Effect of clayey sediment compression on fluoride enrichment in the Quaternary groundwater system of Cangzhou Plain, China.

The effect of clay layer compression on the enrichment of groundwater fluoride remains unknown. Quaternary groundwater with high fluoride levels at the Cangzhou Plain, which has a long history of land subsidence caused by clay layer compression, poses a potential health risk. The spatial distribution and enrichment mechanisms of groundwater fluoride are identified by sample collection, hydrochemical analysis, and geochemical inverse modeling. The results revealed that fluoride concentrations in 82 % of the 122 groundwater samples above the limit in drinking water as 1.0 mg/L in China. Fluoride in shallow groundwater (depth <20 m, ∼average = 2.08 mg/L) was mainly originated from fluorite dissolution and influenced by groundwater HCO3-, pH, and cation exchange levels. Below ∼200 m, the main source of groundwater fluoride (∼average = 3.12 mg/L) was the compression-release of clay pore water with high F- concentration, which was generated by complex water-rock interaction. Based on hydrochemical inverse simulation and end-member mixing models, the pore water released from clayey sediments supplied 53 %-56 % of deep groundwater (>200 m) and contributed 2.07 -2.87 mg/L to F- concentration. The findings of this study provide a theoretical basis for future research on prevention of high fluoride groundwater induced by clayey sediment compression.

Titanium Cages vs PEEK Cages in Interbody Fusions: A Meta-Analysis of Clinical and Radiographic Outcomes.

BACKGROUND: The most widely adopted materials for interbody fusion implants are titanium and polyetheretherketone (PEEK), both of which have their potential advantages and disadvantages. Despite the differences between PEEK and titanium, there is no consensus on which material provides better clinical and radiological outcomes. Therefore, the purpose of this meta-analysis is to analyze the clinical and radiographic outcomes between the two cages. METHODS: Four databases (PubMed, Cochrane, Embase and Google Scholar (page 1-20)) were queried since December 2001 up until December 2023,. The clinical outcomes evaluated included the rates of adverse events, radiographic outcomes, and PROs. RESULTS: Higher rates of subsidence and revision were reported in PEEK cages in the lumbar spine (p=0.0006, and p=0.006 respectively). In the cervical spine, no difference was observed between PEEK and titanium in any analysis. CONCLUSION: In the lumbar spine, titanium cages were shown to have a lower rate of subsidence and revision compared to PEEK. As for the cervical spine, the difference between cages did not reach statistical significance in any of the analyzed outcomes.

MRI-based endplate bone quality score independently predicts cage subsidence after anterior cervical corpectomy fusion.

BACKGROUND: To reduce the amount of radiation that patients receive during surgery, surgeons can evaluate the quality of the bone prior to surgery using computed tomography (CT) or dual-energy X-ray absorptiometry. Recently, lumbar spine vertebral bone quality has been evaluated using an MRI-based scoring system. However, few studies have investigated the connection between cage subsidence in patients following cervical interbody fusion and site-specific MRI bone evaluation. It is unknown how cage subsidence following anterior cervical corpectomy decompression and fusion is related to MRI-based endplate bone quality assessment. PURPOSE: To create a similar MRI-based cervical spine scoring system (C-EBQ) and to investigate the predictive value of the MRI cervical endplate bone quality (C-EBQ) score for cage subsidence after ACCF. METHODS: The patients' demographic, surgical, and radiological data were collected. Cage subsidence was defined as fusion segment height loss ≥ 3 mm. Multivariate logistic regression models were developed to determine correlations between potential risk factors and subsidence, and simple linear regression analyses of statistically significant indicators were performed. RESULTS: Among the patients who underwent single-level ACCF, 72 met the requirements for inclusion. The C-VBQ scores also improved from 2.28 ± 0.12, indicating no subsidence, to 3.27 ± 0.35, which indicated subsidence, and the C-EBQ scores improved in both the nonsubsidence group (1.95 ± 0.80) and the subsidence group (2.38 ± 0.54). There was a statistically significant difference (p < 0.05) among the groups. Higher C-EBQ scores were strongly correlated with subsidence in the multivariate analysis (odds ratio [OR] = 17.249, 95% CI = 2.269 to 7.537, P < 0.001), and the C-VBQ score was the major independent predictor of subsidence following ACCF ([OR] = 4.752, 95% CI = 3.824 to 8.781, P < 0.05). The C-EBQ score outperformed the C-VBQ score (75.6%) in terms of predictive accuracy, with a ROC curve indicating an 89.4% score. CONCLUSIONS: After ACCF, cage subsidence was strongly correlated with higher C-EBQ scores on preoperative MRI. Assessing C-EBQ before ACCF may be a useful way to estimate the likelihood of postoperative subsidence.

Links between climatic histories and the rise and fall of a Pacific chiefdom.

Sea level rise and climate change are shaping present societies, particularly those on oceanic islands. Few historical examples could serve as references for these changes. One such potential model is the Saudeleur Dynasty with its capital Nan Madol on the Pacific Island of Pohnpei. However, the timing of its construction, as well as the dynasty's fluctuations and potential environmental influences, has remained unresolved. Through the analyses of 230Th ages on 171 dates on corals fragments used as building materials and charcoal 14C ages from excavations, 2 major construction phases spanning from the 10th to the 15th century CE can be discerned. The results show that the first phase of the site's construction, spanning the 10th-12th century, marked the dynasty's rise. The second period, spanning from the late 12th to the early 15th century, provides the most substantial evidence for the demise of the island-scale chiefdom and a significant societal reorganization. The phases are centuries earlier than previously believed. With this new evidence, we propose the hypothesis that variations in the El Niño-Southern Oscillation and subsidence-related sea level rise presented major challenges for building and maintaining Nan Madol, and thus, influenced the course of the island's history. This case serves as a compelling example of how adverse climatic conditions can spur investments-in this case, in seawater defense under high sea levels-yet ultimately may contribute to abandonment. It offers lessons for island nations, showcasing coastal resilience in the face of worsening catastrophic events that unfolded over generations.

Magnetic Resonance Imaging-Based Vertebral Bone Quality Score for Prediction of Cage Subsidence and Screw Loosening in Patients Undergoing Degenerative Lumbar Surgery: A Meta-analysis.

OBJECTIVE: Poor bone quality is a risk factor for postoperative complications after degenerative lumbar fusion surgery. The magnetic resonance imaging-based vertebral bone quality (VBQ) score is a good tool for assessing bone quality, and this is the first meta-analysis performed to summarize the predictive value of the VBQ score for cage subsidence and screw loosening in patients undergoing degenerative lumbar surgery. METHODS: Studies were comprehensively searched in electronic databases. The quality of the studies was assessed. The pooled sensitivity, specificity and summary receiver operating characteristic curve were calculated. Publication bias was assessed and meta-regression was conducted. RESULTS: We ultimately included 9 studies with a total of 1,404 patients with a mean age of 60.4 years and a percentage of females of 57.0%. According to the QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies 2) tool to assess methodological quality, the quality of the included studies was relatively low and risks of bias might exist. Results showed that a high VBQ was significantly associated with cage subsidence and screw loosening, and risk factor analysis revealed that the merged odds ratio was 5.37 for cage subsidence and 3.87 for screw loosening. With a VBQ cutoff value of 3.34±0.45, the pooled sensitivity and specificity for the diagnosis of postoperative complications were 0.75 and 0.75, respectively, and the area under the curve was 0.82 (95% confidence interval, 0.78-0.85). CONCLUSION: A high VBQ was associated with a high risk of cage subsidence and screw loosening in patients who underwent degenerative lumbar surgery. The VBQ score could be considered for identifying high-risk patients for further evaluation.

Effect of Cage Material and Size on Fusion Rate and Subsidence Following Biportal Endoscopic Transforaminal Lumbar Interbody Fusion.

OBJECTIVE: Biportal endoscopic transforaminal lumbar interbody fusion (BE-TLIF) is an emerging, minimally invasive technique performed under biportal endoscopic guidance. However, concerns regarding cage subsidence and sufficient fusion during BE-TLIF necessitate careful selection of an appropriate interbody cage to improve surgical outcomes. This study compared the fusion rate, subsidence, and other radiographic parameters according to the material and size of the cages used in BE-TLIF. METHODS: In this retrospective cohort study, patients who underwent single-segment BE-TLIF between April 2019 and February 2023 were divided into 3 groups: group A, regular-sized three-dimensionally (3D)-printed titanium cages; group B, regular-sized polyetheretherketone cages; and group C, large-sized 3D-printed titanium cages. Radiographic parameters, including lumbar lordosis, segmental lordosis, anterior and posterior disc heights, disc angle, and foraminal height, were measured before and after surgery. The fusion rate and severity of cage subsidence were compared between the groups. RESULTS: No significant differences were noted in the demographic data or radiographic parameters between the groups. The fusion rate on 1-year postoperative computed tomography was comparable between the groups. The cage subsidence rate was significantly lower in group C than in group A (41.9% vs. 16.7%, p=0.044). The severity of cage subsidence was significantly lower in group C (0.93±0.83) than in groups A (2.20±1.84, p=0.004) and B (1.79±1.47, p=0.048). CONCLUSION: Cage materials did not affect the 1-year postoperative outcomes of BE-TLIF; however, subsidence was markedly reduced in large cages. Larger cages may provide more stable postoperative segments.

Biomechanical differences of three cephalic fixation methods for patients with basilar invagination and atlantoaxial dislocation in the setting of congenital atlas occipitalization: a finite element analysis.

BACKGROUND CONTEXT: In cases of basilar invagination-atlantoaxial dislocation (BI-AAD) complicated by atlas occipitalization (AOZ), the approach to cranial end fixation has consistently sparked debate, generally falling into two categories: C1-C2 fixation and occipitocervical fixation. Several authors believe that C1-C2 fixation carries a lower risk of fixation failure than occipitocervical fixation. PURPOSE: To study the biomechanical differences among 3 different cranial end fixation methods for BI-AAD with AOZ. STUDY DESIGN: This was a finite element analysis. PATIENT SAMPLE: A 35-year-old female patient diagnosed with congenital BI-AAD and AOZ. OUTCOME MEASURES: range of motion (ROM), peak von Mise stress (PVMS), cage micro-subsidence, cage micro-slippage METHOD: Four finite element models were constructed, including unstable group (BI-AAD with AOZ), C1 lateral mass screw group, occipital plate group, occipitocervical rod group. The flexion and extension (FE), lateral bending (LB) as well as axial rotation (AR) were simulated under a torque of 1.5 Nm. Parameters include C1-C2 ROM, PVMS on screw-rod construct, cage micro-subsidence, cage micro-slippage. RESULTS: The ROM of the C1 lateral mass screw group was smaller than that of the other fixation groups in LB and AR, but not FE. Compared with the occipitocervical rod group, the ROM in LB and AR of the occipital plate group was higher, but not in FE. The PVMS of C1 lateral mass screw group was significantly higher than that of the other groups. The ROM and PVMS of the occipitocervical rod group were in between the other 2 groups. Regarding the screws at the cranial end, the PVMS of the 4-screw occipitocervical rod group was significantly lower than that of the other groups. In general, the cage micro-motion follows the ascending order: C1 lateral mass group < occipitocervical rod group < occipital plate group. CONCLUSION: In cases of BI-AAD with AOZ, the C1 lateral mass screw group provided the least ROM and cage micro-motion, but the screw-rod PVMS was the largest. The advantage of occipital plate fixation lies in the lowest screw-rod PVMS, but the ROM and cage micro-motion is the highest. Four-screw fixation at the cranial end of occipitocervical rod group helps to reduce the PVMS and may prevent screw failure at the cranial end.

The influence of withdrawal-recharging pattern on the deformation characteristics of sand in confined aquifer.

Land subsidence caused by excessive groundwater withdrawal has become a global hazard, which demands further researches and the potential measures to control. Using the FlowTrac Ⅱ consolidation test system, six compression tests were designed to investigate the stress state and stress paths of sand within confined aquifers under conditions of withdrawal and recharging. The deformation characteristics of aquifer sand were studied under different withdrawal-recharging patterns. During pumping and recharge processes, sand deformation responses were observed to lag behind changes in applied stress. The characteristics of this hysteresis effect on deformation were summarized. The alternating phenomenon of rebound and compression of sand deformation under the recharging process is analyzed. When the recharging effect was relatively small than withdrawing effect under the stable withdrawal-recharging pattern, the compression deformation was observed in the recharging process. The research results provide a rational explanation for the continuous compression deformation of the aquifer during groundwater level recovery and offer experimental evidence for the rational design of artificial groundwater recharge in engineering construction.

Impact of the 2011 Tohoku Earthquake on the species diversity of rocky intertidal sessile assemblages.

The impacts of large-scale disturbance events on the species diversity of rocky intertidal sessile assemblages across multiple spatial scales are not well understood. To evaluate the influence of the 2011 Tohoku Earthquake on alpha and beta diversities of rocky intertidal sessile assemblages, we surveyed sessile assemblages in the mid-shore zone from 2011 to 2019 and compared the data with those collected from 2003 to 2010 before the earthquake at the same region. The census was conducted across 22 study plots on five rocky shores along 30 km of the Sanriku Coast of Japan, which is located 150-160 km north-northwest of the earthquake epicenter. Alpha diversity was measured with three Hill numbers (H 0, H 1, and H 2), which represent the number of equally common species that would exist in a community with the same diversity as the sampled community, with higher values of the subscript indicating more weight placed on abundant species. Beta diversity was measured with two metrics (BD total at two spatial scales). Values were compared between the post-earthquake period (2011-2019) and the pre-earthquake period (2003-2010). The results show that the Tohoku Earthquake significantly altered the species diversity of intertidal sessile assemblages across multiple spatial scales. All diversity metrics obtained at multiple spatial scales (i.e., alpha diversities: H 0, H 1, and H 2; beta diversities: BD total at the shore and regional scales) decreased immediately after the earthquake and then increased in subsequent years. At 2 years after the earthquake, H 0 recovered to within the range of pre-earthquake values and H 1 and H 2 became significantly higher than pre-earthquake values. Most metrics of alpha and beta diversities recovered to pre-earthquake levels after several years, but regional BD total remained low for a longer period.

Experimental study on soil deformation caused by overexploitation of groundwater.

Due to the overexploitation of deep groundwater, the largest cone of depression in the world has formed in the North China Plain. This led to severe geological hazards, including land subsidence and ground fissures, and also caused economic losses. The prevention and treatment of subsidence needs to rely on the accurate prediction of subsidence amount. According to the one-dimensional consolidation theory and effective stress principle, combined with stratum structure, groundwater flow, stress distribution, and so forth, the high-pressure consolidation test results of 569.6 m deep borehole soil samples are adopted; with a specific focus on stress and deformation parameters under exploitation of groundwater condition, the soil-water coupling prediction model of groundwater level lowering depth and land subsidence has been established. Verification with measured subsidence data near the study sites demonstrated that the predicted curve is consistent with the measured one and the differences between them are acceptable. The model can be applied in different areas after making adjustment based on different regional stratigraphic structures. Its key advantage lies in the ability to provide land subsidence prediction for areas lacking monitoring data, making it highly valuable for widespread application. PRACTITIONER POINTS: There is a compressible stratum structure; it is the internal factors of land subsidence. The groundwater level decline causes the soil body stress to change. It is land subsidence of the external factors. Based on the one-dimensional consolidation theory and by combining stratigraphic structures, groundwater flow, and stress distribution, a ground settlement prediction model was established.

Research on Spatiotemporal Continuous Information Perception of Overburden Compression-Tensile Strain Transition Zone during Mining and Integrated Safety Guarantee System.

The mining of deep underground coal seams induces the movement, failure, and collapse of the overlying rock-soil body, and the development of this damaging effect on the surface causes ground fissures and ground subsidence on the surface. To ensure safety throughout the life cycle of the mine, fully distributed, real-time, and continuous sensing and early warning is essential. However, due to mining being a dynamic process with time and space, the overburden movement and collapse induced by mining activities often have a time lag effect. Therefore, how to find a new way to resolve the issue of the existing discontinuous monitoring technology of overburden deformation, obtain the spatiotemporal continuous information of the overlying strata above the coal seam in real time and accurately, and clarify the whole process of deformation in the compression-tensile strain transition zone of overburden has become a key breakthrough in the investigation of overburden deformation mechanism and mining subsidence. On this basis, firstly, the advantages and disadvantages of in situ observation technology of mine rock-soil body were compared and analyzed from the five levels of survey, remote sensing, testing, exploration, and monitoring, and a deformation and failure perception technology based on spatiotemporal continuity was proposed. Secondly, the evolution characteristics and deformation failure mechanism of the compression-tensile strain transition zone of overburden were summarized from three aspects: the typical mode of deformation and collapse of overlying rock-soil body, the key controlling factors of deformation and failure in the overburden compression-tensile strain transition zone, and the stability evaluation of overburden based on reliability theory. Finally, the spatiotemporal continuous perception technology of overburden deformation based on DFOS is introduced in detail, and an integrated coal seam mining overburden safety guarantee system is proposed. The results of the research can provide an important evaluation basis for the design of mining intensity, emergency decisions, and disposal of risks, and they can also give important guidance for the assessment of ground geological and ecological restoration and management caused by underground coal mining.

Research on prediction method of coal mining surface subsidence based on MMF optimization model.

Coal seam mining causes fracture and movement of overlying strata in goaf, and endangers the safety of surface structures and underground pipelines. Based on the engineering geological conditions of 22,122 working face in Cuncaota No.2 Coal Mine of China Shenhua Shendong Coal Group Co., Ltd. a similar material model test of mining overburden rock was carried out. The subsidence of overburden rock was obtained through the full-section strain data of distributed optical fiber technology, and the characteristics of mining surface subsidence were studied. The Weibull model was used to adjust the mathematical form of the first half of the surface subsidence curve via the MMF function. On this basis, the prediction model of coal seam mining surface subsidence was established, and the parameters of the prediction model of surface subsidence were determined. The test results show that with the advancement of coal seam mining, the fit goodness of the surface subsidence prediction curve based on the MMF optimization model reaches 0.987. Compared with the measured values, the relative error of the surface subsidence prediction model is reduced to less than 10%. The model displays good prediction accuracy. The time required for settlement stability in the prediction model is positively correlated with parameter a and negatively correlated with parameter b. The research results can be further extended to the prediction of overburden "three zones" subsidence, and provide a scientific basis for the evaluation of surface subsidence compression potential in coal mine goaf.

Insufficient endplate-bone graft contact is a risk factor for high-grade cage subsidence occurring after lateral lumbar interbody fusion supplemented with lateral plate: An analysis of 121 cases.

BACKGROUND: Lateral lumbar interbody fusion (LLIF) is a minimally invasive fusion technique that can be performed with lateral plate. Insufficient contact between the endplate and bone graft may result in cage subsidence. This study aimed to investigate the potential risk factor for high-grade cage subsidence (HCS) occurring after LLIF supplemented with lateral plate. METHODS: Between June 2017 and February 2023, 121 patients (48 males, 73 females; mean age 63.0 years; minimum follow-up period 12 months) undergoing LLIF supplemented with lateral plate were retrospectively reviewed. The incidence of HCS was assessed, and patients were categorized into HCS group or non-HCS group based on the occurrence of HCS. A revision surgery of posterior pedicle screw fixation was performed in patients with cage subsidence and complained with intolerable back pain or radicular symptoms. Comparative analyses were performed on demographic characteristics, surgical variables, and parameters related to endplate-bone graft contact between the two groups. Multivariable logistic regression analysis was employed to identify the potential risk factors associated with HCS. The receiver operating characteristic (ROC) analysis was used to calculate the cutoff values for the risk factors. Clinical outcomes were evaluated using Oswestry Disability Index (ODI), and radiographic fusion at the final follow-up was assessed based on the Bridwell grading system. RESULTS: The HCS group comprised 12 patients, while the non-HCS group included 109 patients. The incidence of HCS occurring after LLIF supplemented with lateral plate was 9.9 %. Compared to non-HCS group, patients in HCS group had lower sagittal and coronal endplate-bone graft contact rates and larger cage-endplate angles. Low sagittal (OR, 1.099; 95 % CI, 1.033-1.169; P=0.003) and low coronal (OR, 1.149, 95 % CI, 1.061-1.243, P=0.001) endplate-bone graft contact rates were determined to be correlated with HCS. The cutoff value of the sagittal and coronal endplate-bone graft contact rate was 63.5 % and 60.9 %. Eleven (91.7 %) patients in HCS group underwent revision posterior pedicle screw fixation. Both HCS and non-HCS groups experienced significant improvements in ODI at the final follow-up, while there were no differences between groups. Ninety-five (87.2 %) patients in non-HCS group, and nine (81.8 %) of the 11 patients who underwent revision surgery in HCS group achieved radiographic fusion at the final follow-up. CONCLUSIONS: The incidence of HCS occurring after LLIF supplemented with lateral plate was 9.9%. Insufficient endplate-bone graft contact is an important risk factor of HCS, and sagittal and coronal endplate-bone graft contact rates can be used as effective predictors for HCS.

Mid-Term Migration Pattern of a Cemented Collared Anatomical Stem-A Retrospective Study Using EBRA-FCA.

Background: Aseptic loosening is one of the leading causes of stem revision. Einzel Bild Röntgen Analyse-Femoral Component Analysis allows for the detection of distal stem migration, which is used as a predictive factor for implant longevity. This study aims to demonstrate the migration behavior of a cemented collared anatomical stem. Methods: This study retrospectively examined all patients who received a cemented Lubinus SP II stem (Waldemar Link, Hamburg, Germany) between 2003 and 2019. We used the EBRA-FCA software (University of Innsbruck, Austria) to determine the migration patterns and thoroughly examined the patients' medical histories. In addition, the potential influence of femoral configuration and BMI on the migration behavior was assessed. Results: This study included 61 patients (48 females and 13 males) with a total of 61 stems that met our inclusion criteria. The mean age at surgery was 76 years (ranging from 30 to 93 years). According to EBRA-FCA migration analysis, a median subsidence of 0.7 mm was observed at 24 months and at the final follow-up (median 78 months). Distal stem migration was significantly higher at the 6-month time point in patients with Dorr type A femurs compared to Dorr type B femurs (p = 0.016). Body mass index (BMI) had no significant effect on stem migration. Conclusions: The measured subsidence of the Lubinus SP 2 stem using EBRA-FCA was below established thresholds, indicating excellent long-term outcomes. Although there was significantly increased subsidence in Dorr type A femurs during the initial 6 months, thereafter, no statistically significant difference was observed compared to Dorr type B femurs.

Does Mal-alignment of the CLS Spotorno Femoral Stem Correlate with Functional Outcome of Patients Undergoing Total Hip Arthroplasty? An Evaluation at Mid-term Follow Up.

Background: The straight and thin design of the CLS Spotorno stem makes it prone for coronal plane mal-alignment, with potential for cortical impingement; reactive osteogenesis and thigh pain have been documented in this situation with some stems. The literature is scarce about the effect of distal mal-alignment with this particular stem, and its relationship with thigh pain, functional outcomes and stem survival. We assessed functional outcomes with incidence of varus/valgus CLS stem alignment, and correlated stem subsidence of these thin stems with hip scores. Methodology: Hip arthroplasty cases with CLS Spotorno stems, operated between 2015 and 2022, with a minimum follow up of 18 months were evaluated. Radiology included 100% pelvis x-rays with bilateral hips (anteroposterior with 15° internal rotation plus lateral views); parameters documented were coronal mal-alignment, stem subsidence, any pedestal formation and heterotrophic ossification (HO); special note was made of any thigh pain, and functional outcomes were recorded using mHHS and SF-36 scores. Results: We evaluated 65 patients with 79 operated hips at an average follow up of 5.26 years. 31.6% (25/79) stems were neutrally aligned, 64.6% (51/79) were in varus alignment and 3.8% (3/79) were in valgus alignment. The mean subsidence was 3.15 mm + 2.26 and 3 cases had Pedestal formation at the stem tip. There was no correlation between varus/valgus stem positions with the mHHS (p = 0.271) and SF-36 score (p = 0.553), which also did not correlate with the stem subsidence. HO formation was seen in 16 hips (20.3%), but no cases in our series needed revision during follow up. Conclusion: Significant distal malalignment with some subsidence were noted in the hips studied; despite these radiological issues, there were excellent mid-term outcomes and good stems survival, implying that distal malposition may have no bearing on functional outcomes.

Ten-Year Results of the Fitmore® Hip Stem with a Focus on Varus/Valgus Alignment and Subsidence-A Retrospective Monocentric Analysis.

Background: Hip arthroplasty is a common elective surgery worldwide, with rising numbers due to demographic changes and an emphasis on maintaining physical activity in the elderly. The development of new implant designs, especially shorter uncemented stems, has contributed to the advancement of minimally invasive implantation techniques. However, the long-term in vivo behaviour of these implants, particularly regarding subsidence, stability, and stress shielding, remains to be fully understood. Methods: This retrospective, monocentric cohort study analyses the long-term radiographic outcomes of the first 141 patients who underwent total hip arthroplasty with the Fitmore® Hip Stem between June 2007 and December 2008. It focuses on subsidence, stability, varus-valgus alignment, and the influence of patient-related, anatomical, and surgical factors on implant behaviour over a 10-year follow-up period. Results: The average change in varus/valgus alignment was 0.7° into varus and the average subsidence was 1.7 mm over 10 years, with most changes occurring within the first six weeks postoperatively. The varus-valgus alignment and subsidence did not significantly change after the first year, indicating stable osteointegration of the implant. Neither patient factors (gender, age) nor surgical and implant factors (implantation angle, approach, stem family, size, total offset) had a significant influence on the long-term behaviour of the implant. Conclusions: The Fitmore® Hip Stem shows highly reliable long-term stability and integration, unaffected by various patient, surgical, and implant factors, as confirmed by excellent register data. Nevertheless, monitoring of this and other new implants should be continued in order to determine implant behaviour, possible weaknesses, and indication limits at an early stage for the benefit of the patient.

Positive Cutibacterium acnes Intervertebral Discs Are Not Associated with Subsidence Following Anterior Cervical Discectomy and Fusion at 3 or 6 Months.

Background/Objectives:Cutibacterium acnes (C. acnes), formerly known as Propionibacterium acnes (P. acnes), is an anaerobic, low-virulent bacterium that has been associated with postoperative infections of the shoulder, knee, and cervical spine. Recent studies have highlighted an association between C. acnes and the development of degenerative disc disease (DDD). The aim of this study is to ascertain whether C. acnes increases the risk of subsidence following anterior cervical discectomy and fusion (ACDF). Methods: After IRB approval, consecutive patients undergoing elective ACDF for DDD from 2017 to 2018 were enrolled in this prospective cohort study. Intervertebral disc samples were taken at each affected level and cultured. A total of 66 patients with radiographic follow-ups were included in the final analysis. The extent of subsidence and cervical lordosis was determined immediately postoperatively and at the 3- and 6-month follow-ups. Results: No significant difference in subsidence was observed at 3 months (p = 0.07) or 6 months (p = 0.11) between culture-positive and -negative cohorts. Additionally, there was no significant difference detected in the change in cervical lordosis observed at 3 months (p = 0.16) or 6 months (p = 0.27) between culture-positive and -negative cohorts. For the most inferiorly fused segment, there was a significant difference in subsidence observed at 3 months (1.5 mm, 95% CI: 0.2-2.7 mm, p = 0.02) but not at 6 months (p = 0.17). Conclusions: Intervertebral discs with a positive C. acnes culture were not associated with greater levels of subsidence at 3 or 6 months following ACDF for DDD. Further research is necessary to endorse these results and to gauge the clinical significance of C. acnes infection.

Monitoring nonlinear large gradient subsidence in mining areas through SBAS-InSAR with PUNet and Weibull model fusion.

The subsidence of the earth's surface in mining areas is characterized by fast speed and large gradients. Conventional small baseline subset interferometric synthetic aperture radar (SBAS-InSAR) monitoring can significantly underestimate results, making it challenging to capture the surface's temporal subsidence features. In this context, this paper proposes a method for monitoring subsidence in mining areas. It utilizes a phase unwrapping network (PUNet) and a fused Weibull model within the SBAS-InSAR framework to address nonlinear and large-gradient subsidence. The basic principle of this method is to first process the SAR images using the small baseline method to obtain the differential interferogram, utilizing the PUNet to obtain reliable large-gradient unwrapped phases. Next, the Weibull model parameters of each pixel are calculated based on the unwrapped phase, and the temporal subsidence of each point on the surface is determined using the calculated parameters. This method introduces a nonlinear model into the SBAS-InSAR solution, which is more consistent with the subsidence characteristics of mining areas. Through experimentation in a backfilled mining working face, the proposed method in this paper yields superior monitoring results compared to conventional approaches.

Symptomatic Subsidence of a Box-Shaped Titanium Cage After Anterior Cervical Discectomy and Fusion: Two Case Reports and Review of the Literature.

This study reports two cases of rare symptomatic subsidence of titanium cages after anterior cervical discectomy and fusion (ACDF). First, an 82-year-old man underwent ACDF at C5/6 and C6/7 using two 6 mm height box-type titanium cages. On the 34th postoperative day, motor weakness occurred in the right upper limb, and CT showed that the cage at C5/6 had subsided 6 mm into the C6 vertebral body. On postoperative day 55, both cages were removed, and C6 corpectomy was performed. The C5-7 space was refixed with a mesh cage and plate. He was discharged home from the rehabilitation hospital three months later. Second, a 41-year-old man underwent ACDF at C5/6 and C6/7 using two 5 mm height box-type titanium cages. He fell violently on the 33rd postoperative day, causing pain from the neck to the left hand, weakness, and skillful movement disorder in the left hand, and CT showed that the cages at C5/6 and C6/7 had subsided by 7 mm and 6 mm, respectively. On the 65th postoperative day, both cages were removed by reoperation, and C6 and 7 corpectomy was performed. The space between C5 and T1 was refixed with a mesh cage and plate. He was discharged home two months later. Possible causes of titanium cage subsidence include osteoporosis, trauma, vertebral cortex damage by an operative procedure, and cage height of 6 mm or more. While ACDF is safe and effective for cervical spondylosis, special caution is needed in older osteoporotic patients.

A novel cervical vertebral bone quality score can independently predict cage subsidence after anterior cervical corpectomy and fusion.

OBJECTIVES: To optimize cervical vertebral bone quality (C-VBQ) score and explore its effectiveness in predicting cage subsidence in Anterior Cervical Corpectomy and Fusion (ACCF) and identify a new method for evaluating subsidence without different equipment and image scale interference. METHODS: Collecting demographic, imaging, and surgical related information. Measuring Cage Subsidence with a new method. Multifactorial logistic regression was used to identify risk factors associated with subsidence. Pearson's correlation was used to determine the relationship between C-VBQ and computed tomography (CT) Hounsfield units (HU). The receiver operating characteristic (ROC) curve was used to assess C-VBQ predictive ability. Correlations between demographics and C-VBQ scores were analyzed using linear regression models. RESULTS: 92 patients were included in this study, 36 (39.1%) showed subsidence with a C-VBQ value of 2.05 ± 0.45, in the no-subsidence group C-VBQ Value was 3.25 ± 0.76. The multifactorial logistic regression showed that C-VBQ is an independent predictor of cage subsidence with a predictive accuracy of 93.4%. Pearson's correlation analysis showed a negative correlation between C-VBQ and HU values. Linear regression analysis showed a positive correlation between C-VBQ and cage subsidence. Univariate analyses showed that only age was associated with C-VBQ. CONCLUSIONS: The C-VBQ values obtained using the new measurements independently predicted postoperative cage subsidence after ACCF and showed a negative correlation with HU values. By adding the measurement of non-operated vertebral heights as a control standard, the results of cage subsidence measured by the ratio method are likely to be more robust, perhaps can exclude unavoidable errors caused by different equipment and proportional.