Search Results (3,804)

Background: Cemented and cementless fixation techniques in total hip arthroplasty (THA) each present distinct biomechanical properties and perioperative risk profiles. While cementless fixation has gained increasing popularity, large-scale nationally representative comparisons of perioperative outcomes between cemented and cementless elective THA remain limited. This study aimed to compare complication rates, healthcare utilization, and temporal trends between cemented and cementless elective THA using the National Inpatient Sample. Methods: A retrospective cohort study was conducted using the National Inpatient Sample database from 2016 to 2021. Adult patients undergoing elective primary total hip arthroplasty were identified using ICD-10-PCS codes and categorized into cemented and cementless fixation groups. Patient demographics, comorbidities, indications, postoperative complications, length of stay, hospital charges, and in-hospital mortality were compared. Multivariate logistic regression analysis was performed to evaluate the independent association between fixation type and postoperative complications while adjusting for demographic, clinical, and hospital-level variables. Results: A total of 81,668 elective THAs were identified, including 40,290 cemented (49.33%) and 41,378 cementless (50.67%) procedures. Cemented THA was associated with a shorter length of stay (2.09 ± 1.88 vs. 2.26 ± 2.47 days, p < 0.001) and lower total hospital charges ($65,584.53 ± 48,797.21 vs. $72,186.84 ± 49,860.20, p < 0.001). Unadjusted analyses demonstrated higher rates of acute kidney injury and sepsis in the cementless group. After multivariate adjustment, cemented fixation was associated with lower odds of acute kidney injury (OR 0.87, 95% CI 0.79–0.96, p = 0.004). However, cemented THA was associated with higher odds of postoperative delirium (OR 1.20, 95% CI 1.02–1.42, p = 0.030), blood transfusion (OR 1.27, 95% CI 1.17–1.37, p < 0.001), and periprosthetic fracture (OR 1.32, 95% CI 1.02–1.71, p = 0.035). Rates of myocardial infarction, pneumonia, venous thromboembolism, urinary tract infection, and in-hospital mortality were similar between groups. Temporal analysis demonstrated comparable utilization trends, with a decline in elective procedures during 2020–2021. Conclusions: In this nationwide analysis, cemented total hip arthroplasty was associated with lower risk of acute kidney injury, shorter length of stay, and lower hospital charges, but higher odds of postoperative delirium, blood transfusion, and periprosthetic fracture compared with cementless fixation. These findings highlight distinct perioperative risk profiles between fixation strategies and may assist surgeons in individualized decision-making for elective total hip arthroplasty. Full article

Background: Hip fractures represent a major public health challenge in aging populations and are associated with high morbidity, mortality, and healthcare costs. While osteoporosis is the main underlying cause, biochemical markers of bone metabolism may provide additional insight into skeletal remodeling processes. However, the relationship between bone turnover biomarkers and specific hip fracture patterns remains poorly understood. Methods: A retrospective observational study was conducted, including patients admitted with hip fractures between January 2022 and December 2023 at our institution. Serum levels of vitamin D, parathyroid hormone (PTH), N-terminal propeptide of type I collagen (PINP), and beta-C-terminal telopeptide of type I collagen (β-CTX) were analyzed. Fractures were classified as intracapsular or extracapsular. Continuous variables were compared using the Mann–Whitney U test. Multivariable logistic regression analysis was performed to identify factors independently associated with extracapsular fractures. Results: A total of 131 patients were included, comprising 57 intracapsular fractures and 74 extracapsular fractures. Patients with extracapsular fractures were significantly older (83 (75–89) vs. 80 (71–86) years; p = 0.0079). No significant differences were observed in vitamin D levels between fracture groups (p = 0.446). PTH levels were higher in extracapsular fractures (p = 0.030), while β-CTX levels tended to be lower (p = 0.080). In multivariable logistic regression analysis, age remained independently associated with extracapsular fracture pattern (OR 1.05, 95% CI 1.01–1.09; p = 0.03). Higher β-CTX levels were inversely associated with extracapsular fractures (OR 0.65, 95% CI 0.43–0.96; p = 0.03), whereas vitamin D levels were not independently associated with fracture type. Conclusions: Extracapsular hip fractures were primarily associated with older age in this cohort. Among bone metabolism biomarkers, β-CTX showed an inverse association with extracapsular fracture pattern after adjustment for confounding factors. These findings should be interpreted with caution and considered exploratory, highlighting the need for prospective studies to clarify their clinical significance. Full article

Background/Objectives: The objective was to evaluate whether surgical timing (daytime vs. nighttime) influences intraoperative and postoperative outcomes in pediatric supracondylar humerus fractures. Methods: A retrospective observational cohort study was conducted at a tertiary center. Pediatric patients aged ≤14 years who underwent surgery for supracondylar humerus fractures between January 2010 and December 2022 were included. Fractures were classified according to the Gartland system. Patients with open fractures, associated neurovascular injury, compartment syndrome, or incomplete follow-up were excluded. Primary outcomes included need for open reduction, reoperation, neuropathy, and loss of joint mobility. Patients were grouped according to the time of surgery: daytime (08:00–22:00) or nighttime (22:00–08:00). Stratified analyses were performed based on fracture severity. Results: Eighty-six patients were included: 56 underwent daytime surgery and 30 underwent nighttime surgery. Groups were comparable in age, sex, and fracture severity. Nighttime surgery was associated with a significantly higher rate of open reduction (33.3% vs. 10.7%, p = 0.023; RR = 3.11). Reoperation (16.6% vs. 5.4%, p = 0.121) and postoperative neuropathy (23.3% vs. 8.9%, p = 0.131) were more frequent in the nighttime group, although these differences were not statistically significant. In complex fractures (Gartland III–IV), nighttime surgery was associated with a significantly higher reoperation rate (20.8% vs. 2.6%, p = 0.026). Conclusions: Nighttime surgery was associated with higher rates of open reduction and reoperation, particularly in complex supracondylar humerus fractures. However, given the retrospective design and limited sample size, these findings may be influenced by residual confounding and should be interpreted as exploratory. Full article

To address the technical challenge of large-area roof hanging and induced strong strata behaviors in deep mines with hard roof strata, a study on pressure relief using hydraulic fracturing technology was conducted, taking the 1012006 working face in the Yuanzigou Coal Mine as the engineering background. Through geological survey and key stratum theory analysis, a low-position key stratum located 23 m above the roadway roof was identified as the target layer for fracturing. True triaxial hydraulic fracturing experiments coupled with acoustic emission (AE) monitoring revealed a synchronous response characterized by a sudden drop in injection pressure and a rapid increase in AE counts. This established a quantitative correlation between rock mass fracturing and AE characteristics, providing a theoretical basis for field microseismic monitoring. Based on the “dual-borehole synergy” borehole layout principle, a fracturing network comprising 6 drilling fields and 12 directional long boreholes was designed, with a total drilling length of 5727 m and 120 planned fracturing stages. Specialized equipment was selected for implementation. Field monitoring results demonstrated: a maximum fracturing influence radius of 27.8 m; that the average daily frequency and total energy of microseismic events decreased by 50.65% and 27.73%, respectively; and that the stress in the deep part of the roadway decreased by 17.69%. These results confirm the effective improvement of the roof stress environment and the successful achievement of the expected pressure relief and rockburst prevention effect. Full article

Numerical simulation of sequential fracturing in horizontal wells for shale gas and oil extraction requires careful consideration of mechanical interactions between proppant and fracture surfaces—a challenge that remains largely unresolved. This study proposes a novel phase-field model featuring a strain-based formulation and a width-dependent proppant reaction force. Unlike previous studies, we integrate an empirical propped force solution, adapted from established work to account for rock properties and proppant support, to capture nonlinear fracture closure. Results show that reaction stress models significantly dictate propped geometry. The model’s fracture length, width, and closure predictions are validated against theoretical solutions. We conducted a sensitivity analysis to evaluate how fracture deflection angles and widths vary with dimensionless fracture spacing, in situ stress contrast, and proppant strength. Numerical results show that proppants induce pronounced morphological asymmetry and distinct geometric discrepancies. Specifically, the heterogeneous support provided by proppants and the resulting stress redistribution alter fracture propagation paths, leading to an 8% reduction in fracture length and a marked difference in fracture orientation of approximately 80° between supported and unsupported fractures, highlighting the important role of proppants in governing fracture geometry. Both dimensionless fracture spacing and in situ stress contrast strongly influence fracture deflection, with proppant strength also contributing. The propped-force formulation is further extended to nonplanar fractures, enabling application to sequential fracturing with multiple fractures. These results highlight fracture propagation mechanisms and demonstrate the robustness of the proposed phase-field model. Full article

Reservoir fracturing combined with thermal stimulation is a highly promising strategy for the development of challenging hydrates. However, the synergistic influence mechanisms of multiple engineering parameters on productivity remain poorly understood. In this study, based on the geological condition of the SH2 site in the Shenhu Area of the South China Sea, a numerical model was built to investigate the development efficiency of challenging hydrates under fracturing and thermal co-stimulation. Using average gas production rates (m³/d) at recovery rates of 0.70 and 0.85 as assessment indicators, eXtreme Gradient Boosting (XGBoost) and SHapley Additive exPlanations (SHAP) algorithms were employed to quantitatively measure multivariable importance. The results indicated that enhancing the inter-well interaction through reservoir fracturing can increase development efficiency by 2 to 5 times; however, it is not the case that larger-scale fracturing is always preferable, as it can lead to more severe water flooding. Additionally, data-driven models revealed that fracture length (SHAP values of 15.55 and 9.19) was the primary factor influencing development efficiency, followed by the fracture conductivity (SHAP values of 6.65 and 6.32), whereas injection pressure (SHAP values of 2.90 and 2.17), injection temperature (SHAP values of 2.41 and 2.13), and production pressure (SHAP values of 2.37 and 1.82) had relatively limited influences. Most importantly, the positive interaction effect between fracture length and fracture conductivity cannot be ignored. In our simulation, the recommended fracture length and conductivity were 40 m and 100 D·cm, respectively. These findings provide important insights and guidance for implementing this novel co-stimulation method in challenging hydrates. Full article

Proppant flowback during the flowback phase after hydraulic fracturing in coal reservoirs critically impacts fracture conductivity and wellbore integrity. However, experimental studies on its critical conditions and controlling mechanisms within coal’s complex fracture networks are scarce compared to sandstone or shale. This study conducted physical simulation experiments using outcrop coal samples from the XD block in China and a modified fracture conductivity system. By establishing a determination method for the critical backflow rate (Q_c), the dynamic evolution process of proppant backflow—characterized by the stages of initial stability, critical instability, severe backflow, and re-equilibration—was revealed. The influences of proppant size, flowback fluid viscosity, proppant concentration, and effective stress on Q_c were systematically analyzed, and the relative weight of each influencing factor was quantified through orthogonal experimental design. Results show that proppant backflow initiates and concentrates preferentially at the fracture outlet region, implying a higher risk of proppant failure in the near-wellbore fracture section. The Q_c decreases with reducing proppant size, increasing flowback fluid viscosity, increasing proppant concentration, and decreasing effective stress, among which effective stress is identified as the dominant controlling factor. Furthermore, no necessary correlation is observed between Q_c and the critical backflow ratio, suggesting that the initiation threshold and post-instability flowback intensity are governed by different mechanisms. This work provides experimental data and a quantitative basis for optimizing flowback strategies in coal reservoir fracturing operations. Full article

While CO₂ huff-n-puff (CO₂ HnP) is a promising technique for shale oil recovery, the characteristics and controlling factors of microscopically movable oil in lacustrine argillaceous-rich shales remain poorly understood. Shale samples from the Qingshankou Formation in the Songliao Basin were collected, and a series of experiments, including low-pressure N₂ adsorption, mercury injection porosimetry, and nuclear magnetic resonance, were conducted. High-pressure and high-temperature CO₂ HnP experiments were then conducted to investigate the effects of cycle number, soaking time and changes in pore structure on movable oil distribution. The shales exhibit multi-scale pores and lamellar fractures containing substantial residual oil (41.33–52.16% saturation). CO₂ HnP effectively mobilizes oil from macropores (50–1000 nm) and fractures (>1000 nm), with a limited effect in micro–mesopores (<50 nm). Three CO₂ HnP cycles were optimal for movable oil extraction. Extending the soaking time increased movable oil by ~4%, primarily from macropores and fractures (5.59–6.05%), with minimal improvement in smaller pores. A combination of CO₂ flooding followed by CO₂ HnP increased total movable oil by 4.83–7.26%, significantly enhancing recovery from micropores (7.26%) and macropores (9.21%). This study clarifies the pore size distribution and mobilization constraints of movable oil in argillaceous-rich shales. The integrated CO₂ flooding and HnP strategy proves to be highly effective, especially for movable oil in micro–mesopores. This study is the first to investigate pore-scale movable oil in lacustrine argillaceous-rich shales during CO₂ huff-n-puff under in situ reservoir conditions, and could provide critical insights for optimizing shale oil recovery in the Songliao Basin and similar lacustrine reservoirs. Full article

To address the technical challenges of difficult deduction, limited field measurement, and ambiguous instability determination of roof separation critical values in mining roadways within the weakly cemented coal-bearing strata of Xinjiang, this paper proposes a discrete element method that integrates the fracture of anchor bolt and anchor cable support materials with the damage degree of the surrounding rock. Taking a specific mine in the Hosh Tolgay coalfield as the research object, a systematic study was conducted. The research process was as follows. (1) Model parameter calibration was performed. Intact rock parameters were obtained through laboratory basic mechanical tests, and rock mass parameters were corrected based on reduction empirical formulas and the Hoek–Brown criterion. Numerical model verification showed that the errors between the simulated and theoretical values of the elastic modulus, compressive strength, and tensile strength of the rock mass were all less than 10%, indicating that the corrected parameters are reasonable. (2) The critical damage values of the rock mass considering a non-constant confining pressure environment were proposed. Through triaxial compression simulations, the differential evolution patterns of rapid damage increase in sandy mudstone under low confining pressure and stable damage accumulation in coal were revealed, thereby clarifying the damage thresholds for rock mass instability under different confining pressures. (3) A large-scale model was established to analyze the evolution laws of the fracture field, support field, and displacement field of the roadway surrounding rock. A comprehensive determination method for the instability of the roof anchored bearing structure was proposed. By comparing the damage thresholds of the scaled rock mass and the roadway surrounding rock and analyzing the fracture conditions of the roadway support system, a dual-criterion consisting of surrounding rock damage and support material fracture was constructed. Based on this criterion theory, the critical values for deep and shallow separation were obtained. The research results indicate that the evolution patterns of damage in coal and sandy mudstone differ with confining pressure. The sandy mudstone layers in the shallow part of the roof are more sensitive to mining-induced unloading disturbances. Consequently, the surrounding rock damage and support fracture of the mine roof exhibit distinct distribution characteristics: the dominant failure of the roadway is shear failure, with wide-range coalescence of shallow fractures and gradual development of deep fractures, alongside the concentrated failure of shallow anchor bolts and partial failure of deep anchor cables. Based on the instability state of the roof monitoring zones, the critical value for shallow separation was determined to be 90.7 mm, and the critical value for deep separation was 129.03 mm. These results are very close to the field measured values, verifying the engineering applicability of the method. This paper reveals the damage characteristics of the rock mass and surrounding rock in weakly cemented strata, as well as the mechanism of roof separation initiation and evolution. The proposed method for determining critical values provides a scientific and feasible practical reference for the support optimization and monitoring and early warning of roadway roofs in weakly cemented strata, possessing significant engineering value for ensuring safe and efficient mine production. Full article

Bone fractures and keel bone damage as a result of osteoporotic implications on skeletal health due to high rates of egg production are of significant concern in the egg industry. This study was conducted to evaluate the effects of two aviary housing configurations and associated exercise opportunities on musculoskeletal health in laying hens. Two commercial aviary designs were compared: Big Dutchman NATURA STEP (STEP) and Big Dutchman NATURA 60 (N60). Musculoskeletal assessments were performed at 60 weeks of age (n = 180), where measurements included CT imaging and radiography, muscle dissections, tibial and humeral biomechanical properties, and bone ash percentage. Results indicated that hens in the STEP aviary exhibited higher tibial breaking strength, humeral stiffness, and heavier muscle groups compared to the N60 system. However, rates of new and old fractures, as well as rates of deviation, were more prevalent in STEP hens compared to N60 hens. These results indicate that housing system design influences musculoskeletal health in laying hens. Full article

There is a risk of wire breakage and falls when constructing high-voltage transmission lines. If this occurs, it seriously endangers the safety of crossing objects. As key structures commonly used in power construction to protect crossing facilities from wire breakage, the scientific design and accurate calculation of the safety margins for suspension-crossing frames are particularly important. However, the existing energy transfer mathematical model for impact-bearing cables after conductor fracture cannot accurately describe the physical process, and the value of the fixed break impact coefficient (e.g., 2.89 for the double circuit) adopted in the design specification is not sufficiently accurate. Thus, there is a large deviation in the bearing cable safety factor, which can cause the safety margin to be either too large or insufficient, in turn seriously affecting the safe and efficient completion of cross-line construction. To this end, in this study, we first constructed a mathematical model of impact energy conversion based on the law of conservation of energy; then, we proposed an accurate method for calculating the safety factor of the bearing cable. To verify the method’s accuracy, a full-scale true wire breakage impact test was conducted. The results show that the error between the impact coefficient calculated by this method and the test result is only 6.7%, significantly better than the 38.3% error, found when the traditional design specification is used to fix the value. This method is applied to a 220 kV crossing project case. The analysis shows that, to meet the same safety requirements, the model recommends the use of Φ12 Dyneema rope, while the traditional method requires Φ16 Dyneema rope; simultaneously, for the Φ18 Dyneema rope, the maximum allowable span calculated by this method is 450 m, which is greater than the 400 m calculated using the traditional method. Thus, this method can calculate a more accurate impact coefficient based on actual working conditions, thereby significantly optimizing the selection of load-bearing cables and increasing the upper limit of span design while ensuring construction safety. Overall, the research conclusions provide important theoretical and technical support for optimizing the design and safety check of the suspension-crossing frame. Full article

This study characterizes the pathological findings in Atlantic Cory’s shearwater (Calonectris borealis) chicks from the Canary Islands associated with illegal hunting cases. A retrospective analysis of necropsy archives, including imaging techniques (X-rays and computed tomography) and histopathological examinations, was conducted on twenty juvenile shearwaters. The study revealed significant cranioencephalic trauma as the primary cause of death in both poaching events. Differences in the methods used by the perpetrators were noted, with variations in skull fractures and associated injuries. These findings highlight the importance of understanding local hunting techniques and sociocultural factors in forensic investigations. Diagnostic imaging, standardized necropsy, and histopathology are essential tools for the forensic investigation of illegal hunting in veterinary sciences. Full article

Gas–liquid gravity displacement poses a significant risk to drilling safety. However, the underlying mechanisms governing this process under downhole high-temperature and high-pressure (HTHP) conditions in deep and ultra-deep wells remain poorly understood. In this study, a numerical simulation method based on the Volume of Fluid (VOF) model was developed to investigate gas–liquid gravity displacement behavior under downhole HTHP conditions. The model was validated against 200 data points from visual laboratory experiments, showing excellent agreement with a relative error below 8.58%. Using this validated model, we then conducted 330 numerical simulations to systematically investigate the characteristics of gravity displacement under downhole HTHP conditions. Compared with surface low-pressure conditions, gravity displacement under downhole HTHP is markedly different, characterized by a narrower displacement window, lower gas influx (e.g., 99.5% reduction at −1500 Pa vs. surface conditions) and loss rates, and a smoother gas–liquid interface. As fracture width decreases, both gas influx and drilling fluid loss rates decline nonlinearly, and the displacement window contracts significantly. A critical fracture width for the onset of gravity displacement was identified, ranging from 0.3 to 0.5 mm depending on downhole conditions such as equivalent depth, drilling fluid density, and viscosity. Furthermore, increasing drilling fluid density expands the displacement window and increases the drilling fluid loss rate, whereas higher viscosity reduces both gas influx and drilling fluid loss rates. In contrast, fracture roughness exhibits minimal influence on gravity displacement. These findings provide practical criteria for optimizing well control strategies, thereby reducing drilling risks and improving operational safety. These findings advance the fundamental understanding of gravity displacement and contribute to a theoretical basis for improving drilling safety in deep fractured gas reservoirs. Full article

Carbonate reservoirs exhibit complex combinations of pores, fractures, and vugs, and their strong heterogeneity makes pore-scale displacement mechanisms and recovery enhancement difficult to predict. In this study, six microfluidic glass-etched models representative of pore-type, vuggy, and fracture-pore carbonate reservoirs were designed from cast thin sections of the S oilfield. Experiments were conducted to investigate the effects of different factors on microscopic displacement behavior and residual-oil distribution. The results show that microscopic residual oil in carbonate reservoirs mainly occurs as film flow, droplet flow, columnar flow, multi-pore flow, and cluster flow, with cluster flow dominating the late stage of development in all model types. Under waterflooding, pore-type reservoirs exhibit the most uniform sweep and the highest recovery factor (44.26%), whereas vuggy reservoirs readily develop preferential flow channels and show the lowest recovery factor (41.58%). For fracture-pore reservoirs, injection perpendicular to the fracture provides the best performance, and wider or denser fractures improve displacement efficiency. Compared with gas flooding, waterflooding increases recovery by 10.48% in pore-type reservoirs and by 16.44% in fracture-type reservoirs. High-rate waterflooding and mid-stage flow diversion further improve recovery by 9.05–10.87% and 17.12–19.63%, respectively. These results provide pore-scale evidence for optimizing development strategies for carbonate reservoirs. Full article

Background/Objectives: Uroflowmetry is done in the surveillance period after End-to-end Anastomotic Urethroplasty for pelvic fracture urethral injury. But is maximum flow rate a reliable surrogate for urethral calibre in these cases? The above question laid the foundation of the study. The aim of the study was: “Is uroflowmetry alone sufficient to predict a successful outcome following urethroplasty after pelvic fracture urethral injury (PFUI)?” Methods: We conducted a prospective masked study of all patients undergoing end-to-end anastomosis (EEA) urethroplasty for PFUI from January 2017 to September 2022. The first follow-up was 4 weeks after surgery, micturating cystourethrogram (MCU) was done after urethral catheter removal and at the same time, uroflowmetry was also done. The second follow-up was 6 months after surgery, when uroflowmetry was repeated, and urethroscopy was performed. The urologist performing urethroscopy was blinded to the uroflowmetry results. Results: In total, 26 patients were included in the study. After 6 months, 1 patient had poor flow (maximum flow rate [Q max] < 10 mL/s), 7 patients had flow with Q max 10–15 mL/s, and 18 patients had normal flow (Q max > 15 mL/s). On urethroscopy, all patients had a normal and easily passable urethra. The International Prostate Symptom Score (IPSS) and quality of life (QoL) scores showed a positive correlation. The urologist performing urethroscopy and the investigator recording uroflowmetry reached different conclusions. Conclusions: A reduced peak on uroflowmetry after EEA urethroplasty in PFUI does not always indicate surgical failure. Urethroscopy enables direct visualisation of the anastomotic site and provides more detailed information than uroflowmetry. The IPSS score and quality of life are more important than Q max alone. Full article