Subsidence Rates Research Articles

Unveiling the Global Extent of Land Subsidence: The Sinking Crisis

AbstractLand subsidence, referring to the vertical sinking of land surface, is a significant geohazard posing serious risks to security of infrastructure, natural resources, built environment, and businesses in numerous places worldwide. Using deep learning approaches combined with more than 46,000 subsidence data, we predicted global land subsidence based on 23 environmental parameters. The generated global map of land subsidence covers historically documented and new subsiding areas. We estimate that more than 6.3 million square kilometers of the global land is influenced by significant subsidence rates. That includes 231,000 square kilometers of urban and dense settlement areas and a population of nearly 2 billion. The model revealed a positive correlation between the intensity of groundwater abstraction and the subsidence rate. Our results offer new insights regarding potential hotspots of land subsidence and provide the information required to devise necessary action plans and develop effective policies to mitigate this growing challenge worldwide.

Biomechanical Comparison of Anterior Cervical Corpectomy Decompression and Fusion, Anterior Cervical Discectomy and Fusion, and Anterior Controllable Antedisplacement and Fusion in the Surgical Treatment of Multilevel Cervical Spondylotic Myelopathy: A Finite Element Analysis.

Multilevel cervical spondylotic myelopathy poses significant challenges in selecting optimal surgical approaches, warranting a comprehensive understanding of their biomechanical impacts. Given the lack of consensus regarding the most effective technique, this study aims to fill this critical knowledge gap by rigorously assessing and comparing the biomechanical properties of three distinct surgical interventions, including anterior controllable antedisplacement and fusion (ACAF), anterior cervical corpectomy decompression and fusion (ACCF), and anterior cervical discectomy and fusion (ACDF). The study offers pivotal insights to enhance treatment precision and patient outcomes. The construction of the cervical spine model involved a detailed process using CT data, specialized software (Mimics, Geomagic Studio, and Hypermesh) and material properties obtained from prior studies. Surgical instruments were modeled (titanium mesh, anterior cervical plate, interbody cage, and self-tapping screws) to simulate three surgical approaches: ACAF, ACCF, and ACDF, each with specific procedures replicating clinical protocols. A 75-N follower load with 2 Nm was applied to simulate biomechanical effects. The range of motion decreased more after surgery for ACAF and ACDF than for ACCF, especially in flexion and lateral bending. ACCF have higher stress peaks in the fixation system than those of ACAF and ACDF, especially in flexion. The maximum von Mises stresses of the bone-screw interfaces at C3 of ACCF were higher than those of ACAF and ACDF. The maximum von Mises stresses of the bone-screw interfaces at C6 of ACDF were much higher than those of ACAF and ACCF. The maximum von Mises stresses of the grafts of ACCF and ACAF were much higher than those of ACDF. The maximum von Mises stresses of the endplate of ACCF were much higher than those of ACAF and ACDF. The ACAF and ACDF models demonstrated superior cervical reconstruction stability over the ACCF model. ACAF exhibited lower risks of internal fixation failure and cage subsidence compared to ACCF, making it a promising approach. However, while ACAF revealed improved stability over ACCF, higher rates of subsidence and internal fixation failure persisted compared to ACDF, suggesting the need for further exploration of ACAF's long-term efficacy and potential improvements in clinical outcomes.

Comparison of instrumented and stand-alone lateral lumbar interbody fusion for lumbar degenerative disease: a systematic review and meta-analysis

BackgroundBoth instrumented and stand-alone lateral lumbar interbody fusion (LLIF) have been widely used to treat lumbar degenerative disease. However, it remains controversial as whether posterior internal fixation is required when LLIF is performed. This meta-analysis aims to compare the radiographic and clinical results between instrumented and stand-alone LLIF.MethodsPubMed, EMBASE and Cochrane Collaboration Library up to March 2023 were searched for studies that compared instrumented and stand-alone LLIF in the treatment of lumbar degenerative disease. The following outcomes were extracted for comparison: interbody fusion rate, cage subsidence rate, reoperation rate, restoration of disc height, segmental lordosis, lumbar lordosis, visual analog scale (VAS) scores of low-back and leg pain and Oswestry Disability Index (ODI) scores.Results13 studies involving 1063 patients were included. The pooled results showed that instrumented LLIF had higher fusion rate (OR 2.09; 95% CI 1.16–3.75; P = 0.01), lower cage subsidence (OR 0.50; 95% CI 0.37–0.68; P < 0.001) and reoperation rate (OR 0.28; 95% CI 0.10–0.79; P = 0.02), and more restoration of disc height (MD 0.85; 95% CI 0.18–1.53; P = 0.01) than stand-alone LLIF. The ODI and VAS scores were similar between instrumented and stand-alone LLIF at the last follow-up.ConclusionsBased on this meta-analysis, instrumented LLIF is associated with higher rate of fusion, lower rate of cage subsidence and reoperation, and more restoration of disc height than stand-alone LLIF. For patients with high risk factors of cage subsidence, instrumented LLIF should be applied to reduce postoperative complications.

Comparing Outcomes of Banana-Shaped and Straight Cages in Transforaminal Lumbar Interbody Fusion for Lumbar Degenerative Diseases: A Systematic Review and Meta-Analysis.

This meta-analysis aims to refine the understanding of the optimal choice between different cage shapes in transforaminal lumbar interbody fusion (TLIF) by systematically comparing perioperative data, radiological outcomes, clinical results, and complications associated with banana-shaped and straight bullet cages. A meticulous literature search encompassing PubMed, Embase, Scopus, Web of Science, China Knowledge Network, and Wanfang Data was executed up to October 5, 2023. Inclusion criteria focused on studies comparing banana-shaped and straight bullet cages in TLIF. The quality of included studies was assessed using appropriate tools such as the Newcastle-Ottawa Scale (NOS) for nonrandomized studies. Rigorous evaluations were performed for radiographic outcomes, including disc height (DH), segmental lordosis (SL), lumbar lordosis (LL), subsidence, and fusion rates. Clinical outcomes were meticulously evaluated using visual analogue scale (VAS), Oswestry Disability Index (ODI), and complications. The analysis incorporated 7 studies, involving 573 patients (297 with banana-shaped cages, 276 with straight cages), all with NOS ratings exceeding 5 stars. No statistically significant differences were observed in operative time, blood loss, or hospitalization between the 2 cage shapes. Banana-shaped cages exhibited greater changes in DH (p = 0.001), SL (p = 0.02), and LL (p = 0.01). Despite statistically higher changes in ODI for straight cages (26.33, p < 0.0001), the actual value remained similar to banana-shaped cages (26.15). Both cage types demonstrated similar efficacy in VAS, complication rates, subsidence, and fusion rates. Although banana-shaped cages can excel in restoring DH, SL, and LL, straight bullet cages can provide comparable functional improvements, pain relief, and complication rates.

Evaluation of the Neogene depositional dynamics in the Malay-Tho Chu Basin based on seismic analysis: effects of local and regional tectonism and paleoclimatic variations

Depositional environments in areas located near sea level are vulnerable to even subtle changes in both tectonism, climate and eustatic sea level. Sorting out mechanisms behind depositional changes in inner shelf-margins and epeiric seas is therefore far from straight forward. The epeiric Malay-Tho Chu Basin, located in the shallow Gulf of Thailand offshore Vietnam, contains a thick uppermost Oligocene to Recent post-rift succession. Based on 18000 km of 2D seismic profiles, the uppermost Oligocene-Recent succession is subdivided into six seismic sequences. Seismic facies mapping of each sequence complemented by information from industry completion reports of 14 wells document a gradual increase in marine influence from latest Oligocene through Middle Miocene time. The increased marine influence reflects the propagation and opening of the southwestern spreading arm of the East Vietnam Sea (South China Sea (East Sea)) combined with rapid subsidence in the Malay-Tho Chu Basin resulting from fast thermal relaxation following Oligocene rifting and amplified by mild fault-controlled subsidence in especially the western part of the area. From the latest Middle Miocene, slowed subsidence and regression occurred in association with uplift in the nearby southwestern East Vietnam Sea. From the latest Miocene, and during the Pliocene and Pleistocene, subsidence rates increased promoting marine conditions towards the East Vietnam Sea in the southeast. Meanwhile, Mekong River avulsion combined with hinterland uplift stimulated fluvial and alluvial deposition in the northern and western parts of the basin. The long-term depositional pattern was controlled primarily by tectonics, drainage evolution and climate. Meanwhile, flood- and delta plain deposits intercalated with stacked fluvial incisions, often filled by estuarine deposits, document short-lived environmental changes most likely controlled by eustatic sea level fluctuations. Such intervals developed during latest Middle Miocene to Pleistocene periods of slow subsidence or fast depositional rates and are interpreted to be the result of substantial eustatic sea level fluctuations.

A Comparison between Structural Allografts and Polyetheretherketone Interbody Spacers Used in Anterior Cervical Discectomy and Fusion: A Systematic Review and Meta-analysis.

Among interbody implants used during anterior cervical discectomy and fusion (ACDF), structural allografts and polyetheretherketone (PEEK) are the most used spacers. Currently, no consensus has been established regarding the superiority of either implant, with US surgeons preferring structural allografts, whereas UK surgeons preferring PEEK. The purpose of this systematic review (level of evidence, 4) was to compare postoperative and patient-reported outcomes between the use of structural allografts PEEK interbody spacers during ACDF. Five electronic databases (PubMed, Embase, Scopus, Web of Science, and Cochrane) were searched for articles comparing the usage of structural allograft and PEEK interbody spacers during ACDF procedures from inception to April 10, 2023. The searches were conducted using the keywords "Spine," "Allograft," and "PEEK" and were performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. Subsequent quality and sensitivity analyses were performed on the included studies. Nine studies involving 1,074 patients were included. Compared with the PEEK group, the structural allograft group had comparable rates of postoperative pseudoarthrosis (p=0.58). However, when stratified according to the number of levels treated, the 3-level ACDF PEEK group was 3.45 times more likely to have postoperative pseudoarthrosis than the structural allograft group (p=0.01). Subsequent postoperative outcomes (rate of subsidence and change in the preoperative and postoperative segmental disc heights) were comparable between the PEEK and structural allograft groups. Patient-reported outcomes (Visual Analog Scale [VAS] of neck pain and Neck Disability Index [NDI]) were comparable. This study showed that for 3-level ACDFs, the use of structural allografts may confer higher fusion rates. However, VAS neck pain, NDI, and subsidence rates were comparable between structural allografts and PEEK cages. In addition, no significant difference in pseudoarthrosis rates was found between PEEK cages and structural allografts in patients undergoing 1- and 2-level ACDFs.

A Comparison between Structural Allografts and Polyetheretherketone Interbody Spacers Used in Anterior Cervical Discectomy and Fusion: A Systematic Review and Meta-analysis.

Among interbody implants used during anterior cervical discectomy and fusion (ACDF), structural allografts and polyetheretherketone (PEEK) are the most used spacers. Currently, no consensus has been established regarding the superiority of either implant, with US surgeons preferring structural allografts, whereas UK surgeons preferring PEEK. The purpose of this systematic review (level of evidence, 4) was to compare postoperative and patient-reported outcomes between the use of structural allografts PEEK interbody spacers during ACDF. Five electronic databases (PubMed, Embase, Scopus, Web of Science, and Cochrane) were searched for articles comparing the usage of structural allograft and PEEK interbody spacers during ACDF procedures from inception to April 10, 2023. The searches were conducted using the keywords "Spine," "Allograft," and "PEEK" and were performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. Subsequent quality and sensitivity analyses were performed on the included studies. Nine studies involving 1,074 patients were included. Compared with the PEEK group, the structural allograft group had comparable rates of postoperative pseudoarthrosis (p=0.58). However, when stratified according to the number of levels treated, the 3-level ACDF PEEK group was 3.45 times more likely to have postoperative pseudoarthrosis than the structural allograft group (p=0.01). Subsequent postoperative outcomes (rate of subsidence and change in the preoperative and postoperative segmental disc heights) were comparable between the PEEK and structural allograft groups. Patient-reported outcomes (Visual Analog Scale [VAS] of neck pain and Neck Disability Index [NDI]) were comparable. This study showed that for 3-level ACDFs, the use of structural allografts may confer higher fusion rates. However, VAS neck pain, NDI, and subsidence rates were comparable between structural allografts and PEEK cages. In addition, no significant difference in pseudoarthrosis rates was found between PEEK cages and structural allografts in patients undergoing 1- and 2-level ACDFs.

Myth or fact: 3D-printed off-the-shelf prosthesis is superior to titanium mesh cage in anterior cervical corpectomy and fusion?

BackgroundTo find out if three-dimensional printing (3DP) off-the-shelf (OTS) prosthesis is superior to titanium mesh cages in anterior cervical corpectomy and fusion (ACCF) when treating single-segment degenerative cervical spondylotic myelopathy (DCSM).MethodsDCSM patients underwent ACCF from January 2016 to January 2019 in a single center were included. Patients were divided into the 3DP group (28) and the TMC group (23). The hospital stays, operation time, intraoperative blood loss, and the cost of hospitalization were compared. The Japanese Orthopedic Association (JOA) scores and Neck Disability Index (NDI) were recorded pre-operatively, 1 day, 3, 6, 12, and 24 months post-operatively. Radiological data was measured to evaluate fusion, subsidence, and cervical lordosis. Patients were sent with SF-36 to assess their health-related quality of life (HRQoL).ResultsThe differences in operative time, intraoperative blood loss, and hospital stay were not statistically significant between groups (p > 0.05). Postoperative dysphagia occurred in 2 cases in the 3DP group and 3 cases in the TMC group, which all relieved one week later. The difference in improvement of JOA and NDI between the two groups was not statistically significant (p > 0.05). No hardware failure was found and bony fusion was achieved in all cases except one in the 3DP group. The difference in cervical lordosis (CL), fused segmental angle (FSA), mean vertebral height (MVH), and subsidence rates between groups at each follow-up time point was not statistically significant and the results of the SF-36 were similar (p > 0.05). The total cost was higher in the 3DP group with its higher graft cost (p < 0.05).ConclusionIn treating single-segment DCSM with ACCF, both 3DP OTS prosthesis and TMC achieved satisfactory outcomes. However, the more costly 3DP OTS prosthesis was not able to reduce subsidence as it claimed.

Present-day kinematics of the northwest Moroccan Atlantic Margin from GNSS data: west southwest extrusion at the western end of the High Atlas

The Global Navigation Satellite System (GNSS) has emerged as a practical and effective technique for studying slow and steady geodynamic movements, enabling continuous monitoring and precise quantification of deformation over different timescales. In Morocco, a network of GNSS stations has been established, offering valuable insights into tectonic processes. This paper focuses on investigating the geodynamic motion of the northwest Moroccan Atlantic Margin. By utilizing GNSS data, subsidence rates and horizontal velocity fields were determined for the first time, providing valuable information for oil and gas exploration activities. The study reveals an active uplift rate of 1 mm/year and a westward horizontal motion of 2.04 mm/year in the Essaouira segment. The paper presents a case study of the Essaouira–Agadir basin (EAB) onshore segment and investigates the anomalous displacement observed in this region compared to other coastal GNSS stations. Possible explanations for the observed movements include local processes such as salt tectonics and regional northwest–southeast compression related to Africa–Eurasia convergence. We suggest that the anomalous movement detected in this work is due to the regional northwest–southeast compression related to Africa–Eurasia convergence imparting an extrusion of the EAB to the west. This research contributes to a better understanding of the geodynamics in the northwest Moroccan Atlantic margin, thereby providing valuable insights for ongoing efforts in oil and gas exploration. Furthermore, it indicates the continued activity of the Agadir fault, which would exhibit a sinistral wrench movement, thus posing a threat to the city of Agadir and its inhabitants.

InSAR and machine learning reveal new understanding of coastal subsidence risk in the Yellow River Delta, China

Coastal subsidence is a geological disaster that has devastating consequences. However, an accurate understanding of its risks involves more than simply assessing the amount or rate of land subsidence. The existing methods used to evaluate geological disaster risks depend on extensive data collection, entail substantial workloads, suffer from error estimation challenges, and lack regional adaptability. These limitations prevent us from fully understanding coastal subsidence risks in estuarine deltas. Therefore, in this study, we propose a new subsidence risk assessment method that addresses the challenges of traditional geological risk assessments in terms of spatial coverage, spatiotemporal resolution, and data collection difficulty. First, Sentinel-1 multitemporal interferometric synthetic aperture radar (MT-InSAR) and cluster analysis were used to estimate the subsidence hazards. Subsequently, Landsat-8 imagery and a random forest (RF) classifier were used to obtain land use and land cover (LULC), and the analytic hierarchy process (AHP) was used to obtain settlement vulnerability. Thereafter, subsidence susceptibility was derived from the sediment layer thickness. By combining subsidence hazard, vulnerability, and susceptibility, the first subsidence risk map with a 30 m resolution was generated. The results showed that 4.54 % of the Yellow River Delta (YRD) area was high-risk, 8.75 % was medium-risk, and 10.14 % was low-risk. Notably, the risk map shows a clear overlap between high-risk and saltwater mining areas in the YRD. The proposed method is expected to improve our understanding of the coastal subsidence risk in estuarine deltas. Considering that the risk in high-value economic areas in the YRD is increasing, whereas the risk in low-value economic areas may change owing to human activity, early preventive measures are required.

Unveiling the driving factors of urban land subsidence in Beijing, China

Land subsidence, an insidious and gradual geological phenomenon, presents a latent threat to future urban development and socio-economic progress. Beijing City, renowned for its high population density, has encountered significant challenges associated with land subsidence. In this study, we leverage time-series interferometric synthetic aperture radar (time-series InSAR) method to analyze the spatio-temporal patterns of land subsidence in Beijing. Furthermore, we quantify the contributions of natural and anthropogenic factors to land subsidence. Our findings reveal that land subsidence primarily occurs in the plain area of Beijing, exhibiting an average rate of −5.6 mm/year (Positive values indicate uplift, while negative values indicate subsidence.). Notably, several large-scale subsidence centers are identified, with the maximum subsidence rate reaching an alarming −232.7 mm/year. The assessments indicate that geological factors, specifically fault activity, account for 33 % of the observed land subsidence, while human activities contribute to the remaining 67 %, with groundwater overexploitation playing a prominent role. The insights gained from this study provide a foundation for understanding the causative factors behind urban land subsidence and can aid in the formulation of effective intervention policies targeting this critical issue.

Monitoring land subsidence in the Peshawar District, Pakistan, with a multi-track PS-InSAR technique.

Peshawar is one of the most densely populated cities of Pakistan with high urbanization rate. The city overexploits groundwater resources for household and commercial usage which has caused land subsidence. Land subsidence has long been an issue in Peshawar due to insufficient groundwater removal. In this research, we employ the persistent scatterer interferometry synthetic aperture radar (PS-InSAR) technique with Sentinel-1 imaging data to observe the yearly land subsidence and generate accumulative time-series maps for the years (2018 to 2020) using the SAR PROcessing tool (SARPROZ). The PS-InSAR findings from two contiguous paths are combined by considering the variance over the overlapping area. The subsidence rates in the Peshawar are from -59 to 17 mm/yr. The results show that subsidence is -28.48 mm/yr in 2018, the subsidence reached -49.02 mm/yr in 2019, while in 2020, the subsidence reached -49.90 mm/yr. The findings indicate a notable rise in land subsidence between the years 2018 and 2020. Subsidence is predicted in the research region primarily due to excessive groundwater removal and soil consolidation induced by surficial loads. The correlation of land subsidence observations with groundwater levels and precipitation data revealed some relationships. Overall, the proposed method efficiently monitors, maps, and detects subsidence-prone areas. The utilization of land subsidence maps will enhance the efficiency of urban planning, construction of surface infrastructure, and the management of risks associated with subsidence.

Subsidence of Artificial Reefs with Bamboo Foundations on a Soft Seabed

The design of artificial reefs must be based on the criteria of both durability and serviceability. In this respect, the seabed subsidence rate related to the weight of the reefs and of their foundation system should be limited. The horizontal drift of the reefs during their life should be small too. In this study, pertaining to the behavior of artificial reefs made of microsilica concrete and realized with foundations in bamboo near the international airport of Hong Kong, 1-year monitoring data and calculations of reef foundation settlements are shown and discussed to assess the performance of the adopted mixed foundation and to deduce the nature of the long-term subsidence. The subsidence related to the settlements of the foundations was monitored using a Multibeam Echo Sounder System. It was found that the observed subsidence rate cannot be justified by the primary consolidation of the soils forming the seabed. Indeed, secondary consolidation seems to play an important role. Overall, after one year of service, the artificial reefs are considered to be effective in terms of limitation of both subsidence and drift.

Mid-term results of a cementless hip stem in femoral revision: how much diaphyseal press-fit do we need?

The aim of this retrospective study was to analyze the clinical and functional outcome of a modular tapered revision hip stem after mid-term follow-up with a special focus on the length of the distal bicortical fixation of the cementless hip stem. Follow-up examination was carried out for all patients with implantation of the Prevision hip stem between 2014 and 2019 to collect demographic, functional, and radiographic data. 44 patients with stem in situ were examined, and 61 patients could be included in the Kaplan-Meier survival analysis. Oxford's hip score was 37.3 at the mean follow-up of 4.0years. Two hip stem revisions were performed due to periprosthetic infection, which resulted in a hip stem survival rate of 96.7% (CI: 87.4-99.1%) at the final follow-up of 7.5years. No aseptic hip stem revision was required. The length of bicortical distal fixation was in the interquartile range of 6.8 to 9.0cm, which was associated with good bone healing and a low rate of subsidence (4.5%). Implant-associated complications were observed in 10 cases (21.7%). The modular revision hip stem provides promising results at medium-term follow-up, with satisfactory clinical and functional outcomes comparable to other modular revision hip stems. The presented length of bicortical distal fixation shows the practice of the study center and was associated with good implant survival, bone healing and radiological results. Clinicaltrials.gov registration: NCT04833634 registered on April 6, 2021.

Systematic Review and Meta-Analysis of the Effect of Osteoporosis on Fusion Rates and Complications Following Surgery for Degenerative Cervical Spine Pathology.

As the elderly population grows, the increasing prevalence of osteoporosis presents a unique challenge for surgeons. Decreased bone strength and quality are associated with hardware failure and impaired bone healing, which may increase the rate of revision surgery and the development of complications. The purpose of this review is to determine the impact of osteoporosis on postoperative outcomes for patients with cervical degenerative disease or deformity. A systematic review using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and Medical Subject Headings terms involving spine surgery for cervical degenerative disease and osteoporosis were performed. This review focused on radiographic outcomes, as well as surgical and medical complications. There were 16 studies included in the degenerative group and 9 in the deformity group. Across degenerative studies, lower bone mineral density was associated with increased rates of cage subsidence in osteoporotic patients undergoing operative treatment for cervical degenerative disease. Most studies reported varied results on the relationship between osteoporosis and other outcomes such as revision and readmission rates, costs, and perioperative complications. Our meta-analysis suggests that osteoporotic patients carry a greater risk of reduced fusion rates at 6 months and 1 year postoperatively. With respect to cervical deformity correction, although individual complication rates were unchanged with osteoporosis, the collective risk of incurring any complication may be increased in patients with poor bone stock. Overall, the literature suggests that outcomes for osteoporotic patients after cervical spine surgery are multifactorial. Osteoporosis seems to be a significant risk factor for developing cage subsidence and pseudarthrosis postoperatively, whereas reports on medical and hospital-related metrics were inconclusive. Our findings highlight the challenges of caring for osteoporotic patients and underline the need for adequately powered studies to understand how osteoporosis changes the risk index of patients undergoing cervical spine surgery. In patients undergoing cervical spine surgery for degenerative disease, osteoporosis is a significant risk factor for long-term postoperative complications-notably cage subsidence and pseudarthrosis. Given the elective nature of these procedures, interdisciplinary collaboration between providers should be routinely implemented to enable medical optimization of patients prior to cervical spine surgery.

Study on surface deformation pattern in mine closure area of complex karst mountainous region based on SBAS-InSAR technology

Liupanshui City in Guizhou Province represents a karst mountainous region with a delicate geological environment. The area has a long history of coal mining, and several coal mines have been progressively closed in recent years. However, even after closure of coal mines, the fractured rock mass in the mined-out areas continues to undergo deformation over a specific period. In karst mountainous regions, this deformation is affected by various factors including elevation, slope, precipitation, and vegetation. In this study, we employed SBAS-InSAR technology to construct a time series of surface deformation data from January 2019 to May 2022 within Liupanshui City’s LuJiaZhai-DaPingDi Minefield. Subsequently, this data was comprehensively analyzed in conjunction with time series vegetation cover, monthly precipitation, elevation, and slope data from the identical period. The key findings of this research are as follows: 1) After the closure of the mine, the subsidence area gradually stabilized, yet the volume of subsidence continues to increase. The subsidence area primarily occurs near the MaiZiGou Coal Mine air-mining area, which had a relatively short closure time, as well as in higher elevation areas in the southern and eastern parts of the minefield. Specifically, the maximum cumulative subsidence and the subsidence rate during the study period reached −60.3 mm and −21.83 mm/a, respectively. 2) Surface deformation is closely linked to slope, vegetation type, and rainfall, with subsidence rates and amounts noticeably higher during the rainy season than in the dry season. 3) Surface vegetation cover types display varied effects on deformation, with grassland or shrub areas being more sensitive to precipitation than forests. Forests, especially pine and fir, show a delayed subsidence response to rain, typically 2–3 months post-rainy season onset. This inhibitory effect lessens with increasing slope, particularly beyond a 25° threshold, where responsiveness to precipitation and associated subsidence significantly increase. The findings of this study hold substantial scientific implications for the restoration and management of closed mining areas, as well as the prevention of geological hazards in karst complex mountainous regions.

Additional cement augmentation reduces cage subsidence and improves clinical outcomes in oblique lumbar interbody fusion combined with anterolateral screw fixation: A retrospective cohort study

PURPOSE: Although OLIF has been well established as a successful surgical treatment for lumbar spondylosis, cage subsidence is one of the troublesome complications. Avoiding risk factors and improving surgical techniques are generally passive ways for cage subsidence prevention. To our knowledge, there has been no active way reported to decrease cage subsidence following OLIF. METHODS: From 2018 to 2021, 63 patients were enrolled and divided into two groups, OLIF group (37 patients) and OLIF with cement augmentation (OLIF-C) group (26 patients). The patients’ characteristics, age, sex, BMI, lesion level, days of hospitalization, visual analogue scale (VAS), surgical data and radiological parameters were recorded and compared. RESULTS: The demographic and surgical data showed no statistical significance between OLIF and OLIF-C groups. OLIF-C group had better pain relief in postoperative 3 months (p = 0.015) and at the last follow-up (p = 0.030), less rate of cage subsidence (p <0.001) with better disc height restoration, segmental lordotic angle maintenance and interbody fusion rate. CONCLUSIONS: Additional cement augmentation for OLIF could minimize the rate of postoperative cage subsidence and the whole procedure was completed through the anterolateral approach without posterior laminectomy and instrumentation, avoiding the damage of posterior back muscle and facet joints.

The Middle Miocene Microfacies, Cyclicity, and Depositional History: Implications on the Marmarica Formation at the Siwa Oasis, Western Desert (Egypt)

Microfacies studies were carried out on the Middle Miocene Marmarica Formation exposed at the Gabal Western Bahi El-Din and Gabal El-Najdeen, the Siwa Oasis, northwestern Desert (Egypt). It was distinguished into the lower, middle, and upper members. Eleven microfacies types were recognized, which include skeletal lime-mudstone, dolomitic lime-mudstone, intraclastic wackestone, bryozoan wackestone, foraminiferal wackestone, foraminiferal bryozoan packstone, glauconitic molluscan packstone, molluscan intraclastic packstone, pelletal peloidal skeletal packstone, dolostones, and claystone microfacies. This formation includes several types of emergence- meter-scale cycles (shallowing-upward). Field observations and petrographic analyses revealed that these cycles consist of pure carbonates and mixed siliciclastic carbonates. These cycles consist of four types of gradual cycles and six types of non-gradual cycles. The gradual emergence cycles indicate a balance between the rate of subsidence, sea level oscillations, and sedimentation rate. The non-gradual cycles indicate an irregular balance between sedimentation rate and subsidence rate. The non-gradual cycles denote high-frequency sea level variation and/or short-term sea level oscillations, which are associated with high carbonate formation. The depositional environments of the Marmarica Formation are restricted to lagoonal at the base, followed upward to open marine conditions. Both environments most probably characterize the platform setting.

The orogenic effects on forebulge evolution: A case study from Cenozoic deposits in the Salento Peninsula, Italy

The Salento Peninsula is a part of the larger Apulia Carbonate Platform, one of the carbonate platforms that have developed along the southern margin of the Tethys Ocean since the Triassic, above the Adria microplate. This peninsula represents the culmination of a lithospheric anticline formed due to the subduction of the Adria Plate beneath two mountain belts migrating in opposite directions: the Dinarides-Albanides-Hellenides (DAH) chain, moving from NE to SW, and the southern Apennines (SA) chain, moving from SW to NE. Consequently, the Salento Peninsula represents the foreland sector of these two mountain belts, whose different migration rates, deeply influenced the carbonate sedimentation and paleogeographic evolution of this area over the last 60 Myr. In our study field analysis, a database of 350 wells, and 90 seismic lines calibrated with 3 exploration wells were employed to characterize the physical stratigraphy and depositional setting of the Salento Peninsula and define its paleogeographic evolution during the Paleogene and Neogene. Our results suggest that temporal variations in sedimentation rates and types as well as the reduced thickness (maximum 200 m) of the Cenozoic stratigraphic succession in the internal sectors and both along the Adriatic and Ionian margins of the Salento Peninsula are directly or indirectly linked to the migration rates of the DAH and SA chains. These migration rates played a role in determining changes in subsidence rates, the occurrence of soft-sediment deformation, and the influx of Plio-Pleistocene fine-grained terrigenous sediments, especially along the Ionian margin. Although the investigated succession exhibits a reduced thickness, it comprises several lithostratigraphic units bounded by unconformity surfaces. Within these units, a stack of complete and incomplete simple and composite high- and low-rank depositional sequences has been recognized. Our data suggest that these units are the result of a multifold cyclicity, reflecting the close interaction between eustatic sea-level changes and the tectonic setting of the area.

Exploring the differences in radiologic and clinical outcomes of transforaminal lumbar interbody fusion with single- and bi-planar expandable cages: a systematic review and meta-analysis.

Transforaminal lumbar interbody fusion (TLIF) is a universal surgical technique used to achieve lumbar fusion. Traditionally static cages have been used to restore the disc space after discectomy. However, newer technological advancements have brought up uniplanar expandable cages (UECs) and more recently bi-planar expandable cages (BECs), the latter with the hope of reducing the events of intra- or postoperative subsidence compared to UECs. However, since BECs are relatively new, there has been no comparison to UECs. In this PRISMA-compliant systematic review, we sought to identify all Medline and Embase reports that used UECs and/or BECs for TLIF or posterior lumbar interbody fusion. Primary outcomes included subsidence and fusion rates. Secondary outcomes included VAS back pain score, VAS leg pain score, ODI, and other complications. A meta-analysis of proportions was the main method used to evaluate the extracted data. Bias was assessed using the ROBINS-I tool. A total of 15 studies were pooled in the analysis, 3 of which described BECs. There were no studies directly comparing the UECs to BECs. A statistically significant difference in fusion rates was found between UECs and BECs (p = 0.04). Due to lack of direct comparative literature, definitive conclusions cannot be made about differences between UECs and BECs. The analysis showed a statistically higher fusion rate for BECs versus UECs, but this should be interpreted cautiously. No other statistically significant differences were found. As more direct comparative studies emerge, future meta-analyses may clarify potential differences between these cage types.