Chondrocyte-targeted exosome-mediated delivery of Nrf2 alleviates cartilaginous endplate degeneration by modulating mitochondrial fission.

BACKGROUND: Cartilaginous endplate (CEP) degeneration, which is an important contributor to intervertebral disc degeneration (IVDD), is characterized by chondrocyte death. Accumulating evidence has revealed that dynamin-related protein 1 (Drp1)-mediated mitochondrial fission and dysfunction lead to apoptosis during CEP degeneration and IVDD. Exosomes are promising agents for the treatment of many diseases, including osteoporosis, osteosarcoma, osteoarthritis and IVDD. Despite their major success in drug delivery, the full potential of exosomes remains untapped. MATERIALS AND METHODS: In vitro and in vivo models of CEP degeneration were established by using lipopolysaccharide (LPS). We designed genetically engineered exosomes (CAP-Nrf2-Exos) expressing chondrocyte-affinity peptide (CAP) on the surface and carrying the antioxidant transcription factor nuclear factor E2-related factor 2 (Nrf2). The affinity between CAP-Nrf2-Exos and CEP was evaluated by in vitro internalization assays and in vivo imaging assays. qRT‒PCR, Western blotting and immunofluorescence assays were performed to examine the expression level of Nrf2 and the subcellular localization of Nrf2 and Drp1. Mitochondrial function was measured by the JC-1 probe and MitoSOX Red. Mitochondrial morphology was visualized by MitoTracker staining and transmission electron microscopy (TEM). After subendplate injection of the engineered exosomes, the degree of CEP degeneration and IVDD was validated radiologically and histologically. RESULTS: We found that the cargo delivery efficiency of exosomes after cargo packaging was increased by surface modification. CAP-Nrf2-Exos facilitated chondrocyte-targeted delivery of Nrf2 and activated the endogenous antioxidant defence system in CEP cells. The engineered exosomes inhibited Drp1 S616 phosphorylation and mitochondrial translocation, thereby preventing mitochondrial fragmentation and dysfunction. LPS-induced CEP cell apoptosis was alleviated by CAP-Nrf2-Exo treatment. In a rat model of CEP degeneration, the engineered exosomes successfully attenuated CEP degeneration and IVDD and exhibited better repair capacity than natural exosomes. CONCLUSION: Collectively, our findings showed that exosome-mediated chondrocyte-targeted delivery of Nrf2 was an effective strategy for treating CEP degeneration.

C4 constant vertebra: a novel benchmark of physiological cervical sagittal alignment.

BACKGROUND: Cervical sagittal alignment is essential, and there is considerable debate as to what constitutes physiological sagittal alignment. The purpose of this study was to identify constant parameters for characterizing cervical sagittal alignment under physiological conditions. METHODS: A cross-sectional study was conducted in which asymptomatic subjects were recruited to undergo lateral cervical spine radiographs. Each subject was classified according to three authoritative cervical sagittal morphology classifications, followed by the evaluation of variations in radiological parameters across morphotypes. Moreover, the correlations among cervical sagittal parameters, age, and cervicothoracic junction parameters were also investigated. RESULTS: A total of 183 asymptomatic Chinese subjects were enrolled with a mean age of 48.4 years. Subjects with various cervical sagittal morphologies had comparable C4 endplate slope angles under all three different typing systems. Among patients of different ages, C2-C4 endplate slope angles remained constant. Regarding the cervicothoracic junction parameters, T1 slope and thoracic inlet angle affected cervical sagittal parameters, including cervical lordosis and C2-7 sagittal vertical axis, and were correlated with the endplate slope angles of C5 and below and did not affect the endplate slope angles of C4 and above. In general, the slope of the C4 inferior endplate ranges between 13° and 15° under different physiological conditions. CONCLUSIONS: In the asymptomatic population, the C4 vertebral body maintains a constant slope angle under physiological conditions. The novel concept of C4 as a constant vertebra would provide a vital benchmark for diagnosing pathological sagittal alignment abnormalities and planning the surgical reconstruction of cervical lordosis.

Evaluation of the modified MRI vertebral bone quality score for bone quality in lumbar degenerative disorders.

OBJECTIVE: The traditional VBQ scoring method may lead to overestimation due to the concentration of intravertebral fat and vascular structures in the posterior half of vertebral bodies, potentially resulting in false-positive outcomes. This study aims to modify the measurement method of VBQ score (Modified-VBQ) and evaluate its effectiveness in evaluating bone quality of lumbar degenerative diseases. METHODS: Retrospective analysis was conducted on clinical data from patients undergoing lumbar surgery for degenerative diseases between September 2022 and September 2023. Preoperative lumbar t1-weighted Magnetic resonance imaging was used for both modified and traditional VBQ scoring. Computed tomography (CT) images and dual-energy X-ray absorptiometry (DEXA) data were collected through the picture archiving and communication system. The effectiveness of the modified VBQ score was evaluated, considering P < 0.05 as statistically significant. RESULTS: The study included 212 patients, revealing a significant difference between the modified VBQ and VBQ scores (P < 0.0001). Notably, patients with a history of hyperlipidemia exhibited a significant difference between the two scores (P = 0.0037). The area under the ROC curve (AUC) for the modified VBQ was 0.86, surpassing the VBQ score (AUC = 0.74). Linear regression analysis demonstrated a moderate to strong correlation between the modified VBQ and DEXA T-score (r = - 0.49, P < 0.0001) and a high correlation with CT Hounsfield units (HU) values (r = - 0.60, P < 0.0001). CONCLUSION: The modified VBQ score provides a simple, effective, and relatively accurate means of assessing bone quality in lumbar degenerative diseases. Preoperative implementation of the modified VBQ score facilitates rapid screening for patients with abnormal bone quality.

Use of MRI-based vertebral bone quality score (VBQ) of S1 body in bone mineral density assessment for patients with lumbar degenerative diseases.

PURPOSE: To evaluate the use of the modified and simplified vertebral bone quality (VBQ) method based on T1-weighted MRI images of S1 vertebrae in assessing bone mineral density (BMD) for patients with lumbar degenerative diseases. METHODS: We reviewed the preoperative data of patients with lumbar degenerative diseases undergoing lumbar spine surgery between January 2019 and June 2022 with available non-contrast T1-weighted magnetic resonance imaging (MRI), computed tomography (CT) images and dual-energy X-ray absorptiometry (DEXA). S1 vertebral bone quality scores (S1 VBQ) and S1 CT Hounsfield units were measured with picture archiving and communication system (PACS). One-way ANOVA was applied to present the discrepancy between the S1 VBQ of patients with normal bone density (T-score ≥ - 1.0), osteopenia (- 2.5 < T-score < - 1.0) and osteoporosis (T-score ≤ - 2.5). The receiver operating characteristic curve (ROC) was drawn to analyze the diagnostic performance of S1 VBQ in distinguishing low BMD. Statistical significance was set at p < 0.05. RESULTS: A total of 207 patients were included. The S1 VBQ were significantly different between groups (p < 0.001). Interclass correlation coefficient for inter-rater reliability was 0.86 (95% CI 0.78-0.94) and 0.94(95% CI 0.89-0.98) for intra-rater reliability. According to the linear regression analysis, the S1 VBQ has moderate-to-strong correlations with DEXA T-score (r = - 0.48, p < 0.001). The area under the ROC curve indicated a predictive accuracy of 82%. A sensitivity of 77.25% with a specificity of 70% could be achieved for distinguishing low BMD by setting the S1 VBQ cutoff as 2.93. CONCLUSIONS: The S1 VBQ was a promising tool in distinguishing poor bone quality in patients with lumbar degenerative diseases, especially in cases where the previously reported VBQ method based on L1-L4 was not available. S1 VBQ score could be useful as opportunistic assessment for screening and complementary evaluation to DEXA T-score before surgery.

Cell-Free Extracts from Human Fat Tissue with a Hyaluronan-Based Hydrogel Attenuate Inflammation in a Spinal Cord Injury Model through M2 Microglia/Microphage Polarization.

Treatment for spinal cord injuries (SCIs) is often ineffective because SCIs result in a loss of nerve tissue, glial scar formation, local ischemia and secondary inflammation. The current promising strategy for SCI is the combination of bioactive materials and cytokines. Bioactive materials support the injured spinal cord, stabilize the morphology, and avoid excessive inflammatory responses. Fat extract (FE) is a cell-free liquid component containing a variety of cytokines extracted from human fat tissue using mechanical methods. In this research, a biocompatible HAMC (hyaluronan and methylcellulose) loaded with FE is used to treat a model of spinal cord contusion in mice. The composite not only inhibits death of neuro- and vascular cells and leads to the preservation of neural and vascular structure, but also modulates the inflammatory phenotype of macrophages in the locally injured region. Specifically, FE promotes the polarization of macrophages from an inflammatory M1 phenotype to an anti-inflammatory M2 phenotype. During the screening of the involved pathways, it is corroborated that activation of the STAT6/Arg-1 signaling pathway is involved in macrophage M2 polarization. In summary, FE is a promising treatment for SCI, as it is easy to obtain, nonimmunogenic, and effective.

A study of screw placement to obtain the optimal pull-out resistance of lumbar pedicle screws-analysis of Hounsfield units measurements based on computed tomography.

OBJECTIVE: The screw path of lumbar pedicle screws in the vertebral body has certain variability. It is not clear whether the screw paths in different directions can obtain the same pull-out resistance. This study intends to use CT (Computed Tomography) to measure the Hounsfield unit (HU value) around the screw paths in different parts of the lumbar vertebral body to obtain the bone mineral density value of the corresponding parts which will provide some reference for the direction of lumbar pedicle screw placement. METHODS: This retrospective study included 200 patients with lumbar degenerative diseases selected randomly from the case base and the patient's basic information was recorded. L1-L5 vertebral body was divided equally into the upper, middle and lower 1/3, which was consistent with the three sagittal entry directions of the pedicle screw head tilt, parallel endplate and caudal tilt, and the HU values were measured by CT cross-sectional scanning to indirectly reflect the local bone density values. The paired t-test (randomized block experiment) was used to compare the HU values of the upper, middle and lower 1 / 3 parts, with P < 0.05 being considered statistically significant. RESULTS: Comparison of HU values in different parts of each vertebral body revealed that HU values in the middle 1/3 of the L1,L2 (163.88 ± 58.44 and 152.94 ± 59.45) and in the lower 1/3 of the L4 (149.86 ± 60.18) were higher than in the other two parts of the vertebral body of the same segment(P < 0.0001,P = 0.0069 and P = 0.0024, respectively); According to the results of each stratification, patients with younger age and better bone condition had higher HU values in the middle 1/3 of L1 and L2, and higher HU values in the lower 1/3 of L3, L4 and L5; With the increase of age, the decrease of bone condition and the difference of HU value in each vertebral body gradually decreased. CONCLUSION: Although further follow-up studies are needed, based on the analysis of the statistical results, we speculate that from the perspective of obtaining the best pull-out resistance of the lumbar pedicle screws, the placement direction of L1 and L2 in the sagittal position may be as parallel to the endplate as possible; L3, L4, and L5 may be as appropriate as possible to the tail tilt theoretically.

Comparative analysis of the biomechanics of anterior cervical discectomy and fusion with multiple segmental plates fixation versus single multilevel plate fixation: a finite element study.

BACKGROUND: This study aimed to compare the biomechanical differences between anterior cervical discectomy and fusion (ACDF) with multiple-level separate plates and conventional long plates by using finite element analysis. METHODS: The following four finite element models were created to simulate various fixations: (1) C4-6 ACDF with multiple plates, (2) C4-6 ACDF with a single plate, (3) C3-6 ACDF with multiple plates, and (4) C3-6 ACDF with a single plate. The maximum Von-mises stress of the cage and fixation, compressive force of the adjacent intervertebral discs and range of motion (ROM) of different segments in the four models were calculated and analyzed. RESULTS: For C4-6 ACDF, the maximum Von-mises stress of the cage and fixation was lower in the multiple plate fixation model in all motion states. Similarly, for the C3-6 ACDF models, the peak stress of the C3-4 and C5-6 cages was lower with multiple plates fixation in all motions but the stress of the C4-5 cage in the multiple plates model was slightly higher in flexion, bending and rotation. Besides, applying multiple plates in C3-6 ACDF models resulted in a decreased maximum stress of the fixation under different motions except for bending. In both the C4-6 ACDF and C3-6 ACDF models, the ROM values of the adjacent motion segments were lower in the multiple plates models in extension, bending and rotation. In the C4-6 ACDF models, the peak stress on the adjacent intervertebral discs in the multiple plates models was slightly smaller. In C3-6 ACDF models, the maximum stress on the adjacent intervertebral discs was larger in the single-plate model under flexion, bending and rotation movements. CONCLUSION: Multiple plates fixation has a positive effect on increasing stiffness and maintaining the ROM of adjacent segments, indicating lower risk of construct failure and adjacent segment degeneration. Further studies are required to confirm its efficacy in clinical practice.

Carbohydrate sulfotransferase 3 (CHST3) overexpression promotes cartilage endplate-derived stem cells (CESCs) to regulate molecular mechanisms related to repair of intervertebral disc degeneration by rat nucleus pulposus.

To investigate the regulatory effect of carbohydrate sulfotransferase 3 (CHST3) in cartilage endplate-derived stem cells (CESCs) on the molecular mechanism of intervertebral disc degeneration after nucleus pulposus repair in rats. We performed GO and KEGG analysis of GSE15227 database to select the differential genes CHST3 and CSPG4 in grade Ⅱ, Ⅲ and Ⅳ intervertebral disc degeneration, IHC and WB to detect the protein profile of CHST3 and CSPG4, Co-IP for the interaction between CHST3 and CSPG4. Then, immunofluorescence was applied to measure the level of CD90 and CD105, and flow cytometry indicated the level of CD73, CD90 and CD105 in CESCs. Next, Alizarin red staining, Alcian blue staining and TEM were performed to evaluate the effects of CESCs into osteoblasts and chondroblasts, respectively, CCK8 for the cell proliferation of osteoblasts and chondroblasts after induction for different times; cell cycle of osteoblasts or chondroblasts was measured by flow cytometry after induction, and WB for the measurement of specific biomarkers of OC and RUNX in osteoblasts and aggrecan, collagen II in chondroblasts. Finally, colony formation was applied to measure the cell proliferation of CESCs transfected with ov-CHST3 or sh-CHST3 when cocultured with bone marrow cells, WB for the protein expression of CHST3, CSPG4 and ELAVL1 in CSECs, transwell assay for the migration of CESCs to bone marrow cells, TEM image for the cellular characteristics of bone marrow cells, and WB for the protein profile of VCAN, VASP, NCAN and OFD1 in bone marrow cells. CHST3 and CSPG4 were differentially expressed and interacted in grade Ⅱ, Ⅲ and Ⅳ intervertebral disc degeneration; CD73, CD90 and CD105 were lowly expressed in CESCs, osteogenic or chondroblastic induction changed the characteristics, proliferation, cell cycle and specific biomarkers of osteoblasts and chondroblasts after 14 or 21 days,; CHST3 affected the cell proliferation, protein profile, migration and cellular features of cocultured CESCs or bone marrow cells. CHST3 overexpression promoted CESCs to regulate bone marrow cells through interaction with CSPG4 to repair the grade Ⅱ, Ⅲ and Ⅳ intervertebral disc degeneration.

Motor unit number index in quantitatively assessing motor root lesions and monitoring treatment outcomes in patients with lumbosacral radiculopathy.

INTRODUCTION: We investigated the feasibility of motor unit number index (MUNIX) in quantitatively assessing motor root lesions and tracking different treatment outcomes in lumbosacral radiculopathy (LR). METHODS: Bilateral MUNIX was recorded from the abductor hallucis, extensor digitorum brevis, and tibialis anterior in 44 normal controls and 108 patients with LR, and this was repeated approximately 12 months after treatment in 60 patients with LR. RESULTS: More abnormalities were observed when side-to-side differences of MUNIX measurements were used to evaluate LR (P < .05). Motor unit number index measurements worsened without progression of muscle weakness after conservative treatment, and MUNIX measurements improved with or without increased muscle strength after surgical treatment (P < .05). DISCUSSION: Motor unit number index may identify a specific L5 or S1 motor root lesion even before muscle weakness occurs, especially when side-to-side differences are used. Changes in MUNIX were larger than those in motor function measures after treatments for LR.

Preparation of antibacterial and osteoconductive 3D-printed PLGA/Cu(I)@ZIF-8 nanocomposite scaffolds for infected bone repair.

BACKGROUND: The repair of large bone defects is a great challenge in clinical practice. In this study, copper-loaded-ZIF-8 nanoparticles and poly (lactide-co-glycolide) (PLGA) were combined to fabricate porous PLGA/Cu(I)@ZIF-8 scaffolds using three-dimensional printing technology for infected bone repair. METHODS: The surface morphology of PLGA/Cu(I)@ZIF-8 scaffolds was investigated by transmission electron microscopy and scanning electron microscopy. The PLGA/Cu(I)@ZIF-8 scaffolds were co-cultured with bacteria to determine their antibacterial properties, and with murine mesenchymal stem cells (MSCs) to explore their biocompatibility and osteoconductive properties. The bioactivity of the PLGA/Cu(I)@ZIF-8 scaffolds was evaluated by incubating in simulated body fluid. RESULTS: The results revealed that the PLGA/Cu(I)@ZIF-8 scaffolds had porosities of 80.04 ± 5.6% and exhibited good mechanical properties. When incubated with H2O2, Cu(I)@ZIF-8 nanoparticles resulted generated reactive oxygen species, which contributed to their antibacterial properties. The mMSCs cultured on the surface of PLGA/Cu(I)@ZIF-8 scaffolds were well-spread and adherent with a high proliferation rate, and staining with alkaline phosphatase and alizarin red was increased compared with the pure PLGA scaffolds. The mineralization assay showed an apatite-rich layer was formed on the surface of PLGA/Cu(I)@ZIF-8 scaffolds, while there was hardly any apatite on the surface of the PLGA scaffolds. Additionally, in vitro, Staphylococcus aureus cultured on the PLGA/Cu(I)@ZIF-8 scaffolds were almost all dead, while in vivo inflammatory cell infiltration and bacteria numbers were dramatically reduced in infected rats implanted with PLGA/Cu@ZIF-8 scaffolds. CONCLUSION: All these findings demonstrate that PLGA/Cu(I)@ZIF-8 scaffolds possess excellent antibacterial and osteoconductive properties, as well as good biocompatibility and high bioactivity. This study suggests that the PLGA/Cu(I)@ZIF-8 scaffolds could be used as a promising biomaterial for bone tissue engineering, especially for infected bone repair.

Analysis of radiological parameters associated with decreased fractional anisotropy values on diffusion tensor imaging in patients with lumbar spinal stenosis.

PURPOSE: Previous studies have indicated that decreased fractional anisotropy (FA) values on diffusion tensor imaging (DTI) are well correlated with the symptoms of nerve root compression. The aim of our study is to determine primary radiological parameters associated with decreased FA values in patients with lumbar spinal stenosis involving single L5 nerve root. METHODS: Patients confirmed with single L5 nerve root compression by transforaminal nerve root blocks were included in this study. FA values of L5 nerve roots on both symptomatic and asymptomatic side were obtained. Conventional radiological parameters, such as disc height, degenerative scoliosis, dural sac cross-sectional area (DSCSA), foraminal height (FH), hypertrophic facet joint degeneration (HFJD), sagittal rotation (SR), sedimentation sign, sagittal translation and traction spur were measured. Correlation and regression analyses were performed between the radiological parameters and FA values of the symptomatic L5 nerve roots. A predictive regression equation was established. RESULTS: Twenty-one patients were included in this study. FA values were significantly lower at the symptomatic side comparing to the asymptomatic side (0.263 ± 0.069 vs. 0.334 ± 0.080, P = 0.038). DSCSA, FH, HFJD, and SR were significantly correlated with the decreased FA values, with r = 0.518, 0.443, 0.472 and - 0.910, respectively (P < 0.05). DSCSA and SR were found to be the primary radiological parameters related to the decreased FA values, and the regression equation is FA = - 0.012 × SR + 0.002 × DSCSA. CONCLUSIONS: DSCSA and SR were primary contributors to decreased FA values in LSS patients involving single L5 nerve root, indicating that central canal decompression and segmental stability should be the first considerations in preoperative planning of these patients. These slides can be retrieved under Electronic Supplementary Material.

The evaluation on neural status of cervical spinal cord in normal and Hirayama disease using diffusion tensor imaging.

PURPOSE: To explore the changes in diffusion tensor imaging (DTI) parameters in cervical spinal cord in Hirayama disease (HD) patients and healthy volunteers and to compare these parameters between cervical flexion and neutral positions in HD patients. METHODS: Seventeen male patients with HD and eleven healthy young males were included to receive DTI scans in cervical flexion and neutral positions. The FA and ADC values of different levels were measured based on the region of interest drawn on the mid-sagittal plane. The dynamic compressed level's parameters were defined as the lowest and the second lowest FA and the highest and the second highest ADC, respectively. The clinical assessment of patients was obtained using their disabilities of the arm, shoulder and hand (DASH) scores. RESULTS: For the HD patients, the FA values in the cervical flexion position were lower and the ADC values were much higher than those in the cervical neutral position. Compared with the controls, the ADC values were significantly higher in the lower levels (C5/6-C7/T1) and the FA values obviously lower at C7/T1 in HD patients in cervical neutral position. The FA and ADC values of the dynamic compressed level in HD patients deviated significantly from the average of the lower levels in controls. Both the FA and ADC values of the dynamic compressed level correlated with the DASH scores (FA, R2 = 0.520, P = 0.001; ADC, R2 = 0.421, P = 0.005). CONCLUSIONS: DTI parameters can support a hypothesis of dynamic cervical flexion compression and noninvasively reveal the neural status of HD patients. These slides can be retrieved under Electronic Supplementary Material.

Does Resection of the Primary Tumor Improve Survival in Patients With Metastatic Chondrosarcoma?

BACKGROUND: Although surgical resection or amputation has been the mainstay of localized chondrosarcoma management for many decades, its efficacy in patients with metastatic chondrosarcoma remains unknown, and likewise we do not know whether there are any tumor- or patient-related factors associated with better survival after surgery for metastatic chondrosarcoma. QUESTIONS/PURPOSES: (1) Is resection of the primary tumor associated with improved survival in patients with metastatic chondrosarcoma? (2) Which subgroups of patients with chondrosarcoma benefit more from resection in terms of survival? METHODS: We identified 200 of 222 patients with metastatic chondrosarcoma in the Surveillance, Epidemiology, and End Results (SEER) database between 1988 and 2014 based on the exclusion criteria. Among those patients, 107 (53.5%) underwent primary tumor resection or amputation. Patient information, including demographics (patient age, gender, race, year of diagnosis), tumor characteristics (primary site, histologic subtype, tumor grade, tumor size), and treatment (record of operation and radiation), was collected and included in the study. Kaplan-Meier analyses, log-rank tests, competing risks framework, multivariable Cox regression modeling, and interaction tests were conducted to assess the association of primary tumor resection and survival in the overall cohort and subgroups. RESULTS: Resection of the primary tumor was associated with improved overall survival (hazard ratio [HR], 0.481; 95% confidence interval [CI], 0.340-0.680; p < 0.001) and cancer-specific survival (HR, 0.493; 95% CI, 0.343-0.709; p < 0.001) after controlling for confounding variables. After controlling further for age, histologic subtype, and grade, primary tumor resection was associated with a survival advantage in patients with conventional subtype and Grade II chondrosarcoma (conventional subtype: HR, 0.403; 95% CI, 0.260-0.623 for overall survival and HR, 0.396; 95% CI, 0.250-0.627 for cancer-specific survival). However, primary tumor resection was not associated with increased survival in patients with metastatic chondrosarcoma who had the dedifferentiated subtype and Grade III malignancy. CONCLUSIONS: The present study demonstrates a possible favorable association between primary tumor resection and survival in some patients with metastatic chondrosarcoma at initial diagnosis. Specifically, patients with conventional subtypes and Grade II malignancies who underwent primary tumor resection had better survival compared with those patients who did not have primary tumor resection. Thus, there might be a benefit from primary tumor resection in these patients, but given the limitations of this database, further prospective studies or randomized trials are needed to confirm our findings. In the meantime, this information might be helpful to consider when discussing surgical options with patients who have conventional, Grade 2 metastatic chondrosarcoma at diagnosis. LEVEL OF EVIDENCE: Level III, therapeutic study.

Survival analysis of patients with metastatic osteosarcoma: a Surveillance, Epidemiology, and End Results population-based study.

PURPOSE: The present study is aimed at investigating whether (1) primary tumour surgery confers an improved survival on patients with metastatic osteosarcoma and (2) primary tumour surgery influences survival of patients with metastatic osteosarcoma differently according to primary tumour site. METHODS: We retrospectively identified 517 patients with high-grade, metastatic osteosarcoma in the Surveillance, Epidemiology, and End Results (SEER) database between 1994 and 2013. The effect of primary tumour surgery on survival was assessed using Kaplan-Meier analyses, log-rank tests, and multivariate Cox proportional hazard regression modeling. RESULTS: Of those 517 patients with metastatic osteosarcoma in the cohort, 351 patients (68%) underwent primary surgery, and 166 patients (32%) did not undergo surgery. Primary tumour surgery was associated with increased overall survival (hazard ratio (HR) = 0.457, 95% CI 0.354-0.590, p < 0.001) and cancer-specific survival (HR = 0.422, 95% CI 0.325-0.550, p < 0.001). When we focused on different primary tumour sites, receipt of primary tumour surgery significantly prolonged the survival of patients with extremity osteosarcoma (p < 0.05 for overall and cancer-specific survival). However, for patients with pelvis/spine osteosarcoma, both univariate and multivariate analyses indicated that primary tumour surgery might not be associated with improved survival (p > 0.05 for overall and cancer-specific survival). CONCLUSIONS: Our study is the first population-based analysis to provide evidence of a favourable prognostic impact of primary tumour surgery on metastatic extremity osteosarcoma patients but not metastatic axial (pelvis/spine) osteosarcoma patients. Moreover, we found that surgery type (resection of the primary tumor without amputation vs. amputation) did not influence survival in patients with metastatic osteosarcoma.

Ecto-5'-nucleotidase (CD73) attenuates inflammation after spinal cord injury by promoting macrophages/microglia M2 polarization in mice.

BACKGROUND: Immune activation, specifically activation of macrophages and resident microglia, leading to inflammation is a key component in the progression of spinal cord injury (SCI). Macrophages/microglia exist in two states-the classically activated M1 phenotype that confers pro-inflammatory effects or the alternatively activated M2 phenotype that confers anti-inflammatory effects. Ecto-5'-nucleotidase (CD73) is an immunosuppressive molecule intricately involved in adaptive and innate immune responses and is able to dephosphorylate AMP to adenosine. However, it is not known if CD73 is able to modulate the macrophages/microglia transformation between the M1 and M2 phenotypes. METHODS: We used gene-deficient mice to determine the role of CD73 in macrophages/microglia polarization post-SCI in vivo. We used small interference RNA (siRNA) or pcDNA3.1 to inhibit or overexpress CD73 in BV2 cells to verify anterior discovery in vitro. A combination of molecular and histological methods was used to detect the macrophages/microglia polarization and explore the mechanism both in vivo and in vitro. RESULTS: We found that SCI induced the upregulation of CD73 expression. CD73 deficient mice were noted to demonstrate overwhelming immune responses, few anti-inflammatory phenotype macrophages/microglia, and had a poorer locomotor recovery in comparison to wild-type mice that were also inflicted with SCI. In vitro studies found that CD73 suppression inhibited the expression of characteristic microglial anti-inflammatory polarization markers in BV2 cells, while the converse was noted in CD73 overexpression. Subsequent experiments confirmed that CD73 promoted microglia alternative activation by stimulating p38 MAPK. CONCLUSION: We were able to conclude that CD73 imparts neuroprotective effects by mediating macrophages/microglia polarization. These findings allow for better understanding of the modulatory factors involved in triggering the change in macrophages/microglia phenotypes, therefore uncovering additional molecules and pathways that may be targeted in the innovation of novel SCI therapies.

Can a Nomogram Help to Predict the Overall and Cancer-specific Survival of Patients With Chondrosarcoma?

BACKGROUND: Many factors have been reported to be associated with the prognosis of patients with chondrosarcoma, but clinicians have few tools to estimate precisely an individual patient's likelihood of surviving the illness. We therefore sought to develop effective nomograms to better estimate the survival of patients with chondrosarcoma. QUESTIONS/PURPOSES: (1) Which clinicopathologic features are independent prognostic factors for patients with chondrosarcoma? (2) Can we develop a nomogram to predict 3- and 5-year overall and cancer-specific survival of individual patients with chondrosarcoma based on personalized information? METHODS: We collected information on patients diagnosed with chondrosarcoma between 1988 and 2011 from the Surveillance, Epidemiology, and End Results (SEER) database. The SEER database consists of 18 cancer registries and covers approximately 30% of the total United States population. One thousand thirty-four adult patients with grade II or III chondrosarcoma were included in the cohort (patients with grade I chondrosarcoma were not evaluated in this study), while 327 patients were excluded from the study owing to missing data regarding tumor size or metastasis. Nine hundred nineteen patients (89%) in the cohort had complete followup for at least 1 year. The X-tile program was used to determine optimal cutoff points. Univariate and multivariate analyses were applied to identify independent factors that were further included in the nomograms predicting 3- and 5-year overall survival and cancer-specific survival. Records of 1034 patients were collected and randomly divided into training (n = 517) and validation (n = 517) cohorts. The nomograms were developed based on training cohort. Data for the training cohort were obtained for internal validation of the nomograms, whereas data for the validation cohort were obtained for external validation of the nomograms. Bootstrapped validation, which used a resample with 500 iterations, was applied to validate the nomograms internally and externally. RESULTS: Six independent prognostic factors for overall survival and six for cancer-specific survival were identified and incorporated to construct nomograms for 3- and 5-year overall and cancer-specific survival. These nomograms can easily be used by providers in the office to estimate a patient's prognosis; the only clinical details a provider needs to use these nomograms effectively are age, histologic subtype, tumor grade, whether surgery was performed, tumor size, and the presence or absence of metastases. Internal and external calibration plots for the probability of 3- and 5-year overall survival and cancer-specific survival showed good agreement between nomogram prediction and observed outcomes. The concordance indices (C-indices) for internal validation of overall survival and cancer-specific survival prediction were 0.803 and 0.829, respectively, whereas the C-indices for external validation were 0.753 and 0.759, respectively. CONCLUSIONS: We were able to develop effective nomograms to predict overall survival and cancer-specific survival for patients with chondrosarcoma; these nomograms require only basic information, which should be available to all providers in the office setting. If these observations can be validated in different registries or databases, the nomograms can assist clinicians in counseling patients regarding therapeutic choices. LEVEL OF EVIDENCE: Level III, prognostic study.

Quantitative analysis of near-implant magnesium accumulation for a Si-containing coated AZ31 cage from a goat cervical spine fusion model.

BACKGROUND: Magnesium (Mg) released from Mg-based implants degradation is believed to be effective in improving osteogenesis, however, studies focusing on Mg-based interbody cages are limited and fusion success was never reported. As excessive Mg accumulation can inhibit new bone formation, this study is designed to explain the possible reasons for the fusion failure of Mg-based cages by analyzing the relationships between the intervertebral Mg accumulation and the resulting interbody fusion. METHODS: The experimental cage was consisted of magnesium alloy (AZ31) substrate and Silicon (Si) -containing coating. C3/C4 and C5/C6 of 24 goats were implanted with cage or autologous iliac crest bone graft (Control group), which were analyzed at 3, 6, 12, and 24 weeks post-operatively. Intervertebral Mg concentrations, Mg-related Calcium (Ca)/ Phosphorus (P) ratios, radiological evaluations and histological findings were recorded for analyzing the relationships between the three of cage corrosion, Mg accumulation, and interbody fusion. RESULTS: Intervertebral Mg levels were significantly increased after cage implantation, especially in the areas that were closer to the cages at 3 weeks post-operatively, and these increased concentrations could persist up to 12 weeks post-operatively, indicating a relatively rapid corrosion process. Significantly lower Mg levels were only found at 24 weeks post-operatively, but these levels were still higher than those of the control group. In addition, Mg was found to be widely distributed at the intervertebral space since high Mg concentrations could even be detected at the posterior boundary of the vertebral body. Under this Mg accumulation profile, interbody fusion was not achieved, as indicated by the decreased Ca/P ratios, low CT fusion scores and negative histological results. CONCLUSIONS: Intervertebral excessive Mg accumulation might be the primary reason for interbody fusion failure. Quantitative Mg analysis can offer insight into the association between cage degeneration and biological response.

Risk factors for metastasis at presentation with conventional chondrosarcoma: a population-based study.

PURPOSE: The aim of the study was to investigate risk factors for metastasis at diagnosis. METHODS: We collected patients diagnosed with conventional chondrosarcoma between 1983 and 2014 from the Surveillance, Epidemiology, and End Results (SEER) database. Each patient was classified as having metastatic or localized disease. Univariate and multivariate logistic regression analyses were applied to determine which characteristics were risk factors for metastasis at diagnosis. RESULTS: Two thousand three hundred forty-nine patients were collected and 180 patients had metastasis at presentation. Data on age, gender, primary site, grade, and tumour size were enrolled into the multivariate logistic analysis. Greater age (60 years or older: OR = 1.872, 95% CI, 1.206 to 2.904), axial or craniofacial location (spine: OR = 1.775, 95% CI, 1.188 to 2.651; thoracic cage: OR = 2.034, 95% CI, 1.321 to 3.134; craniofacial bones: OR = 5.507, 95% CI, 3.001 to 10.107), higher grade (grade II: OR = 1.849, 95%CI, 1.181 to 2.895; grade III: OR = 4.016, 95%CI, 2.513 to 6.418), and larger tumour size (size over 10 cm: OR = 7.135, 95%CI, 2.130 to 23.893) were associated with an increased risk of metastasis at presentation. CONCLUSIONS: Conventional chondrosarcoma patients with greater age, axial or craniofacial tumour location, higher grade, and larger tumor size were more likely to have metastasis at diagnosis.

Does right lateral decubitus position change retroperitoneal oblique corridor? A radiographic evaluation from L1 to L5.

PURPOSE: To determine if the retroperitoneal oblique corridor will be affected by right lateral decubitus position. METHODS: Forty volunteers were randomly enrolled and MRI scan was performed from L1 to L5 in supine and right lateral decubitus positions, respectively. In images across the center of each disc, O was defined as the center of a disc and A (supine) or A' (right lateral decubitus) was located in left lateral border of the aorta or the iliac artery; B (supine) or B' (right lateral decubitus) was on the anterior medial border of the psoas. The distance of AB and A'B' (Recorded as A-Ps and A-Pr, respectively) at each level was recorded and compared to each other. The relationships between A-Pr, sex, BMI and relative psoas cross-sectional area (PCSA) at each level were also evaluated. RESULTS: A-Pr was significantly smaller than A-Ps at L1/2, L2/3 and L3/4 (All p < 0.05); there was no significantly difference of A-Pr between all levels (p = 0.105), but L1/2 seemed to be larger than L3/4, followed by L2/3 and L4/5; A-Pr at each level was not affected by sex (All p > 0.05); linear relationships were found between A-Pr, BMI and PCSA at L1/2 and L3/4. CONCLUSIONS: ROC at L1/2, L2/3 and L3/4 will significantly decrease from supine to right lateral decubitus position and the reason may be due to the relaxed psoas deformation. Using MRI images in supine position for pre-operatively ROC evaluation is not accurate. Spine surgeon should also be more cautious when OLIF is performed at L4/5 where ROC is the smallest. Patients from Asia and those with strong psoas major at L1/2 and L3/4 are also associated with relatively narrow ROC.

The value of applying a melatonin antagonist (Luzindole) in improving the success rate of the bipedal rat scoliosis model.

BACKGROUND: An ideal animal model has always been the key to research the pathogenesis and treatment of adolescent idiopathic scoliosis (AIS), while available methods have obvious disadvantages. The deficiency of melatonin has been proved relating to AIS. In this research, we intended to apply Luzindole, the melatonin antagonist, in bipedal rat model, for the block of combination of melatonin and its receptor, to inhibit the melatonin effect, and then to understand whether this method can effectively improve the scoliosis rate of bipedal rat model, and investigate the role of melatonin in scoliosis. To investigate the feasibility of improving the success rate of bipedal rat scoliosis model via intraperitoneal injection of melatonin antagonist (Luzindole). METHODS: A total of 60 3-weeks-old Sprague-Dawley rats were included in this study, and were divided into 3 groups (A, B and C). Each group included 20 rats. Osteotomy of the bilateral proximal humerus and proximal tailbone was performed in group A and group B; intraperitoneal injection of Luzindole (0.2 mg/kg) was performed in group A and group C. X-rays were taken before the surgery, 1 month after the surgery, 3 months after the surgery, and 6 months after the surgery, to calculate the Cobb's angle of the spine (>10° was considered scoliosis). The weight of every rat was also measured at the same time. Rats were euthanized 6 months after surgery to determine the calmodulin level in thrombocytes. RESULTS: The rate of scoliosis in group A (14/20) was significantly higher than those in group B (6/20) and group C (0/20) (P < 0.05). The differences in the weights of the 3 groups were non-significant; as were differences in the calmodulin level in thrombocytes. CONCLUSION: The application of the melatonin antagonist of Luzindole can improve the success rate of the bipedal rat scoliosis model. Meanwhile, this study indicates that a decreased melatonin level is not the primary cause of scoliosis, but that it may increase the likelihood and severity of scoliosis.