were Lee and Weinstein. Spine was the most impactful and cited journal. Weinstein (JAMA 296:2441-2450, 2006) had the highest number of co-citations and Weinstein(N Engl J Med 358:794-810, 2008) had the highest number of citations. The keyword "low back pain" was ranked first for frequency and total link strength, whereas "risk factor" was ranked first for centrality. Topics including pathogenesis (disc herniation), examination methods (MRI), treatment methods (non-surgical treatment, surgical treatment), surgical options (laminectomy, discectomy), clinical observations (double-blind, efficacy, outcome, learning curve), and evaluation of efficacy (meta-analysis) of LDH have been the focus of leading-edge research in 2001-2020. Conclusion: Using bibliometric methods, this study mapped the knowledge map of LDH research in the past 20 years. The study identifies existing trends to provide a framework for further research.

Hope for bone regeneration: The versatility of iron oxide nanoparticles.

Although bone tissue has the ability to heal itself, beyond a certain point, bone defects cannot rebuild themselves, and the challenge is how to promote bone tissue regeneration. Iron oxide nanoparticles (IONPs) are a magnetic material because of their excellent properties, which enable them to play an active role in bone regeneration. This paper reviews the application of IONPs in bone tissue regeneration in recent years, and outlines the mechanisms of IONPs in bone tissue regeneration in detail based on the physicochemical properties, structural characteristics and safety of IONPs. In addition, a bibliometric approach has been used to analyze the hot spots and trends in the field in order to identify future directions. The results demonstrate that IONPs are increasingly being investigated in bone regeneration, from the initial use as magnetic resonance imaging (MRI) contrast agents to later drug delivery vehicles, cell labeling, and now in combination with stem cells (SCs) composite scaffolds. In conclusion, based on the current research and development trends, it is more inclined to be used in bone tissue engineering, scaffolds, and composite scaffolds.

Poor bone mineral density aggravates adjacent segment's motility compensation in patients with oblique lumbar interbody fusion with and without pedicle screw fixation: An in silico study.

Objective: Motility compensation increases the risk of adjacent segment diseases (ASDs). Previous studies have demonstrated that patients with ASD have a poor bone mineral density (BMD), and changes in BMD affect the biomechanical environment of bones and tissues, possibly leading to an increase in ASD incidence. However, whether poor BMD increases the risk of ASD by aggravating the motility compensation of the adjacent segment remains unclear. The present study aimed to clarify this relationship in oblique lumbar interbody fusion (OLIF) models with different BMDs and additional fixation methods. Methods: Stand-alone (S-A) OLIF and OLIF fixed with bilateral pedicle screws (BPS) were simulated in the L4-L5 segment of our well-validated lumbosacral model. Range of motions (ROMs) and stiffness in the surgical segment and at the cranial and caudal sides' adjacent segments were computed under flexion, extension, and unilateral bending and axial rotation loading conditions. Results: Under most loading conditions, the motility compensation of both cranial and caudal segments adjacent to the OLIF segment steeply aggravated with BMD reduction in S-A and BPS OLIF models. More severe motility compensation of the adjacent segment was observed in BPS models than in S-A models. Correspondingly, the surgical segment's stiffness of S-A models was apparently lower than that of BPS models (S-A models showed higher ROMs and lower stiffness in the surgical segment). Conclusion: Poor BMD aggravates the motility compensation of adjacent segments after both S-A OLIF and OLIF with BPS fixation. This variation may cause a higher risk of ASD in OLIF patients with poor BMD. S-A OLIF cannot provide instant postoperative stability; therefore, the daily motions of patients with S-A OLIF should be restricted before ideal interbody fusion to avoid surgical segment complications.