scholarly journals Relationship between Microstructure, Material Distribution, and Mechanical Properties of Sheep Tibia during Fracture Healing Process

2013 ◽  
Vol 10 (11) ◽  
pp. 1560-1569 ◽  
Author(s):  
Jiazi Gao ◽  
He Gong ◽  
Xing Huang ◽  
Juan Fang ◽  
Dong Zhu ◽  
...  
Author(s):  
Satoshi Kimura ◽  
Keisuke Oe ◽  
Yohei Kumabe ◽  
Tomoaki Fukui ◽  
Takahiro Niikura ◽  
...  

Biomedicines ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 691
Author(s):  
Jan Barcik ◽  
Devakara R. Epari

The impact of the local mechanical environment in the fracture gap on the bone healing process has been extensively investigated. Whilst it is widely accepted that mechanical stimulation is integral to callus formation and secondary bone healing, treatment strategies that aim to harness that potential are rare. In fact, the current clinical practice with an initially partial or non-weight-bearing approach appears to contradict the findings from animal experiments that early mechanical stimulation is critical. Therefore, we posed the question as to whether optimizing the mechanical environment over the course of healing can deliver a clinically significant reduction in fracture healing time. In reviewing the evidence from pre-clinical studies that investigate the influence of mechanics on bone healing, we formulate a hypothesis for the stimulation protocol which has the potential to shorten healing time. The protocol involves confining stimulation predominantly to the proliferative phase of healing and including adequate rest periods between applications of stimulation.


2017 ◽  
Vol 09 (05) ◽  
pp. 1750076 ◽  
Author(s):  
Şeref Doğuşcan Akbaş

The purpose of this study is to investigate the thermal effects on the free vibration of functionally graded (FG) porous deep beams. Mechanical properties of the FG deep beam are temperature-dependent and vary across the height direction with different porosity models. The governing equations problem is obtained by using the Hamilton’s principle. In the solution of the problem, plane piecewise solid continua model and finite element method are used. The effects of porosity parameters, material distribution, porosity models and temperature rising on the vibration characteristics are presented and discussed with porosity effects for FG deep beams.


2010 ◽  
Vol 43 (3) ◽  
pp. 557-562 ◽  
Author(s):  
Jared A. Weis ◽  
Michael I. Miga ◽  
Froilán Granero-Moltó ◽  
Anna Spagnoli

Author(s):  
Yuen-Shan Leung ◽  
Huachao Mao ◽  
Yong Chen

Functionally graded materials (FGM) possess superior properties of multiple materials due to the continuous transitions of these materials. Recent progresses in multi-material additive manufacturing (AM) processes enable the creation of arbitrary material composition, which significantly enlarges the manufacturing capability of FGMs. At the same time, the fabrication capability also introduces new challenges for the design of FGMs. A critical issue is to create the continuous material distribution under the fabrication constraints of multi-material AM processes. Using voxels to approximate gradient material distribution could be one plausible way for additive manufacturing. However, current FGM design methods are non-additive-manufacturing-oriented and unpredictable. For instance, some designs require a vast number of materials to achieve continuous transitions; however, the material choices that are available in a multi-material AM machine are rather limited. Other designs control the volume fraction of two materials to achieve gradual transition; however, such transition cannot be functionally guaranteed. To address these issues, we present a design and fabrication framework for FGMs that can efficiently and effectively generate printable and predictable FGM structures. We adopt a data-driven approach to approximate the behavior of FGM using two base materials. A digital material library is constructed with different combinations of the base materials, and their mechanical properties are extracted by Finite Element Analysis (FEA). The mechanical properties are then used for the conversion process between the FGM and the dual material structure such that similar behavior is guaranteed. An error diffusion algorithm is further developed to minimize the approximation error. Simulation results on four test cases show that our approach is robust and accurate, and the framework can successfully design and fabricate such FGM structures.


2021 ◽  
Author(s):  
Antonion Korcari ◽  
Alayna E Loiselle ◽  
Mark R Buckley

Tendon injuries are very common and result in significant impairments in mobility and quality of life. During healing, tendons produce a scar at the injury site, characterized by abundant and disorganized extracellular matrix and by permanent deficits in mechanical integrity compared to healthy tendon. Although a significant amount of work has been done to understand the healing process of tendons and to develop potential therapeutics for tendon regeneration, there is still a significant gap in terms of assessing the direct effects of therapeutics on the functional and material quality specifically of the scar tissue, and thus, on the overall tendon healing process. In this study, we focused on characterizing the mechanical properties of only the scar tissue in flexor digitorum longus (FDL) tendons during the proliferative and remodeling healing phases and comparing these properties with the mechanical properties of the composite healing tissue. Our method was sensitive enough to identify significant differences in structural and material properties between the scar and tendon-scar composite tissues. To account for possible inaccuracies due to the small aspect ratio of scar tissue, we also applied inverse finite element analysis (iFEA) to compute mechanical properties based on simulated tests with accurate specimen geometries and boundary conditions. We found that the scar tissue linear tangent moduli calculated from iFEA were not significantly different from those calculated experimentally at all healing timepoints, validating our experimental findings, and suggesting the assumptions in our experimental calculations were accurate. Taken together, this study first demonstrates that due to the presence of uninjured stubs, testing composite healing tendons without isolating the scar tissue overestimates the material properties of the scar itself. Second, our scar isolation method promises to enable more direct assessment of how different treatment regimens (e.g., cellular ablation, biomechanical and/or biochemical stimuli, tissue engineered scaffolds) affect scar tissue function and material quality in multiple different types of tendons.


2021 ◽  
Vol 10 (16) ◽  
pp. 3554
Author(s):  
Dionysios J. Papachristou ◽  
Stavros Georgopoulos ◽  
Peter V. Giannoudis ◽  
Elias Panagiotopoulos

Fracture-healing is a complex multi-stage process that usually progresses flawlessly, resulting in restoration of bone architecture and function. Regrettably, however, a considerable number of fractures fail to heal, resulting in delayed unions or non-unions. This may significantly impact several aspects of a patient’s life. Not surprisingly, in the past few years, a substantial amount of research and number of clinical studies have been designed, aiming at shedding light into the cellular and molecular mechanisms that regulate fracture-healing. Herein, we present the current knowledge on the pathobiology of the fracture-healing process. In addition, the role of skeletal cells and the impact of marrow adipose tissue on bone repair is discussed. Unveiling the pathogenetic mechanisms that govern the fracture-healing process may lead to the development of novel, smarter, and more effective therapeutic strategies for the treatment of fractures, especially of those with large bone defects.


1998 ◽  
Vol 38 (2) ◽  
pp. 62-67
Author(s):  
Akio NOMURA ◽  
Ikuo YOSHIDA ◽  
Yukio NAKATSUCHI ◽  
Akira TSUCHIKANE

2021 ◽  
Vol 3 (2) ◽  
pp. 192-206
Author(s):  
Sergey G. Sсherbak ◽  
Stanislav V. Makarenko ◽  
Olga V. Shneider ◽  
Tatyana A. Kamilova ◽  
Alexander S. Golota

The mechanical properties of tendons are thought to be affected by different loading levels. Changes in the mechanical properties of tendons, such as stiffness, have been reported to influence the risk of tendon injuries chiefly in athletes and the elderly, thereby affecting motor function execution. Unloading resulted in reduced tendons stiffness, and resistance exercise exercise counteracts this. Transforming growth factor-1 is a potent inducer of type I collagen and mechanosensitive genes encoding tenogenic differentiation markers expression which play critical roles in tendon tissue formation, tendon healing and their adaptation during exercise. In recent years, our understanding of the molecular biology of tendons growth and repair has expanded. It is probable that the next advance in the treatment of tendon injuries will result from the application of this basic science knowledge and the clinical solution will encompass not only the the best postoperative rehabilitation protocols, but also the optimal biological modulation of the healing process.


2019 ◽  
Vol 19 (07) ◽  
pp. 1940029
Author(s):  
MONAN WANG ◽  
XINYU WANG ◽  
QIYOU YANG

According to the mechanical conditions of fracture fixation and the oxygen levels in the tissues, a simulation model of fracture healing process was built to describe the relationship among mechanical stability, oxygen levels in tissues and tissue differentiation during the second fracture healing. Different from the previous simulation model, in this paper, we took the three-dimensional model as the research object, solved the mechanical stimulation by finite element method, established the partial differential equation to solve the spatial and temporal variation of the oxygen in tissues. The process of tissue differentiation was described by fuzzy control method. The initial stage of fracture healing, intramembranous ossification, chondrogenesis, cartilage calcification and endochondral ossification during the fracture healing process were simulated, and the properties of tissue materials were continuously updated to complete the iterative process. The simulation program of fracture healing process was independently developed in Eclipse environment, and the simulation results were compared with experimental data and those of other fracture healing simulation models to verify the simulation program in this paper. Finally, the processes of transverse fracture healing in rats with different axial stability under normoxic, hypoxic and hyperoxic conditions was simulated, and the effects of different tissue oxygen levels and interosseous stabilities on fracture healing were analyzed. It is concluded by simulation that the delayed healing or non-union of bone will occur when in state of tissue hypoxia or interosseous instability, normal healing will occur when in state of tissue normoxia, and the healing will be accelerated when in state of tissue hyperoxia.


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