“Stress fracture”

PURPOSE: The application of robotics in the operating theatre for total knee arthroplasty (TKA) remains controversial. As with all new technology, the introduction of new systems is associated with a learning curve and potentially associated with extra complications. Therefore, the aim of this study is to identify and predict the learning curve of robot-assisted (RA) TKA. METHODS: A RA TKA system (MAKO) was introduced in April 2018 in our service. A retrospective analysis was performed of all patients receiving a TKA with this system by six surgeons...

Endodontic rotary files are cutting instruments used to perform root canal procedures within a tooth interior. Focusing on quantitative fractographic analysis increases necessary, clinical performance understanding of file separation failure. This research employed controlled, dynamic testing to failure of commercial rotary files, analyzing the fractographic, forensic characteristics in relation to Weibull reliability determination, considering: (1) design analysis; (2) stress concentrations; (3) times to failure; (4) number of cycles to failure (NCF)...

Ulnar stress fractures have been reported in athletes performing repetitive, high-impact activities, such as baseball pitchers and gymnasts. Crutch-assisted walking also results in cyclical forearm loading. We report the first case of ulnar stress reaction due to axillary crutch use. A 23-year-old right-handed woman experienced right forearm pain and imaging confirmed a right ulnar stress injury. The patient was also found to have mild hypercortisolism, low bone mass and vitamin D deficiency. Crutches were discontinued and physical therapy to normalise weight bearing through the left leg was prescribed...

Intramedullary nails are the common treatment options for femoral intertrochanteric fractures. However, aseptic loosening is considered to be one of the primary forms of failure that can be caused by the stress shielding between the bone and implants. The matching in mechanical properties of implant and bone is a key issue to prevent this failure. Polyetheretherketone (PEEK) and Function-graded (FG) materials are widely used in clinical because of their excellent mechanical properties. In this study, to investigate the biomechanical behaviors of intramedullary nails made of Ti-6Al-4V alloy, Stainless Steel (SS), PEEK and two FG materials, three-dimensional finite element models of intertrochanteric fracture femur with intramedullary nail were constructed with ABAQUS...

The objective of this study is to understand the fracture mechanisms in the lithium manganese oxide (LiMn2 O4 ) electrode at the molecular level by studying mechanical properties of the material at different values of the State of Charge (SOC) using the principles of molecular dynamics (MD). A 2 × 2 × 2 cubic structure of the LiMn2 O4 unit cell containing eight lithium ions, eight trivalent manganese ions, eight tetravalent manganese ions, and 32 oxygen ions is studied using a large-scale atomic/molecular massively parallel simulator...

The notch sensitivity of additively manufactured IN 625 superalloy produces by laser powder bed fusion (LPBF) has been investigated by tensile testing of cylindrical test pieces. Smooth and V-notched test pieces with four different radii were tested both in as-built state and after a stress relief heat treatment for 1 h at 900 °C. Regardless of the notch root radius, the investigated alloy exhibits notch strength ratios higher than unity in both as-built and in stress-relieved states, showing that the additive manufactured IN 625 alloy is not prone to brittleness induced by the presence of V-notches...

The main purpose of this paper is to propose, based on the literature review, a new multiaxial fatigue strain criterion, analogous to the Dang Van stress criterion, considering the maximum amplitude of the shear strain and volumetric strain. The proposed strain criterion was successfully verified by fatigue tests in cyclic bending with torsion of specimens made of 2017A-T4 and 6082-T6 aluminum alloy. The scatter of test results for cyclic bending and the combination of cyclic bending and torsion is included in the scatter of tests for the cyclic torsion of the analyzed materials...

Open reduction followed by internal fixation (ORIF) has been regarded as the most effective technique for surgical repair of zygomaticomaxillary complex (ZMC) fractures. However, the ideal internal fixation method to achieve stable reduction remains controversial. This research aims to assess and compare the stability of the 2- and 3-point screw-plate fixation methods using finite element method (FEM). Based on computed tomography (CT), the finite element models of 2-point (ZFS + IOR) and 3-point (ZFS + IOR + ZMB) fixation for isolated displaced ZMC fracture were reconstructed...

OBJECTIVE: To assess the biomechanical properties that influence wrist fracture, so as to provide the theoretical basis for simulation experiments to aid the optimal design of wrist protectors. METHODS: Six cadaveric wrists were included as experimental specimens. Wrist specimens wearing wrist protectors formed the experimental group and unprotected wrist specimens formed the control group. The wrist specimens were axially loaded under physiological loads and the stress magnitude and distribution of the experimental and control groups were obtained...

Self-assembled membranes with periodic wrinkled patterns are the critical building blocks of various flexible electronics, where the wrinkles are usually designed and fabricated to provide distinct functionalities. These membranes are typically metallic and organic materials with good ductility that are tolerant of complex deformation. However, the preparation of oxide membranes, especially those with intricate wrinkle patterns, is challenging due to their inherently strong covalent or ionic bonding, which usually leads to material crazing and brittle fracture...

The main symptom in patients with axial spondyloarthritis (axSpA) is inflammatory back pain, caused principally by inflammation of the sacroiliac joints and the spine. However, not all back pain in patients with axSpA is related to active inflammation: other types of pain can occur in these patients, and may be related to structural damage (e.g. ankylosis), degenerative changes, vertebral fractures or comorbid fibromyalgia, which are not uncommon in these patients. Structural damage and ankylosis may lead to a biomechanical stress, which can lead to chronic mechanical pain; and degenerative changes of the spine may also exist in patients with axSpA also leading to mechanical pain...

BACKGROUND: The incidence of totally implantable catheter fracture ranges from 0.48% to 5.00%, and these fractures represent a potentially fatal complication. The fracture mechanism of catheters implanted via the jugular vein is unclear, and whether extreme arm movements represent an additional risk factor for repetitive stress of the material remains unknown. The aim of this study was to demonstrate and classify catheter deformations caused by extreme arm mobilization and associations with changes in catheter function and displacement...

INTRODUCTION: Methotrexate (MTX)-related osteopathy is rare, defined by the triad of pain, osteoporosis, and "atypical fractures" when it was first described in the 1970s in children treated with high doses MTX for acute leukemia. Since then, several cases have been reported in patients treated with low-dose MTX for inflammatory diseases. METHODS: A systematic research of cases of MTX-related osteopathy was performed in records of Rheumatology Department of Rennes University Hospital...

Different fixation modalities are available for fixation of posterior malleolar fractures (PMFs), but the best method is still unclear. The purpose of this study was to carry out a comparative biomechanical analysis of three commonly used fixation constructs for PMFs using experimental and finite element analysis (FEA). 15 human cadaveric ankle specimens were randomly divided into three groups. Specimens in group-A were fixed with two anteroposterior (AP) lag screws, group-B with two posteroanterior (PA) lag screws, and for group-C, a posterior plate was used...

Contemporary earthquake hazard models hinge on an understanding of how strain is distributed in the crust and the ability to precisely detect millimeter-scale deformation over broad regions of active faulting. Satellite radar observations revealed hundreds of previously unmapped linear strain concentrations (or fractures) surrounding the 2019 Ridgecrest earthquake sequence. We documented and analyzed displacements and widths of 169 of these fractures. Although most fractures are displaced in the direction of the prevailing tectonic stress (prograde), a large number of them are displaced in the opposite (retrograde) direction...

BACKGROUND: Working length have been reported to affect the plate stress and fixation stiffness. However, the results of previous studies have been controversial. The present study was to determine working length effects on different locations of femoral bone gap. METHODS: Five composite femurs with wide bone gaps at five levels (G1, 2, 3, 5, and 7), were fixed with locking plates. G1-3, G5 and G7 represented gaps at distal femur, distal-middle femur and middle femur respectively...

The stress corrosion cracking is the central issue for high-strength wires under high tensile stress used in civil engineering. This paper explores the resistance of stress corrosion cracking of three typical steel wires of high-strength carbon through a laboratory test, combining the actions of tensile stress and corrosive solution. Besides, the impact of tensile stress and immersion time are also investigated. During the tests, the wires were subject to electrochemical measurements of potentiodynamic polarization and electrochemical impedance spectroscopy, and the microstructure analysis was performed on the fractured cross sections...

To analyze the stress distribution of the maxillary central incisor with oblique fracture, repaired by different methods, using 3-dimensional finite element analysis. From the biomechanical point of view, it is expected to provide a reference for clinical selection of restoration method which is more conducive to stress distribution and preservation of dental tissue as much as possible.Use cone beam CT and finite element software to establish the finite element models of the maxillary central incisor with oblique fracture, and then create models according to 5 repairing methods(A...

BACKGROUND: Tibial fractures cause ~3% of racehorse deaths. Pre-existing stress fractures have been associated with multiple racing and training fractures, but not complete tibial fractures. OBJECTIVES: To describe racehorse tibial fractures and compare signalment and exercise histories of affected and control racehorses. STUDY DESIGN: Retrospective analysis of necropsy reports. METHODS: Racehorses that had a complete tibial fracture (1990-2018) were retrospectively reviewed...

<b/> Standard nitinol stents (SNS), with or without drug eluting technology, are an essential tool within the interventional armamentarium in the treatment of patients with peripheral arterial disease. However, they are plagued by a number of limitations: a.) stent fractures, although observed predominately in first-generation stents, do still occur in state-of-the art stent platforms, b.) lack of radial strength, resulting in inadequate stent expansion, c.) kinking up to a complete collapse of the stent, therefore compromising its use in areas of high mechanical stress such as bending zones...