Aims To construct a mechanical model using a spatial Cartesian coordinate system and vectors, and to explore the role of facet joint morphology and mechanical parameters in degenerative lumbar spondylolisthesis (DLS). Methods A retrospective imaging study was conducted to collect the demographic data and imaging parameters of patients with and without DLS. The 3D structure and mechanical parameters of facet joint were constructed for comparative analysis. Receiver operating characteristic and regression analysis explore predictors for DLS. A total of 149 patients (67.8% female) were included in the study, with a median age of 63 years (IQR 58.5 to 68.0). Results Compared with non-DLS patients, there were significant differences in the facet joint angle (FJA), facet degeneration of L4-5, the sagittal joint angle (SJA), and intervertebral angles of L3-5 in DLS. Regardless of correction, the L4-5 posterior shear force of DLS patients is smaller than non-DLS. Posterior shear force has a high area under the curve and is significantly different from FJA, medial shear force, and vertical stress. High SJA and low posterior shear force are independent predictors for the progression of lumbar spondylolisthesis. Conclusion In addition to the FJA, the larger SJA and lower posterior shear forces are also a good index to predict the progress of DLS. The posterior shear force is a more valuable indicator for predicting DLS progression, and may be a direct factor in the anterior displacement. When the posterior shear force is less than 0.537, the possibility of lumbar spondylolisthesis greatly increases. At this time, even in cases where patients do not experience spondylolisthesis, muscle exercise or intraoperative fixation are recommended to maintain lumbar stability. Cite this article: Bone Joint Res 2026;15(7):880–890.

Understanding the mechanical response and damage characteristics of rock masses with non-persistent cracks under water-rock interactions is of significant research importance. It provides a basis for the mechanical assessment of rock masses in reservoir areas and for disaster prevention and control. For this purpose, uniaxial compression tests were performed on limestone specimens with different degrees of water-rock interactions damage, crack types, and crack inclinations. Acoustic emission (AE) and digital image correlation (DIC) techniques were employed in this study. The effects of water-rock interactions damage and crack geometry on the stress characteristics and failure modes of limestone with non-persistent cracks were systematically investigated. On this basis, the Hoek-Brown (H-B) strength criterion was modified. A damage constitutive model for rock masses with non-persistent cracks under water-rock interactions was then established by coupling micro-scale and macro-scale damage. The results indicate that the water absorption process of dry cracked limestone follows a three-stage evolution characterized by exponential decay. The water absorption rate is positively correlated with crack inclination, with 45° identified as a critical threshold, and the overall water absorption behavior is governed by the spatial geometric characteristics of the cracks. Water-rock interactions accelerates strength degradation of the rock masses and advances the onset of AE activity and strain localization. The macroscopic crack configuration governs crack propagation paths, and the failure modes show a complex tensile-shear evolution with changes in crack inclination and type. By comparing the experimental data with the model predictions, the proposed model was validated and shown to accurately capture the deformation and strength characteristics of rock masses with non-persistent cracks under uniaxial compression after water-rock interactions damage. It provides a theoretical basis and technical support for the stability assessment and geological hazard prevention of rock masses on reservoir bank slopes under long-term water level fluctuations and seepage effects.

STUDY DESIGN:A retrospective cohort study. OBJECTIVE:To compare the clinical and radiologic outcomes of these treatments, focusing on functional recovery, intervertebral space height, spondylolisthesis reduction, and complication rates. BACKGROUND:Lumbar disc herniation (LDH) is a leading cause of disability worldwide, necessitating effective interventions to restore function and alleviate pain. Radiofrequency ablation and lumbar fusion are common interventions, yet their comparative efficacy remains underexplored. METHODS:A retrospective cohort study of 330 LDH patients was conducted. Patients were divided into a control group (radiofrequency ablation, n=264) and a study group (lumbar fusion, n=66). Outcomes were assessed using the Oswestry Disability Index (ODI), Japanese Orthopaedic Association (JOA) scores, intervertebral space height, and spondylolisthesis grade. Clinical efficacy was categorized as "excellent," "good," "fair," or "poor," with total efficacy rates calculated. Complications and fusion rates were analyzed using SPSS 23.0, with P<0.05 considered significant. RESULTS:Lumbar fusion showed superior functional recovery (ODI: 35.27±5.05 to 12.39±2.46; JOA: 8.08±1.79 to 29.68±4.25, P<0.001) compared with radiofrequency ablation (ODI: 35.59±5.43 to 26.49±3.65; JOA: 7.66±1.75 to 18.81±2.50). Fusion maintained better intervertebral space height, achieved greater spondylolisthesis reduction, and had fewer complications (7.57% vs. 11.36%, P=0.049) with a higher fusion rate (96.96%). CONCLUSIONS:Lumbar fusion offers superior functional and structural outcomes, with fewer complications compared with radiofrequency ablation, particularly in advanced LDH cases, while ablation remains a viable minimally invasive option for early-stage LDH.

Epidemiological studies have suggested a link between 6:2 chlorinated polyfluoroalkyl ether sulfonate (6:2 Cl-PFESA) and skeletal disorders, but its effect on postmenopausal osteoporosis has yet to be investigated. The effects and molecular mechanisms of 6:2 Cl-PFESA on bone mineral density (BMD) of ovariectomized (OVX) mice were explored in this study. After 40 days on treatment with 6:2 Cl-PFESA, OVX mice exhibited reduced BMD and trabecular bone mass along with increased osteoclast formation. Bioinformatics analysis found that Nos2 was upregulated. Nos2 knockdown lowered the markers of osteoclasts. STRING analysis showed a strong link between Nos2 and pathways related to oxidative stress. The study observed that 6:2 Cl-PFESA elevated the expression of ROS, mtDNA, STING, and NF-ĸB. Treatment with the ROS scavenger (GSH) lowered the levels of osteoclast markers, mtDNA, STING, and NF-ĸB. Additionally, giving the STING pathway inhibitor RTA408 prevented bone loss resulting from 6:2 Cl-PFESA by blocking osteoclast activation in OVX mice.

ObjectiveTo investigate the association between hyperlipidemia lumbar disc degeneration (LDD) in patients hospitalized for low back pain.MethodsA total of 165 patients with hyperlipidemia hospitalized for low back pain (mean age 44.06 ± 9.69 years; BMI 25.95 ± 2.55 kg/m²; 59.39% male) were enrolled and compared with 165 age-, sex-, and BMI-matched non-hyperlipidemic controls. The Pfirrmann grading system was utilized to evaluate the severity of LDD in both groups. The primary outcome was the difference in radiographic features of disc degeneration between groups, while secondary outcomes assessed the correlation between specific lipid profiles and the severity of LDD.ResultsThe hyperlipidemia group exhibited a significantly higher number of degenerated discs compared to the non-hyperlipidemia group (P<0.05), with significant differences observed particularly at the L1/2, L2/3, and L3/4 levels (P<0.05). The number of severely degenerated discs was also significantly higher in the hyperlipidemia group (P = 0.008), most notably at the L1/2 and L2/3 levels (P = 0.044 and P = 0.026, respectively). Furthermore, the prevalence of multi-level LDD was significantly higher in the hyperlipidemia group (P<0.05). While there was no significant difference in the number of patients with 3-level degeneration between the two groups (P = 0.238), significant differences were found in 4-level and 5-level degeneration (P<0.05). Abnormalities in Total Cholesterol (TC), Triglycerides (TG), and Lipoprotein(a) [Lp(a)] were associated with LDD (P<0.05); however, no significant difference in LDD severity was found among the four subtypes of hyperlipidemia (hypercholesterolemia, hypertriglyceridemia, mixed hyperlipidemia, and low HDL cholesterolemia) (P>0.05).ConclusionThis study demonstrates a significant association between hyperlipidemia and lumbar disc degeneration. Patients with hyperlipidemia hospitalized for low back pain present with a greater number of degenerated discs, a higher propensity for multi-level degeneration, and a significantly higher proportion of severe degeneration. Elevated levels of TC, TG, and Lp(a) are correlated with the severity of lumbar disc degeneration. Future research is needed to conduct a forward-looking study to determine whether lipid regulation has a preventive or therapeutic effect on intervertebral disc-related low back pain.

This study aims to explore the relationship between postoperative bone loss and cage subsidence (CS), as well as paraspinal muscle state and CS. The difference in vertebral Hounsfield Units (HU) between preoperative and postoperative CT scans was used to assess bone loss. Baseline characteristics of CS and non-CS groups were compared, followed by propensity score matching (PSM) and inverse probability treatment weighting (IPTW) for balance. Potential predictors from univariate analysis were adjusted for sex, age, and BMI in multivariate analysis to identify independent risk factors for CS. A total of 129 participants were included in the final analysis. The subsidence rate was 34.9

Paravertebral muscle segmentation holds significant clinical importance for devising effective personalized rehabilitation strategies for low back pain. However, challenges such as blurred boundaries and varied muscle shapes hinder accurate segmentation. Existing methods, though incorporating Transformer-based backbone networks for enhanced global information capture, still face difficulties in delineating complex boundaries. To overcome these limitations, a Boundary Uncertainty-area Feature reFinement network (BUFF-Net) is proposed, which is designed to improve segmentation accuracy in both muscle and boundary regions. The network incorporates three key modules. A Boundary Feature Refinement (BFR) module is introduced to extract and refine low-level boundary features. To enhance sensitivity to boundary regions, a Boundary Uncertain Area Augmentation (BUAA) module is proposed. In addition, a Multi-Scale Residual (MSR) module captures features across varying muscle scales while preserving fine-grained details. To validate the proposed method, a paraspinal muscle dataset is constructed, comprising 1060 axial lumbar spine magnetic resonance imaging (MRI) scans with corresponding muscle masks. Experiments are conducted on this dataset in conjunction with a public dataset. Results demonstrate that BUFF-Net improves the Dice coefficient by 4.01% and 1.44% compared to TransUNet on the respective datasets, effectively addressing challenges of blurred boundaries and scale variability. These findings highlight the potential of BUFF-Net as a precise and reliable tool for diagnosing and planning treatments for low back pain.

A recent study demonstrated that subcutaneous fat tissue thickness (SFTT) at the L1–L2 level is predicting paraspinal muscle fatty infiltration. Given that fat distribution patterns differ between males and females, we calibrated the SFTT index to obtain a standardized subcutaneous fat index (SSFI). A total of 175 patients admitted between January 2023 and July 2024 were included in this study. Based on lumbar CT attenuation values, patients were classified into an osteoporosis group (HU ≤ 110) and a normal bone density group (HU > 110). Demographic characteristics and clinical variables, including age, BMI, sex, medical history, and the standardized subcutaneous fat index (SSFI), were compared between the two groups. Pearson correlation analysis was subsequently performed to evaluate the associations between SSFI1 and other variables. Multiple linear regression analyses were conducted to further assess the relationships between SSFI1 and multifidus fatty infiltration, erector spinae fatty infiltration, frailty index, and vertebral bone quality (VBQ). Finally, receiver operating characteristic (ROC) curve analysis was performed to evaluate the ability of SSFI1 to discriminate osteoporosis. Patients with osteoporosis were older than the control group, while no significant differences were observed in smoking, alcohol consumption, diabetes, or hypertension between the two groups. Compared with controls, patients with osteoporosis showed lower SSFI1 values, greater paraspinal muscle fatty infiltration, and higher frailty index and VBQ scores. Moreover, SSFI was lower in both male and female patients with osteoporosis. Pearson correlation analysis further demonstrated that SSFI1 was significantly associated with paraspinal muscle fatty infiltration, lumbar bone mineral density, femoral bone mineral density, frailty index, and VBQ. Multiple linear regression analysis revealed that SSFI1 was associated with VBQ. ROC curve analysis indicated that SSFI1 had potential value in distinguishing osteoporosis from non-osteoporotic individuals. When the cutoff value of SSFI1 was < 0.29, the area under the curve (AUC) was 0.642, with a sensitivity of 0.696 and a specificity of 0.921, suggesting that SSFI1 may serve as a potential imaging marker for osteoporosis. SSFI1 was significantly reduced in patients with osteoporosis and was closely associated with paraspinal muscle fatty infiltration, bone mineral density, frailty index, and VBQ. In addition, SSFI1 demonstrated potential value in distinguishing osteoporosis from non-osteoporotic individuals. These findings suggest that SSFI1 may serve as a simple and accessible imaging biomarker for evaluating bone quality and may provide a novel approach for the early identification and risk stratification of osteoporosis.

BackgroundZero-P VA device is a unique zero-profile device comprising only two integrated variable-angle screws which may provide inferior mechanical stability compared with other types of devices. There is a lack of comprehensive clinical and radiological evidence comparing the plate-cage construct (PCC) and the Zero-P VA device in single-level anterior cervical discectomy and fusion (ACDF).MethodsWe retrospectively reviewed consecutive patients who underwent single-level ACDF using either the Zero-P VA device (50 cases) or the PCC (51 cases). Clinical outcomes were evaluated using the Visual Analogue Scale (VAS) and Japanese Orthopaedic Association (JOA) scores. Radiological outcomes were assessed using standard lateral cervical x-ray films. Data were recorded preoperatively, immediately postoperatively, and at 3- and 12-month follow-up visits.ResultsVAS and JOA scores, cervical alignment, segmental angle, and surgical segment height were all significantly improved postoperatively in both groups. However, in the Zero-P VA group, the segmental angle and anterior height of the surgical segment at 3 and 12 months decreased significantly compared with immediate postoperative values and were significantly lower than those observed in the PCC group. The rate of segmental kyphosis was significantly higher in the Zero-P VA group at the 12-month follow-up (12% vs. 0%, p < 0.05), while fusion rates were comparable.ConclusionThe Zero-P VA device provides short-term clinical outcomes comparable to those of the PCC for single-level ACDF. However, it is associated with inferior radiological outcomes, specifically greater loss of segmental lordosis and anterior surgical segment height. The surgeon's choice of implant therefore involves a clinical trade-off between the established surgical advantages of a zero-profile system and the superior radiological stability offered by the PCC.

Bone regeneration is a complex and coordinated physiological process, and the different stages of this process have corresponding microenvironments to support cell development and physiological activities. However, biological scaffolds that provide different three-dimensional environments during different stages of bone regeneration are lacking. In this study, we report a novel composite scaffold (NPE@DCBM) inspired by the stages of bone regeneration; this scaffold was composed of a fibrin hydrogel loaded with nanoplatelet vesicles (NPVs), designated as NPE, and decellularized cancellous bone matrix (DCBM) microparticles. Initially, the NPE rapidly established a temporary microenvironment conducive to cell migration and angiogenesis. Subsequently, the DCBM simulated the molecular structure of bone and promoted new bone formation. In vitro, the NPVs regulated lipid metabolism in bone marrow mesenchymal stem cells (BMSCs), reprogramed the fate of BMSCs by activating the PI3K/AKT and MAPK/ERK positive feedback pathways, and increased BMSC functions, including proliferation, migration and proangiogenic potential. In vivo, NPV@DCBM accelerated bone tissue regeneration and repair. Initially, the NPE rapidly induced angiogenesis between DCBM microparticles, and subsequently, BMSCs differentiated into osteoblasts with DCBM microparticles at their core. In summary, the design of this composite scaffold that sequentially mimics different bone regeneration microenvironments may provide a promising strategy for bone regeneration, with clinical translational potential.

Study Design.A multicenter retrospective cohort studyObjective.To overcome the limitations of former single-center strategy studies, an updated classification guiding surgical management of Atlantoaxial dislocation (AAD) is proposed in this study based on a large multicenter retrospective cohort study with mid-to-long-term follow-up.Summary of Background Data.AAD is the most prevalent disorder affecting the craniovertebral junction, often leading to myelopathy and impairment of cranial nerve function, which can result in significant morbidity or even mortality. Although the treatment algorithm we previously proposed for these diseases in 2013 has been widely adopted, its effectiveness and safety in multicenter settings have yet to be thoroughly evaluated.Methods.Patients with AAD who underwent surgical treatment were recruited from eight tertiary spine centers in eight provinces (two northeastern, two southwestern, one northwestern, one southeastern, and two central) across China between January 2011 and December 2021. Patient classification, surgical procedure, postoperative recovery progress, and occurrence of complications of the patients were collected and analyzed.Results.In total, 2354 patients were included. Type I and type II constituted most patients (76.0%). For type III AAD, our goal was conversion to type II, first using posterior intra-articular release (212/523 patients, 40.5%), and if failed, transoral release (311/523 patients, 59.5%). For type IV, we also attempted conversion to type II, using posterior or transoral osteotomy (37/42 patients, 88.1%). Transoral and transnasal odontoidectomy was the last resort for decompression for patients whose AAD could not be reduced despite all efforts (5/42 patients, 11.9%). At an average follow-up of 5.3 years, 85.9% of patients achieved complete anatomical AAD reduction, and 98.8% demonstrated clinical or radiological signs of solid fusion.Conclusions.The classification system of AAD was updated. Advancements have been made in the management of irreducible and bony AAD, and the transoral release and odontoidectomy procedures were required by less AAD patients.

Objective:To explore the effectiveness of percutaneous kyphoplasty (PKP) combined with different anti-osteoporosis drugs in the treatment of osteoporotic vertebral compression fractures (OVCF) by assessing bone mineral density, pain, lumbar functional recovery, and incidence of vertebral refractures after the combined therapy. Methods:In this single-center retrospective study, medical records of 138 patients with OVCF who underwent PKP in the Third Hospital of Hebei Medical University between January 2021 and October 2022 were retrospectively analyzed. Among them, 41 patients treated with calcium and alfacalciferol supplementation after PKP (Group-A), 58 patients treated with calcium and calcitonin after PKP (Group-B), and 39 patients treated with calcium, calcitonin, and alendronate sodium after PKP (Group-C). Bone mineral density, pain, lumbar functional recovery, and incidence of vertebral refractures in the three groups were compared before and after PKP. Results:At six and 12 months after PKP, bone density T-values of Group-B and Group-C were significantly higher than Group-A (P<0.05). The visual analogue scale (VAS) scores of Group-B and Group-C were significantly lower than Group-A (P<0.05). At 12 months after PKP, T-value of bone density in Group-C was significantly higher, while the VAS score was significantly lower than Group-B; At six months after PKP, the Cobb angle in Group-B and Group-C was significantly lower than Group-A (P<0.05). At 12 months after PKP, Oswestry disability index (ODI) and Cobb angle of Group-B and Group-C were significantly lower than Group-A, and the lowest in Group-C. The extent of vertebral loss in Group-C was significantly lower than Groups A and B (P<0.05). Conclusions:In the treatment of osteoporotic vertebral compression fractures after percutaneous kyphoplasty, a combination of calcium therapy with calcitonin and alendronate sodium had a positive effect, which may effectively improve bone density, pain, and functional status, and reduce the incidence of vertebral body fractures.

Background Current research on Modic Changes (MCs) in Posterior Lumbar Interbody Fusion (PLIF) has predominantly focused on types 1, 2, and 3; however, findings remain inconsistent. To address this gap, we introduce a novel classification system based on endplate sclerosis status (sclerotic vs. non-sclerotic) to better evaluate the influence of MCs on PLIF outcomes. Methods Patients were divided into Group A (normal endplates), Group B (MCs without endplate sclerosis), and Group C (MCs with endplate sclerosis), with fifty patients in each group. VAS and ODI scores were recorded preoperatively, postoperatively, and during follow-up to assess clinical outcomes. At least one year after surgery, CT scans were performed to evaluate postoperative cage subsidence and bony fusion. Results The postoperative cage subsidence rate recorded were 4% for Group A, 16% for Group B, and 2% for Group C, with a statistically significant difference (P < 0.05). The postoperative bony fusion rate were 98% for Group A, 96% for Group B, and 80% for Group C, with a statistically significant difference (P < 0.05). At the final follow-up, the Visual Analog Scale(VAS) and Oswestry Disability Index(ODI) scores in Group C were significantly higher than those in Groups A and B (P < 0.05), indicating worse clinical outcomes. Conclusion MCs without endplate sclerosis increase the risk of cage subsidence after PLIF surgery but do not effect clinical outcomes. MCs with endplate sclerosis are associated with a reduced bony fusion rate following PLIF surgery, leading to worse long-term clinical outcomes.

To investigate the predictive value of different vertebral specificity of BMD for cage subsidence among patients undergoing ACDF. BMD at different vertebrae was measured by CT image and MRI image. Cage subsidence was defined as ≥ 3 mm loss of fusion segmental height. Logistic regression analysis was used to identify BMD at specific vertebrae associated with cage subsidence. Receiver operating characteristic curve analysis was used to evaluate the value of BMD of different vertebrae in predicting cage subsidence. 117 patients (182 intervertebral spaces) were included, with a mean age of 54.6 ± 10.9years. The mean follow-up was 12.5 ± 3.8months. Of the 182 intervertebral spaces, subsidence was found in 85 (46.7

To identify the clinical characteristics of and risk factors for pathological fractures secondary to osteoarticular infections (OAI) in children. We conducted a retrospective analysis of 159 children with acute OAI treated at our institution between July 2012 and June 2024. Patients were divided into a pathological fracture group (n = 24) and a no-fracture group (n = 135). Data analyzed included age, sex, time to admission, Pediatric Intensive Care Unit (PICU) admission and length of stay, non-orthopedic admission, disseminated infection, delayed surgery, precipitating factors, initial symptoms, pre-hospital peak temperature, inflammatory markers, extent of infection, affected bone diameter, bacteremia, pathogen (MSSA or MRSA) and susceptibility, antibiotic use, number of infected sites, surgical method, number of pre-fracture and total surgeries, postoperative fever duration, recurrent fever, length of stay, and number of hospitalizations. The median time to pathological fracture was 55 days, which was significantly positively correlated with age (r = 0.719, P < 0.001). Children aged ≤ 49.5 months constituted the largest proportion of the fracture group (70.8

Background:Adjacent segment disease (ASD) combined with retrolisthesis of the adjacent vertebrae is a common radiological phenomenon. However, its characteristics remain unclarified. This study aimed to investigate the epidemiology of ASD with retrolisthesis, preliminarily analyze its radiological features, and identify its risk factors. Methods:The diagnostic criteria for symptomatic ASD were defined as the recurrence of radiating lower limb pain after the initial surgery and radiological evidence of degeneration at the adjacent fused segment indicating revision surgery. Retrolisthesis in ASD was defined as a ≥3 mm posterior slip of the superior vertebra of the affected segment on a lateral X-ray, no-slip status as the absence of anterior or posterior slippage of the superior vertebra in the affected segments, and anterolisthesis as a ≥3 mm anterior slip of the superior vertebral body. All patients who underwent surgical treatment for symptomatic ASD between November 2020 and July 2024 at the Third Hospital of Hebei Medical University with an initial operation of posterior lumbar interbody fusion (PLIF) were analyzed. Patients were divided into a retrolisthesis group (group A), a no-slip group (group B), and a anterolisthesis group (group C). The demographic information and imaging data were compared between the groups. In addition, we collected preoperative imaging data from the initial surgery for patients in each group and performed a comparative analysis. Results:A total of 165 patients were included in this study, with 102 (61.8%) being included in group A (retrolisthesis group), 20 (12.1%) in group B (no-slip group), and 43 (26%) in group C (anterolisthesis group). Group A, as compared to group B, had significantly lower disc height (0.76±0.25 vs. 0.96±0.23; P<0.001), more severe degeneration of discs (3.58±0.72 vs. 2.98±0.64; P<0.001) and facet joints (3.58±0.72 vs. 2.98±0.64, P<0.001), and a smaller multifidus (MF) relative muscle cross-sectional area (RCSA) (0.17±0.70 vs. 0.21±0.67; P=0.004). The risk factors for ASD with retrolisthesis were identified to be reduced disc height [odds ratio (OR) =11.185; 95% confidence interval (CI): 1.276-98.045; P=0.029], more severe disc degeneration (OR =0.400; 95% CI: 0.194-0.823; P=0.013), and greater MF atrophy (OR =4.087; 95% CI: 1.378-12.122; P=0.011). Conclusions:ASD combined with retrolisthesis was the most common of the three patterns of ASD, and patients with this condition had severe degeneration of discs and facet joints and significant atrophy of the MF. Reduced disc height, severe disc degeneration, and atrophy of the MF were the risk factors for ASD combined with retrolisthesis. In summary, we hypothesize that early lumbar muscle-strengthening exercises may reduce ASD risk in patients with adjacent vertebral retrolisthesis detected on postoperative follow-up radiographs after lumbar fusion. This should be validated in controlled, prospective studies.

STUDY DESIGN:A multicenter retrospective cohort study. OBJECTIVE:To overcome the limitations of former single-center strategy studies, an updated classification guiding surgical management of Atlantoaxial dislocation (AAD) is proposed in this study based on a large multicenter retrospective cohort study with mid-to-long-term follow-up. SUMMARY OF BACKGROUND DATA:AAD is the most prevalent disorder affecting the craniovertebral junction, often leading to myelopathy and impairment of cranial nerve function, which can result in significant morbidity or even mortality. Although the treatment algorithm we previously proposed for these diseases in 2013 has been widely adopted, its effectiveness and safety in multicenter settings have yet to be thoroughly evaluated. METHODS:Patients with AAD who underwent surgical treatment were recruited from eight tertiary spine centers in eight provinces (two northeastern, two southwestern, one northwestern, one southeastern, and two central) across China between January 2011 and December 2021. Patient classification, surgical procedure, postoperative recovery progress, and occurrence of complications of the patients were collected and analyzed. RESULTS:In total, 2354 patients were included. Type I and type II constituted most patients (76.0%). For type III AAD, our goal was conversion to type II, first using posterior intra-articular release (212/523 patients, 40.5%), and if failed, transoral release (311/523 patients, 59.5%). For type IV, we also attempted conversion to type II, using posterior or transoral osteotomy (37/42 patients, 88.1%). Transoral and transnasal odontoidectomy was the last resort for decompression for patients whose AAD could not be reduced despite all efforts (5/42 patients, 11.9%). At an average follow-up of 5.3 years, 85.9% of patients achieved complete anatomical AAD reduction, and 98.8% demonstrated clinical or radiological signs of solid fusion. CONCLUSIONS:The classification system of AAD was updated. Advancements have been made in the management of irreducible and bony AAD, and the transoral release and odontoidectomy procedures were required by less AAD patients.

BACKGROUND: Lumbar instability and endplate defects are commonly seen in patients with spondylolisthesis. However, little is known about associations between segmental stability and endplate defects. The present study explored associations between stability-related radiographic parameters and endplate defect scores and assessed whether endplate defect scores can predict lumbar stability in lumbar spondylolisthesis. METHODS: Neutral, flexion, and extension radiographs of 159 patients with monosegmental lumbar spondylolisthesis were analyzed. Radiographic parameters included average intervertebral disc height (IDH), slip distance, sagittal translation (ST) and sagittal angulation (SA). Correlation analysis and linear regression analysis were used to explore associations between endplate defect scores and radiographic parameters. Logistic regression analysis was used to assess associations between endplate defect scores and ST stability. Receiver-operating characteristic curve (ROC) analysis was used to evaluate the value of the endplate defect score in predicting ST stability. RESULTS: A total of 11.9% of patients had ST >= 4 mm, and 30% of patients had SA >= 10 degrees. Endplate defect scores were negatively correlated with ST and IDH and positively correlated with slip distance in isthmic spondylolisthesis but not in degenerative spondylolisthesis. In multiple regression analysis, endplate defect scores were significantly associated with ST, slip distance, IDH, and disc degeneration. ST instability was associated with endplate defect scores in isthmic spondylolisthesis (OR=0.460, P = 0.010). The AUCs for using the endplate defect score to evaluate ST stability in overall patients and isthmic spondylolisthesis patients were 0.672 and 0.774, respectively. The optimal threshold of the endplate defect score constructed by the Youden index was 7.5 for predicting ST stability. CONCLUSIONS: Endplate defect scores increase with a reduction in IDH, progression of slippage and a decrease in ST in isthmic spondylolisthesis but not in degenerative spondylolisthesis. ST instability was associated with endplate defect scores in isthmic spondylolisthesis, and endplate defect scores could be used to reflect lumbar stability at the slippage segment.

OBJECTIVE Low bone mineral density (BMD) significantly increases the risk of complications in patients undergoing spinal fusion. Existing evidence indicates that traditional dual -energy x-ray absorptiometry (DEXA) and quantitative CT (QCT) screening are underutilized in spine surgery. The MRI-based vertebral bone quality (VBQ) score provides a tool for primary screening of bone density. The validity of this score as a predictor across sexes has not been investigated. This study aimed to explore the effect of sex on the diagnostic efficacy of the VBQ in predicting osteopenia/osteoporosis and whether a sex -specific threshold exists. METHODS In this retrospective cohort study, patients who underwent lumbar fusion at a tertiary care center were reviewed. VBQ was obtained by noncontrast T1 -weighted MRI. Patients were stratified according to sex and bone density. Data were analyzed between the groups. Pearson correlation analysis and linear regression were used to analyze the correlation between the VBQ and DEXA T values. Receiver operating characteristic (ROC) curve analysis, including area under the curve (AUC) calculation, was used to evaluate the predictive performance of VBQ for low BMD in both sexes. RESULTS A total of 271 patients (92 male, 179 female patients) were analyzed. The correlation coefficient between VBQ and the lowest T value was -0.40 for male and -0.554 for female patients. In comparing the bone density sub- groups, among male patients a significant difference in the VBQ scores was observed only between the normal and osteoporosis subgroups (p = 0.012). VBQ demonstrated statistically significant differences among female patients across all three subgroups (p < 0.001). The ROC analysis revealed that the predictive performance of VBQ in detecting low BMD was more consistent with the gold -standard DEXA results in female than in male patients (AUC 0.647 vs AUC 0.823, p = 0.02). The optimal thresholds were similar in both sexes. CONCLUSIONS Compared with male patients, VBQ has better discrimination between female patients with low BMD and those with normal bone density. Although the correlation between VBQ and bone density is weaker in male than in female patients, the optimal thresholds are similar in both sexes.