Risk Of Subsidence Research Articles

Full-Endoscopic Posterior Lumbar Interbody Fusion: A Review and Technical Note

Remarkable innovations in spinal endoscopic surgery have broadened its applications over the past 20 years. Full-endoscopic fusions have been widely reported, and several full-endoscopic approaches for interbody fusion have been published. In general, full-endoscopic lumbar interbody fusion (LIF) is called Endo-LIF, and facet-preserving endo-LIF through the transforaminal route is called trans-Kambin’s triangle LIF, which has a relatively longer history than facet-sacrificing endo-LIF via the posterolateral route. Both approaches can reduce intraoperative and postoperative bleeding. However, there is a higher risk of subsidence and exit nerve root injury. There is no direct decompression in either of the interbody fusions, and additional decompression is required if there is severe lumbar bony canal stenosis. However, the posterior interlaminar approach, which is a well-known standard in full-endoscopic spine surgery, has rarely been applied in the field of endoscopic lumbar fusion surgery. Full-endoscopic posterior LIF (FE-PLIF) via an interlaminar approach can accomplish direct decompression of bony canal stenosis and safe interbody fusion. FE-PLIF via an interlaminar approach demonstrated a longer operation time, less blood loss, and shorter hospitalization duration than minimally invasive transforaminal LIF. FE-PLIF, which can accomplish direct decompression for bony spinal canal stenosis, is superior to other Endo-LIFs. However, FE-PLIF requires technical dexterity to improve efficiency and reduce technical complexity.

Radiographic fusion and subsidence rates for stand-alone cage versus anterior cage-plate construct in ACDF

Study DesignRetrospective cohort BackgroundThe addition of an anterior cervical plate to a structural allograft during ACDF is thought to provide extra stability and enhance fusion, but it may increase the risk of complications like dysphagia. Stand-alone cages were designed to provide this extra stability without the need for the plate, but these may increase a patient's risk of subsidence, cervical dislocation, and cervical kyphosis. The purpose of this study was to assess reoperation rates and radiographic outcomes during follow-up longer than 6 months for patients who underwent ACDF with a cage and plate compared to stand-alone cage. MethodsACDF cases were retrospectively identified for four fellowship trained spine surgeons from 2016 – 2020 from two academic hospitals. A total of 57 stand-alone structural allograft constructs were matched via propensity scoring with a cohort of 65 patients with plate-secured structural allograft constructs. The primary outcome was reoperation rate within the follow-up period and secondary outcomes included complications, operative characteristics, readmission within 30 days, reoperation within 30 days and within follow-up, and radiographic outcomes. Immediate post-operative radiographs were compared to final follow-up radiographs at least 6 months post-operation to assess for evidence of subsidence, fusion, and change in cervical kyphosis using the Cobb angle technique. ResultsThere were 5 patients (5.26 %) in the stand-alone cohort and 4 patients (3.15 %) in the plate cohort that had cervical reoperation at any time in follow-up (P = 0.83). At final follow-up, 58 patients (92.1 %) in the plate group and 37 patients (75.5 %) in the stand-alone group had radiographic evidence of fusion (P = 0.015). There were 38 patients (77.6 %) in the stand-alone group and 29 patients (46 %) in the plate group with evidence of subsidence (P = 0.0007). Patients with subsidence had a greater change in kyphosis angle at final follow-up and this change was significantly decreased in the plate group compared to the stand-alone group. ConclusionThe use of anterior cage-plate constructs in ACDF produces higher rates of fusion and lower rates of subsidence than stand-alone cage constructs. Subsidence significantly increases the change in kyphosis angle between post-op and final follow-up, and the presence of a spanning plate significantly reduces this angle change compared to stand-alone cages. There were no statistically significant differences in reoperation rates, regardless of radiographic evidence of subsidence.

New Axially Expandable Oblique Cage Designed for Anterior to Psoas (ATP) Approach: Indications-Surgical Technique and Clinical-Radiological Outcomes in Patients with Symptomatic Degenerative Disc Disease.

Background: Standard oblique cages cannot cover endplates side-to-side, which is an important biomechanical factor for reducing the risk of cage subsidence and for restoring correct segmental lordosis. The aim of this study is to evaluate the radiological and clinical results of a new oblique lumbar interbody fusion (OLIF) axially expandable cage. Methods: This is a prospective observational case-control study. From March 2018 to June 2020, 28 consecutive patients with lumbar degenerative disease underwent an ATP approach, with the insertion of a new axially expandable cage, which was used as a stand-alone procedure or followed by posterior percutaneous pedicle fixation. Results: Twenty-eight patients in both groups met the inclusion criteria. The mean follow-up time was 31.2 months (range of 13-37). The clinical results were not significantly different, although in the control group, two major intraoperative complications were recorded, and slight improvements in ODI and SF-36 scores were observed in the study group. The radiological results showed a less frequent incidence of subsidence and a higher rate of fusion in the study group compared to controls. Conclusions: The axially expandable oblique cage for lumbar inter body fusion, specifically designed for the ATP approach, represents an innovation and a technical improvement. The insertion and the axial expansion technique are safe and easy. The large footprint could obtain solid and effective arthrodesis, potentially reducing the risk of subsidence.

Can zoledronic acid reduce the risk of cage subsidence after oblique lumbar interbody fusion combined with bilateral pedicle screw fixation in the elderly population? A retrospective study

BackgroundThe objective of this study was to evaluate the potential of zoledronic acid for reducing the incidence of cage subsidence and enhancing interbody fusion rates following oblique lumbar interbody fusion (OLIF) surgery, particularly as the first reported evidence of the role of zoledronic acid combined with OLIF.MethodsA retrospective analysis was conducted on data from 108 elderly patients treated for degenerative lumbar diseases using OLIF combined with bilateral pedicle screw fixation from January 2018 to December 2021. Patients were divided into the zoledronic acid (ZOL) group (43 patients, 67 surgical segments) and the control group (65 patients, 86 surgical segments). A comparative analysis of the radiographic and clinical outcomes between the groups was performed, employing univariate and multivariate regression analyses to explore the relationships between cage subsidence and the independent variables.ResultsRadiographic outcomes, including anterior height, posterior height, disc height, coronal disc angle, foraminal height, and lumbar lordosis, were not significantly different between the two groups. Similarly, no statistically significant differences were noted in the back visual analog scale (VAS) scores and Oswestry Disability Index (ODI) scores between the groups. However, at the 1-year follow-up, the leg VAS score was lower in the ZOL group than in the control group (P = 0.028). The ZOL group demonstrated a notably lower cage subsidence rate (20.9%) than did the control group (43.0%) (P < 0.001). There was no significant difference in the interbody fusion rate between the ZOL group (93.0%) and the control group (90.8%). Non-use of zoledronic acid emerged as an independent risk factor for cage subsidence (OR = 6.047, P = 0.003), along with lower bone mineral density, lower postoperative anterior height, and concave endplate morphology. The model exhibited robust discriminative performance, with an area under the curve (AUC) of 0.872.ConclusionThe administration of zoledronic acid mitigates the risk of cage subsidence following OLIF combined with bilateral pedicle screw fixation in elderly patients; however, it does not improve the interbody fusion rate.

The Effect of Intraoperative Overdistraction on Subsidence Following Anterior Cervical Discectomy and Fusion.

Retrospective cohort. The purpose of this study was to evaluate the effect of overdistraction on interbody cage subsidence. Vertebral overdistraction due to the use of large intervertebral cage sizes may increase the risk of postoperative subsidence. Patients who underwent anterior cervical discectomy and fusion between 2016 and 2021 were included. All measurements were performed using lateral cervical radiographs at 3 time points - preoperative, immediate postoperative, and final follow-up >6 months postoperatively. Anterior and posterior distraction were calculated by subtracting the preoperative disc height from the immediate postoperative disc height. Cage subsidence was calculated by subtracting the final follow-up postoperative disc height from the immediate postoperative disc height. Associations between anterior and posterior subsidence and distraction were determined using multivariable linear regression models. The analyses controlled for cage type, cervical level, sex, age, smoking status, and osteopenia. Sixty-eight patients and 125 fused levels were included in the study. Of the 68 fusions, 22 were single-level fusions, 35 were 2-level, and 11 were 3-level. The median final follow-up interval was 368 days (range: 181-1257d). Anterior disc space subsidence was positively associated with anterior distraction (beta = 0.23; 95% CI: 0.08, 0.38; P = 0.004), and posterior disc space subsidence was positively associated with posterior distraction (beta = 0.29; 95% CI: 0.13, 0.45; P < 0.001). No significant associations between anterior distraction and posterior subsidence (beta = 0.07; 95% CI: -0.06, 0.20; P = 0.270) or posterior distraction and anterior subsidence (beta = 0.06; 95% CI: -0.14, 0.27; P = 0.541) were observed. We found that overdistraction of the disc space was associated with increased postoperative subsidence after anterior cervical discectomy and fusion. Surgeons should consider choosing a smaller cage size to avoid overdistraction and minimize postoperative subsidence.

The Community’s Understanding and Responses Regarding Land Subsidence, Waterlogging, and the Link Between the Two in Rural South-western Coastal Bangladesh

Land subsidence has triggered severe waterlogging problems in the southwestern coastal zone of Bangladesh, which affects the biodiversity as well as people’s lives, and livelihoods. The members of the affected community, however, appear to have a poor understanding of the nature of land subsidence and its consequences. This study, therefore, aims to assess the community members’ understanding of as well as the actions that they take to solve problems of this nature in the rural, southwestern coastal zone of Bangladesh. A qualitative comparative case study approach was employed in this study, where two rural communities from the southwestern coastal districts were selected as the cases. By subjecting the data to thematic analysis, the study found that, although a few civil society members and activists are, to some extent, aware of the occurrence of land subsidence and its linkage with waterlogging, however, most of the members of the communities lack adequate knowledge or an understanding about the nature, causes and consequences of the land subsidence issue and its connection to the waterlogging problem in their locality. Thus, it was found that they take no or very few measures to cope with the risk of land subsidence. The study’s findings imply that the policymakers should formulate a strategy for making the members of the community aware of the nature, causes, and consequences of land subsidence issues.

Quantifying land subsidence and its nexus with groundwater depletion in isfahan-borkhar plain: An integrated approach using radar interferometry and spatial bivariate relationships

Land subsidence has emerged as a significant global concern, particularly in arid regions like Iran. Among these vulnerable areas, the Isfahan-Borkhar plain stands out due to its strategic importance and critical high-population settlements. In this study, we focus specifically on land subsidence within this plain. This study specifically examines land subsidence in this plain. Utilizing the precise radar interferometry technique, considered the most accurate method, this study investigates the vertical changes of the Earth's surface in the Isfahan-Borkhar plain between 2015 and 2022 by analyzing Sentinel-1 satellite data. To establish causality, we correlate these subsidence patterns with spatial water extraction data, employing a spatial bivariate relationship model. The results obtained from this seven-year monitoring period reveal that average annual subsidence in different areas of the Isfahan-Borkhar plain ranges from 25 to 45 cm, while the average annual decline in the water table in this aquifer is 230 cm. The pronounced subsidence observed aligns with areas experiencing the highest water level decline, emphasizing the critical role of water table depletion. In summary, our study underscores the need for sustainable water management practices to mitigate land subsidence risks in this strategically vital region.

Risk assessment of land subsidence based on GIS in the Yongqiao area, Suzhou City, China.

This study focuses on the Yongqiao District in Suzhou City, Anhui Province, China, aiming to analyze the current situation of ground settlement and its influencing factors in the area. The selected risk indices include settlement rate, cumulative settlement amount, groundwater level drop funnel, thickness of loose sediment layer, thickness of soft soil layer, and the number of groundwater extraction layers. Additionally, vulnerability indices such as population density, building density, road traffic, and functional zoning are considered. An evaluation index system for assessing land Subsidence risk was established. The risk evaluation of land Subsidence was conducted using the Hierarchical analysis-composite index method and ArcGIS spatial analysis, The evaluation results show that the area of higher risk area is about 2.82 km2, accounting for 0.96% of the total area, mainly distributed in the area of Jiuli village, Sanba Street. The middle risk area is distributed around the higher area, with an area of about 9.18 km2, accounting for 3.13% of the total area. The lower risk areas were distributed in most of the study area, covering an area of 222.24 km2, accounting for 75.82% of the total area. The low risk assessment area is mainly distributed in Bianhe Street and part of Zhuxianzhuang Town, with an area of about 58.88 km2, accounting for 20.09% of the total area. The findings of this study are not only crucial for informing local policies and practices related to land use planning, infrastructure development, and emergency response but also enhance our understanding of the complexities of land Subsidence processes and their interactions with human activities, informing future research and practice in environmental risk assessment and management.

Subchondral rafting wires reduce tibial plateau fracture subsidence

PurposeTo determine if subchondral rafting wires retained as adjunctive tibial plateau fracture fixation affect postoperative articular subsidence.MethodsA retrospective cohort study was conducted at one Level 1 trauma center and one academic university hospital. Consecutive adults with closed, displaced OTA/AO 41B/C tibial plateau fractures treated between 2018 and 2023 with open reduction internal fixation were included. Patients who were not ambulatory, with contralateral injuries limiting weight bearing, and without follow-up radiographs of the injured extremity were excluded. The intervention was retention of subchondral rafting wires as definitive fixation. The primary outcome was linear articular surface subsidence between postoperative and follow-up AP knee radiographs. Linear subsidence was compared between groups using Welch’s two sample t test. Associations of linear subsidence with patient, injury, and treatment characteristics were assessed by multivariable linear regression.ResultsWe identified 179 patients of a mean age of 44 ± 14 years, of whom 15 (8.4%) received subchondral rafting wires. Median follow-up was 121 days. No patients who received rafting wires as definitive implants experienced linear subsidence ≥ 2 mm, while 22 patients (13.4%) who did not receive rafting wires experienced linear subsidence ≥ 2 mm (p = 0.130). Subchondral rafting wires were associated with less linear subsidence (0.3 mm [95% confidence interval − 0.3–0.9 mm] vsersus 1.0 mm [− 0.9–2.9 mm], p < 0.001). The depth of linear subsidence was significantly associated on multivariable regression with male sex, depressed plateau area, active smoking, and retained rafting wires.ConclusionSubchondral rafting wires were associated with a small reduction in articular subsidence after internal fixation of tibial plateau fractures. Routine rafting wires may be useful for patients and fractures at high risk of articular subsidence.

Advanced risk assessment framework for land subsidence impacts on transmission towers in salt lake region

To ensure the continuous transmission of clean energy for electricity, transmission towers often traverse geologically challenging terrains. This is particularly evident in the Salt Lake region, where the convergence of unique geological attributes and environmental stressors leads to recurrent land subsidence incidents, jeopardizing the integrity of power lines. In light of the prohibitive costs associated with indiscriminate remedial actions, precision in risk assessment and management is imperative to streamline these interventions. The objective of this study is to propose an accurate and effective framework for assessing the risk of land subsidence for power transmission towers. To achieve this, by utilizing the Small Baseline Subset Interferometric Synthetic Aperture Radar (SBAS-InSAR) technology and cross-validation from field investigations, representative sample disaster datasets of surface deformation points of transmission towers are obtained in the first. Two optimization approaches for susceptibility modeling were employed to further enhance the susceptibility model for land subsidence and obtain high-precision susceptibility results along the transmission towers. Then, combined on-site damage investigation with SBAS-InSAR technology to conduct subsidence vulnerability analysis of transmission towers. Finally, the ultimate outcome of this process was the development of a risk assessment matrix based on spatial probability (susceptibility) and damage scales (vulnerability), aimed at more accurately assessing land subsidence risk. This framework could identify the spatial distribution of subsidence susceptibility in transmission towers exposed to potential damage, which could be followed by a more detailed transmission tower-based vulnerability and risk assessment. The method has been successfully applied in the Salt Lake area, and the susceptibility results based on the Grey Wolf Optimization-Random Forest (GW0-RF) model have shown the best modeling effect, and the area under of receiver operating characteristic curve (AUC) = 0.95. The vulnerability results show that 105 towers have been most severely damaged by land subsidence The risk distribution map shows that the central part of the Salt Lake area is the core zone for future land subsidence risk management. A total of 101 towers are in the high and very high risk level. The insights garnered from this investigation furnish a comprehensive understanding of the risk landscape for transmission towers, underpinning future-focused design, planning, and management strategies.

MRI Vertebral Bone Quality Correlates With Interbody Cage Subsidence After Anterior Cervical Discectomy and Fusion.

Retrospective observational study of consecutive patients. The purpose of the study was to evaluate VBQ as a predictor of interbody subsidence and to determine threshold values that portend increased risk of subsidence. Many risk factors have been reported for the subsidence of interbody cages in anterior cervical discectomy and fusion (ACDF). MRI Vertebral Bone Quality (VQB) is a relatively new radiographic parameter that can be easily obtained from preoperative MRI and has been shown to correlate with measurements of bone density such as DXA and CT Hounsfield Units. All patients who underwent 1- to 3-level ACDF using titanium interbodies with anterior plating between the years 2018 and 2020 at our tertiary referral center were included. Subsidence measurements were performed by 2 independent reviewers on CT scans obtained 6 months postoperatively. VBQ was measured on pre-operative sagittal T1 MRI by 2 independent reviewers, and values were averaged. Eight-five fusion levels in 44 patients were included in the study. There were 32 levels (38%) with moderate subsidence and 12 levels with severe subsidence (14%). The average VBQ score in those patients with severe subsidence was significantly higher than those without subsidence (3.80 vs. 2.40, P<0.01). A threshold value of 3.2 was determined to be optimal for predicting subsidence (AUC=0.99) and had a sensitivity of 100% and a specificity of 94.1% in predicting subsidence. VBQ strongly correlates with the subsidence of interbody grafts after ACDF. A threshold VBQ score value of 3.2 has excellent sensitivity and specificity for predicting subsidence. Spine surgeons can use VBQ as a readily available screening tool to identify patients at higher risk for subsidence. Level-IV.

Biomechanical analysis of 3D printed porous extremely-low modulus Ti-24Nb-4Zr-8Sn lumbar interbody fusion cage-A finite element study

ABSTRACT This study aimed to design and assess the biomechanical properties of a 3D-printed porous titanium alloy lumbar fusion cage, comparing it to traditional PEEK cages in lumbar PLIF surgery using finite element modelling. Employing Ti-24Nb-4Zr-8Sn (Ti2448) and Ti-6Al-4 V (Ti64) materials via EBM-3D printing, the fabricated cage exhibited enhanced mechanical stability when paired with the same internal fixation system. Biomechanical analysis revealed superior performance of both Ti2448 and Ti64 porous models over PEEK, notably Ti2448. These porous titanium cages effectively mitigate maximum stress at the cage-endplate interface, ensuring uniform stress distribution and minimizing subsidence risk. Additionally, their porous structure fosters osteogenesis, while the low modulus titanium alloy, resembling human cancellous bone, enhances interbody fusion and diminishes the probability of cage subsidence.

Single-Stage Lateral Anterior-to-Psoas Interbody Fusion and Facet Screws as a Treatment for L5–S1 Adjacent Segment Disease in a Patient With a Long-Segment Construct

Objective: Adjacent segment disease (ASD) occurs in 9% of patients with long-segment lumbar spine fusion and results from the transmission of a greater degree of stress to the segments cranial and caudal to a fused segment. The treatment of symptomatic ASD typically involves extending fusion to the involved segment. Revision and extension of posterior instrumentation bears the disadvantage of involving the exposure and modification of old hardware. Lateral interbody fusion cannot be performed at L5/S1 due to the iliac crest. Anterior lumbar interbody fusion typically still requires flipping the patient to augment the construct posteriorly. Here, we present a method to treat L5/S1 ASD using single-position anterior-to-psoas (ATP) interbody fusion combined with facet screw instrumentation.Methods: An 80-year-old man, who had undergone L2-5 fusion 27 years ago, presented with persistent lower back pain and gait dysfunction with imaging findings of L5/S1 spondylosis and ASD. Under intraoperative computed tomography navigation, left L5/S1 ATP interbody fusion was performed with simultaneous L5/S1 percutaneous facet screw fixation. Results: The abdominal incision was 4.0 cm and the single posterior incision was 1.5 cm long. Blood loss was lower than 10 mL, and the procedure lasted for less than 1.5 hours. The patient was discharged to rehabilitation after 3 days.Conclusion: ATP interbody fusion enabled the placement of an interbody device with a large footprint to promote fusion and reduce the risk of subsidence and pseudoarthrosis. The combined use of interbody fusion and facet screws obviates the need to link to the previous construct.

A Comparison of 2 Cage Sizes in Biportal Endoscopic Transforaminal Lumbar Interbody Fusion.

Retrospective study. This study compared the fusion and subsidence rate and clinical outcomes when using different-sized static PEEK cages in BE-TLIF. Biportal endoscopic techniques for transforaminal lumbar interbody fusion (BE-TLIF) have been shown to have similar clinical and fusion outcomes with faster clinical recovery in comparison to tubular surgery. Subsidence of the interbody, however, could be a complication. Patients who underwent 1 or 2 level BE-TLIF for degenerative and isthmic spondylolisthesis between January 2019 and January 2022 were included. A 32×10mm cage (group A) and a 40×15mm cage (group B) were compared. The visual analog scale (VAS) for back and leg symptoms, and Oswestry disability index (ODI) were collected. Plain radiographs and computed tomography assessed fusion and subsidence at a minimum of 12 months. Of the 69 enrolled patients, 39 group A patients (51 levels) and 30 group B patients (32 levels) were compared. The operation time per level was 123 ± 15.8 and 138 ± 10.5 minutes per fusion level in groups A and B, respectively (P < 0.05). ODI improved from 64.8 ± 6.2 to 15.7 ± 7.1 in group A and from 65.3 ± 5.6 to 15.1 ± 6.3 in group B at the final follow-up (P < 0.05). VAS leg and back score improvement between the groups did not differ; however, the 3-month postoperative VAS back improvement was significantly higher in group B. The final fusion rate at the final follow-up did not significantly differ; however, the fusion ratio at 1 year was higher in group B (P < 0.05). Subsidence occurred in 5 cases (9.8%) in group A and none in group B (P < 0.05). BE-TLIF using a larger cage can be performed safely with similar patient-reported outcome measures with a faster fusion rate with less subsidence risk. III.

Applying an Analytic Hierarchy Process and a Geographic Information System for Assessment of Land Subsidence Risk Due to Drought: A Case Study in Ca Mau Peninsula, Vietnam

The increase in extreme weather events causes secondary hazards that can influence people and the environment enormously. The Ca Mau Peninsula is known as one of the areas most severely affected by drought, and excessive groundwater exploitation is one of the reasons leading to a higher risk of land subsidence. This study uses the Delphi method and the KAMET rule table to analyze and select indicators that affect subsidence. The study uses the analytic hierarchy process (AHP) analytical hierarchy method to evaluate the weights of influencing factors, combined with geographic information system (GIS) technology to overlay the map layers of the main influencing factors and build a subsidence risk warning zoning map of the study area. The influencing factors selected to evaluate the impact on land subsidence in the study area during the drought period included geological structure, soil characteristics, groundwater flow exploitation, water flow in the dry season, current land use status, and evaporation in the dry season. The weights of these factors were evaluated based on the synthesis of relevant documents as well as consultation with experts. The results indicate that nearly two-thirds of the Ca Mau Peninsula area is currently at very low or low risk of subsidence. Meanwhile, 23% of the area is at medium risk, nearly 9% is at high risk, and 0.1% of the study area is at very high risk. Subsidence risk warning zoning maps can provide a visual and general overview of areas with high subsidence risk, supporting managers in making reference plans for socio-economic development in the Ca Mau Peninsula.

Ground Subsidence, Driving Factors, and Risk Assessment of the Photovoltaic Power Generation and Greenhouse Planting (PPG&amp;GP) Projects in Coal-Mining Areas of Xintai City Observed from a Multi-Temporal InSAR Perspective

In recent years, photovoltaic power generation and greenhouse planting (PPG&amp;GP) have become effective approaches for reconstructing and restoring the ecological environment of old coal-mining industry bases, such as Xintai City. However, the ecological impacts or improvements of the PPG&amp;GP projects and their daily operations on the local environment are still unclear. To solve these problems, this study retrieved the ground deformation velocities and time series of the study region by performing the Small-Baseline Subset (SBAS)-Interferometric Synthetic Aperture Radar (InSAR) technique on the Advanced Land Observing Satellite (ALOS) PALSAR and Sentinel-1 SAR datasets. With these deformation results, the spatial analysis indicated that the area of the subsidence region within the PPG&amp;GP projects reached 10.70 km2, with a magnitude of approximately −21.61 ± 12.10 mm/yr. Also, even though the ground deformations and their temporal changes were both visible in the construction and operation stages of the PPG&amp;GP projects, the temporal analysis demonstrated that most observation points finally entered into the stationary phases in the late stage of the observation period. This phenomenon validated the effectiveness of the PPG&amp;GP projects in enhancing the ground surface stability in coal-mining areas. Additionally, the precipitation, geological structure, increased coal-mining depths, and emergent agricultural modes were assumed to be the major impact factors controlling the ground deformation within the local PPG&amp;GP projects. Finally, a novel risk assessment method with a designed index of IRA was utilized to classify the ground subsidence risks of the PPG&amp;GP projects into three levels: Low (69.7%), Medium (16.9%), and High (9.4%). This study sheds a bright light on the ecological monitoring and risk management of the burgeoning industrial and agricultural infrastructures, such as the PPG&amp;GP projects, constructed upon the traditional coal-mining areas in China from a multi-temporal InSAR perspective.

Evaluation and prediction of compound geohazards in highly urbanized regions across China's Greater Bay Area

Natural hazards could have devastating consequences globally, making hazard assessment and spatial prediction crucial for enhancing the resilience of urbanized regions. However, current disaster prediction and assessment research often neglect the compound effects between multiple geohazards highly in urbanized regions. To address the concern, we employed comparative methodology, evaluating four machine learning algorithms—Extreme Gradient Boosting (XGBoost), Random Forest (RF), Back Propagation Neural Network (BP), and Long Short-Term Memory (LSTM)—in the creation of Geohazard Susceptibility Maps (GSM) for the highly urbanized Guangdong-Hong Kong-Macao Greater Bay Area (GBA). Additionally, the study investigated the triggering mechanisms and the compound interaction between multiple geohazards using the conditional vine copula model. The results showed that the XGBoost model outperformed other models (AUC = 0.89) for predicting multiple geohazards. Geohazards were predominantly concentrated in urban areas in the GBA, with surface subsidence being the most severe, followed by collapse and landslide. The primary triggers for multi-geohazards include distance to roads, slope length, and lithology, with slope length and lithology identified as the primary causative factors in urban areas. Urbanization within the GBA increased the probability of multi-geohazards by 10%, compared to their univariate counterparts. Urban regions exhibited increased risks of landslides, surface subsidence, and collapse by approximately 31%, 44%, and 32%, respectively compared to non-urban regions. Additionally, compound geohazards in the GBA were primarily triggered by heavy rainfall, resulting in the formation of landslide-collapse and collapse-landslide geohazard chains. The probability of compound geohazards is approximately 5% lower than that of univariate geohazards. This is because compound geohazards necessitate a higher cumulative rainfall, and the rainfall threshold was approximately 2–3 times higher than that of univariate geohazards. In the cascading hazard pattern, the occurrence of primary geohazards during local heavy rain increased the probability of secondary geohazards by approximately 10%. The study provides essential insights for mitigating compound geohazards in urbanized areas.

Distal Radius Fracture Subsidence after Nonoperative Treatment

Abstract Background Our primary aim was to identify risk factors for subsidence development in nonoperatively treated distal radius fractures (DRFs). Secondary aims of the study included comparisons of subsidence progression over time with respect to DRF radiographic parameters. Methods A retrospective cohort study of 70 patients with DRFs treated nonoperatively and followed for a minimum of 12 weeks was performed. Of the 70 patients, 29 had subsidence and 41 did not have subsidence. Radiographic measurements assessed the radial height (RH), ulnar variance (UV), volar tilt (VT), and radial inclination (RI). Outcome measures included demographics, injury characteristics, closed reduction, and radiographic measurements. Results Nearly 95% of DRF subsidence occurred within the first 6 weeks after nonoperative treatment. The mean age of the 41 patients without DRF subsidence was 57.6 ± 16.8 years, and 31/41 (76%) patients were females. Conversely, the mean of the 29 patients with DRF subsidence was 63.8 ± 17.5 years, and 22/29 (76%) patients were females. Fractures requiring closed reduction were associated with more overall subsidence (p = 0.0009) and subsidence within the first 2 weeks posttreatment. Type C and comminuted fractures were associated with DRF subsidence (p = 0.02 and 0.01, respectively). The initial radiographic parameters and step-off measures were not associated with a higher risk of subsidence (p ≥ 0.05). Significant differences between subsidence progressions with respect to RH, UV, VT, and RI were observed. Conclusion Most DRF subsidence occurs within the first 6 weeks of nonoperative treatment. Closed reduction, comminution, and AO fracture type are predictors of subsidence development. Moreover, DRF subsidence progresses at different rates depending on the radiographic parameter assessed.

The Role of Bone Mineral Density in a Successful Lumbar Interbody Fusion: A Narrative Review.

The incidence of osteoporosis is a prime concern, especially in parts of the world where the population is aging, such as Europe or the US. Many new therapy strategies have been described to enhance bone healing. Lumbar interbody fusion (LIF) is a surgical procedure that aims to stabilize the lumbar spine by fusing two or more vertebrae using an interbody cage. LIF is a standard treatment for various spinal conditions, such as degenerative disc disease, spinal stenosis, and spondylolisthesis. However, successful fusion is challenging for patients with osteoporosis due to their reduced bone mineral density (BMD) and increased risk of cage subsidence, which can lead to implant failure and poor clinical outcomes. A comprehensive literature search yielded 220 articles, with 16 ultimately included. Keywords included BMD, cage subsidence, osteoporosis, teriparatide, and lumbar interbody fusion. This review examines the relationship between BMD and LIF success, emphasizing the importance of adequate bone quality for successful fusion. Preoperative assessment methods for BMD and the impact of low BMD on fusion rates and patient outcomes are discussed. Additionally, techniques to improve fusion success in patients with weakened bone density, such as biological enhancement and BMD-matched interbody cages, are explored. However, consensus on the exact BMD threshold for a successful outcome remains elusive. While an apparent correlation between BMDand fusion rate in LIFprocedures is acknowledged, conclusive evidence regarding the precise BMD threshold indicative of an increased risk of unfavorable outcomes remains elusive.Surgeons are advised to exercise caution in surgical planning and follow-up for patients with lower BMD.Furthermore, future research initiatives, particularly longitudinal studies, are encouraged to prioritize the examination of BMD as a fundamental risk factor, addressing gaps in the literature.

Impact of Implant Size and Position on Subsidence Degree after Anterior Cervical Discectomy and Fusion: Radiological and Clinical Analysis.

Implant subsidence is recognized as a complication of interbody stabilization, although its relevance remains ambiguous, particularly in terms of relating the effect of the position and depth of subsidence on the clinical outcome of the procedure. This study aimed to evaluate how implant positioning and size influence the incidence and degree of subsidence and to examine their implications for clinical outcomes. An observational study of 94 patients (157 levels) who underwent ACDF was conducted. Radiological parameters (implant position, implant height, vertebral body height, segmental height and intervertebral height) were assessed. Clinical outcomes were evaluated using the Visual Analogue Scale (VAS) and Neck Disability Index (NDI). Subsidence was evaluated in groups according to its degree, and statistical analyses were performed. The findings revealed that implant-to-endplate ratio and implant height were significant risk factors associated with the incidence and degree of subsidence. The incidence of subsidence varied as follows: 34 cases (41.5%) exhibited displacement of the implant into the adjacent endplate by 2-3 mm, 32 cases (39%) by 3-4 mm, 16 cases (19.5%) by ≥4 mm and 75 (47.8%) cases exhibited no subsidence. The findings underscore that oversized or undersized implants relative to the disc space or endplate length elevate the risk and severity of subsidence.