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Background In recent years, there has been increasing research on adolescent idiopathic scoliosis (AIS), leading to many publications on this topic. To our knowledge, no study has focused on the research trends in this field. Methods Using the Web of Science Core Collection database for all articles on AIS, the number of citations, authorship, year of publication, journal of publication, country and institution of origin, and keywords were subjected to co-occurrence analysis using VOSviewer software. The top 100 most-cited articles on AIS were analyzed. Results Between 1985 and 2020, 2266 articles related to AIS were identified. The frequency of publication on AIS has increased substantially over time. Among all countries, the United States has contributed the most articles on AIS (n = 671). The most productive institution has been Nanjing University (n = 154). Spine topped the list of journals and has published 569 AIS-related articles, which received 19,862 total citations. The clinical description of AIS has been the most common research focus in the AIS literature. Conclusions The scientific literature on AIS has rapidly expanded in recent years. This study represents the updated bibliometric analysis of scientific articles on AIS and provides a research trend for the first time, which aims to give a unique insight into the development of AIS research focus and serve as a useful guide to clinicians and researchers in the field.

Background Circular RNAs (circRNAs) are emerging as crucial regulators in various human diseases. So far, the expression profile and regulatory mechanism of circRNAs in postmenopausal osteoporosis (PMOP) are less studied and should be deciphered urgently. Herein, we aimed to reveal key circRNAs affecting PMOP and clarify their compounding regulatory actions. Methods To reveal key circRNAs affecting PMOP and clarify their compounding regulatory actions, whole transcriptome sequencing and bioinformatics analysis were performed to identify differentially expressed circRNAs (DECs). The expression pattern and regulatory networks of DECs in peripheral blood mononuclear cells (PBMCs) were unearthed. Results A total of 373 DECs comprising 123 intronic, 100 antisense, 70 exonic, 55 intergenic, and 25 sense-overlapping circRNAs were identified. Among these, 73 circRNAs were upregulated and 300 were downregulated. These DECs exerted pivotal functions in the pathogenesis of PMOP as demonstrated by Gene Ontology (GO) annotation and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. The circRNA-miRNA-mRNA co-expression network comprising 28 DECs, 145 miRNAs, and 175 differentially expressed mRNAs predicted the possible mechanism of the pathogenesis and progression of PMOP. Conclusion The results of the present study provided a further comprehension of circRNA-associated competing endogenous RNA regulatory mechanism in PMOP. The steadily expressed and disease-specific DECs may serve as promising diagnostic and prognostic biomarkers for PMOP.

Study design A bibliometric review of current literature. Objective The purpose of this study was to identify and analyze the 100 most cited articles in spinal disc arthroplasty (SDA) research. Summary of background data In the last several decades, SDA has been widely performed all over the world, with increasing popularity of cervical disc arthroplasty (CDA). While there is a large number of articles on this topic, to our knowledge, there is no bibliometric analysis yet. Methods All databases from the Web of Science were searched in a three-step approach. The information of the 100 most cited studies was collected, including title, first and last author, year of publication, journal, total citations, geographic origin, subspecialty, and types of artificial intervertebral disc for further analysis. Results The 100 most-cited articles were published from 1966 to 2015 in 9 different journals and were cited from 66 to 346 times. A total of 11 countries contributed to the 100 articles and the United States topped the list, with 54 articles, followed by Germany and France, with 10 and nine articles, respectively. There were more studies in CDA (n = 53) than lumbar disc arthroplasty (n = 35). Most of the studies reported clinical and radiographic outcomes (n = 33). The most productive periods were from 2006 to 2010. The majority of publications were in Spine, which published 43 articles. In total, 12 authors published more than two articles on the list. Conclusion Of the top 100 most cited articles on SDA, cervical papers outnumbered lumbar articles and the United States had 55 articles, with no other countries having more than 10. Our paper can help readers determine which of the thousands of articles on this topic are the most impactful and important ones to be familiar with. Level of evidence 3.

Introduction Over the last several decades, both percutaneous kyphoplasty (PKP) and percutaneous vertebroplasty (PVP) have been used for pain relief in patients with osteoporotic vertebral compression fractures. The purpose of our study was to use citation analysis to identify and review the top 100 most-cited publications regarding PKP and PVP. Methods All databases of the Web of Science were searched using the keywords “kyphoplasty” and “vertebroplasty.” All publications with >100 citations were identified and the results were ranked in descending order of citations. The 100 most-cited publications were included for analysis. Results A total of 6271 publications on PKP and PVP were identified. The number of citations of the 100 most-cited studies ranged from 735 to 109, with a mean of 225.3 citations per study. The most productive period was 2001–2010, which produced 79 of the top 100 publications. Thirteen journals published these 100 studies, with Spine publishing the largest number (23) of studies. Most of the identified articles originated in the United States, with France and Switzerland found to be the next most heavily represented countries of origin of the 11 countries that produced them. Most of the studies focused on treatment of osteoporotic vertebral compression fractures, followed by pathologic fractures caused by tumors. Conclusions We identified the 100 most-cited publications on PKP and PVP and performed a bibliometric analysis characterizing distinguishing features of these studies. This list can help guide clinical decision making and future research directions as clinicians and researchers continue to explore these controversial therapeutic techniques.

Purpose Hidden blood loss (HBL) is a growing area of interest for spinal surgeons. Simultaneously, spine surgeons’ pursuit of minimally invasive spine surgery has never ceased, as evidenced by the increasing number of articles comparing percutaneous endoscopic transforaminal lumbar interbody fusion (Endo-TLIF) and minimally invasive transforaminal lumbar interbody fusion (Mis-TLIF). However, there has been no comparison of HBL between Endo-TLIF and Mis-TLIF. This study aimed to compare HBL, visible blood loss (VBL), and total blood loss (TBL) following Endo-TLIF and Mis-TLIF and evaluate the clinical significance of these procedures. Methods Between October 2017 and October 2019, 370 patients underwent lumbar interbody fusion at our institution and were followed up for at least 24 months. Our study included 41 Endo-TLIF and 43 Mis-TLIF cases. We recorded each patient’s age, height, weight, and haematocrit and calculated the TBL, which was used to indirectly obtain the HBL. Additionally, we compared the clinical outcomes of these two groups, including visual analogue scores for the lumbar spine and leg (VAS-Back; VAS-Leg), Oswestry Disability Index (ODI), Japanese Orthopaedic Association (JOA) scores, disease type, operative segment, and intervertebral fusion and complication rates. Results Endo-TLIF had significantly lower HBL, VBL, and TBL values than Mis-TLIF (P Conclusion Endo-TLIF significantly reduced HBL, VBL, and TBL compared to Mis-TLIF and improved short-term clinical outcomes; however, long-term clinical outcomes and fusion rates remained comparable between the two groups, as did the incidence of peri-operative complications.

Background Von-Hippel Lindau (VHL) disease is rare neurocutaneous disorder arising from an inactivating mutation of the VHL gene on chromosome 3p35. The disease is inherited in an autosomal dominant fashion and predominantly involves tissues originating from the ectodermal germ layer. Although hemangioblastomas of retina and cerebellum are the most common clinical features, multiple-organ involvement in the form of renal cell carcinomas, spinal hemangioblastomas, renal cysts, and pancreatic cysts have also been reported. Hemangioblastomas of the spinal canal could present as cauda equina syndrome. Case Description We describe the case of a 55-year-old man with cauda equina syndrome as his first manifestation. An initial magnetic resonance imaging scan uncovered hemangiomas in the spinal canal. A thorough family history strongly suggested an autosomal dominant pattern of disease inheritance. Further physical examination and imaging revealed additional organ involvement consistent with VHL. We performed laminectomy and partial resection of hemangioblastoma for decompression. He recovered satisfactorily with his cauda equina syndrome resolving quickly post operation. No deterioration was apparent by the 12-month follow-up visit. Conclusions To the best of our knowledge, this is the first case with cauda equina syndrome as the first manifestation of VHL disease. Laminectomy and partial resection of hemangioblastoma are safe and effective treatments to resolve impingement of the spinal cord. VHL disease resulting in hemangioblastoma in the spinal canal is rarely seen but should be included in the differential diagnosis of cauda equina syndrome to facilitate genetic counseling for the proband and offspring.

Osteosarcoma (OS) is one of the most common primary bone malignant tumors. Osteoclasts have been shown to have a valuable role in OS. In the present study, we analyzed the differentiation states of osteoclasts in OS and their prognostic significance based on integrated scRNA-seq and bulk RNA-seq data. Osteoclasts in distinct differentiation states were characterized, and 661 osteoclasts differentiation-related genes (ODRGs) were obtained. ORDGs in distinct differentiation states were enriched in distinct functions and pathways. TPM1, S100A13, LOXL1, PSMD10, ST3GAL4, PEF1, SERPINE2, TUBB, FAM207A, TUBA1A, and DCN were identified as the significant survival-predicting ODRGs. We successfully developed a risk score model based on these survival-predicting ODRGs. In addition, we generated a nomogram applicable for clinical with both ODRGs signatures and clinicopathological parameters, and validated in OS cohorts to predict OS patient outcome. This study proposed and verified the important roles of osteoclasts differentiation in the prognosis of patients with OS, suggesting promising therapeutic targets for OS.

Background In recent years, there has been increasing study of ossification of the posterior longitudinal ligament (OPLL), leading to many articles on this topic. We aimed to identify trends in OPLL-related research and to analyze the most highly cited scientific articles on OPLL. Methods We searched the Web of Science Core Collection database for all articles on OPLL. The years of publication, countries, journals, institutions, and total citations were extracted and analyzed. Results related to countries, institutions, and keywords were subjected to co-occurrence analysis using VOSviewer software. The top 100 most-cited articles on OPLL were analyzed. Results A total of 876 articles related to OPLL were identified. The frequency of publication on OPLL has increased substantially over time. Among all countries, Japan has contributed the most articles on OPLL (n = 349). The most productive institution has been Hirosaki University (n = 57). Spine topped the list of journals and has published 120 OPLL-related articles, which received 4221 total citations. The surgical treatment of OPLL has been the most common research focus in the OPLL literature. Conclusions The scientific literature on OPLL has rapidly expanded in recent years. This study represents the first bibliometric analysis of scientific articles on OPLL and can serve as a useful guide to clinicians and researchers in the field.

Rationale: Intraspinal tophaceous gout is relatively rare condition presenting with major clinical manifestations, such as spinal cord or nerve roots compressions (radiculopathy). It is usually difficult to differentiate intraspinal tophaceous gout, lumbar disc herniation, stenosis of spinal canal, ossification of ligamentum flavum, and other degenerative spinal disorders from each other. Patient concerns: A 64-year-old man was admitted with a history of progressive low back pain for 11 months. He also presented with radiculopathy and numbness of his left lower extremity. Diagnoses: Preoperative computed tomography (CT) and magnetic resonance imaging (MRI) showed L4/5 disc herniation and lateral recess stenosis on the left side. During the operation of percutaneous transforaminal endoscopic decompression, intraspinal chalky white material was seen. Post-operative pathologic results confirmed the diagnosis of gouty tophi. Interventions: Percutaneous transforaminal endoscopic decompression was performed as treatment. Intraspinal chalky white material was seen. We removed most of the chalky white material and extruded nucleus. Outcomes: His symptom subsided rapidly and no deterioration was noted 1 year post-operatively. Lessons: Although intraspinal tophaceous gout is not commonly seen, clinicians should take it into consideration as a possible differential diagnosis when the patient exhibits axial pain or neurological deficits with risk factors of gout. We identified and treated this case with percutaneous transforaminal endoscopic decompression for the first time and got an excellent outcome. Percutaneous transforaminal endoscopic surgery proved to be an effective and minimally invasive alternative for identifying and treating intraspinal tophaceous gout.

Background/Aims: Preventing cell metastasis is an effective therapeutic strategy to treat osteosarcoma and improve prognosis. Statins have been found to have anticancer effects in addition to their cholesterol-lowering action. As a new target of statins, cysteine-rich 61 (CYR61) was recently identified to promote cell migration and metastasis in osteosarcoma. However, the underlying mechanisms mediating the regulation of CYR61 expression by statins remain unknown. Methods: Human osteosarcoma cell lines MG63 and SaOS2 were used to clarify the effect of lovastatin on CYR61 expression. Real-time PCR was performed to detect mRNA or microRNA (miRNA) levels and western blot was performed to detect protein levels. Cell invasive ability was determined using Transwell assays. Lentivirus encoding CYR61 cDNA or sterol regulatory element-binding protein 2 (SREBP-2) shRNA was used to upregulate CYR61 expression or downregulate SREBP-2 expression. Binding of the CYR61 3’ untranslated region (UTR) and miR-33a was analyzed by luciferase reporter assay. Results: We found that lovastatin treatment decreased CYR61 expression, inhibited cell invasion and altered epithelial-to-mesenchymal-transition (EMT)-related protein expression, while CYR61 overexpression abolished the effect of lovastatin. Moreover, lovastatin increased the expression of SREBP-2 and miR-33a, which were then downregulated by SREBP-2 silencing. Bioinformatics analysis indicated that the CYR61 3′UTR harbored a potential miR-33a binding site and luciferase reporter assay demonstrated that CYR61 was a target of miR-33a in osteosarcoma cells. Furthermore, miR-33a could inhibit cell invasion and alter EMT-related protein expression. SREBP-2 silencing or miR-33a inhibitor upregulated CYR61 expression and reversed the effects of lovastatin on cell invasion and EMT-related proteins. Conclusion: Our findings suggest lovastatin suppresses osteosarcoma cell invasion through the SREBP-2/miR-33a/CYR61 pathway.

Background Multiple surgical procedures are applied in young patients with symptomatic lumbar spondylolysis when conservative treatments fail. Although the optimal surgical procedure option is controversial, the treatment paradigm has shifted from open surgery to minimally invasive spine surgery. To date, a limited number of studies on the feasibility of percutaneous endoscopic-assisted direct repair of pars defect have been carried out. Herein, for the first time, we retrospectively explore the outcomes of pars defect via percutaneous endoscopy. Methods We retrospectively examined young patients with spondylolysis treated using the percutaneous endoscopic-assisted direct repair of pars defect supplemented with autograft as well as percutaneous pedicle screw fixation between September 2014 and December 2018. Six patients with a mean age of 18.8 years were enrolled in the study. We used preoperatively computed tomographic (CT) scans to evaluate the size of pars defect, and graded disc degeneration using Pfirrmann’s classification through magnetic resonance images (MRI). We assessed the clinical outcomes using the Oswestry Disability Index (ODI), 36-Item Short-Form Health Survey (SF-36) as well as Visual Analogue Scale for back pain (VAS-B). Results Our findings revealed that pain intensity and function outcomes, including VAS-B, ODI, and SF-36 (PCS and MCS) scores, were markedly improved after surgery and at the final follow-up visit. The change in the gap distance of the pars defect was remarkably significant after surgery and during the follow-up period. Only one of the 12 pars repaired was reported as a non-union at the final follow-up visit. Moreover, no surgery-related complications were reported in any of the cases. Conclusion Percutaneous endoscopic-assisted direct repair of pars defect without general anesthesia, a minimally invasive treatment option, supplemented with autograft and percutaneous pedicle screw fixation, could be a satisfying treatment alternative for young patients with symptomatic lumbar spondylolysis.

MicroRNAs (miRNAs) are small noncoding RNAs of 19-25 nt that can regulate gene expression at a posttranscriptional level. Increasing evidence indicates that miRNAs participate in almost every step of cellular processes and are often aberrantly expressed in human cancer. The aim of this study was to investigate the functional significance of miR-191 and to identify its possible target genes in osteosarcoma cells. Here, we found that the expression level of miR-191 was increased in osteosarcoma tissues in comparison with the adjacent normal tissues. The enforced expression of miR-191 was able to promote cell proliferation in Saos-2 and MG62 cells, while miR-191 antisense oligonucleotides blocked cell proliferation. At the molecular level, our results further revealed that expression of tumor suppressor gene, checkpoint kinase 2, was negatively regulated by miR-191. Therefore, we consider that miR-191 act as an onco-MicroRNA for osteosarcoma and it would offer a new way in molecular targeting cancer treatment.

Many miRNAs play critical roles in modulating various biological processes of osteoclast differentiation and function. Microphthalmia-associated transcription factor (MITF), a target of miR-340, served as pivotal transcription factor involved in osteoclast differentiation. However, the role of miR-340 and MITF during osteoclast differentiation has not yet been clearly established. Tartrate-resistant acid phosphatase (TRAP) staining assay was performed to identify osteoclasts differentiated from bone marrow-derived macrophages (BMMs). Quantitative reverse transcription PCR (qRT-PCR) or Western blotting was undertaken to examine the mRNA or protein expression respectively. Luciferase reporter assay was performed to investigate the interaction between miR-340 and MITF. MITF was knocked down and miR-340 was overexpressed and transfected into BMMs to detect their effects on osteoclast differentiation. Firstly, qRT-PCR analysis showed that miR-340 was down-regulated during osteoclast differentiation stimulated by macrophage-colony stimulating factor (M-CSF) and receptor activator of nuclear factor (NF)-κB (RANK) ligand (RANKL). Besides, we found that overexpression of miRNA-340 inhibited osteoclast differentiation and suppressed both the mRNA and protein level of MITF. Finally, Western blot and qRT-PCR analysis revealed that silencing MITF inhibited TRAP, calcitonin receptor, V-ATPase d2, and cathepsin K. miR-340 suppresses osteoclast differentiation by inhibiting MITF. Our findings may provide promising therapeutic targets for osteoclast-associated diseases.

Background Zero-profile implant has become more and more popular in anterior cervical discectomy and fusion (ACDF) for the treatment of degenerative cervical spondylosis. However, there was no enough evidence judging its efficiency and safety. The aim of this analysis was to evaluate the efficacy and safety of Zero-profile implant compared with conventional cage-plate (CCP) in ACDF. Methods All studies directly comparing the outcomes between the Zero-profile implant and CCP implant in ACDF were included, and the search strategy followed the requirements of the Cochrane Library Handbook. Two of the authors extracted relevant data and checked the accuracy independently using standardized data collection form. Results Seven studies involving 560 patients were included, 262 in the Zero-profile group and 298 in the CCP group. Zero-profile implant had a lower rate of postoperative dysphagia at 2 weeks, 6 months, and 1 year (p = 0.0002, p = 0.008, and p = 0.001, respectively) than CCP implant. Zero-profile also reduced blood loss (p = 0.0001), while operation time and incidence of postoperative transient dysphagia had no statistical significance (p = 0.92, p = 0.42, respectively) between two groups. Conclusion Based on the results of our analysis, the application of Zero-profile implant in ACDF had a lower rate of postoperative dysphagia at 2 weeks, 6 months, and 1 year than CCP implant. Zero-profile implant also had fewer blood loss during operation. More rigorous and adequately powered prospective randomized controlled trials with larger sample size are required to elucidate a more objective outcome.