What are risk factors for subsequent fracture after vertebral augmentation in patients with thoracolumbar osteoporotic vertebral fractures

Background Due to its unique mechanical characteristics, the incidence of subsequent fracture after vertebral augmentation is higher in thoracolumbar segment, but the causes have not been fully elucidated. This study aimed to comprehensively explore the potential risk factors for subsequent fracture in this region. Methods Patients with osteoporotic vertebral fracture in thoracolumbar segment who received vertebral augmentation from January 2019 to December 2020 were retrospectively reviewed. Patients were divided into refracture group and non-refracture group according to the occurrence of refracture. The clinical information, imaging findings (cement distribution, spine sagittal parameters, degree of paraspinal muscle degeneration) and surgery related indicators of the included patients were collected and compared. Results A total of 109 patients were included, 13 patients in refracture group and 96 patients in non-refracture group. Univariate analysis revealed a significantly higher incidence of previous fracture, intravertebral cleft (IVC) and cement leakage, greater fatty infiltration of psoas (FIPS), fatty infiltration of erector spinae plus multifidus (FIES + MF), correction of body angle (BA), BA restoration rate and vertebral height restoration rate in refracture group. Further binary logistic regression analysis demonstrated previous fracture, IVC, FIPS and BA restoration rate were independent risk factors for subsequent fracture. According to ROC curve analysis, the prediction accuracy of BA restoration rate was the highest (area under the curve was 0.794), and the threshold value was 0.350. Conclusions Subsequent fracture might cause by the interplay of multiple risk factors. The previous fracture, IVC, FIPS and BA restoration rate were identified as independent risk factors. When the BA restoration rate exceeded 0.350, refractures were more likely to occur.

Experimental Study on the Initiation and Propagation of Multi-Cluster Hydraulic Fractures within One Stage in Horizontal Wells

Competitive propagation of fractures initiated from multiple perforation clusters is universal in hydraulic fracturing of unconventional reservoirs, which largely influences stimulation. However, the propagation mechanism of multi-fractures has not been fully revealed for the lack of a targeted laboratory observation. In this study, a physical simulation experiment system was developed for investigating the initiation and propagation of multi-cluster hydraulic fractures. Different from the traditional hydro-fracking test system, the new one was equipped with a multi-channel shunting module and a strain monitoring system, which could guarantee the full fracture extension at each perforation clusters and measure the internal deformation of specimens, respectively. Several groups of true tri-axial fracturing tests were performed, considering the factors of in situ stress, cluster spacing, pumping rate, and bedding structures. The results showed that initiation of multi-cluster hydraulic fractures within one stage could be simultaneous or successive according to the difference of the breakdown pressure and fracturing fluid injection. For simultaneous initiation, the breakdown pressure of the subsequent fracture was lower than or equal to the value of the previous fracture. Multiple fractures tended to attract and merge. For successive initiation, the breakdown pressures of fractures were gradually increasing. The subsequent fracture tended to intersect with or deviated from the previous fracture. Multiple fractures interaction was aggravated by the decrease of horizontal stress difference, bedding number and cluster spacing, and weakened by the increase of pump rate. The propagation area of multiple fractures increased with the pump rate, decreased with the cluster spacing. The strain response characteristics corresponded with the initiation and propagation of fracture, which was conducive to understanding the process of the fracturing. The test results provide a basis for optimum design of hydraulic fracturing.

Mechanical properties of CAD/CAM-fabricated in comparison to conventionally fabricated functional regulator 3 appliances

Manufacturing of Fränkel's functional regulator 3 (FR3) is complicated and requires extensive knowledge from the dental technician. To determine whether FR3s produced by CAD/CAM techniques (CAD-FR3) meet similar mechanical properties like conventional FR3s (Con-FR3), for each of 10 patient cases, three CAD-FR3 designs (palatal connector cross-section 3 × 3 mm, 4 × 1 mm or 5 × 2 mm) and one Con-FR3 were subjected to cyclic loading and subsequent fracture testing in a universal testing device. Transversal load capacity (Fmax(FR3)) and stiffness were compared among the different CAD-FR3 designs and Con-FR3s using Friedman and Wilcoxon tests with a significance level of α = 0.05. All CAD-FR3 designs had significantly higher mean Fmax(FR3) (p ≤ 0.007) and stiffness (p ≤ 0.005) than the Con-FR3s. The CAD-FR33×3 had the highest mean Fmax(FR3) (98.2 ± 26.2 N) and stiffness (37.1 ± 15.5 N/mm), closely followed by the CAD-FR35×2 (Fmax(FR3): 90.3 ± 24.7 N; stiffness: 30.0 ± 12.3 N/mm). Among the CAD appliances, CAD-FR34×1 had the lowest values (p ≤ 0.007 for all pairwise tests) with Fmax(FR3) of 45.8 ± 17.9 N and stiffness of 12.5 ± 7.3 N/mm. CAD-FR3s have superior mechanical properties in comparison to Con-FR3s if certain design parameters are followed. Further clinical investigations have to examine if they can serve as an alternative in practice.

Osteoporotic fractures and subsequent fractures: imminent fracture risk from an analysis of German real-world claims data

Purpose In osteoporosis, prior fracture is a strong predictor of subsequent fracture. This study aimed to assess the imminent risk of subsequent fracture following an initial fracture in osteoporosis patients in Germany, and to identify clinical and demographic characteristics that are independently associated with subsequent fracture risk. Methods In this retrospective, observational cohort study using German real-world claims data, male and female patients aged ≥ 50 years with osteoporosis who experienced an initial (“index”) hip/femur, vertebral, forearm/wrist/hand or shoulder/upper arm fracture between 2010 and 2014 were included. The incidence and timing of subsequent fractures during a 1-year follow-up period were analyzed. Independent risk factors for subsequent fracture were identified by multivariate regression analysis. Results A total of 18,354 patients (mean age: 77 years; standard deviation: 9.8) were included. Of these, 2918 (15.9%) suffered a subsequent fracture during the 1-year follow-up period. The incidence of subsequent fracture was higher following an index vertebral fracture (18.0%) than after an index forearm/wrist/hand fracture (14.1%) or index hip/femur fracture (12.1%). Subsequent 1-year fracture incidence was generally higher in older patients. Index fracture type, age, epilepsy/use of antiepileptics, and heart failure were all independently associated with subsequent fracture risk. Conclusion Osteoporosis patients in Germany are at imminent risk of subsequent fracture during the first year following an initial fracture. They should be targeted for immediate post-fracture treatment to reduce the risk of further fractures, especially in the presence of specific risk factors such as old age or index vertebral fracture.

577 Risk Factors Analysis for Contralateral Neck of Femur Fracture in Elderly Population

Introduction Neck of femur fracture (NOFF) carries significant morbidity, mortality, and cost implication to the health system. Subsequent contralateral fracture(SCNOFF) further decreases patient performance and increases healthcare burden. The aim of this study was to identify and evaluate potential risk factors and effects of SCNOFF. Method Retrospectively analysed NOFF database from 2012 to 2019 was. Inclusion criteria were patients over 60 years with low energy fractures. Polytrauma, pathological and atypical fractures were excluded. Results There were 114 patients (4.18%) with contralateral hip fractures out of 2727 total NOFF patients. Mean age was 82 years old for the first hip fracture and 85 years for the second. Average time interval between fractures was 36 months. During the two admissions, mean decline in Abbreviated Mental Test Score(AMTS) was 0.4, deterioration of Clinical Fragility Score and Charlson Morbidity Index were from 4.5 to 5.9 (P < 0.0001), and from 5.4 to 6.1 respectively. Mobility was dropped by one level. institutional residency was increased from 23 to 46 (P > 0.0014). Conclusions There is a drastic decline in clinical frailty, mobility status and increase residential dependency following a subsequent fracture. Our findings demonstrate the importance of emphasizing preventive measures to reduce the incidence of SCNOFF.

Распределение напряжений при статическом растяжении цилиндрических образцов из мелко- и крупнозернистого алюминиевого сплава 6101

Проблема расчета прочности и долговечности различных конструкций из металлов является одной из важнейших в современном мире. Для ее решения необходимо понимание определенных механических критериев материала, таких как прочность, пластичность и др. [1, 2]. В данной работе приводятся данные расчета и указан характер распределения критических напряжений, которые определяют зарождение пор внутри материала, в данном случае в Al-6101, при статическом нагружении. Зарождение и слияние пор представляют собой первую стадию разрушения материала. При наличии данных о критических напряжениях материала можно спрогнозировать его дальнейшее разрушение [3, 4]. Calculation of strength and durability of various metal structures presents one of the most significant tasks in the contemporary world. To achieve it, the different mechanical criteria of the material, such as strength, ductility, etc. [1, 2] should be known. The calculation data and t distribution pattern of critical stresses that define formation of pores in the material (in our case, Al-6101) under static loading are presented in this article. The first phase of material fracture is the pore formation and merging. Therefore, its subsequent fracture can be estimated using the data on the critical stresses of the material [3, 4].

Fragility fracture identifies patients at imminent risk for subsequent fracture: real-world retrospective database study in Ontario, Canada

Background The secondary fracture prevention gap in the osteoporosis field has been previously described as a ‘crisis’. Closing this gap is increasingly important in the context of accumulating evidence showing that an incident fragility fracture is associated with an increased risk of subsequent fracture within 1–2 years, known as imminent fracture risk. The objective of this study was to use health services data to characterize the time between index fragility fractures occurring at different osteoporotic sites and subsequent fractures. Methods This retrospective observational study used de-identified health services data from the publicly funded healthcare system in Ontario, the largest province of Canada. Patients aged > 65 with an index fragility fracture occurring between 2011 and 2015 were identified from the ICES Data Repository using International Classification of Diseases (ICD)-10 codes. We examined median time to subsequent fragility fractures for osteoporotic fracture sites until the end of follow-up (2017). BMD assessment and use of osteoporosis therapies following index fracture were also characterized. Results Among 115,776 patients with an index fragility fracture, 17.8% incurred a second fragility fracture. Median time between index and second fracture occurring at any site was 555 days (interquartile range: 236–955). For each index fracture site examined, median time from index to second fracture was < 2 years. The proportion of patients with BMD assessment was 10.3% ≤1 year prior to and 16.4% ≤1 year post index fracture. The proportion of patients receiving osteoporosis therapy was 29.8% ≤1 year prior, 34.6% ≤1 year post, and 25.9% > 3 years post index fracture. Conclusions This cohort of Canadian patients aged > 65 years who experienced a fragility fracture at any site are at imminent risk of experiencing subsequent fracture within the next 2 years and should be proactively assessed and treated.