Frequency Of Fractures Research Articles

Fractures in faulted sandstone reservoir

The Chang 8 Member of the Yanchang Formation in southwest Ordos Basin is a typical faulted sandstone oil reservoir. The development characteristics of fractures have obvious controlling effect on the formation of sweet spots of tight reservoir. In this paper, taking the Chang 8 Member of the southwestern Ordos Basin as an example, the development characteristics and controlling factors of fractures in faulted sandstone oil reservoir are systematically studied. The results show that the faulted sandstone oil reservoirs in the study area are distributed along the main strike-slip faults. The fracture system includes vertical fractures and horizontal bedding fractures. The fracture surface of vertical fractures generally has good oil display, and mostly presented as oil spot and oil immersion level; however, the oil level of horizontal bedding fractures is usually presented as oil spot level. The development frequency of horizontal bedding fractures is 62.5 %, while that of vertical fractures is 37.5 %. The fractures are mainly developed in fine sandstone and a small amount of medium-grained sandstone and siltstone. The factors that affect the fracture development degree in faulted oil reservoir include the distance from main fault, sand thickness, lithology and structural location. For the Jinghe and Honghe Oilfields, the degree of fracture development decreases sharply when the distance from the main fault is greater than 1.25 km and 1.5 km, respectively. Single sand body thickness also controls the degree of fracture development. Single sand bodies with thickness within 6 m have more developed fractures, and the fracture development decreases sharply when the thickness exceeds 6 m. The sand body in the wing part of river channel is relatively thin with fine grain size and small compacted space, which is easy to break under tectonic activity. The fractures of the Chang 8 Member in the study area are mainly developed near the faults, the top of anticline and its wing part.

Fiber-Optics Approach Monitors Drainage Profile of Multistage Stimulation

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 212364, “Can You Feel the Pressure? Strain-Based Pressure Estimates,” by Kyle Haustveit, SPE, and Jackson Haffener, SPE, Devon Energy. The paper has not been peer reviewed. _ The combination of horizontal wells and hydraulic stimulation has been key in unlocking vast unconventional resources across North America and elsewhere, but much remains to be understood regarding how the reservoir is drained across the miles of laterals accessing a resource. The density of pressure gauges required to accurately measure the drainage pattern from a horizontal multistage stimulation is currently not realistic economically or technologically. In this case study, the authors describe a method of monitoring the drainage profile of a horizontal multistage stimulation using optical fiber. Introduction An advanced subsurface diagnostic project was deployed as part of the Hydraulic Fracture Test Site I, Phase 3, funded by the Department of Energy. A lateral observation well was positioned approximately 225 ft away from the nearest two stimulated and producing horizontal wells. Using optical fiber and Raleigh frequency-shift distributed strain sensing (RFS-DSS), strain change was measured in the far field as the offset well was stimulated and first produced. RFS-DSS provides a spatial resolution of 20 cm, allowing for the monitoring of strain changes at finer spatial resolution than can be sensed accurately with low-frequency distributed acoustic sensing. The strain change during the interference test correlated with both the strain change during the crosswell refracturing monitoring and the pressure-gauge change along the monitor well during the interference test. The strong correlation between crosswell refracturing and interference strain monitoring suggests that the magnitude of crosswell strain responses is directly proportional to the intensity of strain change when the offsetting wells are put online. The comparison of data recorded from RFS-DSS and six reservoir-sensing pressure gauges displayed a strong correlation between the total strain change and total pressure drawdown. Three gauges positioned in regions of large negative strain change during first production, interpreted as drawdown, showed large pressure declines; the other three gauges, positioned in areas of small strain change, saw small pressure declines. The correlation was applied to the total length of the wellbore based on the strain change to estimate a pressure along the entire lateral, including areas without pressure gauges. Pilot Design Located in DeWitt County, Texas, the project consisted of a combination of production infill wells (12H and 13H), pre-existing primary wells (2H, 4H, 6H, and 8H), liner refracturing wells (3H and 5H) and one unstimulated observation well (14H). The wells are landed in the lower Eagle Ford formation. While drilling the observation lateral, horizontal core was collected and used to investigate the frequency of hydraulic and propped fractures created from the 4H and 5H original stimulations. The 14H lateral was equipped with permanent optical fiber, one internal pressure-sensing gauge used for sealed wellbore pressure monitoring, and nine reservoir-sensing pressure gauges to monitor fracture interactions and pressure drawdown from the offset wells. Three of the gauges failed to show connection to the reservoir and were discarded for this analysis.

Strukturne determinante povećane koštane fragilnosti kod starijih osoba - višestruke perspektive

Numerous epidemiological studies have shown that increased bone fragility and a higher risk of fractures are present in the aged, which reduces their quality of life and represents a significant socio-economic burden for the healthcare system. However, morphological and structural determinants underlying increased bone fragility have yet to be fully explained. This paper aimed to provide an overview of modern studies that dealt with determinants of increased bone fragility, analyzing different hierarchical levels of bone tissue organization (macro-, micro-, and nano-levels) in aged individuals and individuals with chronic comorbidities (mainly in individuals with chronic liver disease, renal disorders, and type 2 diabetes mellitus). Also, variable frequency of fractures at different skeletal sites in aged persons and individuals with chronic diseases was shown, indicating that aging-related bone loss is not a uniform process. A complete understanding of the spatial pattern of impaired bone quality can aid in the targeted evaluation of individualized fracture risk. Establishing a firm connection between the results of the clinical assessment of bone status and the analysis of numerous structural and mechanical bone properties (on various hierarchical levels) can represent a solid base for developing adequate guidelines and algorithms for prevention and treatment of increased bone fragility in aged individuals and individuals with chronic diseases.

COMPARATIVE ANALYSIS OF CONSERVATIVE AND SURGICAL TREATMENT OUTCOMES IN PATIENTS WITH DIAPHYSEAL HUMERUS FRACTURES

The frequency of diaphyseal humerus fractures varies from 1% to 5% of the total number of skeletal fractures in humans. A clear bimodal gender and age distribution of patients with fractures in the studied area has been established. The main methods of treatment for closed intra-articular humerus fractures are conservative functional and surgical treatment. Treatment of diaphyseal humerus trauma involves not only restoring the axis and length of the bone but also ensuring sufficient mobility of adjacent joints. The aim of the study was to conduct a comparative analysis of the outcomes of conservative and surgical treatment in patients with diaphyseal humerus fractures. The study involved 57 patients with diaphyseal humerus fractures aged from 19 to 83 years. The first clinical group comprised of 24 patients aged from 24 to 80 years who were treated using functional fixation devices. The second clinical group consisted of 33 patients aged from 19 to 83 years who were treated using surgical techniques, namely antegrade locked intramedullary nailing and cortical plate and screw osteosynthesis. Rehabilitation measures were initiated within the first two days for patients in the first group and in the early postoperative period for patients in the second group. The range of motion of adjacent joints was assessed using the CMS and MEPS scales. The use of surgical treatment techniques in combination with early rehabilitation measures, compared to conservative functional treatment, allows achieving significantly higher and statistically significant (p<=0.01) functional outcomes of elbow joint mobility.

Prediction of fragility fractures in men with prostate cancer under androgen deprivation therapy: the importance of a multidisciplinary approach using a mini-invasive diagnostic tool.

Bone fragility in men who are treated with androgen deprivation therapy (ADT) has a complex pathophysiology that differs from that of primary and post-menopausal osteoporosis. Fracture risk assessment based on bone mineral density (BMD) and Fracture Risk Assessment Tool (FRAX) score might not be effective in this patient setting, since high frequency of fragility fractures has been reported even in subjects with low FRAX risk and normal BMD. In this paper we want to emphasize the importance in the individual assessment of bone fragility and prediction of fractures by measuring parameters of bone quality, assessing morphometric vertebral fractures and evaluating body composition that in subjects under hormone-deprivation therapies can play a crucial role. Noteworthy, a single mini-invasive diagnostic tool, i.e., the dual energy x-ray absorptiometry (DXA) scan, offers the opportunity to evaluate reliably parameters of bone quality (e.g., trabecular bone score) and body composition, besides measurement of BMD and assessment of vertebral fractures by a morphometric approach. This article highlights the values and cost-effectiveness of this mini-invasive tool in the context of multidisciplinary approach to subjects with prostate cancer under ADTs.

Differentiating fatal one-punch assaults from standing height falls based on skeletal trauma: a pilot study

ABSTRACTA fatal one-punch assault is defined as a single punch to a person’s head or neck resulting in death. In some of these assaults, it may be important to understand which injuries stemmed from the punch, the resulting fall, or both. The aim of this study was to identify if there were differences in skull and cervical fractures between deaths from a one-punch, one-punch with fall, and fall from standing height. Relevant cases were extracted from the Victorian Institute of Forensic Medicine’s database, and case circumstances and biological variables were recorded from coronial documentation. Fracture patterns and types were documented from post-mortem computed tomography scans. Trauma was analysed in the context of the variables using descriptive and bivariate models. Six one-punch, 15 one-punch with fall, and 30 standing height fall deaths were included. There were subtle fracture differences. All skull regions fractured in the three events; however, the frequency of fractures varied, and cervical vertebrae fractures did not occur in the isolated one-punch deaths. Variations of linear fractures resulted from falls while linear, diastatic and blowout fractures resulted from a punch. The findings augment the evidence base for trauma interpretations in one-punch assaults and provide the foundation for a large-scale study.

Leadless pacemaker tine damage and fracture: novel complications of a novel device fixation mechanism

BackgroundLeadless pacemakers represent a paradigm-changing advancement. However, they required innovative and novel device design, including the use of nitinol tines for fixation. ObjectiveWe aimed to understand the potential for fracture in the novel tine-based fixation mechanism. MethodsA retrospective approach was used to search the Manufacturer and User Facility Device Experience (MAUDE) database for events related to Micra pacemaker tine fracture and damage. Review of each report was performed to ascertain frequency of tine fracture and damage. ResultsOf 4241 MAUDE reports (2104 Micra VR, 2167 Micra AV), 230 included the terms “fracture” or “tine”, which yielded 7 tine fractures and 19 reports of tine damage. Overall, 2/7(29%) tine fractures were noted during implant, whereas 2/7(29%) were discovered ≥1 week after implant; 5/7(71%) tine fracture reports described no associated patient signs or symptoms, and 4/7 (57%) described no change in pacing parameters. Tine damage occurred during implant in 16/19 (84%), compared with 2/19 (11%) noted ≥1 week after implant;15/19 (79%) tine damage cases reported no associated signs or symptoms, and 7/19 (37%) described no changes in pacing parameters. Among all cases, there was 1 case of device embolization. ConclusionsThe novel tine-based fixation mechanism appears susceptible to a novel failure mechanism – tine fracture and/or damage. Our analysis suggests these events may not always be associated with adverse signs or symptoms. Diligent attention at implant, and future bench or clinical studies are needed to understand the rate, clinical impact, and mechanism of such failures, and role of surveillance.

Imaging Patterns of Temporal Bone Fracture among Patients with Head Injury at Tikur Anbessa Specialized Hospital, Ethiopia.

Temporal bone fracture is usually a sequel of significant blunt head injury. Fracture of the temporal bone is mainly classified according to the orientation of the fracture plane and whether there is involvement of the otic capsule. Despite its frequent occurrence, there is limited research on the frequency and pattern of temporal bone fractures in our setup. Retrospective cross-sectional hospital - based study of 60 patients who underwent computed tomography of the head for head trauma at Tikur Anbessa Specialized Hospital during the study period from October 2020 - October 2022. Among the 60 patients enrolled in the study, the mean age of presentation was 31.1 years with a male-to-female ratio of 4:1. There were 69 temporal bone fractures, 9(15%) were bilateral and 51(85%) unilateral The longitudinal fracture pattern was the most common fracture pattern, occurring in 40(78.4%) of unilateral cases, 15(83.3%) of bilateral cases. Otic capsule sparing fractures accounted for 49(96.07%) of unilateral fracture cases, and all patients with bilateral involvement had an otic capsule sparing fracture. Among the 42 patients for whom data regarding post-traumatic hearing outcome was available, 4 patients had post-traumatic hearing impairment. Anatomically, the squamous portion of the temporal bone was involved in 30(43.5%) of cases. Fractures affecting the squamous portion of the temporal bone, longitudinal fracture patterns, and otic capsule sparing were the most frequent forms. The majority of temporal bone fractures were associated with other bone fractures and intracranial injuries.

Evaluation of Bone Mineral Density in Lung Transplant Recipients by Chest Computed Tomography

Introduction: Lung transplantation (LT) recipients are at risk of bone mineral density (BMD) loss. Pre- and post-LT BMD loss has been reported in some cross-sectional studies; however, there are limited studies regarding the serial BMD change in LT recipients. The aim of this study was to investigate the serial BMD changes and the clinical characteristics associated with BMD decline. Methods: This was a single-center, retrospective observational study. BMD was serially measured in thoracic vertebral bodies (Th4, 7, 10) using computed tomography (CT) before and 3 and 12 months after LT. The frequency of osteoporosis and factors associated with pre-LT osteoporosis and post-LT BMD loss were evaluated. The frequency of post-LT compression fracture and its associated factors were also analyzed. Results: This study included 128 adult LT recipients. LT recipients had decreased BMD (151.8 ± 42.2 mg/mL) before LT compared with age-, sex-, and smoking index-matched controls (176.2 ± 35.7 mg/mL). The diagnosis of COPD was associated with pre-LT osteoporosis. LT recipients experience further BMD decline after transplantation, and the percentage of recipients classified as exhibiting osteoporosis increased from 20% at baseline to 43% at 12 months. Recipients who had been taking no or small doses of glucocorticoids before LT had rapid BMD loss after LT. Early bisphosphonate use (within 3 months) after LT attenuated BMD loss and decreased new-onset compression fracture. Conclusion: LT recipients are at high risk for BMD loss and compression fracture after LT. Early bisphosphonate use may decrease BMD loss and compression fracture.

Spinal Sagittal Imbalance is Associated with Vertebral Fracture without a Definite History of Falls: Cross-Sectional, Comparative Study of Cohort with and without a Distal Radius Fracture

Background: Treating osteoporosis in patients with a distal radius fracture (DRF) became paramount at the Fracture Liaison Service. Spinal sagittal imbalance emerged as a risk factor for subsequent fractures. Therefore, here we investigated the spinal profile of patients with DRF to investigate its association with a history of falls and prevalent vertebral fractures.Methods: We reviewed the cases of 162 women presenting with DRF and 162 age-matched women without fracture who underwent an osteoporosis evaluation including bone mineral density (BMD) and lateral spine imaging. We compared the incidence of prevalent vertebral fracture and sagittal vertical axis (SVA) to measure spinal sagittal imbalance. We also performed a regression analysis of the risks of prevalent vertebral fracture, such as age, body mass index (BMI), BMD, and SVA.Results: The SVA was significantly smaller (indicating more stable sagittal balance) in patients with a DRF versus controls (16 mm vs. 34 mm, respectively; <i>p</i><0.001). The incidence of a prevalent vertebral fracture was similar between groups (12% vs. 15%, respectively; <i>p</i>=0.332). In both groups, the SVA was significantly greater in those with versus without a vertebral fracture. The vertebral fracture was significantly associated with age and SVA but not BMI or spinal BMD.Conclusions: Spinal sagittal balance was superior in DRF patients, yet the frequency of prevalent vertebral fractures was similar. The identification of this unique spinal profile in patients with DRF may increase our understanding of osteoporotic fractures.

Bone Fracture in Rett Syndrome: Mechanisms and Prevention Strategies.

The present study aimed to evaluate the burden and management of fragility fractures in subjects with Rett syndrome. We searched all relevant medical literature from 1 January 1986 to 30 June 2023 for studies under the search term "Rett syndrome and fracture". The fracture frequency ranges from a minimum of 13.9% to a maximum of 36.1%. The majority of such fractures occur in lower limb bones and are associated with low bone mineral density. Anticonvulsant use, joint contractures, immobilization, low physical activity, poor nutrition, the genotype, and lower calcium and vitamin D intakes all significantly impair skeletal maturation and bone mass accrual in Rett syndrome patients, making them more susceptible to fragility fractures. This review summarizes the knowledge on risk factors for fragility fracture in patients with Rett syndrome and suggests a possible diagnostic and therapeutic care pathway for improving low bone mineral density and reducing the risk of fragility fractures. The optimization of physical activity, along with adequate nutrition and the intake of calcium and vitamin D supplements, should be recommended. In addition, subjects with Rett syndrome and a history of fracture should consider using bisphosphonates.

Multiscale fractures, stress and reservoir quality characterization: The Mississippian Meramec and Osage intervals, STACK play, Central Oklahoma

This study characterized in-situ stress-fields and multi-scale fractures in the low porosity and low permeability Mississippian-aged “Meramec and Osage” intervals in the Anadarko Basin of central Oklahoma. As the two reservoirs' productivity is influenced by fractures, understanding fracture nature, frequency and distribution is important for the development of these reservoirs. The study implemented an integrated approach to characterize in-situ stress-fields and related fractures utilizing 3D seismic data, cores, petrophysics, and formation micro-imaging logs. Density of fractures was interpreted from integrated analyses of seismic, petrophysical, core, and FMI log data. Fracture orientations were determined from the seismic and FMI log data. Detected fractures in the “Meramec” interval preferentially occur in pervasively calcite-cemented rock with low porosity. Because of the adverse effect of calcite cementation, fractures did not significantly improve reservoir quality within the “Meramec” interval. In contrast, detected fractures in the “Osage” interval added sufficient porosity and permeability to overcome negative cementation effects and improved the overall reservoir quality. This study revealed a rotation of the horizontal stress orientations from ancient stress regimes to the present-day in-situ stress regimes. The study demonstrated the application of integrated seismic and non-seismic data in fracture and stress-field characterization, improved our understanding of the effects of fractures on reservoir quality to reduce risks associated with exploring low-porosity/low-permeability mixed carbonate and siliciclastic reservoirs.

Association of osteoporosis with ankle fractures in the geriatric population

Ankle fractures are common in older people. However, their association with osteoporosis remains controversial. This systematic review aims to determine the relationship between ankle fracture and bone mineral density (BMD). The article presents an overview of articles that have statistical data on the relationship of bone mineral density with the frequency of ankle fractures in the elderly. The aim of the review is to define ankle fracture associations in the geriatric population. Search was performed in PubMed, Medline, Scopus publications for articles in which a study of elderly patients with ankle fractures was conducted with an assessment of bone mineral density, followed by statistical processing with the presentation of the results. Ankle fractures in the geriatric population are due to generalized bone loss and changes in trabecular bone microarchitectonics, fragility, and therefore should be considered osteoporotic fractures, regardless of BMD. Correlation relationships were established with female sex, overweight, type 2 diabetes mellitus, arterial hypertension, which are characterized by a decrease in the trabecular structure. The FRAX fracture algorithm underestimates the likelihood of fractures in geriatric patients who have a high BMI and comorbid physical pathology, so it is necessary to focus on independent clinical risk factors for BMD in order to optimize fracture prevention.

A Comprehensive Look at Maxillofacial Traumas: On the Basis of Orbital Involvement.

Orbital wall fractures that may develop in maxillofacial traumas (MFTs) may cause ophthalmic complications (OCs). The aim of this study is to determine the frequency of orbital fractures (OFs) accompanying MFTs and findings suspicious for orbital traumatic involvement. Computed tomography (CT) images of 887 patients who presented to the emergency department within a 1-year period with a history of MFT were retrospectively scanned. During the examination, patients with orbital wall fractures, craniofacial bone fractures, and posttraumatic soft tissue changes were recorded. OF was observed in 47 (5.3%) of the patients admitted for MFT. In cases with OFs, accompanying nasal (25.5%), ethmoid (2.1%), frontal (19.1%), maxillary (38%), and zygomatic bone fracture (10.6%), sphenoid (4.3%), and soft tissue damage (55.3%) were observed. It was observed that the pathologies mentioned at these levels were significantly higher than in patients without orbital involvement (p < 0.05). In our study, mild (48.9%) and moderate-severe (2.12-4.25%) OCs accompanying OFs were observed after MFT. The frequency of MFT varies depending on various factors, and such studies are needed to take preventive measures. Knowing the risk and frequency of orbital damage accompanying MFTs may help reduce complications by allowing rapid and accurate diagnosis.

Diagnosis of Rib Fracture and Related Complications in Patients with Blunt Chest Wall Trauma Using Point-of-Care Ultrasound vs. Computed Tomography Scan

Background: One of the most common reasons for the referrals of patients to the trauma center is blunt chest injury. Objectives: To determine and compare the diagnostic value of point-of-care ultrasound (POCUS) and computed tomography (CT) scans in detecting rib fractures and their complications in patients with blunt chest wall trauma. Methods: The current cross-sectional study (October 2017-March 2018) was conducted in Shahid Rajaei Hospital, Shiraz, southern Iran. Convenient non-random sampling was employed. Patients with stable vital signs underwent ultra-sonography and later were evaluated by CT scan for fractures and related complications. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPP), positive likelihood ratio (PLR), negative likelihood ratio (NLR), and accuracy were calculated and compared between the two procedures. Results: A total of 113 patients with a mean ± standard deviation (SD) age of 44.07 ± 20.07 years were enrolled, of whom 75 (66.3%) and 62 (54.9%) patients had at least one broken rib based on CT scan and sonography, respectively. The frequency of double fractures was higher than other conditions in both CT scans and ultrasound (35.53% and 37.10%). The overall sensitivity of ultrasound was calculated to be 81.58%, and with an increasing number of broken ribs, the sensitivity of ultrasound also increased (73.08% for identifying patients with one damaged rib versus 100% for detecting patients with five or more broken ribs). None of the 13 definite cases of pneumothorax were detected on ultrasound, while the sensitivity of ultrasound was appropriate for hemothorax and subperiosteal hematoma (85.71% and 80.23%, respectively). Conclusions: Ultrasound offers high sensitivity, specificity, and diagnostic power in diagnosing fractures and their complications, but considering the setting of our study, care should be taken when generalizing the findings of this study.

Incidence of postoperative complications in patellar fractures related to different methods of osteosynthesis procedures - a retrospective cohort study

BackgroundPatellar fractures have a comparatively low incidence compared to all fracture frequencies of the musculoskeletal system. However, surgical management is crucial to prevent postoperative complications that affect the knee joint. The purpose of the present study was to evaluate the incidence of postoperative complications and onset of postoperative osteoarthritis related to the chosen technique of patellar fracture management.MethodsIn a retrospective cohort study consecutive managed, isolated patella fractures were reviewed for demographic data, trauma mechanism, patella fracture type, fixation technique and postoperative complications. The results were documented radiographically and clinically and analysed statistically. The reporting followed the STROBE guidelines.ResultsA total of 112 patients were eligible for data evaluation. Surgical management of comminuted patellar fractures with small fragment screws showed significant fewer postoperative complications compared to other fixation techniques (8%, p < 0.043). The incidence of posttraumatic infection was significantly higher following the hybrid fixation technique with cannulated screws and tension wire than following the other analysed techniques (p = 0.024). No postoperative wound infection was observed after screw fixation or locking plate fixation. Symptomatic hardware was most frequently seen after tension-band fixation. Onset of posttraumatic osteoarthritis was most often found after the hybrid fixation technique (55%).ConclusionSurgical management of patellar fractures remains crucial but fracture fixation using plating systems or small fragment screws is least associated with postoperative complications.Trial registrationTrial registration number (DRKS):00027894.

Radiographic cervical spine injury patterns in admitted blunt trauma patients with and without prehospital spinal motion restriction

ObjectivesSelective prehospital cervical spine motion restriction (C-SMR) following blunt trauma has increasingly been used by emergency medical service (EMS) providers. We determined rates of prehospital C-SMR and concomitant radiographic injury...

Accurate prediction of indicators for engineering failures in complex mining environments

Due to seismic load, complex geological and geo-mechanical conditions of rock mass in Steeply Inclined and Extremely Thick Coal Seam (SIETCS) mines, the prediction and prevention of dynamic disasters remain quite challenging. Traditionally, physical models and numerical simulations are widely practiced for disaster prediction at shallow depths which becomes difficult in SIETCS mines. The drilling tests and above models are generally time-consuming and uneconomic providing miniature coverage. Whilst, rockburst driven disasters require detailed regional geological understanding and mechanical behavior of rock mass. For this purpose, a non-invasive and cost-effective geophysical workflow covering regional-scale geology is introduced for accurate identification and prediction of rockburst in a SIETCS mine of northwestern China. Passive seismological in-situ observations were made for a period of twenty-four months to compute the seismic source parameters, map fracturing process, identify regional lineaments and calculate important rockburst prediction indicators. The spatiotemporal distribution of induced-microseismicity, three-states stress theory, and mapped fractures helped in the identification of three rockbursts, several high-energy tremors, and the prediction of two new rockburst-prone regions. The mapped fractures through the novel ‘Seismo-Frac model’ showed that for the simultaneous excavation in B3 + 6 and B2 + 1 coal seams subjected to repetitive episodes of seismic deformation, the shear-displacement accumulation, prying effects of rock pillar and roof coupled with dynamic stress are the primary mode of deformation. The mapped fractures and lineaments are unevenly distributed in the minefield with a maximum density of the fractures concentrated in the B3 + 6 coal seam and rock pillar. Furthermore, through conditional probability analysis, the prediction efficiency of source parameter averages (E and N), seismological parameters (b-value and Δb), and maximum potential magnitude (Mm) was compared. A sharp-increase in source parameter averages while a sharp-decrease in the seismological parameters proved to be effective rockburst prediction indicators. This study also introduces decreasing occurrence frequency of fractures and lineaments as the new prediction indicators. This method, while a panacea for imaging the entire fracturing phenomenon, provides insights with widespread implications for academic researchers and industry practitioners to mitigate dynamic disasters in global underground engineering excavation.

Real-time microseismic evaluation of coalbed methane reservoir stimulation based on improved metaheuristic inversion strategy

For the enhancement of coalbed methane production, the microseismic source location plays a crucial role in evaluating fracture information during hydraulic fracturing (HF). A swift and precise microseismic source location is essential for optimizing HF schemes. This optimization necessitates an inversion strategy characterized by low computational costs and high optimization accuracy. In this study, we propose an SM-MFO inversion strategy that functions in parallel with the simplex (SM) algorithm and is founded on the original moth flame optimizer (MFO) algorithm. This strategy was validated through gas blast microseismic monitoring field tests to assess the source location performance of the SM-MFO inversion strategy, followed by its application in real-time evaluation of staged HF for the Xinji 1# horizontal well. The results reveal that within the SM-MFO inversion strategy, SM can prevent local convergence by leveraging the capabilities of MFO. Conversely, MFO can bolster local search abilities with the assistance of SM. As a result, both the convergence speed and global optimization abilities of the strategy are enhanced. In field tests, the average location error of the SM-MFO algorithm was 18.11 m. This figure is more favorable compared to the errors in the MFO algorithm (22.15 m) and the SM algorithm (35.83 m). Moreover, the SM-MFO inversion strategy facilitates real-time evaluation of HF with a computational cost of just 1.01 s for a single microseismic event. Upon analysis of the overall incidence across the nine stages in the radial direction, a span of 270 m is attained, with fewer frequency of fractures observed in the southeast direction at each respective stage Additionally, the geometric parameters of the fractures and the stimulated reservoir volume (SRV) exhibit a positive correlation with the total fluid volume. The injected fluid volume peaks in the second and sixth stages, leading to fracture mesh dimensions of 312 m and 316 m, respectively. In summary, the total SRV of the Xinji 1# horizontal well is 201.7 × 105 m³, and the reservoir stimulation effect aligns with the anticipated results. This work highlights the efficacy of the SM-MFO inversion strategy in enhancing the efficiency and accuracy of microseismic source location for hydraulic fracturing, contributing valuable insights to the field.

Frequency and pathogenesis of periprosthetic atypical femoral fractures associated with total knee arthroplasty: A multicenter prospective study with complementary histopathological and biomechanical analysis

IntroductionAlthough the diagnostic criteria for atypical femoral fracture (AFF) exclude periprosthetic fractures, reports of periprosthetic femoral fractures with characteristics of AFF are rapidly increasing. In this study, we investigated the frequency and pathogenesis of periprosthetic AFF associated with total knee arthroplasty (TKA) based on a theory of AFF subtypes that divides AFFs into two main types: fragility stress fractures of the bowed femoral shaft in the mid-shaft and “typical” subtrochanteric AFFs due to suppression of bone turnover (e.g., by bisphosphonates). Patients and MethodsThis multicenter prospective study of AFFs was conducted from 2015 through 2022. Clinical, pathological, and morphological characteristics were investigated in patients with periprosthetic AFFs associated only with non-stem TKA. Then, biomechanical investigation of the periprosthetic AFF was performed by computer tomography-based finite element analysis (CT/FEA) using two models with different load axes to examine how the correction of lower limb alignment by TKA influences the tensile stress distribution of the femur and the location of the AFF. ResultsFour of 61 AFFs (6.6%) were identified to be periprosthetic AFF (1 mid-shaft; 3 subtrochanteric). Periprosthetic AFFs had characteristics including mechanical stress due to bowing deformity and potentially suppressed bone turnover due to long-term exposure to specific drugs (e.g., bisphosphonates and glucocorticoids). Although 2 periprosthetic AFFs appeared to involve a bowed femur, one with both of the aforementioned characteristics occurred in the subtrochanteric region, which would be an unusual site for a bowed AFF, and it was demonstrated histologically to have biological activity at the fracture site, suggesting a stress fracture. Furthermore, CT/FEA revealed that tensile stress distribution changed proximally as load axis was shifted laterally according to correction of lower limb alignment by TKA. ConclusionOrthopedic surgeons should recognize the presence of TKA-associated periprosthetic AFF caused by various factors including specific drugs, bowing deformity, and lower limb alignment. X-rays of the full-length femurs should be checked regularly after TKA, especially in patients with bowed femurs or long-term exposure to specific drugs.