Biomonitoring urinary organophosphorus flame retardant metabolites by liquid-liquid extraction and ultra-high performance liquid chromatography-tandem mass spectrometry and their association with oxidative stress.

Organophosphate flame retardants (OPFRs) are widely used as substitutes for traditional brominated flame retardants, necessitating a reliable and sensitive method for biomonitoring their urinary metabolites to assess human exposure. This study conducted biomonitoring of 10 metabolites of OPFRs in 152 adults and assessed their association with oxidative stress biomarkers 8-hydroxydeoxyguanosine and 8-hydroxyguanosine. Urinary metabolites of OPFRs were released via enzymatic deconjugation. The addition of sodium chloride to the urine samples increases the ionic strength, inducing a salting-out effect that reduces the solubility of these compounds, thereby facilitating their extraction with a mixture of ethyl acetate and acetonitrile. Then, the metabolites of OPFRs were quantified by ultra-high performance liquid chromatography-tandem mass spectrometry, and we validated the method for linear range, precision, matrix effect, and method detection limit. The detection limit of the metabolites of OPFRs ranged from 0.01 to 0.2 µg/L, and these metabolites were detected with high frequencies ranging from 25.0 to 98.68% in the urine samples. The concentration of bis (2-chloroethyl) phosphate was significantly higher in males than in females, with the geometric mean concentration of 0.88 µg/L for males and 0.53 µg/L for females, respectively. Spearman correlation analysis revealed weak but statistically significant positive correlations among the urinary metabolites. Bayesian kernel machine regression analysis showed a significant positive association between elevated urinary concentrations of metabolites of OPFRs and increased oxidative stress levels. Di-n-butyl phosphate was identified as the metabolite that significantly contributed to the elevated level of 8-hydroxyguanosine.

Treatment of L5-S1 Floating Calcified Lumbar Disc Herniation with Percutaneous Endoscopic Interlaminar Discectomy.

OBJECTIVE: The floating calcified tissue in floating calcified lumbar disc herniation (FCLDH) is hard and often adheres to the dura mater, which can easily cause nerve root damage during surgery, making the operation challenging. We proposed the classification of FCLDH and a new technique for removing floating calcified tissue and reported the clinical efficacy and safety of this new technique in clinical practice. METHODS: From January 2019 to October 2021, 24 patients (13 males and 11 females, 46.4 ± 7.72 years) with L5-S1 floating calcified lumbar disc herniation were treated with percutaneous endoscopic interlaminar discectomy (PEID). According to FCLDH classification, a total of Type Ia: nine cases, Type Ib: five cases, Type IIa: four cases, and Type IIa: six cases were included. The visual analogue scale (VAS) and Oswestry disability index (ODI) were recorded pre-operatively and 3 days postoperatively, 6 months postoperatively, and at the last follow-up. The postoperative curative effect was evaluated according to the modified MacNab criteria. Computed tomography (CT) and magnetic resonance imaging (MRI) of the lumbar spine were performed 3 days after surgery to evaluate the efficacy of the surgery. RESULTS: All patients successfully underwent PEID. The VAS and ODI scores at 3 days postoperatively, 6 months postoperatively, and at the last follow-up were significantly improved and statistically significant compared to those of the preoperative period (p < 0.05). All the patients were followed up for 12-24 months (mean, 16.6 ± 4.6 months). At the last follow-up, according to the modified MacNab criteria, 15 cases were excellent, eight were good, and one was fair. The combined excellent and good rate was 95.83% (23/24). Postoperative review revealed that all floating calcified tissues were effectively removed and the nerve roots were adequately decompressed without complications such as cerebrospinal fluid leakage and lumbar spine infection. CONCLUSION: The classification of FCLDH we proposed can well guide the selection of surgical plans. PEID combined with floating calcified tissue removal technology has good efficacy in the treatment of L5-S1 FCLDH, ensuring accurate removal of calcified tissue, reducing complications and improving the quality of life of affected individuals.

The non-causative role of abnormal serum uric acid in intervertebral disc degeneration: A Mendelian randomization study.

Background: Intervertebral disc degeneration (IDD) is a common musculoskeletal disorder that contributes significantly to disability and healthcare costs. Serum urate concentration has been implicated in the development of various musculoskeletal conditions. While previous observational studies have suggested an association between the two conditions, it might confound the effect of serum urate concentrations on IDD. This Mendelian randomization (MR) study aimed to investigate the causal relationship between serum urate concentration and IDD. Methods: We performed a two-sample MR analysis using summary-level data from genome-wide association studies (GWAS) of serum urate concentration (n = 13 585 994 European ancestry) and IDD (n = 16 380 337 European ancestry). Single nucleotide polymorphisms (SNPs) significantly associated with serum urate concentration (p < 5 × 10-8) were selected as instrumental variables. The associations between genetically predicted serum urate concentration and IDD were estimated using the inverse-variance weighted (IVW) method, with sensitivity analyses employing the weighted median, MR-Egger, and MR-PRESSO approaches to assess the robustness of the findings. Results: In the primary IVW analysis, genetically predicted serum urate concentration was unrelated associated with IDD (odds ratio [OR] = 1.00, 95% confidence interval (CI): 1.00-1.00, p = 0.17)). The results remained consistent across the sensitivity analyses, and no significant directional pleiotropy was detected (MR-Egger intercept: p = 0.15). Conclusions: This MR study provides evidence that there is no causal relationship between serum urate concentration and IDD. It suggests previous observational associations may be confounded. Serum urate levels are unlikely to be an important contributor to IDD.

Corylifol A suppresses osteoclastogenesis and alleviates ovariectomy-induced bone loss via attenuating ROS production and impairing mitochondrial function.

Osteoporosis is a systemic disease characterized by an imbalance in bone homeostasis, where osteoblasts fail to fully compensate for the bone resorption induced by osteoclasts. Corylifol A, a flavonoid extracted from Fructus psoraleae, has been identified as a potential treatment for this condition. Predictions from network pharmacology and molecular docking studies suggest that Corylifol A exhibits strong binding affinity with NFATc1, Nrf2, PI3K, and AKT1. Empirical evidence from in vivo experiments indicates that Corylifol A significantly mitigates systemic bone loss induced by ovariectomy by suppressing both the generation and activation of osteoclasts. In vitro studies further showed that Corylifol A inhibited the activation of PI3K-AKT and MAPK pathways and calcium channels induced by RANKL in a time gradient manner, and specifically inhibited the phosphorylation of PI3K, AKT, GSK3 ß, ERK, CaMKII, CaMKIV, and Calmodulin. It also diminishes ROS production through Nrf2 activation, leading to a decrease in the expression of key regulators such as NFATcl, C-Fos, Acp5, Mmp9, and CTSK that are involved in osteoclastogenesis. Notably, our RNA-seq analysis suggests that Corylifol A primarily impacts mitochondrial energy metabolism by suppressing oxidative phosphorylation. Collectively, these findings demonstrate that Corylifol A is a novel inhibitor of osteoclastogenesis, offering potential therapeutic applications for diseases associated with excessive bone resorption.

Perchlorate in honey from China: Levels, pollution characteristics and health risk assessment.

The release and accumulation of perchlorate into the environment have raised concerns about safety to food, however, the dietary risk of perchlorate in honey have not yet received attention. Herein, we investigated the pollution characteristics and assessed the human health risks of perchlorate in honey from China. A total of 151 honey samples collected from 20 provinces of China were analyzed, and overall detection frequencies was 95.4 %. The levels of perchlorate ranged from below limit of quantitation to 612 µg/kg, with a mean value of 34.5 µg/kg. Lychee honey samples had the highest mean perchlorate concentration (163 µg/kg). The mean concentration of perchlorate in the honey samples produced in South China was significantly higher than that in honey from Southwest China, East China and North China (P < 0.05). The health risk assessment showed that mean hazard quotient (HQ) values of different honey for children (ranged from 0.0108 to 0.400) and adults (ranged from 0.0123 to 0.453) were less than 1. This result indicated that mean pollution levels of perchlorate in various honey were unlikely to pose health risk. However, perchlorate concentrations in two lychee honey samples had associated HQ values were >1, suggesting potential health risks. This work not only offers valuable information for honey consumer, but also important reference for comparison of honey samples in the future. ENVIRONMENTAL IMPLICATION: Perchlorate contamination has become a hot environmental issue in connection with human health due to its potential thyroid toxicity and widespread occurrence in environment and foods. Honey not only was widely beloved by consumers worldwide but also considered a potential indicator of environmental pollution. Here, a national investigation and risk assessment of perchlorate levels in different types of honey from China was conducted. The results describe the perchlorate contamination were extensive in honey samples, mean levels of perchlorate in various honey were unlikely to cause health risks. However, significantly high level of contamination in lychee honey should be of concern.

Electrocatalytic Interconversions of CO2 and Formate on a Versatile Iron-Thiolate Platform.

Exploring bidirectional CO2/HCO2- catalysis holds significant potential in constructing integrated (photo)electrochemical formate fuel cells for energy storage and applications. Herein, we report selective CO2/HCO2- electrochemical interconversion by exploiting the flexible coordination modes and rich redox properties of a versatile iron-thiolate platform, Cp*Fe(II)L (L = 1,2-Ph2PC6H4S-). Upon oxidation, this iron complex undergoes formate binding to generate a diferric formate complex, [(L-)2Fe(III)(µ-HCO2)Fe(III)]+, which exhibits remarkable electrocatalytic performance for the HCO2--to-CO2 transformation with a maximum turnover frequency (TOFmax) ∼103 s-1 and a Faraday efficiency (FE) ∼92(±4)%. Conversely, this iron system also allows for reduction at -1.85 V (vs Fc+/0) and exhibits an impressive FE ∼93 (±3)% for the CO2-to-HCO2- conversion. Mechanism studies revealed that the HCO2--to-CO2 electrocatalysis passes through dicationic [(L2)-•Fe(III)(µ-HCO2)Fe(III)]2+ generated by unconventional oxidation of the diferric formate species taking place at ligand L, while the CO2-to-HCO2- reduction involves a critical intermediate of [Fe(II)-H]- that was independently synthesized and structurally characterized.

[Advances in surgical strategies for ossification of posterior longitudinal ligament involving the C 2 segment].

Objective: To evaluate the application of surgical strategies for the treatment of cervical ossification of the posterior longitudinal ligament (OPLL) involving the C 2 segment. Methods: The literature about the surgery for cervical OPLL involving C 2 segment was reviewed, and the indications, advantages, and disadvantages of surgery were summarized. Results: For cervical OPLL involving the C 2 segments, laminectomy is suitable for patients with OPLL involving multiple segments, often combined with screw fixation, and has the advantages of adequate decompression and restoration of cervical curvature, with the disadvantages of loss of cervical fixed segmental mobility. Canal-expansive laminoplasty is suitable for patients with positive K-line and has the advantages of simple operation and preservation of cervical segmental mobility, and the disadvantages include progression of ossification, axial symptoms, and fracture of the portal axis. Dome-like laminoplasty is suitable for patients without kyphosis/cervical instability and with negative R-line, and can reduce the occurrence of axial symptoms, with the disadvantage of limited decompression. The Shelter technique is suitable for patients with single/double segments and canal encroachment >50% and allows for direct decompression, but is technically demanding and involves risk of dural tear and nerve injury. Double-dome laminoplasty is suitable for patients without kyphosis/cervical instability. Its advantages are the reduction of damage to the cervical semispinal muscles and attachment points and maintenance of cervical curvature, but there is progress in postoperative ossification. Conclusion: OPLL involving the C 2 segment is a complex subtype of cervical OPLL, which is mainly treated through posterior surgery. However, the degree of spinal cord floatation is limited, and with the progress of ossification, the long-term effectiveness is poor. More research is needed to address the etiology of OPLL and to establish a systematic treatment strategy for cervical OPLL involving the C 2 segment.

Isoimperatorin attenuates bone loss by inhibiting the binding of RANKL to RANK.

Osteoporosis, an immune disease characterized by bone mass loss and microstructure destruction, is often seen in postmenopausal women. Isoimperatorin (ISO), a bioactive, natural furanocoumarin isolated from many traditional Chinese herbal medicines, has therapeutic effects against various diseases; however, its effect on bone homeostasis remains unclear. In this study, we investigated the effect of ISO on the differentiation and activation of osteoclast and its molecular mechanism in vitro, and evaluated the effect of ISO on bone metabolism by ovariectomized (OVX) rat model. In vitro experiments showed that ISO affected RANKL-induced MAPK, NFAT, NFATc1 trafficking and expression, osteoclast F-actin banding, osteoclast-characteristic gene expression, ROS inhibitory activity, and calcium oscillations, NF-κB signaling pathway. In vivo experiments showed that oral administration of ISO effectively reduced bone loss caused by ovariectomy and retained bone mass.Collectively, ISO inhibits RANK/RANKL binding, thereby reducing the activity of NFATc1, calcium, and ROS and inhibiting osteoclast generation. In addition, ISO protects bone mass by slowing osteoclast production and downregulating NFATc1 gene and protein expression in the bone tissue microenvironment and inhibits OVX-induced bone loss in vivo.

Isoliensinine suppresses bone loss by targeted inhibition of RANKL-RANK binding.

BACKGROUND: Osteoporosis, a systemic metabolic bone disease, is often caused by the disruption of dynamic equilibrium between osteoclasts and osteoblasts. Overactive bone resorption, in which osteoclasts play a major role, is one of the most common and major causes of osteoporosis. Less costly and more effective drug treatments for this disease are needed. Based on the combination of molecular docking techniques and in vitro cell assays, this study aimed to explore the mechanism by which Isoliensinine (ILS) protects the bone loss by inhibiting osteoclast differentiation. METHODS: A virtual docking model based on molecular docking technology was used to investigate the interactions between ILS and the Receptor Activator of Nuclear Kappa-B (RANK)/Receptor Activator of Nuclear Kappa-B Ligand (RANKL).In this study, we determined the effective dose of action of ILS to inhibit osteoclast differentiation in vitro and, using bone resorption experiments, RT-CPR and Western Blot investigated the effects of ILS on bone resorption function and normal expression of osteoclast-associated genes and proteins, and validated potential mechanistic pathways. In vivo experiments revealed that ILS could inhibit bone loss through Micro-CT results. Finally, the molecular interaction between ILS and RANK/RANKL was investigated using biomolecular interaction experiments to verify the correctness and accuracy of the computational results. RESULTS: ILS binds to RANK and RANKL proteins, respectively, through virtual molecular docking. The Surface Plasmon Resonance (SPR) experiment results revealed that phosphorylated JNK, ERK, P38, and P65 expression was significantly downregulated when ILS were targeted to inhibit RANKL/RANK binding. At the same time, the expression of IKB-a was significantly increased under the stimulation of ILS, which rescued the degradation of IKB-a. ILS can significantly inhibit the levels of Reactive Oxygen Species (ROS) and Ca2 + concentration in vitro. Finally, the results of Micro-CT showed that ILS can significantly inhibit bone loss in vivo, indicating that ILS has a potential role in the treatment of osteoporosis. CONCLUSION: ILS inhibits osteoclast differentiation and bone loss by preventing the normal binding of RANKL/RANK, affecting downstream signaling pathways, including MAPK.NF-KB, ROS, Ca2+, genes, and proteins.

Dehydromiltirone inhibits osteoclast differentiation in RAW264.7 and bone marrow macrophages by modulating MAPK and NF-κB activity.

Background: Osteoporosis is a type of systematic metabolic bone disease caused by the decrease in osteogenic activity or excessive resorption of bone with the relative enhancement of osteoclast function. As osteoporosis seriously affects the quality of patients' life, effective drugs are needed to treat this disease. Based on the combination of network pharmacology and cellular studies, this study aimed to investigate the probable mechanism of Dehydromiltirone (DHT) in the treatment of osteoporosis. Method: The targets of DHT in osteoporosis were searched using the PharmGKB, OMIM, and Genecard platforms. The PPI core targets, and the GO and KEGG enrichment analysis results were obtained using Cytoscape software, and the David and Metascape databases, respectively. The network pharmacology results were also verified via in vitro cellular experiments. Results: Through network pharmacology and docking analysis, we found DHT was involved in peptide tyrosine phosphorylation, cell surface receptor tyrosine kinase signaling pathways, and MAPK signaling pathways. According to the molecular docking results, the binding of DHT to MAPK14 was more stable than other proteins, which suggests that DHT may affect osteoclast formation through the MAPK signaling pathway. Moreover, DHT was found to inhibit the expression of osteoclast-associated genes, including NFATc1, CTSK, c-Fos, Acp5, and MMP9; as well as the phosphorylation of P38, ERK, and JNK of the MAPK signaling pathway; and the degradation of IκB-α of NF-κB signaling pathway. Conclusion: DHT exhibited an anti-osteoclastogenesis effect by reducing the expression of related genes, ultimately inhibiting bone resorption in vitro.

A Parent Iron Amido Complex in Catalysis of Ammonia Oxidation.

Parent amido complexes are crucial intermediates in ammonia-based transformations. We report a well-defined ferric ammine system [Cp*Fe(1,2-Ph2PC6H4NH)(NH3)]+ ([1-NH3]+), which processes electrocatalytic ammonia oxidation to N2 and H2 at a mild potential. Through establishing elementary e-/H+ conversions with the ferric ammine, a formal Fe(IV)-amido species, [1-NH2]+, together with its conjugated Lewis acid, [1-NH3]2+, was isolated and structurally characterized for the first time. Mechanism studies indicated that further oxidation of [1-NH2]+ induces the reaction of the parent amido unit with NH3. The formation of hydrazine is realized by the non-innocent nature of the phenylamido ligand that facilitates the concerted transfer of one proton and two electrons.

Association between matrix metalloproteinase-3 gene polymorphisms and tendon-ligament injuries: evidence from a meta-analysis.

BACKGROUND: Tendon-ligament injuries (TLIs), including Achilles tendinopathy, cruciate ligament injury, tennis elbow, rotator cuff injury, patellar tendinopathy, and tibial tendinopathy, are common musculoskeletal soft injuries during physical activity. Matrix metalloproteinase-3 (MMP-3) gene polymorphisms have been implicated in the etiology of TLIs in several genetic association studies with inconsistent results. The purpose of this study was to collect and synthesize the current evidences on the association of MMP-3 polymorphisms and TLIs. METHODS: The search was conducted using PubMed, Web of Science, EMBASE, Cochrane Library, CNKI and Wanfang databases, prior to July, 2021. Newcastle Ottawa Scale was used to appraise the study quality. Strengths of association were represented by odds ratios (ORs) and 95% confidence intervals (95% CIs). RESULTS: Thirteen studies with 2871 cases and 4497 controls met the eligibility criteria, and each study was in high quality. The overall analyzes suggested rs3025058 was associated with an increased TLIs risk (5A vs. 6A, OR = 1.20, 95% CI 1.03-1.40, P = 0.020). However, the association was not found for rs679620, rs591058, and rs650108 polymorphisms. Subgroup analysis by injury type suggested that rs679620 polymorphism was associated with a reduced risk to Achilles tendon rupture (AA + AG vs. GG, OR = 0.46, 95% CI 0.25-0.87, P = 0.020), and rs3025058 was associated with an elevated risk to anterior cruciate ligament injury (5A5A + 5A6A vs. 6A6A, OR = 1.46, 95% CI 1.03-2.06, P = 0.030). When stratified by ethnicity, the findings indicated that rs3025058 polymorphism was associated with an increased TLIs risk among Caucasians (5A6A vs. 6A6A, OR = 1.55, 95% CI 1.09-2.42, P = 0.020) and Brazilians (5A5A vs. 5A6A + 6A6A, OR = 2.80, 95% CI 1.44-5.45, P = 0.002). CONCLUSION: Findings of this study suggest that rs679620 polymorphism is associated with a reduced Achilles tendon rupture risk, and rs3025058 polymorphism contributes to an increased TLIs risk in Caucasians and Brazilians. However, rs591058 and rs650108 polymorphisms do not show any association with TLIs.

A meta-analysis and systematic review of holmium laser treatment of bladder stones.

BACKGROUND: Holmium lasers have been used to treat bladder stones and achieve good therapeutic effects, but its efficacy remains to be explored. METHODS: The PubMed, Embase, Medline, Ovid, Springer, and Web of Sciences databases were searched from their establishment to December 31, 2020. Studies of randomized control trials (RCTs) examining the treatment of vesical calculi by holmium laser lithotripsy were identified. The Cochrane Handbook for Systematic Reviews of Intervention 5.0.2 was used to assess risk bias, and Rev Man5.3 was used to conduct the meta-analysis. RESULTS: A total of 10 studies, comprising 1,642 subjects, were included. The meta-analysis results showed that the surgery time and the hospitalization time of patients treated with holmium laser lithotripsy decreased, and the calculus removal rate increased. The experimental group had a lower incidence of adverse reactions, such as postoperative urinary tract infection, mucosal damage, vesical perforation, residual calculi, hematuria, and abdominal pain than the control group; however, no notable difference was observed in relation to surgery time, hospital stay, the calculus removal rate, mucosal damage, bladder perforation, hematuria, and abdominal pain between the 2 groups. DISCUSSION: Holmium laser lithotripsy significantly reduced the hospitalization time of patients treated with holmium laser lithotripsy and elevated the removal rate.

Long-term efficacy and safety of bone cement-augmented pedicle screw fixation for stage III Kümmell disease.

This study aimed to evaluate the efficacy and safety of bone cement-augmented pedicle screw fixation for stage III Kümmell disease. Twenty-five patients with stage III Kümmell disease who received bone cement-augmented pedicle screw fixation at the First Affiliated Hospital of Guangzhou University of Chinese Medicine between June 2009 and December 2015 were enrolled. All patients were females with a history of osteoporosis. The vertebral Cobb angle (V-Cobb angle), the fixed segment Cobb Angle (S-Cobb angle), pelvic parameters, visual Analogue Scale (VAS) score, and Oswestry Disability Index (ODI) were assessed preoperatively, postoperatively and at the final follow-up. Complications, loosening rate, operation time, and intraoperative bleeding were recorded. The average lumbar vertebral density T-value was - 3.68 ± 0.71 SD, and the average age was 71.84 ± 5.39. The V-Cobb angle, S-Cobb angle, and Sagittal Vertical Axis (SVA) were significantly smaller postoperatively compared to the preoperative values. The VAS and ODI at 1 month after surgery were 3.60 ± 1.00 and 36.04 ± 6.12%, respectively, which were both significantly lower than before surgery (VAS: 8.56 ± 1.04, ODI: 77.80 ± 6.57%). Bone cement-augmented pedicle screw fixation is a safe and effective treatment for stage III Kümmell disease. It can effectively correct kyphosis, restore and maintain sagittal balance, and maintain spinal stability.

Carnosol suppresses RANKL-induced osteoclastogenesis and attenuates titanium particles-induced osteolysis.

Osteolysis is a common medical condition characterized by excessive activity of osteoclasts and bone resorption, leading to severe poor quality of life. It is essential to identify the medications that can effectively suppress the excessive differentiation and function of osteoclasts to prevent and reduce the osteolytic conditions. It has been reported that Carnosol (Car), isolated from rosemary and salvia, has anti-inflammatory, antioxidative, and anticancer effects, but its activity on osteolysis has not been determined. In this study, we found that Car has a strong inhibitory effect on the receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation dose-dependently without any observable cytotoxicity. Moreover, Car can inhibit the RANKL-induced osteoclastogenesis and resorptive function via suppressing NFATc1, which is a result of affecting MAPK, NF-κB and Ca2+ signaling pathways. Moreover, the particle-induced osteolysis mouse model confirmed that Car could be effective for the treatment of bone loss in vivo. Taken together, by suppressing the formation and function of RANKL-induced osteoclast, Car, may be a therapeutic supplementary in the prevention or the treatment of osteolysis.

Highly sensitive determination of amanita toxins in biological samples using ß-cyclodextrin collaborated molecularly imprinted polymers coupled with ultra-high performance liquid chromatography tandem mass spectrometry.

In this work, a ß-cyclodextrin functional vinyl monomer was synthesized and the common moiety of five amanita toxins was used as the template for preparing molecularly imprinted polymers (MIPs). Chemical calculation was used to evaluate and describe the binding interactions between the template and the functional monomer. The preparation conditions were optimized and the resultant MIPs were characterized and employed as solid-phase extraction (SPE) sorbents. The SPE conditions including the amount of sorbent, extraction solution, and eluting solution were also optimized for the enrichment of the five toxins. Using an ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS), detection limits ranging from 0.34-0.42 µg/L, 0.16-0.33 µg/L, and 0.035-0.056 µg/kg were achieved for the five toxins in serum, urine and liver samples, respectively. The proposed method was further applied to the determination of the amanita toxins in suspected samples and showed great potential in the diagnosis of mushroom poisoning.

Influence of cement-augmented pedicle screws with different volumes of polymethylmethacrylate in osteoporotic lumbar vertebrae over the adjacent segments: a 3D finite element analysis.

BACKGROUND: Polymethylmethacrylate (PMMA) is commonly used for cement-augmented pedicle screw instrumentation (CAPSI) to improve the fixation stability and reduce the risk of screw loosening in the osteoporotic thoracolumbar spine. Biomechanical researches have shown that various dose of cement (1-3 ml) can be injected to enhance screw stability. To date, there have been no studies on the relationship between adjacent segment degeneration and the volume of PMMA. This study aimed to explore the influence of CAPSI with different volumes of PMMA in osteoporotic lumbar vertebrae over adjacent segments by using finite element analysis. METHODS: Seven different finite element models were reconstructed and simulated under different loading conditions, including (1) an intact model, (2) three single-level CAPSI models with different volumes of PMMA (1, 1.73, and 2.5 ml), and (3) three double-level CAPSI models with different volumes of PMMA (1, 1.73, and 2.5 ml). To improve the accuracy of the finite element analysis, the models of the injectable pedicle screw and bone cement were created by using a three-dimensional scanning machine and the CAPSI patient's CT data, respectively. The range of motion (ROM), the stress of intervertebral discs, and the stress of facet in the adjacent segment were comparatively analyzed among the different models. RESULTS: The ROMs of the different segments were compared with experimental data, with good agreement under the different load conditions (21.3°, 13.55°, 13.99°, and 6.11° in flexion, extension, bending, and rotation at L3-S1 level, respectively). Compared with the intact model, the ROM, disc stresses, and facet stress in adjacent segments were found to be higher in the six operative models. Otherwise, with a larger volume of PMMA injected, the ROM, disc stresses, and facet stress slightly increased at the adjacent segment. However, the differences were insignificant with the biggest difference less than 3.8%. CONCLUSIONS: CAPSI could increase the incidence of disk degeneration in the adjacent segment, while within a certain range, different volumes of PMMA provided an approximate impact over the adjacent segment degeneration.

Pedicle Screw Fixation in Single-Level, Double-Level, or Multilevel Posterior Lumbar Fusion for Osteoporotic Spine: A Retrospective Study with a Minimum 2-Year Follow-Up.

BACKGROUND: Pedicle screw loosening is a common postoperative complication for osteoporotic patients, and several studies have identified the important role of fusion length in internal fixation failure, but the relationship between the number of fusion segments and the potential risks remains unclear. This study aimed to investigate the rate and risk factors of screw loosening in osteoporotic patients with different levels of degenerative lumbar disease. METHODS: The total cohort of 217 patients was divided into 3 groups according to the different fusion levels: single-level (group A; 100 cases), double-level (group B; 73 cases), and multilevel group (group C; 44 cases). Patient baseline demographic characteristics and assessments with a visual analog scale (VAS) and the Oswestry Disability Index (ODI) before operation and at the last follow-up were compared among the 3 groups. RESULTS: Compared with preoperative values, VAS and ODI scores at the last follow-up were significantly improved in all 3 groups. Operative time, blood loss, length of hospital stay, screw loosening rate, fusion rate, and VAS and ODI scores at the last follow-up obviously increased with the increasing number of fusion segments (group C> group B> group A). Of note, all the screw loosening was observed in cranial and caudal vertebra. Furthermore, multivariate logistic regression analysis identified lumbosacral fixation, larger pelvic incidence (PI)-lumbar lordosis (LL) difference (PT-LL), and greater postoperative pelvic tilt (PT) as independent predictors of screw loosening. However, sex, bone mineral density, body mass index, LL, sacral slope, PI, the change in LL, and preoperative PT were not relevant to screw loosening (P > 0.05). CONCLUSIONS: Owing to the high rate of screw loosening in cranial and caudal vertebra, osteoporotic patients with double-level or multilevel pedicle screw fixation benefited less than those with single-level pedicle screw fixation. Larger PI-LL, larger PT, and lumbosacral fixation are other risk factors for screw loosening. An instrument with stronger holding strength at cranial and caudal pedicle screws is recommended for those high-risk patients.

Effect and potential risks of using multilevel cement-augmented pedicle screw fixation in osteoporotic spine with lumbar degenerative disease.

BACKGROUND: The increase of augmented level and bone cement dose are accompanied by the rising incidence of cement leakage (CL) of cement-augmented pedicle screw instrumentation (CAPSI). But the effect and potential risks of the application of CAPSI to osteoporotic lumbar degenerative disease (LDD) have not been studied in the case of multilevel fixation. This study aimed to investigate the effectiveness and potential complications of using multilevel CAPSI for patients with osteoporotic LDD. METHODS: A total of 93 patients with multilevel LDD were divided into the CAPSI group (46 subjects) and the conventional pedicle screw (CPS) group (47 subjects), including 75 cases for three levels and 18 cases for four levels. Relevant data were compared between two groups, including baseline data, clinical results, and complications. RESULTS: In the CAPSI group, a total of 336 augmented screws was placed bilaterally. The CL was observed in 116 screws (34.52%). Three cemented screws (0.89%) were found loosened during the follow-up and the overall fusion rate was 93.47%. For perioperative complications, two patients (4.35%) experienced pulmonary cement embolism (PCE), one patient augmented vertebral fracture, and three patients (6.52%) wound infection. And in the CPS group, thirty-three screws (8.46%) suffered loosening in cranial and caudal vertebra with a fusion rate of 91.49%. The operation time and hospital stay of CAPSI group were longer than the CPS group, but CAPSI group has a lower screw loosening percentage (P<0. 05). And in terms of blood loss, perioperative complications, fusion rate, and VAS and ODI scores at the follow-up times, there were no significant differences between the two groups. CONCLUSIONS: Patients with osteoporotic LDD underwent multilevel CPS fixation have a higher rate of screw loosening in the cranial and caudal vertebra. The application of cemented pedicle screws for multilevel LDD can achieve better stability and less screw loosening, but it also accompanied by longer operating time, higher incidence of CL, PCE and wound infections. Selective cement augmentation of cranial and caudal pedicle screws may be a worthy strategy to decrease the complications.

Stability Evaluation of Oblique Lumbar Interbody Fusion Constructs with Various Fixation Options: A Finite Element Analysis Based on Three-Dimensional Scanning Models.

BACKGROUND: Little is known about the biomechanical performance of various fixation constructs after oblique lumbar interbody fusion (OLIF). This study aimed to explore the stability of various fixation options for OLIF by using finite element analysis based on three-dimensional scanning models. METHODS: Six validated finite element models of the L3-L5 segment were reconstructed via computed tomography images, including (1) intact model, (2) stand-alone model with no instrument, (3) lateral rod-screw model, (4) lateral rod-screw plus contralateral translaminar facet screw (LRS-CTLFS) model, (5) unilateral pedicle screw model, and (6) bilateral pedicle screw (BPS) model. Models of the OLIF cage and pedicle screw were created with three-dimensional scanning to improve the accuracy of finite element analysis. Range of motion, stress of the cage, and stress of fixation were evaluated in the different models. RESULTS: Range of motion increased from least to greatest as follows: BPS, LRS-CTLFS, unilateral pedicle screw, lateral rod-screw, stand-alone. Differences in range of motion between BPS and LRS-CTLFS were not significant for all loading cases. Compared with the other 3 models, the stress of the cage was found to be lower in BPS and LRS-CTLFS under all loading conditions, especially in BPS. Stress exerted on the fixation was the greatest in LRS-CTLFS, and the stress experienced by the translaminar facet screw was concentrated in part of the facet joint. CONCLUSIONS: The BPS model provided the best biomechanical stability for OLIF; the stand-alone model could not provide sufficient stability. The LRS-CTLFS procedure increases the approximate stability and reduces stress at the cage-endplate interface; however, it causes an increase in screw stress.