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Stress fracture

Santosh K Yadav, Fengshuo Hu, John J La Scala, Giuseppe R Palmese
The aim of this work is to develop a series of advanced biobased tougheners for thermosetting epoxy resins suitable for high-performance applications. These bio-rubber (BR) tougheners were prepared via a one-step chemical modification of epoxidized soybean oil using biobased hexanoic anhydride. To investigate their toughening performance, these BR tougheners were blended with diglycidyl ether of bisphenol A epoxy monomers at various weight fractions and cured with anhydride hardeners. Significant improvements in fracture toughness properties, as well as minimal reductions in glass transition temperature ( T g ), were observed...
March 31, 2018: ACS Omega
Yue Guo, Mingxing Zhou, Xingdong Sun, Long Qian, Lijia Li, Yingjie Xie, Zeyang Liu, Di Wu, Liguo Yang, Tong Wu, Dan Zhao, Jinguo Wang, Hongwei Zhao
Effects of temperature and strain rate on the fracture behaviors of an Al-Zn-Mg-Cu alloy are investigated by isothermal uniaxial tensile experiments at a wide range of temperatures and strain rates, from room temperature (RT) to 400 °C and from 10-4 s-1 to 10-1 s⁻1 , respectively. Generally, the elevation of temperature leads to the increasing of elongation to fracture and the reduction of peak stress, while higher strain rate results in the decreasing of elongation to fracture and the increasing of peak stress...
July 18, 2018: Materials
Francesco Di Pietto, Vito Chianca, Marcello Zappia, Stefania Romano
Soccer is one of the most popular sports worldwide engaging millions of participants each year. During play, injuries occur rather frequently and most of them involve the hip joint and the surrounding structure. In professional athletes, injuries are often complex scenarios and in the case of misdiagnosis, patients' return to play is delayed or it may progress to a more serious injury with consequent damage for their career and for the soccer team. The most frequent articular pathologies are Femoro-acetabular impingement and labral tears...
August 2018: European Journal of Radiology
Kátia R Weber, Paula Benetti, Álvaro Della Bona, Pedro H Corazza, Juliana A Medeiros, Ediléia Lodi, Márcia Borba
STATEMENT OF PROBLEM: Variables involving the indication, manufacturing, and clinical use of ceramic restorations make the standardization of in vitro studies a challenge and raise questions as to the clinical validity of the resulting data. PURPOSE: The purpose of this in vitro study was to assess the effect of piston material on the fracture behavior of ceramics tested under compressive load. MATERIAL AND METHODS: Two ceramics were evaluated: a lithium disilicate-based glass-ceramic (D) and a feldspathic porcelain (P)...
July 13, 2018: Journal of Prosthetic Dentistry
Akira Kodama, Takaya Mizuseki, Nobuo Adachi
BACKGROUND: On the basis of the intra-articular findings during Kudo type 5 elbow prosthesis revision surgery, we infer the mechanisms leading to implant failure. MATERIALS AND METHODS: We performed primary Kudo type 5 total elbow arthroplasty on 60 rheumatoid elbows in 45 patients between 1994 and 2003. Revision surgery was performed in 8 patients (9 elbows) because of implant failure. We radiographically assessed their status before this surgical procedure and then assessed the surgical intra-articular findings based on surgery records and photographs...
August 2018: Journal of Shoulder and Elbow Surgery
Fatih Duygun, Cengiz Aldemir
OBJECTIVES: This study aims to investigate the effects of different amounts of compression used in intramedullary nailing on the stress values of the fracture surface and time of the union process in tibia diaphysis fractures treated with intramedullary nails. PATIENTS AND METHODS: Seventy patients (50 males, 20 females; mean age 34.0±10.7 years; range, 20 to 56 years) who had suffered from tibial shaft fractures between January 2007 and December 2015 were included in the study...
August 2018: Eklem Hastalıkları Ve Cerrahisi, Joint Diseases & related Surgery
Mehmet Nuri Konya, Ahmet Aslan, Sibel Bakbak
OBJECTIVES: This study aims to evaluate the effects of lesser trochanter (LT) and iliopsoas tendon on implant stability by using finite element analysis (FEA). MATERIALS AND METHODS: Effects of iliacus and psoas major muscles on hip joint was evaluated with inverse dynamics methods to calculate joint reaction and muscle forces. Intertrochanteric femur fracture was simulated according to AO (Arbeitsgemeinschaft für Osteosynthesefragen) 31A1 and 31A2 classifications in three-dimensional modelling software...
August 2018: Eklem Hastalıkları Ve Cerrahisi, Joint Diseases & related Surgery
Katharina Pils
Proximal femoral fractures in old age are known as fragility fractures. They are the sequelae of osteoporosis and an expression of a general reduced capacity and an increase in sensory and functional deficits against the background of multimorbidity. They are often caused by reduced compensation strategies. Simultaneously, for many older people they represent a life event. Despite modern osteosynthesis techniques and less stressful anesthesia procedures, the occurrence of a proximal femoral fracture shakes the labile equilibrium of those affected...
July 16, 2018: Zeitschrift Für Gerontologie und Geriatrie
Jennifer Kurowicki, Samuel J Mease, Steven Palacios, Anthony Festa, Vincent K McInerney, Anthony J Scillia
Recurrent patella instability is a common condition that may potentiate substantial knee dysfunction resulting in loss of time from work and sports. There are numerous factors that contribute to recurrent patella instability including tearing of the medial patellofemoral ligament (MPFL), shallow trochlea, valgus alignment, externally rotated tibia tubercle, ligamentous laxity, elevated Q angle, and increased tibial tuberosity trochlear groove distance. Reconstruction of the MPFL has been shown to restore patella stability where concomitant pathology is within acceptable limits...
June 2018: Arthroscopy Techniques
Jan Borys, Mateusz Maciejczyk, Bożena Antonowicz, Adam Krętowski, Danuta Waszkiel, Piotr Bortnik, Katarzyna Czarniecka-Bargłowska, Magdalena Kocisz, Julita Szulimowska, Marek Czajkowski, Napoleon Waszkiewicz, Anna Zalewska
Due to the high biotolerance, favourable mechanical properties, and osseointegration ability, titanium is the basic biomaterial used in maxillofacial surgery. The passive layer of titanium dioxide on the surface of the implant effectively provides anticorrosive properties, but it can be damaged, resulting in the release of titanium ions to the surrounding tissues. The aim of our work was to evaluate the influence of Ti6Al4V titanium alloy on redox balance and oxidative damage in the periosteum surrounding the titanium miniplates and screws as well as in plasma and erythrocytes of patients with mandibular fractures...
2018: Oxidative Medicine and Cellular Longevity
Subhadeep Roy, Takahiro Hatano
We study the dynamical aspects of a statistical-mechanical model for fracture of heterogeneous media: the fiber bundle model with various interaction ranges. Although the model does not include any nontrivial elementary processes such as nonlinear rheology or stochasticity, the system exhibits creeplike behaviors under a constant load being slightly above the critical value. These creeplike behaviors comprise three stages: primary, secondary, and tertiary. In the primary and tertiary stages, the strain rate exhibits power-law behaviors with time, which are well described by the Omori-Utsu and the inverse Omori laws, respectively, although the exponents are larger than those typically observed in experiments...
June 2018: Physical Review. E
Efstathia Polychronopoulou, David N Herndon, Craig Porter
Severe burn injury causes a profound stress response that leads to muscle and bone cachexia. Evidence suggests that these deficits persist for several months or even years after injury and are associated with growth delay, increased incidence of fractures, and increased hospital admissions for musculoskeletal disorders. Thus, there is an overwhelming need to determine the optimal acute and rehabilitative strategies to mitigate these deficits and improve quality of life for burn survivors. To date, there is limited research on the long-term impact of cachexia on functional performance and overall health, as well as on the lasting impact of pharmacological, nutritional, and exercise interventions...
July 13, 2018: Journal of Burn Care & Research: Official Publication of the American Burn Association
Ru Mu, Luansu Wei, Xiaowei Wang, Hui Li, Longbang Qing, Jian Zhou, Quanming Zhao
The aim of this work is to present an approach, inspired by the way in which a compass needle maintains a consistent orientation under the action of the Earth's magnetic field, for manufacturing a cementitious composite reinforced with aligned steel fibers. Aligned steel fiber reinforced cementitious composites (ASFRC) were prepared by applying a uniform electromagnetic field to fresh mortar containing short steel fibers, whereby the short steel fibers were driven to rotate in alignment with the magnetic field...
June 27, 2018: Journal of Visualized Experiments: JoVE
Xin Ye, James P Gaewsky, Derek A Jones, Logan E Miller, Joel D Stitzel, Ashley A Weaver
OBJECTIVE: This study aimed to reconstruct 11 motor vehicle crashes (six with thoracolumbar fractures and five without thoracolumbar fractures), and analyze the fracture mechanism, fracture predictors, and associated parameters affecting thoracolumbar spine response. METHODS: Eleven frontal crashes were reconstructed with a finite element simplified vehicle model (SVM). The SVM was tuned to each case vehicle and the Total HUman Model for Safety (THUMS) v4.01 was scaled and positioned in a baseline configuration to mimic the documented pre-crash driver posture...
July 16, 2018: Traffic Injury Prevention
Mohammad Zandi, Abbas Shokri, Maryam Mousavi, Sanaz Rajaei, Naser Mohammad Gholi Mezerji
INTRODUCTION: The aim of this study was to evaluate the effect of zoledronate therapy on susceptibility of mandibular bone to fracture in rats. METHODS: Fifty rats were randomly allocated to two groups of 25 animals. The rats in group Z received monthly intravenous infusion of 0.06 mg/kg zoledronate for 6 months. The rats in the group C were injected with an equal volume of saline in the same manner. A month after the last zoledronate/saline administration, all 50 rats were euthanized...
July 6, 2018: Injury
Alessandro Navacchia, Chadd W Clary, Xuzheng Han, Kevin B Shelburne, Abraham P Wright, Paul J Rullkoetter
Patellar complications after total knee replacement (TKR), such as maltracking, fracture, wear, and loosening, can lead to implant failure and revision surgery. However, few in vitro patellofemoral durability tests for the implanted joint have been developed. Existing standards for patellofemoral loading profiles (ISO 14243-5, draft) are generic (not implant-specific) and do not include patient variability. The goal of this study was to derive implant-specific loading profiles to simulate a motor task that reaches high knee flexion and include patient variability...
June 28, 2018: Journal of the Mechanical Behavior of Biomedical Materials
E Roitero, M Anglada, F Mücklich, E Jiménez-Piqué
The aim of this work is to test the mechanical properties of dental zirconia surfaces patterned with Nd:YAG laser interference (λ = 532 nm and 10 ns pulse). The laser treatment produces an alteration of the topography, engraving a periodic striped pattern. Laser-material interaction results mainly in thermal effects producing microcracking, phase transformation and texturization. The role of such microstructural modifications and collateral damage on the integrity and mechanical performances has been assessed...
June 28, 2018: Journal of the Mechanical Behavior of Biomedical Materials
Jakub Sikora-Klak, Steven J Narvy, Justin Yang, Eric Makhni, F Daniel Kharrazi, Nima Mehran
Vitamin D is a lipophilic prohormone integral to musculoskeletal, autoimmune, oncologic, cardiovascular, and mental health. Of particular importance to the orthopedic surgeon is the role of vitamin D in the regulation of bone mass, muscle strength, and physical performance. Although vitamin D-related skeletal pathologies are rare in industrialized nations, emerging research in the field has shown that most American adults have inadequate levels of vitamin D. Even among athletes, there is a high prevalence of vitamin D deficiency, which may place competitors at risk of stress fractures, illness, and delayed muscle recovery...
July 5, 2018: Permanente Journal
Nathan Truex, Travis J Menge
This report discusses an unusual case of bilateral chronic exertional compartment syndrome (CECS) of the lower leg, a syndrome found mainly in young athletes. Pathophysiology includes exercise-induced muscle expansion against noncompliant fibro-osseous membranes separating compartments of the lower leg. A 24-year-old female distance runner with a history significant for misdiagnosed shin splints and tibial stress fracture presented with acute-on-chronic right lower leg pain. History revealed exertional pain and numbness, alleviated by rest...
July 2018: South Dakota Medicine: the Journal of the South Dakota State Medical Association
Yuval Mulla, Giorgio Oliveri, Johannes T B Overvelde, Gijsje H Koenderink
In viscoelastic materials, individually short-lived bonds collectively result in a mechanical resistance which is long lived but finite as, ultimately, cracks appear. Here, we provide a microscopic mechanism by which a critical crack length emerges from the nonlinear local bond dynamics. Because of this emerging length scale, macroscopic viscoelastic materials fracture in a fundamentally different manner from microscopically small systems considered in previous models. We provide and numerically verify analytical equations for the dependence of the critical crack length on the bond kinetics and applied stress...
June 29, 2018: Physical Review Letters
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