Search

Summary Pedicle screw loosening after posterior lumbar fusion is associated with poor bone quality, which often determines screw pull‐out strength, insertion torque, and vertebral body loading characteristics. Magnetic resonance imaging (MRI)‐based vertebral bone quality (VBQ) score were associated with poor bone quality. Current evidence suggests that pedicle bone quality (PBQ) has a greater impact on screw stability. However, the correlation between MRI‐based PBQ score and screw loosening has not been reported. Purpose To introduce and evaluate an MRI‐based PBQ score to determine its effectiveness in predicting pedicle screw loosening following lumbar fusion surgery. Methods The retrospective study analyzed 244 patients who underwent posterior lumbar interbody fusion (PLIF) with pedicle screws between December 2017 and December 2021, with CT and MRI imaging before surgery. Data collected included patient demographics and preoperative radiological data. Radiographic screw loosening was measured at 12 months postoperatively. Clinical assessments included pain visual analog scale (VAS) and Oswestry Disability Index (ODI) scores. The PBQ score was measured using MRI scans. We use univariate analysis for preliminary screening of the risk factors of screw loosening. Subsequent analysis involved multivariate logistic regression to identify independent predictive factors for screw loosening. We constructed the receiver operating characteristic (ROC) curve to ascertain the discriminative capacity of the PBQ score. The area under the curve (AUC) quantified its predictive accuracy. Additionally, we evaluated the association between PBQ score and screw loosening using Spearman's correlation analysis. Results Overall, 244 patients who underwent PLIF with pedicle screw fixation participated in this study, including 35 in the loosening group and 209 in the non‐loosening group. PBQ score in the loosening group was significantly higher than that in the non‐loosening group. On multivariate logistic regression, the higher PBQ score (OR = 8.481, 95% CI: 3.158–22.774; p

Objectives Currently, anterior‐only (AO), posterior‐only, and combined anterior–posterior spinal fusions are common strategies for treating cervical kyphosis in patients with neurofibromatosis‐1 NF‐1. Nevertheless, the choice of surgical strategy remains a topic of controversy. The aim of our study is to evaluate the safety and effectiveness of anterior decompression and spinal reconstruction for the treatment of cervical kyphosis in patients with NF‐1. Methods Twelve patients with NF‐1‐associated cervical kyphotic deformity were reviewed retrospectively between January 2010 and April 2020. All patients underwent AO correction and reconstruction. The X‐ray was followed up in all these patients to assess the preoperative and postoperative local kyphosis angle (LKA), the global kyphosis angle (GKA), the sagittal vertical axis, and the T1 slope. The visual analog scale score, Japanese Orthopedic Association (JOA) score, and neck disability index (NDI) score were used to evaluate the improvement inclinical symptoms. The results of the difference in improvement from preoperatively to the final follow‐up assessment were assessed using a paired t‐test or Mann–Whitney U‐test. Results The LKA and GKA decreased from the preoperative average of 64.42 (range, 38–86) and 35.50 (range, 10–81) to an average of 16.83 (range, −2 to 46) and 4.25 (range, −22 to 39) postoperatively, respectively. The average correction rates of the LKA and GKA were 76.11% and 111.97%, respectively. All patients had achieved satisfactory relief of neurological symptoms (p

Objective Both two‐level anterior cervical corpectomy and fusion (t‐ACCF) and posterior open‐door laminoplasty (ODLP) are effective surgical procedures for the treatment of ossification of the posterior longitudinal ligament (OPLL). Previous studies have identified different effects of different surgical procedures on the upper and subaxial cervical spine (UCS, SCS), however, there are no studies on the effects of t‐ACCF and ODLP on the occipito‐atlantoaxial complex. Therefore, the purpose of this study is to compare the changes in sagittal parameters and range of motion (ROM) of the occipito‐atlantoaxial complex in OPLL patients treated with t‐ACCF and ODLP. Methods This was a retrospective study that included 74 patients who underwent t‐ACCF or ODLP for the treatment of OPLL from January 2012 to August 2022 at our institution. Preoperative, 3‐month, and 1‐year postoperative cervical neutral, flexion‐extension, and lateral flexion radiographs were taken. Sagittal parameters including Cobb angle of C2‐7, C0‐2, C0‐1, C1‐2, C2 slope, and the ROM were measured. The clinical outcome was assessed using the JOA, VAS, and NDI scores preoperatively and at 3 and 12 months postoperatively. Multiple linear regression was employed to identify factors influencing changes in UCS. Results In the ODLP group, the SCS (C2‐7) Cobb angle was significantly reduced (12.85 ± 10.0 to 7.68 ± 11.27; p

Objective The Isobar TTL dynamic fixation system has demonstrated favorable outcomes in the short‐term treatment of lumbar degenerative disc diseases (LDDs). However, there is a paucity of extensive research on the long‐term effects of this system on LDDs. This study aimed to evaluate the long‐term clinical and radiological outcomes of patients with LDDs who underwent treatment utilizing the Isobar TTL dynamic fixation system. Methods The study analyzed the outcomes of 40 patients with LDDs who underwent posterior lumbar decompression and received single‐segment Isobar TTL dynamic internal fixation at our hospital between June 2010 and December 2016. The evaluation of clinical therapeutic effect involved assessing postoperative pain levels using the visual analogue scale (VAS) and Oswestry disability index (ODI), both before surgery, 3 months after, and the final follow‐up. To determine the preservation of functional motion in dynamically stable segments, we measured the range of motion (ROM) and disc height of stabilized and adjacent segments preoperatively and during the final follow‐up. Additionally, we investigated the occurrence of adjacent segment degeneration (ASD). Results Forty patients were evaluated, with an average age of 44.65 years and an average follow‐up period of 79.37 months. Fourteen patients belonged to the spondylolisthesis group, while the remaining 26 were categorized under the stenosis or herniated disc group. The preoperative ROM of the stabilized segment exhibited a significant reduction from 8.15° ± 2.77° to 5.00° ± 1.82° at the final follow‐up (p 0.05). Conclusion The Isobar TTL dynamic fixation system is an effective treatment for LDDs, improving pain relief, quality of life (QoL) and maintaining stabilized segmental motion. It has demonstrated excellent long‐term clinical and radiographic results.

ObjectiveTo investigate the relationship between degeneration of cervical intervertebral disc and degeneration of paravertebral muscles[multifidus (MF), cervical semispinalis (SCer), semispinalis capitis (SCap) and splenius capitis (SPL)].Methods82 patients with chronic neck pain were randomly selected, including 43 males and 39 females, with 50.73 0.7.51 years old. All patients were scanned by 3.0T MRI Philips Ingenia performed conventional MRI sequence scanning and fat measurement sequence mDIXON-Quant scanning of cervical. Fat infiltration (FI) and cross-sectional area (CSA) of cervical paravertebral muscle (MF, SCer, SCap and SPL) at central level of C5–6 disc were measured by Philips 3.0T MRI image post-processing workstation. According to Pfirrmann grading system, there was no grade I in the included cases. The number of grade IIr IV cases were n=16, 40, 19 and 7 respectively. CSA and FI of cervical paravertebral muscles were compared with t test or one-way ANOVA, Spearman correlation analysis was used to evaluate the correlation between age, disc degeneration, and CSA, FI of cervical paravertebral muscles, and multiple linear regression analysis was used to analyze the independent influencing factors of CSA and FI.ResultsCSA of cervical paravertebral muscles in male patients was significantly higher than that in female patients (all P0.05). Age was weakly correlated with CSA of MF+SCer, moderately correlated with CSA of SCap and SPL (r=-0.256, -0.355 and -0.361, P

Objective Recently, the MRI‐based vertebral bone quality (VBQ) score has been shown to correlate with Hounsfeld units (HU) value, dual‐energy X‐ray absorptiometry (DEXA) T‐score and predict osteoporotic fractures. Preoperative cervical HU value is an independent correlative factor for early titanium mesh cage (TMC) subsidence after anterior cervical corpectomy and fusion (ACCF). However, to date the direct association between cervical VBQ score and TMC subsidence has not been studied. This study aims to investigate the predictive effect of cervical VBQ score derived from sagittal non‐contrast‐enhanced T1‐weighted MRI on the early TMC subsidence after ACCF. Methods Patients who underwent one‐level ACCF from January 2016 to January 2020 were included. We retrospectively collected baseline data on age, sex, body mass index (BMI), disease type, level of surgery and radiology parameters. The cervical VBQ score was measured using preoperative non‐contrast‐enhanced T1‐weighted MRI. Univariate and multivariate logistic regression analysis were performed to screen the independent risk factors of TMC subsidence. The receiver operating characteristic (ROC) curve and area under curve (AUC) were performed to assess the predictive ability of TMC subsidence based on the cervical VBQ score. Spearman correlation analysis was used to determine the correlations between the cervical VBQ score and TMC subsidence. Results A total of 134 patients who underwent one‐level ACCF were included in this study, and 46 (34.33%) patients had TMC subsidence. Univariable analyses demonstrated that the age, TMC placement depth and VBQ score were associated with subsidence. The cervical VBQ score in the subsidence group was significantly higher than that in the no subsidence group (3.75 ± 0.45 vs. 3.20 ± 0.42, p

Objective Previous studies have confirmed that the nanohydroxyapatite/polyamide‐66 (n‐HA/PA66) cage is an ideal alternative material for degenerative lumbar disease (DLD) comparable to the polyether ether ketone (PEEK) cage due to its similar radiographic fusion, subsidence rate, and clinical results. However, these studies were restricted to one‐level surgery. The aim of this study was to analyze the long‐term clinical and radiologic outcomes between n‐HA PA66 cage and PEEK cage for patients with multi‐level degenerative lumbar diseases (DLDs). Methods We retrospectively reviewed all patients who underwent multi‐level transforaminal lumbar interbody fusion (TLIF) from June 2010 to December 2016 with a minimum 6‐year follow‐up. Matched‐pair analysis was performed using a 1‐to‐1 closest neighbor approach to match patients who received an n‐HA PA66 cage with those who received a PEEK cage. Clinical outcomes and radiographic evaluations were compared between the two groups. The independent student's t‐test and χ2‐test were applied to compare the differences between groups. Results At the end of the propensity score matching (PSM) analysis, 48 patients from n‐HA/PA66 group were matched to 48 patients in the PEEK group. No significant difference was observed in cage subsidence and bony fusion except for adjacent segment degeneration (ASD). The occurrence of ASD was 14.58% (7/48) in the n‐HA/PA 66 group, which was significantly less than that in the PEEK group (33.33% [16/48]) (p = 0.031). Although the intervertebral space height (IH), segmental angle (SA) and lumbar lordosis (LL) significantly increased after surgery in both groups, there was no significant difference at any time point after surgery (p > 0.05). The visual analogue scale (VAS) and Oswestry disability index (ODI) scores significantly improved in both groups at 3m postoperative, 1y postoperative and at final follow‐up. However, there were no significant differences in the VAS and ODI score at any time point (p > 0.05). The total complications and re‐admission rate were not different between the two groups. Conclusion Overall, our data suggest that the outcomes of n‐HA/PA66 cage group are comparable to those of the PEEK cage group, with a similar high fusion rate and low cage subsidence rate as PEEK cages, except its lower rate of ASD occurrence.

PurposePrevious studies have confirmed the advantages and disadvantages of autogenous iliac bone and nano-hydroxyapatite/polyamide 66 (n-HA/PA66) cage. However, there is no conclusive comparison between the efficacy of the two implant materials in spinal tuberculosis bone graft fusion. The aim of this study was to analyze the mid-to long-term clinical and radiologic outcomes between n-HA/PA66 cage and autogenous iliac bone for anterior reconstruction application of spinal defect for thoracolumbar tuberculosis.MethodsWe retrospectively reviewed all patients who underwent anterior debridement and strut graft with n-HA/PA66 cage or iliac bone combined with anterior instrumentations between June 2009 and June 2014. One-to-one nearest-neighbor propensity score matching (PSM) was used to match patients who underwent n-HA/PA66 cage to those who underwent iliac bone. Clinical outcomes were assessed using the Japanese Orthopaedic Association (JOA) and visual analogue score (VAS). Radiographic evaluations included cage subsidence and segmental angle.ResultsAt the end of the PSM analysis, 16 patients from n-HA/PA66 cage group were matched to 16 patients in Iliac bone group. The C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) values in the n-HA/PA66 group decreased significantly from 33.19 ± 10.89 and 46.63 ± 15.65 preoperatively, to 6.56 ± 2.48 and 9.31 ± 3.34 at the final follow-up, respectively (p < 0.001). There were no significant differences in the CRP and ESR values between the two groups at the final follow-up. The VAS and JOA scores in the iliac bone and n-HA/PA66 group were significantly improved at the 3-month follow-up postoperatively (both p < 0.001). Then, improvements of VAS and JOA scores continue long at final follow-up. However, there were no significant differences in the VAS and JOA scores at any time point between the two groups (p > 0.05). Although the segmental angle (SA) significantly increased after surgery in both groups, there was no significant difference at any time point after surgery (p > 0.05). There were no significant differences in the cage subsidence and fusion time between the two groups.ConclusionOverall, our data suggest that the n-HA/PA66 cage outcomes are comparable to those in the autogenous iliac bone, with a similar high fusion rate as autogenous iliac bone.

Interbody fusion devices are critical in spinal surgery to restore spinal stability, reduce pain and improve function. Polyetheretherketone (PEEK) has become a commonly used alternative material for fusion cages owing to its excellent mechanical properties and biocompatibility, but its biological inertness limits bone regeneration and may lead to poor fusion. In this study, a novel strategy for preparing bioactive biomineralized PEEK cages was developed using a unique combination of osteoinductive CaP bioceramic fillings in the cage window, acid sulfonation and simulated body fluid incubation. In vitro experiments showed that biomineralized PEEK cages and CaP bioceramics regulate immunity and promote angiogenesis and bone integration via activation of hypoxia-inducible factor 1-alpha and cyclic guanosine monophosphate/protein kinase G signaling pathways. In vivo goat spinal fusion experiments demonstrated that PEEK cages filled with CaP bioceramics resulted in good bone growth and spinal fusion. Therefore, the high mechanical strength and good biocompatibility of biomineralized PEEK cages, together with the excellent bioactivity and degradation properties of CaP bioceramics, provide an ideal microenvironment for bone fusion. The development of this composite material not only addresses some of the limitations of existing fusion devices but also will facilitate the development of spinal fusion technology.

Objective Previous studies have found satisfactory clinical results with the nano‐hydroxyapatite/polyamide 66 (n‐HA/PA66) cage to reconstruct the stability of anterior cervical column. However, studies evaluating the long‐term outcomes of the n‐HA/PA66 cage in multi‐level degenerative cervical myelopathy (MDCM) have not been reported. This study aims to compare the outcomes of corpectomy anterior cervical discectomy and fusion (ACDF) hybrid procedures between the n‐HA/PA66 cage and titanium mesh cage (TMC) to treat MDCM. Methods After the screening for eligibility, this retrospective study involved 90 patients who underwent corpectomy ACDF hybrid (CACDFH) procedure from June 2013 to June 2018. The CACDFH procedure is the combination of ACDF and anterior cervical corpectomy and fusion (ACCF). According to the cage utilized, we categorized patients into a n‐HA/PA66 cage group and a TMC group. Then, stepwise propensity score matching (PSM) was performed to maintain comparable clinical data between groups. All the patients were followed up ≥4 years and the longest follow‐up time was 65.43 (±11.49) months. Cage subsidence, adjacent segment degeneration (ASD), segmental height (SH), segmental angle (SA), cervical lordosis (CL), and clinical data (visual analogue scale [VAS] and Japanese Orthopaedic Association [JOA] score) was evaluated preoperatively, at 1 week, and at the final surgery follow‐up. The independent student's t test and chi‐square test were applied to compare the differences between groups. Results Through PSM analysis, 25 patients from the n‐HA/PA66 group were matched to 25 patients in the TMC group. The occurrence of ASD was 16.0% (4/25) in the n‐HA/PA 66 group, which was significantly less than in the TMC group at 44.0% (11/25) (p = 0.031). Moreover, the cage subsidence rate was significantly higher in the TMC group as compared to the n‐HA/PA 66 group (40.0% vs. 12.0%, p = 0.024). But there was no significant difference in SH, SA, and CL at any time after surgery as determined through follow‐up. The VAS and JOA scores significantly improved in both groups at 3 months postoperative and at final follow‐up. However, there were no significant differences in the VAS and JOA score at any time between the two groups in preoperative (p > 0.05). Conclusion The n‐HA/PA66 cage is associated with lower rate of cage subsidence and ASD than the TMC in the treatment of MDCM. The n‐HA/PA66 cage could be superior to the TMC in corpectomy ACDF hybrid procedures.

Objective Although direct isthmic repair, such as PSVPH, did not affect the mobility of the fixed segment and adjacent segment, it has a relatively low rate of isthmic fusion compared with conventional fusion. The Isobar TTL dynamic internal fixation system has been widely used in clinical practice and has achieved satisfactory clinical results. However, the use of the Isobar TTL system in combination with direct isthmic repair for lumbar spondylolysis has rarely been reported. The aim of this study was to compare the clinical and radiologic outcomes between patients who underwent Isobar TTL system and PSVPH with direct repair of defect for lumbar spondylolysis. Methods Stepwise propensity score matching (PSM) for age and sex were performed to keep comparable clinical data between groups in this retrospective and matched‐pair case control study. A total of 50 patients diagnosed with lumbar spondylolysis underwent surgical implantation of the Isobar TTL group (n = 25) or PSVPH group (n = 25) from June 2009 to June 2016. Clinical outcomes were assessed using the Oswestry disability index (ODI), and visual analog score (VAS). Radiographic evaluations included range of motion (ROM) and the disc heights of stabilized segment and adjacent segment, adjacent segment degeneration (ASD) and bony fusion. Three‐dimensional reconstruction of lumbar CT scan was obtained to evaluate bone fusion of the isthmic at final follow‐up. The independent Student's t test and chi‐square test were applied to compare the differences between groups. Results A total of 25 patients from TTL group were matched to 25 patients in PSVPH group for age, sex, body mass index (BMI), defect side, spondylolisthesis meyerding, and follow‐up duration. The intervertebral space height (IH) of stabilized segment at postoperative 1 week and final follow‐up in the TTL group was higher than those in the PSVPH group, respectively (P = 0.030; P = 0.013). The ROM of stabilized segment at final follow‐up in the TTL group was significantly lower than that in the PSVPH group (P

Introduction Several systematic reviews and meta-analyses have confirmed that percutaneous vertebroplasty and percutaneous kyphoplasty showed safety and beneficial efficacy in patients with osteoporotic vertebral compression fractures. Whereas, there is wide variation among results, which are not conducive to the evaluation and use of clinicians. This study will investigate the efficacy and safety of percutaneous vertebroplasty and percutaneous kyphoplasty for the treatment of osteoporotic vertebral compression fractures, aiming to provide a more reliable evidence base for clinical practice in treating osteoporotic vertebral compression fractures.Methods and analysis We will retrieve the relevant articles using the five databases(PubMed, Scopus, EMBASE, Cochrane Library and Web of Science) from inception to March 2023 for systematic review and meta-analysis comparing the overall safety and efficacy of percutaneous vertebroplasty and percutaneous kyphoplasty in patients with osteoporotic vertebral compression fractures. Three reviewers will screen citation titles, abstracts and evaluate the full text of each relevant citation based on prespecified eligibility criteria. Any discrepancies in decisions between reviewers will be resolved through discussion. We will assess the methodological quality of the included studies according to A MeaSurement Tool to Assess systematic Reviews 2 checklist.Ethics and dissemination This umbrella review will inform clinical and policy decisions regarding the benefits and harms of percutaneous vertebroplasty versus percutaneous kyphoplasty for osteoporotic vertebral compression fractures. Neither primary data nor individual patient information will be collected, thus ethics approval is not required. Findings will be reported through a peer-reviewed publication, conference presentations and the popular press.PROSPERO registration number CRD42021268141.

Abstract Introduction New vertebral compression fractures (NVCFs) are adverse events after vertebral augmentation of osteoporotic vertebral compression fractures (OVCFs). Predicting the risk of vertebral compression fractures (VCFs) accurately after surgery is still a significant challenge for spinal surgeons. The aim of our study was to identify risk factors of NCVFs after vertebral augmentation of OVCFs and develop a nomogram. Methods We retrospectively reviewed the medical records of patients with OVCFs who underwent percutaneous vertebroplasty (PVP) or percutaneous kyphoplasty (PKP). Patients were divided into the NVCFs group and control group, base on the patients with or without NVCFs within 2 years follow-up period after surgery. A training cohort of 403 patients diagnosed in our hospital from June 2014 to December 2016 was used for model development. The independent predictive factors of postoperative VCFs were determined by least absolute shrinkage and selection operator (LASSO) logistic regression, univariate analysis and multivariate logistic regression analysis. We provided a nomogram for predicting the risk of NVCFs based on independent predictive factors and used the receiver operating characteristic curve (ROC), calibration curve, and decision curve analyses (DCA) to evaluated the prognostic performance. After internal validation, the nomogram was further evaluated in a validation cohort of 159 patients included between January 2017 and June 2018. Results Of the 403 patients in the training cohort, 49(12.16%) were NVCFs at an average of 16.7 (1 to 23) months within the 2 years follow-up period. Of the 159 patients in the validation cohort, 17(10.69%) were NVCFs at an average of 8.7 (1 to 15) months within the 2 years follow-up period. In the training cohort, the proportions of elderly patients older than 80 years were 32.65 and 13.56% in the NVCFs and control group, respectively (p = 0.003). The percentages of patients with previous fracture history were 26.53 and 12.71% in the NVCFs and control group, respectively (p = 0.010). The volume of bone cement were 4.43 ± 0.88 mL and 4.02 ± 1.13 mL in the NVCFs and Control group, respectively (p = 0.014). The differences have statistical significance in the bone cement leakage, bone cement dispersion, contact with endplate, anti-osteoporotic treatment, post-op Cobb angle and Cobb angle restoration characteristics between the two groups. The model was established by multivariate logistic regression analysis to obtain independent predictors. In the training and validation cohort, the AUC of the nomogram were 0.882 (95% confidence interval (CI), 0.824-0.940) and 0.869 (95% CI: 0.811-0.927), respectively. The C index of the nomogram was 0.886 in the training cohort and 0.893 in the validation cohort, demonstrating good discrimination. In the training and validation cohort, the optimal calibration curves demonstrated the coincidence between prediction and actual status, and the decision curve analysis demonstrated that the full model had the highest clinical net benefit across the entire range of threshold probabilities. Conclusion A nomogram for predicting NVCFs after vertebral augmentation was established and validated. For patients evaluated by this model with predictive high risk of developing postoperative VCFs, postoperative management strategies such as enhance osteoporosis-related health education and management should be considered.

Abstract Background Current findings suggest that percutaneous vertebroplasty(PVP) is a suitable therapeutic approach for osteoporotic vertebral compression fractures (OVCFs). The present retrospective study aimed to investigate the differences in clinical efficacy and related complications between the two bone cement distribution modes. Methods We retrospectively reviewed the medical records of the patients with single-segment OVCFs who underwent bilateral percutaneous vertebroplasty. Patients were divided into blocky and spongy group according to the type of postoperative bone cement distribution. Clinical efficacy and related complications was compared between the two bone cement distribution modes on 24 h after the operation and last follow-up. Results A total of 329 patients with an average follow up time of 17.54 months were included. The blocky group included 131 patients, 109 females(83.2 %) and 22 males(16.8 %) with a median age of 72.69 ± 7.76 years, while the Spongy group was made up of 198 patients, 38 females(19.2 %) and 160 males(80.8 %) with a median age of 71.11 ± 7.36 years. The VAS and ODI after operation improved significantly in both two groups. The VAS and ODI in the spongy group was significantly lower than that in the blocky group, 24 h postoperatively, and at the last follow-up. There were 42 cases (12.8 %) of adjacent vertebral fractures, 26 cases (19.8 %) in the blocky group and 16 cases (8.1 %) in the spongy group. There were 57 cases (17.3 %) of bone cement leakage, 18 cases (13.7 %) in blocky group and 39 cases (19.7 %) in the spongy group. At 24 h postoperatively and at the last follow-up, local kyphosis and anterior vertebral height were significantly corrected in both groups, but gradually decreased over time, and the degree of correction was significantly higher in the spongy group than in the block group. The change of local kyphosis and loss of vertebral body height were also less severe in the spongy group at the last follow-up. Conclusions Compared with blocky group, spongy group can better maintain the height of the vertebral body, correct local kyphosis, reduce the risk of the vertebral body recompression, long-term pain and restore functions.

Abstract In this letter to the editor, we discuss the article by Zhang et al., published recently in the Journal of Orthopaedic Surgery and Research. The authors reviewed the efficacy and safety of platelet-rich plasma combined with hyaluronic acid versus platelet-rich plasma alone for knee osteoarthritis. Whether the authors' purpose in grouping was to investigate the role of hyaluronic acid in the treatment of knee osteoarthritis is a question we would like to raise. In terms of the methodology of the study, combining randomized controlled trials with cohort studies in this meta-analysis is a methodological error. Secondly, the study methodology of the four included randomized controlled trial studies lacked a clear method of randomization. In addition to this, the completeness of the search needs to be taken into consideration. Some of the results of this study were highly heterogeneous, and no sensitivity analysis or meta-regression was performed to further analyse the sources of heterogeneity. The above issues will affect the conclusions of the article, and we believe this needs further improvement and discussion.

Objective. Current findings suggest that percutaneous vertebroplasty (PVP) is a suitable therapeutic approach for osteoporotic vertebral compression fractures (OVCFs). However, a significant minority of patients still experience residual back pain after PVP. The present retrospective study was designed to determine the risk factors for residual back pain after PVP and provides a nomogram for predicting the residual back pain after PVP. Methods. We retrospectively reviewed the medical records of patients with single-segment OVCFs who underwent bilateral percutaneous vertebroplasty. Patients were divided into group N and group R according to the postoperative VAS score. Group R is described as the VAS score of residual back pain ≥ 4. Pre- and postoperative factors that may affect back pain relief were evaluated between two groups. Univariate and multivariate logistic regression analysis were performed to identify risk factors affecting residual back pain after PVP. We provided a nomogram for predicting the residual back pain and used the receiver operating characteristic curve (ROC), concordance index (C-index), calibration curve, and decision curve analyses (DCA) to evaluate the prognostic performance. Results. Among 268 patients treated with PVP, 37 (13.81%) patients were classified postoperative residual back pain. The results of the multivariate logistical regression analysis showed that the presence of an intravertebral vacuum cleft (IVC) (OR 3.790, P=0.026), posterior fascia oedema (OR 3.965, P=0.022), severe paraspinal muscle degeneration (OR 5.804, P=0.01; OR 13.767, P

Abstract Oral cancer remains a deadly disease worldwide. Lymph node metastasis and invasion is one of the causes of death from oral cancer. Elucidating the mechanism of oral cancer lymph node metastasis and identifying critical regulatory genes are important for the treatment of this disease. This study aimed to identify differentially expressed genes (gene signature) and pathways that contribute to oral cancer metastasis to lymph nodes. The GSE70604-associated study compared gene profiles in lymph nodes with metastasis of oral cancer to those of normal lymph nodes. The GSE2280-associated study compared gene profiles in primary tumor of oral cancer with lymph node metastasis to those in tumors without lymph node metastasis. There are 28 common differentially expressed genes (DEGs) showing consistent changes in both datasets in overlapping analysis. GO biological process and KEGG pathway analysis of these 28 DEGs identified the gene signature CCND1, JUN and SPP1, which are categorized as key regulatory genes involved in the focal adhesion pathway. Silencing expression of CCND1, JUN and SPP1 in the human oral cancer cell line OECM-1 confirmed that those genes play essential roles in oral cancer cell invasion. Analysis of clinical samples of oral cancer found a strong correlation of these genes with short survival, especially JUN expression associated with metastasis. Our study identified a unique gene signature – CCND1, JUN and SPP1 – which may be involved in oral cancer lymph node metastasis.

Abstract Background Overexpression of PTK7 has been found in multiple cancers and has been proposed to serve as a prognostic marker for intrahepatic cholangiocarcinoma. Its role in esophageal cancer, however, remains to be clarified. We hypothesize that PTK7 positively regulates tumorigenesis of esophageal cancer. Methods We examined PTK7 expression pattern in human esophageal squamous carcinoma by Oncomine expression analysis and by immunohistochemistry (IHC) staining. We knocked down PTK7 in two esophageal squamous cell carcinoma cell lines, TE-5, and TE-9, by siRNA, and evaluated cell proliferation, apoptosis, and migration ofPTK7-defective cells. Expressions of major apoptotic regulators and effectors were also determined by quantitative real-time PCR in PTK7-defective cells. We further overexpressed PTK7 in the cell to evaluate its effects on cell proliferation, apoptosis, and migration. Results Both Oncomine expression and IHC analyses showed that PTK7 is overexpressed in clinical esophageal squamous cell carcinoma tumors. PTK7 siRNA suppressed cell growth and promoted apoptosis of TE-5 and TE-9. PTK7-defective cells further displayed reduced cellular migration that was concomitant with upregulation of E-cadherin. Conversely, overexpression of PTK7 promotes cell proliferation and invasion, while apoptosis of the PTK7-overexpressing cells is repressed. Notably, major apoptotic regulators, such as p53 and caspases, are significantly upregulated in siPTK7 cells. Conclusions PTK7 plays an oncogenic role in tumorigenesis and metastasis of esophageal squamous carcinoma. PTK7 achieves its oncogenic function in esophageal squamous cell carcinoma partially through the negative regulation of apoptosis.

Abstract At present, most of the analyses or studies about inductive power transfer (IPT) with constant current (CC) output and constant voltage (CV) output are carried out without considering misalignment conditions or different gaps. An IPT system satisfying battery charging demand and anti‐misalignment requirements simultaneously is infrequent. This paper proposes a multi‐objective particle swarm optimization method of IPT reconfigurable topology to realize CC and CV modes at varying resistance conditions and wide coupling ranges. The output characteristics of an inductor–capacitor–capacitor (LCC)–LCC compensation circuit have been explored, and it is found that the secondary‐side compensated capacitors have a greater impact on the output power, which can be used to improve power regulation ability accompanied by coupling varying. Eight optimization compensated parameters of the reconfigurable topology are obtained from the Pareto front to achieve the required CC and CV charging outputs. By switching the compensated capacitors, the selected parameters can make the current and voltage fluctuation less than 9.3% and 7.9%, respectively, during the coupling charging range from 0.3 to 0.22. Moreover, primary zero voltage switching operation is achieved to enable high efficiency. The simulation and the experimental verification are carried out to verify the validity of the proposed method.

Selective harmonic elimination pulse-width modulation (SHE-PWM) method has been widely used in various industrial multilevel converters befitting from low switching frequencies and precise elimination of low-order harmonics. Most of existing studies focus on accelerating calculation of switching angles or optimizing predictive neural networks. However, these offline methods cannot dynamically deal with the errors introduced by nonuniform dc sources of multilevel converters or biased placements of switching angles. This paper proposes an online adaptive SHE (OA-SHE) algorithm to compensate these errors. Errors caused by nonideal dc (NID) sources and leading-lagging placements (LLPs) are analyzed in detail. The error of output waveform is comprehensive result of NID sources and LLPs. By introducing feedback, the output waveform accuracy of multilevel converters can be increased greatly. Realization of the particle swarm optimization (PSO) with an embedded control system is presented to acquire good real-time performance. With the OA-SHE method, the value of particles has been higher than the initial value. High order harmonics, including 1st, 5th, 7th, 11th, and 13th components, are suppressed by the low-pass filter. Comparing to existing studies, this online algorithm does not need detailed model parameters and can be directly applied to practical applications achieving multi-objective optimization. Finally, both simulations and experiments are carried out to verify the effectiveness of this algorithm.

The hazard of ice accretion on overhead power circuits is significant, yet predicting it is very difficult. The key reason lies in the shortage of sufficient observational data on ice thickness, and previous studies have also rarely taken into account micro-terrain and micro-meteorological conditions. In response to the challenge of simulating overhead line icing, this study introduces a new icing simulation technique that fully considers the effects of micro-terrain and micro-meteorology. For this technique, typical micro-terrains of overhead line areas are first identified by using high-resolution elevation data, and the icing thickness characteristics in different micro-terrains are analyzed. Subsequently, icing thickness simulations for different micro-terrains are conducted. The results indicate that during the icing process, the icing thickness ranges from 5 mm to 8 mm under three types of micro-terrain, namely, “uplift type”, “alpine drainage divide type” and “canyon wind channel type”, whereas the icing thickness is less than 5 mm in the “flat type” of micro-terrain. This finding suggests that the first three micro-terrain types facilitate icing on overhead transmission lines due to the condensation and uplifting effects of water vapor caused by terrain. However, flat terrain lacks the conditions necessary for water vapor accumulation and thus is not easy to form icing. The results are advantageous for the deployment of overhead power lines in intricate terrain. It is advisable to steer clear of regions susceptible to icing, and endeavor to install circuits in level territories whenever feasible. In addition, the simulated icing thickness under different terrains is in good agreement with the observations. Specifically, the correlation coefficient between simulated and observed icing thickness is significant at the 0.99 confidence level, and the deviations between them are within 0.5 mm. This signifies that the forecasting methodologies employed are dependable and possess significant implications as a reference for disaster prevention and mitigation efforts.

Abstract Dispatchable energy storage system (ESS) plays a critical role in the smart grid through energy shift and power support. However, it exhibits different operational strategies and economic benefits in different application scenarios due to its inherent degradation behaviour. This paper aims to explore the technical and economic feasibility of the flexible traction power supply system (FTPSS) integrating ESS and renewable energy sources (RES) based on the traction load characteristics. First, a battery degradation model applicable in its frequent charging and discharging operating conditions is derived. Then this paper develops an operational‐sizing co‐optimization framework for the ESS in the FTPSS, where the operation decisions are made considering the degradation costs varying with the sizes and energy throughput. To solve this large‐scale non‐linear intertemporal decision‐making problem, an iterative method with a linear programming (LP) core is proposed to achieve the trade‐off between computational efficiency and accuracy. The results of the extensive comparative cases show that the proposed approach can achieve approximately 10% higher economic benefits than the existing bi‐level sizing strategies for FTPSS.

Due to their excellent performance, the inductor–capacitor–capacitor-series (LCC-S)-compensated topologies are extensively used in inductive power transfer (IPT) applications. However, perfect alignment of the system’s contactless couplers is difficult, which leads to serious deterioration of the system output characteristics. In this paper, the influence of the coupler misalignment on the performance of the conventional resonant system is studied. To obtain stable output against varying couplings and loads in a certain range, a novel parameter design method based on the multi-objective particle swarm optimization (MOPSO) algorithm is introduced. The multi-objective optimization framework is developed to analyze the Pareto trade-offs between three conflicting performance metrics, namely output current/voltage ripple, reactive power transmission and component stress. Optimization results depict that misalignment tolerances in both constant current output (CCO)-type and constant voltage output (CVO)-type LCC-S-compensated IPT systems are improved, while a wider load range is suitable for a CCO-type system using the method of compensation parameter optimization. Experimental results are highly consistent with the design, achieving a current fluctuation of no more than 10.5% with a load range from 50 Ω to 100 Ω and a voltage fluctuation of less than 10.4% with a narrow load from 90 Ω to 100 Ω over 100% of coupling variations (from 0.25 to 0.5).

With the increasing requirements of the railway sector for electrified railways and the development of society, the traction power supply system needs to become more flexible, economic and reliable. The traditional traction power supply system has many problems due to its own topology, such as negative sequence current, load fluctuation, low utilization rate of regenerative braking energy, and inability to use the distributed generation along the railway. In order to solve these problems and make the traction power supply system (TPSS) more flexible, efficient and reliable, a novel TPSS called flexible smart traction power supply system (FSTPSS) is proposed. This traction power supply system consists of AC-DC-AC traction substation and the microgrid along the railway. It can effectively mitigate the problems of negative sequence current, improve regenerative braking energy utilization and distributed generation utilization. A hierarchical energy management strategy is also proposed here, which can effectively improve the operating economy of FSTPSS and reduce the load fluctuation of FSTPSS. And based on the actual load measurement power of a traction substation of China’s Beijing-Shanghai high-speed railway, the proposed energy management strategy has been verified for the economic improvement and load fluctuation reduction of TPSS.

The inherent resonant frequency of a traction power supply system (TPSS) needs to be accurately identified in order to provide crucial information for resonance suppression, safe operation, and system optimization of electrified railways. In this paper, implementation of experiments was carried out in actual railway systems to evaluate the inherent harmonic resonances of the TPSS. The field tests were based on a harmonic generator (HG) constructed with cascaded H-bridge converters (CHBCs). Compared to other experimental setups, the field tests of this paper, which were performed in the 25kV practical system, can provide straightforward results in a wide frequency range up to 5000 Hz. Such a wide frequency range is necessary for assessing and taking effective measures to address the harmonic resonance problem. The results of this paper will supply valuable data for the modeling of TPSSs and the stability analysis of train converters contributing to improvement of the power quality of electric railways.

The simple increasing impedance model is usually adopted by calculation or computer simulation to represent the harmonic behaviors of the power source in the studies of impedance-frequency characteristics (IFCs) of the traction power supply system (TPSS) in electrified railways. However, this model is a little rough and sometimes even introduces inevitable errors in stability analysis, resonance estimation, and filter design, etc. This paper proposes an improved calculation method based on field tests to evaluate the impact of the power source on the equivalent harmonic impedance at the pantograph terminal seen from trains. Then two field tests are presented in detail to verify the difference between the classical method and the proposed method. The compared results proved the effectiveness of the analysis of this paper. Furthermore, the accuracy of the 2 × 25 kV electrified railway's impedance-frequency estimation was significantly improved through the proposed calculation method.

To solve the three-phase unbalance and reactive power problems in the electric railway power supply system, this paper proposes a Scott transformer based hypotenuse hybrid traction power system (Scott-HHPS). Compared with other co-phase traction power supply systems, the Scott-HHPS could achieve the same compensation objective with smaller active compensation capacity. The paper analyzes the basic principle and makes a comparison between the Scott-HHPS and typical co-phase power supply system. The mathematical relationships among the load current, power factor and capacity demand in condition of power factor variation and regenerative braking are analyzed. In order to further reduce the compensation capacity of the Scott-HHPS, the partial compensation strategy in respect to the index of power factor and unbalance is proposed. Besides, an instantaneous current detection method based on the theorem of conservation of power is adopted to simplify the control algorithms. Simulations and experiments are both constructed and the results demonstrate that the Scott-HHPS can effectively improve the power quality in the electric railway power supply system.

Many new types of locomotives are put to use in electric railway systems, resulting in instability problems such as high-order harmonic resonance occurring as a consequence of the interaction between the electrical locomotive (including electrical multiple units) and the traction network. In order to investigate this problem, this paper adopts the impedance-based approach to analyze the stability properties of the system interaction. The detailed impedance of the traction network is obtained by taking its distributed parameters into account. Then the locomotive converter with single-phase transient current control algorithm (TCCA), which can represent the locomotive when performing the impedance-based stability analysis, is modeled as the dq-frame impedance by single-phase dq decomposition. By plotting bode diagrams of the impedance for the traction network and the locomotive separately, and calculating the phase margin at the intersection point of the magnitude of the two impedances, the stability of the locomotive-network system is evaluated and thus the high-order harmonic resonance can be predicted. Moreover, a time-domain model of locomotive-network systems is established in this paper, which can reproduce the high-order harmonic resonance in the time domain as a first validation step of the analysis. Finally, a field test in a traction substation of the Beijing-Harbin Railway is carried out to finally validate the effectiveness of the proposed method. The stability analysis method in this paper is simple and effective without the need for a complex calculation of some norms or Eigenvalues. As a result, the high-order harmonic resonance can be predicted before a new type of locomotive is put into use.

High-order harmonic resonance is a key issue in the traction power supply systems (TPSS) of electric railways for safe operation. The effective evaluation of the resonance frequency is critical for taking measures to suppress harmonic resonance. In this paper, the influence of the distributed parameters of traction networks on resonance frequencies based on accurate calculation is proposed. The quantitative assessments of the distributed impedance and admittance are investigated. Furthermore, the theoretical calculation is directly verified using field tests at a high voltage level equal to 25 kV. The results show that the resonance frequencies of the TPSS are mainly affected by the distributed parameters, including the self-admittance and self-impedance of the contact wires, and the self-admittance of the positive feeders. In addition, the admittance connected in parallel has a greater effect than the series-connected impedance. The calculation method is also adapted to TPSS connected to renewable energy.

Harmonic resonance is a kind of oscillatory instability phenomenon occurring in the electric railway. To investigate this problem, the frequency-domain model of the single-phase voltage source converter for locomotives is derived based on the transfer function of the current control loop. The equivalent circuit of the traction network is also included in this frequency-domain model. Particularly, the time delay and zero-order-holder effect of the digital pulse width modulation are taken into consideration in order to obtain more accurate a model of the digital controller. After that, the harmonic resonance of the locomotive-network system is assessed through the passivity properties of the interacted frequency-domain impedance model. Finally, the effectiveness of the theoretical analysis is demonstrated by simulations and experiments. As a result, the harmonic resonance can be predicted before a new electric railway is put into use so that some mitigation measures can be taken in advance.

Harmonic overvoltage in electric railway traction networks can pose a serious threat to the safe and stable operation of the traction power supply system (TPSS). Existing studies aim at improving the control damping of grid-connected converters, neglecting the impedance frequency characteristics (IFCs) of the actual TPSS. The applicable frequency range of these studies is relatively low, usually no more than half of the switching frequency, and there is a large gap with the actual traction network harmonic overvoltage frequency range of 750 Hz–3750 Hz. In this paper, first, the IFCs of the actual TPSS in the wide frequency range of 150 Hz–5000 Hz are obtained through field tests, and the resonant frequency distribution characteristics of TPSS are analyzed. After that, the aliasing effect of the sampling process and the sideband effect of the modulation process of the digital control of the grid-connected converter are considered. Based on the relative relationships among the inherent resonant frequency of the TPSS, sampling frequency and switching frequency, an impedance matching analysis method is proposed for the wide frequency range of the vehicle–grid coupling system. By this method, the sampling frequency and switching frequency can be decoupled, and the harmonic overvoltage of traction network in the frequency range of two times switching frequency and above can be directly estimated. Finally, the method proposed in this paper is validated by the comparative simulation analysis of seven different cases.

This paper presents the four-quadrant operation modes of bidirectional chargers for electric vehicles (EVs) framed in smart car parks. A cascaded model predictive control (MPC) scheme for the bidirectional two-stage off-board chargers is proposed. The controller is constructed in two stages. The model predictive direct power control for the grid side is applied to track the active/reactive power references. The model predictive direct current control is proposed to achieve constant current charging/discharging for the EV load side. With this MPC strategy, EV chargers are able to transmit the active and reactive powers between the EV batteries and the power grid. Apart from exchanging the active power, the vehicle-for-grid (V4G) mode is proposed, where the chargers are used to deliver the reactive power to support the grid, simultaneously combined with grid-to-vehicle or vehicle-to-grid operation modes. In the V4G mode, the EV battery functions as the static var compensator. According to the simulation results, the system can operate effectively in the full control regions of the active and reactive power (PQ) plane under the aforementioned operation modes. Fast dynamic response and great steady-state system performances can be verified through various simulation and experimental results.

Based on the double-sided LCC (DLCC) compensation topology circuit, a battery charging method is proposed to meet various charging requirements. Firstly, mathematical model was obtained by modeling primary and secondary sides of DLCC. The current gain and voltage gain of the inductive power transfer (IPT) system are derived. Then, taking into account the smooth conversion of charging mode, the parameter configuration conditions for constant current (CC) output and constant voltage (CV) output are designed systematically. Finally, after choosing parameters, the CC and CV modes can be achieved by adding one switch and an auxiliary capacitor. With few additional components and non-sophisticated control, both cost and complexity can be significantly reduced. An experimental prototype with 64 V charging voltage and 1A charging current is built. The experimental results show that the charging voltage and current fluctuation of the system are small and the method can meet the above requirements.

Purpose: Polarization voltage of the lithium-ion battery is an important parameter that has direct influence on battery performance. The paper aims to analyze the impedance characteristics of the lithium-ion battery based on EIS data. Design/methodology/approach: The effects of currents, initial SOC of the battery on charge polarization voltage are investigated, which is approximately linear function of charge current. The change of charge polarization voltage is also analyzed with the gradient analytical method in the SOC domain. The charge polarization model with two RC networks is presented, and parts of model parameters like Ohmic resistance and charge transfer impedance are estimated by both EIS method and battery constant current testing method. Findings: This paper reveals that the Ohmic resistance accounts for much contribution to battery total polarization compared to charge transfer impedance. Practical implications: Experimental results demonstrate the efficacy of the model with the proposed identification method, which provides the foundation for battery charging optimization. Originality/value: The paper analyzed the impedance characteristics of the lithium-ion battery based on EIS data, presented a charge polarization model with two RC networks, and estimated parameters like Ohmic resistance and charge transfer impedance.