Internal Remodeling Research Articles

Chemotherapy and adjuvant therapies' impact on the internal remodeling process of bone and its mechanical behavior for breast cancer patients.

Breast cancer is a significant public health issue affecting women worldwide. While advancements in treatment options have led to improved survival rates, the impact of breast cancer and its treatments on bone health cannot be overlooked. Bone remodeling is a complex process regulated by the delicate balance between bone formation and resorption. Any disruption to this balance can lead to decreased bone density, increased fracture risk, and compromised physical function. To investigate the effects of breast cancer and its treatments on bone remodeling, a finite element model was developed in this study. This model incorporated bone remodeling equations to simulate the mechanical behavior of bone under different conditions. The ABAQUS/UMAT software was used to simulate the behavior of bone tissue under the influence of breast cancer and treatments. Our findings suggest that bone loss is more pronounced after secondary breast cancer and treatment, leading to bone loss (6%-19% decrease in BV/TV), reduced bone stimulation, and decreased effectiveness of physical activity on recovery. These results highlight the importance of early intervention and management of bone health in breast cancer patients to mitigate the negative impact of cancer and treatment on bone remodeling.

Bone remodeling following mandibular reconstruction using fibula free flap

To investigate bone remodelling responses to mandibulectomy, a joint external and internal remodelling algorithm is developed here by incorporating patient-specific longitudinal data. The primary aim of this study is to simulate bone remodelling activity in the conjunction region with a fibula free flap (FFF) reconstruction by correlating with a 28-month clinical follow-up. The secondary goal of this study is to compare the long-term outcomes of different designs of fixation plate with specific screw positioning. The results indicated that the overall bone density decreased over time, except for the Docking Site (namely DS1, a region of interest in mandibular symphysis with the conjunction of the bone union), in which the decrease of bone density ceased later and was followed by bone apposition. A negligible influence on bone remodeling outcome was found for different screw positioning. This study is believed to be the first of its kind for computationally simulating the bone turn-over process after FFF maxillofacial reconstruction by correlating with patient-specific follow-up.

Thermodynamic formulations of the growth of solid bodies subjected to electromechanical interactions and application to bone external and internal remodeling

The thermodynamics of open systems exchanging mass, heat, energy and entropy with their environment is examined as a convenient unifying framework to describe the evolution of growing solid bodies subjected to electromechanical stimulations in the context of volumetric growth. Extending the framework of non-equilibrium thermodynamics to open systems, the balance laws for continuum solid bodies undergoing growth phenomena incorporating mass sources and mass fluxes in the presence of electromechanical stimuli are expressed. As an alternative, general balance laws for growing solid bodies in presence of electromechanical couplings are expressed in generic format without explicit consideration of the transport phenomena and chemical reactions responsible for growth and the production of mass. The proposed formulations are next extended to the writing of flexoelectric models for growing solid bodies. Applications to electrically induced bending of thin plates and to the combine volumetric and surface growth of the diaphyseal part of the femur are provided as two illustrations of the derived state laws and kinetic equations for irreversible phenomena. The paper concludes with the elaboration of a combined internal to external surface growth model for bone remodeling describing surface apposition of mineral and local density changes, incorporating the driving effects of both electrical and mechanical signals.

Investigation of a bone lesion in a gorgonopsian (Synapsida) from the Permian of Zambia and periosteal reactions in fossil non-mammalian tetrapods.

While only distantly related to mammals, the anatomy of Permian gorgonopsians has shed light on the functional biology of non-mammalian synapsids and on the origins of iconic 'mammal-like' anatomical traits. However, little is known of gorgonopsian behaviour or physiology, which would aid in reconstructing the paleobiological context in which familiar mammalian features arose. Using multi-modal imaging, we report a discrete osseous lesion in the forelimb of a late Permian-aged gorgonopsian synapsid, recording reactive periosteal bone deposition and providing insights into the origins and diversity of skeletal healing responses in premammalian synapsids. We suggest that the localized lesion on the anterolateral (preaxial) shaft of the left radius represents acute periostitis and, conservatively, most likely developed as a subperiosteal haematoma with subsequent bone deposition and limited internal remodelling. The site records an inner zone of reactive cortical bone forming irregular to radial bony spicules and an outer, denser zone of slowed subperiosteal bone apposition, all of which likely occurred within a single growing season. In surveys of modern reptiles-crocodylians, varanids-such haematomas are rare compared to other documented osteopathologies. The extent and rapidity of the healing response is reminiscent of mammalian and dinosaurian bone pathologies, and may indicate differing behaviour or bone physiology compared to non-dinosaurian reptiles. This report adds to a growing list of putative disease entities recognized in early synapsids and broadens comparative baselines for pathologies and the evolution of bone response to disease in mammalian forebears. This article is part of the theme issue 'Vertebrate palaeophysiology'.

Study of surface wave vibration in rotating human long bones of cylindrical shape under the magnetic field influence

ABSTRACT Internal remodeling of Bone models describes the process by which bone adapts its histological structure to change in the long duration of mechanical load areas. In orthopedics, wave propagation over bone is used in monitoring the rate of fracture healing. The present problem studies the effect of initial stress, rotation and magnetic field on wave propagation in long dry bones. A dry long bone has been considered as an orthotropic hollow cylinder. The equation of motion is solved in terms of displacements. Bisection method has been used to calculate the phase velocity of harmonic wave and frequencies of vibration in anisotropic long bone. Peculiar effects of rotation, initial stress, surface span and magnetic field on vibrations in long bone medium have been investigated and presented through graphs. The present study finds its applications in wave propagation and vibration test to determine the vivo properties of long bones. As an outcome, there is a significant effect of initial stress on long bone structure as compared to rotation and magnetic parameter. Findings may also be useful for theoretical development of orthopedic studies related to cylindrical poroelastic long bones.

Topology optimization of bone using cubic material design and evolutionary methods based on internal remodeling

In the present paper, the influence of the loading conditions on the trabecular architecture of a femur is investigated by using the cubic material design and an evolutionary approach based on internal remodeling. The response of bone to mechanical loading stimuli leads to alterations of the internal architecture of bone, traduced by a modification of its effective density and mechanical properties. The cubic material design approach deals with the minimum compliance problem of femur bone made of a non-homogeneous elastic material with cubic symmetry. The optimal cubic material characteristics are in fact reflected by the properties of the underlying microstructure. Internal remodeling is here also considered and thus belongs to the class of evolutionary topology optimization methods. The effective continuum mechanical properties of the trabecular bone are derived from an initially discrete planar hexagonal structure representative of femur bone microstructure, relying on the discrete homogenization approach. This leads to scaling laws of the effective elastic properties of bone versus density at an intermediate mesoscopic scale. The performed simulations of the optimal trabecular bone architecture illustrate the respective advantages and limitations of the employed methods. The simulation results indicate that the proposed approaches could reasonably mimic the major geometrical and material features of the natural bone.

A physics-based micromechanical model for electroactive viscoelastic polymers

Electroactive polymers with time-dependent behavior are considered in the present paper by way of a new physics-based micromechanical model; such viscoelastic response is described by the internal evolution of the polymer network, providing a new viewpoint on the stress relaxation occurring in elastomers. The main peculiarity of such internally rearranging materials is their capacity to locally reset their reference stress-free state, leading to a mechanical behavior that relaxes out (eases off) an induced stress state and that can thus be assimilated to a sort of internal self-healing process. Such high deformability and recoverability displayed by dynamically cross-linked polymers can be conveniently exploited when they are coupled in electromechanical problems; the deformation induced by an electric field can be easily tuned by the intensity of the electric field itself and the obtained shape can be maintained without any electric influence once the material microstructure has rearranged after a sufficient curing time. In the present paper, both features of the polymeric material, that is, internal remodeling and electromechanical coupled response, are considered and a theoretical framework is established to simulate representative boundary value problems.

A Simplified Scheme for Piezoelectric Anisotropic Analysis in Human Vertebrae Using Integral Methods

This paper outlines a computational model for the analysis of the piezoelectric behaviour of the vertebral body remodelling process. Particular attention is paid to the algorithms for the simulation of the stress energy density for each point of the geometry and the distribution of the density in the bone. In addition, the model takes into account the piezoelectric effect and the anisotropy (transversal isotropy) of the bone. A model for internal anisotropic piezoelectric bone remodelling of a human vertebra is discussed in detail. The model consists of the implementation of an algorithm which includes the elastic and electric variables in a single equation using boundary element method. The presented results show a good agreement with biological data and the model does not include any electric additional charge.

Combined bone internal and external remodeling based on Eshelby stress

Models for the internal and external bone remodeling are developed in the framework of the thermodynamics of irreversible processes. Internal remodeling is essentially accounted for by an evolution of the internal bone density versus the trace of the Eshelby stress. The growing surface is endowed with a specific mechanical behavior elaborated from a surface potential, depending upon the elastic surface strain and the external normal vector. The surface remodeling velocity is related to the driving force for growth identified as the surface divergence of Eshelby stress. The developed formalism is applied to simulate bone internal and external remodeling for 2D geometries, showing the influence of external mechanical stimuli on the evolution of the external shape of bone. Simulations of the evolution of the shape and density of bone structures are carried out successively at mesoscopic, microscopic and macroscopic levels, the former representing cellular level simulations of the trabecular unit cell. At the macroscopic level, a linear elastic constitutive law for trabecular bone is derived, relying on the discrete homogenization approach, whereby the continuum parameters such as stiffness evolve with morphology as remodeling occurs within bone. The developed numerical platform is able to simulate combined bone internal and external remodeling at both trabecular and macroscopic scales.

From Clinging to Digging: The Postembryonic Skeletal Ontogeny of the Indian Purple Frog, Nasikabatrachus sahyadrensis (Anura: Nasikabatrachidae).

The Indian Purple frog, Nasikabatrachus sahyadrensis, occupies a basal phylogenetic position among neobatrachian anurans and has a very unusual life history. Tadpoles have a large ventral oral sucker, which they use to cling to rocks in torrents, whereas metamorphs possess adaptations for life underground. The developmental changes that underlie these shifts in habits and habitats, and especially the internal remodeling of the cranial and postcranial skeleton, are unknown. Using a nearly complete metamorphic series from free-living larva to metamorph, we describe the postembryonic skeletal ontogeny of this ancient and unique monotypic lineage. The torrent-dwelling larva possesses a dorsoventrally flattened body and a head with tiny dorsal eyes, robust lower and upper jaw cartilages, well-developed trabecular horns, and a definable gap between the trabecular horns and the tip of the snout. Unlike tadpoles of many other frogs, those of Nasikabatrachus retain larval mouthparts into late metamorphic stages. This unusual feature enables the larvae to maintain their clinging habit until near the end of metamorphosis. The subsequent ontogenetic shift from clinging to digging is correlated with rapid morphological changes and behavioral modifications. Metamorphs are equipped with a shortened tibiafibula and ossified prehallical elements, which likely facilitate initial digging using the hind limbs. Subsequently, the frogs may shift to headfirst burrowing by using the wedge-shaped skull, anteriorly positioned pectoral girdle, well-developed humeral crests and spatula-shaped forelimbs. The transition from an aquatic life in torrents to a terrestrial life underground entails dramatic changes in skeletal morphology and function that represent an extreme in metamorphic remodeling. Our analysis enhances the scope for detailed comparative studies across anurans, a group renowned for the diversity of its life history strategies.

Internal structure consistent with remodelling in very small drusen, revealed by filipin histochemistry for esterified cholesterol

Background/aimsDrusen, the pathognomonic lesion of age-related macular degeneration, are dynamic and undergo both growth and regression. Using histochemistry to localise esterified cholesterol (EC), we investigated small drusen to discover signs...

Effect of magnetic field on poroelastic bone model for internal remodeling

This paper studies the effects of the magnetic field and the porosity on a poroelastic bone model for internal remodeling. The solution of the internal bone remodeling process induced by a magnetic field is presented. The bone is treated as a poroelastic material by Biot’s formulation. Based on the theory of small strain adaptive elasticity, a theoretical approach for the internal remodeling is proposed. The components of the stresses, the displacements, and the rate of internal remodeling are obtained in analytical forms, and the numerical results are represented graphically. The results indicate that the effects of the magnetic field and the porosity on the rate of internal remodeling in bone are very pronounced.

Simulation of bone remodelling in orthodontic treatment

Orthodontic treatments not only displace irregular teeth but also induce responses in surrounding bone tissues. Bone remodelling is regarded as the regulatory mechanism triggered by mechanical loading. This study was aimed at investigating the effect of orthodontic loading on both tooth movement and neighbouring bone density distribution. A set of computational algorithms incorporating both external and internal remodelling mechanisms was implemented into a patient-specific 3D finite element (FE) model to investigate and analyse orthodontic treatment under four typical modes of orthodontic loading. The consequence of orthodontic treatment was reproduced numerically by using this FE-based technique. The results indicated that the diverse modes of orthodontic loading would result in different magnitudes of tooth movement and particular morphology of bone density distribution. It is illuminated that the newly developed algorithms may replicate the clinical situation more closely compared with the previous proposed method.

Histología Ósea del TitanosaurioBonitasaura salgadoi(Dinosauria: Sauropoda) del Cretácico Superior de Patagonia

Abstract. BONE HISTOLOGY OF THE TITANOSAUR BONITASAURA SALGADOI (DINOSAURIA: SAUROPODA) FROM THE UPPER CRETACEOUS OF PATAGONIA. The bone histology analysis of the titanosaur Bonitasaura salgadoi, from Rio Negro Province, Argentina, was analysed in detail. It represents the first complete histological characterization of a South American sauropod based on a single specimen. Multiple samples were taken from different parts of the skeleton according to available fragmentary elements as well as to their paleohistological importance. The femur and humerus are characterized by a wide cortex mainly composed of primary, highly vascularized fibrolamellar tissue, interrupted by at least one growth mark. None of the samples show external avascular lamellar tissue (EFS). Samples from the ulna, one metacarpal and a caudal vertebral zygapophysis show histological similarities, allowing recognition of great internal remodeling with several generations of secondary tissue. Although very reduced, the primary fibrolamellar...

Resection Guide For the ARC™ Tissue Conserving (Neck Sparing) Total Hip Stem - Case Report

Neck sparing total hip designs have been advocated as the next step in tissue preserving total hip arthroplasty1,2,3. In the proximal femur, the femoral neck and the adjoining medial aspect of the femur in the calcar region show the strongest bone structure (Fig. 1) with a high load capacity to support the stem. There are considerable short-term biomechanical advantages concerning reduced bending and torsional moments of the femoral implant/bone interface4 with resection at that level, however, historical review has demonstrated less than desirable bone maintenance over time5. According to Wolff’s Law, the reduction of stresses relative to the pre-implant anatomy would cause bone to adapt itself by reducing its mass, either by becoming more porous (internal remodeling) or by getting thinner (external remodeling)7. The ARC™Neck Sparing stem has a novel internal conical flair that engages the medial calcar and is designed to offload compressive loads maintaining a positive stress transfer to the medial calcar6. The combination of neck resection level and angle are important considerations for neck preserving stem designs. This case report demonstrates a new resection guide that has proven to be simple and reliable. Key Words: femoral neck, stress transfer, resection guide, conical flair

The Theory Of Adaptive Elasticity (Hegedus And Cowin,1976) That Deals With Internal Bone Remodeling, Could Also Be Used In Order To Describe The Sur- Face Bone Remodeling.

In the present paper we proved that the theory of the adaptive elasticity (Hegedus and Cowin, 1976) that deals with internal bone remodeling, can also be used in order to study the surface bone remodeling. Particularly we considered the problem of a long bone which is under an axial load. Our theoretical findings, predicts the results of the studies that describes the athrophy (Uhthoff and Jaworski, 1978; Jaworski , et., al.,1980) and the hypertrophy of the bone ( Woo, et., al., 1981; Clisouras, 1984; Kaplan, 1997, Monaco, 1997, Beck, 1998; Amendola, 1999,Walker,1999; Bouche,1999; Coutoure and Karlson, 2002; Magnusson, 2003, Hester, 2006, American Academy of Orthopaedic Surgeons, 2007) and comes to agreement with the classic theory of surface bo-ne remodeling, proposed by Cowin and Firoozbaksh (1981). INTRODUCTION Living bone is continually undergoing processes of growth, reinforcement and resorption, termed collectively remodeling. There are two kinds of bone remodeling: internal and surface (Frost, 1964). Hegedus and Cowin (1976) proposed a theory for internal remodeling, ter-med as “theory of adaptive elasticity” which has been used in various problems (Cowin and Van-Buskirk,1978; Tsili, 2000; Qin and Ye, 2004). The purpose of this work is to show that the theory of adaptive elasticity, can also be successfully used in order to study the surface remodeling of long bone. THE METHOD Initially, that is for t a(t) The diaphyseal crosssection area S(t) is given by : S(t) = π(b(t) ─ a(t)) >0. The inner and outer radius and the cross-section area in reference configuration, were ao, bo and So = π(bo 2─ao ) >0 respectively. The equations of the adaptive elasticity (Hegedus ─ Cowin, 1976) in cylindrical coordinates are, the rate re-modeling equation: Figure 1 the straindisplacement equations: Figure 2 the stress in equilibrium state: The Theory Of Adaptive Elasticity (Hegedus And Cowin,1976) That Deals With Internal Bone Remodeling, Could Also Be Used In Order To Describe The SurFace Bone Remodeling.

Computational simulation of internal bone remodelling around dental implants: a sensitivity analysis

This study aimed to predict the distribution of bone trabeculae, as a density change per unit time, around a dental implant based on applying a selected mathematical remodelling model. The apparent bone density change as a function of the mechanical stimulus was the base of the applied remodelling model that describes disuse and overload bone resorption. The simulation was tested in a finite element model of a screw-shaped dental implant in an idealised bone segment. The sensitivity of the simulation to different mechanical parameters was investigated; these included element edge length, boundary conditions, as well as direction and magnitude of the implant loads. The alteration in the mechanical parameters had a significant influence on density distribution and model stability, in particular at the cortical bone region. The remodelling model could succeed to achieve trabeculae-like structure around osseointegrated dental implants. The validation of this model to a real clinical case is required.

Prediction of shape and internal structure of the proximal femur using a modified level set method for structural topology optimisation

A computational framework was developed to simulate the bone remodelling process as a structural topology optimisation problem. The mathematical formulation of the Level Set technique was extended and then implemented into a coronal plane model of the proximal femur to simulate the remodelling of internal structure and external geometry of bone into the optimal state. Results indicated that the proposed approach could reasonably mimic the major geometrical and material features of the natural bone. Simulation of the internal bone remodelling on the typical gross shape of the proximal femur, resulted in a density distribution pattern with good consistency with that of the natural bone. When both external and internal bone remodelling were simulated simultaneously, the initial rectangular design domain with a regularly distributed mass reduced gradually to an optimal state with external shape and internal structure similar to those of the natural proximal femur.

Exercise aggravates cardiovascular risks and mortality in rats with disrupted nitric oxide pathway and treated with recombinant human erythropoietin

Chronic administration of recombinant human erythropoietin (rHuEPO) can generate serious cardiovascular side effects such as arterial hypertension (HTA) in clinical and sport fields. It is hypothesized that nitric oxide (NO) can protect from noxious cardiovascular effects induced by chronic administration of rHuEPO. On this base, we studied the cardiovascular effects of chronic administration of rHuEPO in exercise-trained rats treated with an inhibitor of NO synthesis (L-NAME). Rats were treated or not with rHuEPO and/or L-NAME during 6weeks. During the same period, rats were subjected to treadmill exercise. The blood pressure was measured weekly. Endothelial function of isolated aorta and small mesenteric arteries were studied and the morphology of the latter was investigated. L-NAME induced hypertension (197±6mmHg, at the end of the protocol). Exercise prevented the rise in blood pressure induced by L-NAME (170±5mmHg). However, exercise-trained rats treated with both rHuEPO and L-NAME developed severe hypertension (228±9mmHg). Furthermore, in these exercise-trained rats treated with rHuEPO/L-NAME, the acetylcholine-induced relaxation was markedly impaired in isolated aorta (60% of maximal relaxation) and small mesenteric arteries (53%). L-NAME hypertension induced an internal remodeling of small mesenteric arteries that was not modified by exercise, rHuEPO or both. Vascular ET-1 production was not increased in rHuEPO/L-NAME/training hypertensive rats. Furthermore, we observed that rHuEPO/L-NAME/training hypertensive rats died during the exercise or the recovery period (mortality 51%). Our findings suggest that the use of rHuEPO in sport, in order to improve physical performance, represents a high and fatal risk factor, especially with pre-existing cardiovascular risk.

Internal Bone Remodeling Induced By The Distance-Running And The Unknown Remodeling Rate Coefficients.

Internal Bone Remodeling Induced By The Distance-Running And The Unknown Remodeling Rate Coefficients.