Search results for "Modeling"
showing 10 items of 4489 documents
Numerical simulations on periprosthetic bone remodeling: a systematic review
2021
Abstract Background and objective The aim of the present study was to review the literature concerning the analysis of periprosthetic bone remodeling through finite element (FE) simulation. Methods A systematic review was conducted on 9 databases, taking into account a ten-year time period (from 2009 until 2020). The inclusion criteria were: articles published in English, publication date after 2009, full text articles, articles containing the keywords both in the abstract and in the title. The articles were classified through the following parameters: dimensionality of the simulation, modelling of the bone-prosthesis interface, output parameters, type of simulated prosthesis, bone remodeli…
Cathepsin L in metastatic bone disease: therapeutic implications
2010
AbstractCathepsin L is a lysosomal cysteine proteinase primarily devoted to the metabolic turnover of intracellular proteins. However, accumulating evidence suggests that this endopeptidase might also be implicated in the regulation of other important biological functions, including bone resorption in normal and pathological conditions. These findings support the concept that cathepsin L, in concert with other proteolytic enzymes involved in bone remodeling processes, could contribute to facilitate bone metastasis formation. In support of this hypothesis, recent studies indicate that cathepsin L can foster this process by triggering multiple mechanisms which, in part, differ from those of t…
Effect of training with Supejump® on bone metabolism in women
2021
Physical exercise is recommended to decrease bone loss in elderly women. Supejump® is a new workout activity performed on a modified elastic mini trampoline that mixes aerobic and anaerobic exercises. The aim of the study was to investigate the long-term effects of training with Supejump® on bone metabolism in women. Twelve women were involved in the study. They performed Supejump®, three times a week, each session lasting 60 mins for a total of 20-weeks. Blood samples were collected at baseline and at the end of the 20-weeks of training. The biomarkers of bone resorption (c-terminal telopeptide region of collagen type 1 (β-CTX)), bone formation (osteocalcin), and calcitonin, parathyroid ho…
Periacetabular Cortical and Cancellous Bone Mineral Density Loss After Press-Fit Cup Fixation
2012
The impact of total hip arthroplasty on strain adaptive bone remodeling has been extensively analyzed by dual-energy x-ray absorptiometry. In this study, we present a prospective computed tomography-assisted study of periacetabular cortical and cancellous bone mineral density (in milligrams of calcium hydroxyapatite [CaHA] per milliliter, or mgCaHA/mL) changes 10 days and 1, 3, and 7 years after press-fit cup implantation for 38 hips in vivo. Cancellous bone mineral density decreased by O -63% ventral and O -85% dorsal to the cup; cortical bone mineral density, by O -22% ventral and O -18% dorsal to the cup. The presented periacetabular strain adaptive bone mineral density data are the most…
Serum and urine markers of type I collagen metabolism in elderly women with high and low bone mineral density.
1996
The serum markers of bone formation (carboxy-terminal propeptide of type I collagen, PICP) and resorption (pyridinoline cross-links containing telopeptide of type I collagen, ICTP), as well as urinary resorption markers, pyridinoline (Pyr) and deoxypyridinoline (Dpyr), were studied in 78-year-old women with high (n = 18) and low (n = 17) bone mineral density (BMD) measured from the calcaneus and tibia. The low-BMD group had higher values for PICP (P = 0 center dot 025), Pyr (P = 0 center dot 001) and Dpyr (P < 0 center dot 001) than the high-BMD group. No inverse relationship between these markers and BMD was, however, observed within the study groups. ICTP, Pyr and Dpyr correlated with eac…
Bone mineral density and bone turnover in Romanian children and young adults with classical 21-hydroxylase deficiency are influenced by glucocorticoi…
2009
Summary Objective It remains controversial if glucocorticoid replacement therapy impairs bone mineral density (BMD) in young patients with 21-hydroxylase deficiency. We aimed to analyze the impact of treatment variables, phenotype and genotype on BMD and bone metabolism in these patients. Design Cross-sectional study. Measurements Twenty-eight Caucasian patients with classical 21-hydroxylase deficiency (5–39 years). Clinical parameters, hormonal status, osteocalcin (OC), C-terminal telopeptide of type I collagen (CTX), genotype and lumbar BMD (Z-scores) were assessed. Cumulative and mean hydrocortisone equivalent doses were calculated for the entire treatment period. Results Patients wi…
Experimental evidence of pharmacological management of anchorage in Orthodontics: A systematic review
2015
Introduction: Orthodontic anchorage is one of the most challenging aspects of Orthodontics. Preventing undesired movement of teeth could result in safer and less complicated orthodontic treatment. Recently, several reviews have been published about the effects of different molecules on bone physiology and the clinical side effects in Orthodontics. However, the effects of local application of these substances on the rate of orthodontic tooth movement have not been assessed.Objectives: The aim of this research was to analyze the scientific evidence published in the literature about the effects of different molecules on orthodontic anchorage.Methods: The literature was systematically reviewed …
Fundamental solutions for general anisotropic multi-field materials based on spherical harmonics expansions
2016
Abstract A unified method to evaluate the fundamental solutions for generally anisotropic multi-field materials is presented. Based on the relation between the Rayleigh expansion and the three-dimensional Fourier representation of a homogenous partial differential operator, the proposed technique allows to obtain the fundamental solutions and their derivatives up to the desired order as convergent series of spherical harmonics. For a given material, the coefficients of the series are computed only once, and the derivatives of the fundamental solutions are obtained without any term-by-term differentiation, making the proposed approach attractive for boundary integral formulations and efficie…
A model for low-cycle fatigue in micro-structured materials
2020
A microscale formulation for low-cycle fatigue degradation in heterogeneous materials is presented. The interface traction-separation law is modelled by a cohesive zone model for low-cycle fatigue analysis, which is developed in a consistent thermodynamic framework of elastic-plastic-damage mechanics with internal variables. A specific fatigue activation condition allows to model the material degradation related to the elastic-plastic cyclic loading conditions, with tractions levels lower than the static failure condition. A moving endurance surface, in the classic framework of kinematic hardening, enables a pure elastic behaviour without any fatigue degradation for low levels of cyclic tra…
Coupled VEM–BEM Approach for Isotropic Damage Modelling in Composite Materials
2023
Numerical prediction of composite damage behaviour at the microscopic level is still a challenging engineering issue for the analysis and design of modern materials. In this work, we document the application of a recently developed numerical technique based on the coupling between the virtual element method (VEM) and the boundary element method (BEM) within the framework of continuum damage mechanics (CDM) to model the in-plane damage evolution characteristics of composite materials. BEM is a widely adopted and efficient numerical technique that reduces the problem dimensionality due to its underlying formulation. It substantially simplifies the pre-processing stage and decreases the compu…