소형견의 요척골 골절에서 원형 외고정 장치 적용에 대한 평가

류재준 충북대학교 2018 국내석사

Fracture of limbs is the most common orthopedic problem in dogs. Several fixation methods are applied for fracture repairment. The purpose of this study was to compare circular external skeletal fixators (C-ESF) and other repairment method in dogs with limb fractures. The C-ESF requires continuous and regular maintenance compared to other internal fixation methods. This metehod did not interfere with intramedullary blood supply. In addition, the stability against standing, bending and rotating was excellent. Medical records of 80 cases with their limb fractured referred to veterinary teaching hospital were reviewed. The collected records include breeds, weight, age, cause of fracture, radiological findings, fracture site, repairment methods, surgical time, callus formation time, implant maintained time and duration of clinical union. Eighty cases of fractures, 50 (62.5%) were affected the thoracic limb fracture and 30 (37.5%) were affected the pelvic limb fracture. Radioulnar fracture had the highest overall fracture occurance. Fracture repairment was accomplished by circular external skeletal fixators (C-ESF), linear external skeletal fixators (L-ESF), plate/screw, and coaptation. Thirty one cases with radioulnar fracture under 5kg were compared. The correlation among callus formation time and implant maintained time were investigated in radius/ulna fractures. Callus formation time was a significant difference between C-ESF and IM-pin, C-ESF and plate/screw method (P<0.05). C-ESF could be an alternative method to toy breed dogs with radioulnar fractures. The advantages of C-ESF is that it minimally affects the biological environment of the fracture. This facilitates bone healing by enabling axial micro-movement, unlike other fracture treatment methods. so it can be make clinical union.

(The) role of polaprezinc in fracture healing by differentiation of both osteoclasts and osteoblasts

박유정 Graduate School, Yonsei University 2023 국내박사

Fractures and fracture related complications are common causes of morbidity and mortality nowadays. According to the data from National Health Insurance and Assessment Service, over 2,200,000 fractures are sustained every year in South Korea of all ages and sexes. Although the majority heal satisfactorily, 5% to 10% go on to delayed union or non-union. Vitamin D and calcium are the broadly available medications for fracture healing, while zinc has been recognized as a nutritional supplement for healthy bones. We aimed to use polaprezinc, an anti-ulcer drug and a chelate form of zinc and L-carnosine, as a supplement for fracture healing. To investigate whether polaprezinc could be a candidate small molecule for drug repurposing to bone-related diseases, we used hBMSCs and mBMMs to determine whether polaprezinc acts as a positive or negative modulator during osteoblast and osteoclast differentiation. Next, we confirmed the effects of polaprezinc on hBMSC differentiation to osteogenic lineage at the early and late stages of differentiation. We compared the mRNA levels of osteogenic-related genes between vehicle- and polaprezinc-treated hBMSCs. To clarify the effect of polaprezinc on osteoclast differentiation, mBMMs were induced by treatment with mRANKL in the presence of polaprezinc dose dependently. To evaluate whether polaprezinc may serve as a supplement for enhancing the treatment of fracture healing, mice with femoral fractures were employed for animal studies in vivo. Polaprezinc enhanced expression of osteogenesis-related genes and enhanced osteogenic potential of human bone marrow-derived mesenchymal stem cells such as RUNX2 protein level and the osteoclast differentiation potential of mouse bone marrow-derived monocytes such as TRAP activities induced by RANKL. In mouse experimental models with bone fractures, oral administration of polaprezinc accelerated fracture healing and maintained a high number of both osteoblasts and osteoclasts in the fracture areas. μCT image showed polaprezinc group had lower remaining callus volume and callus BMD was significantly increased in orally administered polaprezinc mice. In conclusion, polaprezinc promotes the fracture healing process efficiently by enhancing the activity of both osteoblasts and osteoclasts. Therefore, these data suggest that drug repositioning of polaprezinc as a fracture healing therapy would be helpful for patients with fractures. 서론: 골절과 골절 관련 합병증은 최근 가장 흔한 질병 및 사망의 원인중 하나이다. 국민건강보험공단 자료에 따르면 한국에서는 남녀노소를 불문하고 매년 220만 건 이상의 골절이 발생하고 있다. 대다수가 만족스럽게 치유되지만 5~10%는 지연유합 또는 불유합으로 진행된다. 비타민 D와 칼슘은 골절 치료에 널리 사용되는 보충제이며, 아연 역시 건강한 뼈를 위한 영양 보충제로 인식되어 왔다. 본 연구에서는 골절 치유를 위한 치료제로서 아연과 L-카르노신의 킬레이트 형태의 약물인 폴라프레징크를 골절의 치료제로서 사용 가능한지를 알아보고자 하였다. 방법: 폴라프레징크가 골절의 치료제로서 약물 재배치의 좋은 후보가 될 수 있는지를 알아보기 위해, 인간 골수 유래 중간엽 줄기세포와 생쥐 골수 유래 단핵구를 사용하여 폴라프레징크가 조골세포와 파골세포분화 동안 양의 조절제 또는 음의 조절제로 작용하는지 여부를 관찰하였다. 다음으로, 분화 초기 및 후기 단계에서 인간 골수 유래 중간엽줄기세포 분화에서 골형성 계통으로의 폴라프레징크 영향을 관찰하였다. 폴라프레징크로 처리된 인간 골수 유래 중간엽 줄기세포와 대조군 간의 골형성 관련 유전자의 mRNA 수준을 비교했다. 파골세포 분화에 대한 폴라프레징크의 영향을 명확히 하기 위해 생쥐 골수 유래 단핵구는 mRANKL로 처리하여 폴라프레징크의 양을 다르게 하여 유도하였다. 폴라프레징크가 골절 치료제로서의 역할을 할 수 있는지를 평가하기 위해 대퇴골 골절이 있는 쥐를 동물 연구에 사용하였다. 결과: 폴라프레징크는 인간 골수 유래 중간엽 줄기세포에서 조골세포분화를 촉진하고, 생쥐 골수 유래 단핵구에서 파골세포 분화를 촉진하였다. 즉, 조골세포와 파골세포의 분화에 이중양성 효과를 보였는데, 이는 일반 아연의 역할과는 차이가 있었다. 폴라프레징크의 조골세포 및 파골세포 분화는 특히 전사 활성에서 YAP의 존재에 따라 달라졌다. 폴라프레징크를 경구 투여하면 다수의 조골세포와 파골세포에 의한 능동적인 뼈 항상성을 통해 대퇴골 골절이 있는 쥐에게 신속하고 성공적인 골절 치유를 유도할 수 있었다. 결론: 폴라프레징크는 조골세포와 파골세포의 활성을 향상시켜 골절 치유 과정을 효율적으로 촉진한다. 따라서, 우리는 폴라프레징크가 성공적인 골절 치유를 위한 치료제일 뿐만 아니라 약물 재배치를 통해 임상적용에 좋은 후보가 될 수 있다고 생각한다.

A study on the deformation and fracture of anodes in Li ion batteries

최용석 서울대학교 대학원 2016 국내박사

Silicon and germanium are considered as one of the best candidates of anode material for the Li-ion batteries due to its enormous capacity. However, it has been known that the Li ion insertion and extraction during electrochemical cycling results in a huge volume expansion and shrinkage, which can lead to fracture of the anode. This mechanical degradation can lead to the fading of the capacity of the battery by isolating active materials, and by creating new surface area for solid electrolyte interface (SEI) growth. Thus, understanding of how electrodes are able to sustain electrochemical reaction without mechanical degradation is essential for the development of high-capacity Li-ion batteries. This thesis explores the deformation and fracture of anode materials during electrochemical cycling to provide a guideline for the practical design of high-capacity lithium ion batteries to avoid fracture. First, we report observations of microstructural changes in {100} and {110} oriented silicon wafers during initial lithiation under relatively high current densities. Evolution of the microstructure during lithiation was found to depend on the crystallographic orientation of the silicon wafers. In {110} silicon wafers, the phase boundary between silicon and LixSi remained flat and parallel to the surface. In contrast, lithiation of the {100} oriented substrate resulted in a complex vein-like microstructure of LixSi in a crystalline silicon matrix. A simple calculation demonstrates that the formation of such structures is energetically unfavorable in the absence of defects due to the large hydrostatic stresses that develop. However, TEM observations revealed micro-cracks in the {100} silicon wafer, which can create fast diffusion paths for lithium and contribute to the formation of a complex vein-like LixSi network. This defect-induced microstructure can significantly affect the subsequent delithiation and following cycles, resulting in degradation of the electrode. Second, we have measured the fracture energy of lithiated silicon thin-film electrodes as a function of lithium concentration using a simple bending test. Silicon thin-films on copper substrates were lithiated to various states of charge. Then, bending tests were performed by deforming the substrate to a pre-defined shape, allowing for a variation in the curvature along the length of the electrode. From the bending test, the critical strains at which cracks initiate in the lithiated silicon were determined. Using the substrate curvature technique, we also measured the elastic modulus and stresses that develop in the electrodes during electrochemical lithiation. From these measurements, the fracture energy was calculated as a function of lithium concentration using a finite element simulation of fracture of an elastic film on an elastic-plastic substrate. The fracture energy was determined to be 12.0 ± 3.0 J m-2 for amorphous silicon and 10.0 ± 3.6 J m-2 for Li3.28Si, with little variation in the fracture energy for intermediate Li concentrations. Third, we measure stresses that develop in sputter-deposited amorphous Ge thin films during electrochemical lithiation and delithiation. Amorphous LixGe electrodes are found to deform plastically at stresses that are significantly smaller than those of their amorphous LixSi counterparts. The stress measurements allow for quantification of the elastic modulus of amorphous LixGe as a function of lithium concentration, indicating a much-reduced stiffness compared to pure Ge. Additionally, we observe that thinner films of Ge survive a cycle of lithiation and delithiation, whereas thicker films fracture. By monitoring the critical conditions for crack formation, the fracture energy is calculated using an analysis from fracture mechanics. The fracture energies are determined to be 8.0 J m-2 for a-Li0.3Ge and 5.6 J m-2 for a-Li1.6Ge. These values are similar to the fracture energy of pure Ge and are typical for brittle fracture. Despite being brittle, the ability of amorphous LixGe to deform at relatively small stresses during lithiation results in an enhanced ability of Ge electrodes to endure electrochemical cycling without fracture.

A Study on the Fracture Behavior of Inhomogeneous Biological Materials and Interfaces

다네시와 미시라 아주대학교 2011 국내박사

Material inhomogeneity is common in every walk of life. Whether the materials are manmade or natural/biological; they are inherently inhomogeneous. Present days’ trend of material development focuses on composites which are made up of various layers and have inherent inhomogeneity with many interfaces. Interfaces and inhomogeneity are the most susceptible to failure. In another side, biological materials are inherently inhomogeneous and have interfaces but designed in such a way that the load transfer takes place so nicely such that mostly cracks are arrested at interfacial layers. Most common example of this case is dentine enamel junction (DEJ), which is an interfacial layer that connects very brittle enamel and relatively tougher dentine of tooth. This interfacial layer arrests/bridges the cracks which grows from enamel towards dentine. Knowing this aspect of materials in use for various applications, it is worthwhile to study fracture behavior of inhomogeneous materials especially the biological materials and interfaces so that future material development can be mimicked from the understanding of design of materials and interfaces in nature. This thesis has two goals, first goal is to study inhomogeneous materials for its fracture behavior by developing closed form solution and the second aim is to understand this aspect in the biological materials and interfaces. To achieve these goals, a coated circular inclusion embedded in an infinite matrix has been analyzed in the framework of two-dimensional isotropic linear elasticity. A closed-form solution has been obtained for the case of far-field uniaxial tension using Muskelishvili’s complex potential method. The solutions for the stress and strain distributions for all three regions, i.e., matrix, coating, and inclusion, have been obtained for various coating-to-matrix shear modulus ratios, while keeping the fiber and matrix shear moduli the same. Test cases for inclusion without the coating and hollow inclusion have also been studied. The energy release rate has been evaluated using the path-independent M-integral, which is used to calculate the energy release rate for the self-similar expansion of defects surrounded by the closed contour of the integral. The results for the stress and strain concentrations along with the energy release rate due to this material inhomogeneity were analyzed to yield a better understanding of the mechanics of materials with inhomogeneity. The analytical results obtained in closed form has been realized for fracture behavior study for biological material human tooth layers, namely enamel and dentine and the interfacial layer dentine enamel junction (DEJ) by finite element tool ABAQUS considering their various microconstituent, orientations of cracks and crack bridging capability of the interfacial layer DEJ. The crack growth has been simulated for various crack geometry for enamel and DEJ by extended finite element analysis (XFEA) considering their functionally graded structure. Fracture toughness of these layers has been evaluated in terms of J-integral which is measure of energy release rate. The critical value of energy release rate can be characterized as fracture toughness. In case of enamel and DEJ, this has been found to be location dependent in place of constant material property as in homogeneous elastic materials. The crack arresting/bridging behavior of DEJ has been simulated by introducing one-D spring elements. The stiffness of these spring elements found to be 1% of the Young’s modulus of DEJ at that location which can achieve crack closure within a distance of 10-15μ from the enamel surface. Dentine is the inner layer of tooth which is mineralized tissue made up of dentinal tubules and collagen. These dentinal tubules have been used for fluid circulation that ultimately makes it tougher. Permeability and porosity are important parameters to contribute for failure of dentine because of internal fluid circulation in the dentinal tubules. The fluid circulation i.e. rate of permeation increases with increase in pore size that makes the dentine like bio-composite hydrated and provide resistance to fracture. Thus it is important to understand fracture toughening behavior of dentine like bio-composite in terms of porosity and permeability change. The first study on dentine has been focused on evaluating fracture toughness for different values of porosity and permeability by finite element analysis tool ABAQUS for continuum model of dentine and its unit cell model to understand the heirachical aspect of biological materials. It has been observed that the fracture toughness increases with increase in porosity when simulation is carried out at continuum level with isotropic and elastic material properties. At the cell level, this is not true as we found that up to 10% of porosity, the J-Integral and strain energy density increases and thereafter it decreases. This explains role of the bonding of dentinal tubules at continuum level on fracture strength of dentine composite. In second analysis, dentine composite is modeled at unit cell level considering its constituents peri-tubular and inter-tubular dentine. The micro-constituents of both peri-tubular and inter-tubular dentines, the collagen fibers and apatite minerals have been considered while modeling the unit cell model of dentine composite. The fracture toughness has been evaluated with various fraction of collagen fraction in both peri-tubular and inter-tubular dentine. It is found that fracture toughness of dentine composite increases with increase in collagen fraction. This is in agreement with the result for elastic modulus which decreases with increase in collagen fraction as presented in literatures. It can be described as decrease in elastic modulus resulted to decrease in brittleness which refers to increase in toughness. Collagen has very important role in shaping up mechanical properties and toughening of biomaterials like bone, dentine composite and so on. This study helps to understand fracture behavior of inhomogeneous materials especially the biological materials which is characterized as inherent inhomogeneous and hierarchical materials and can help to understand how these materials becomes tougher and stiffer even though made up of softer and brittle micro constituents like protein and minerals. This work can also be helpful to understand the biological interfaces in terms of its fracture behavior and crack arresting/bridging nature such that future material design and development can be benefited with the better understanding of these natural interfaces. Dhaneshwar Mishra

Implicit and explicit fracture shear slip analysis for geological storage of carbon dioxide and nuclear waste

이재원 서울대학교 대학원 2014 국내박사

Shear slip at a fracture is a critical issue for many applications of geological engineering, such as the design of the geosequestration of CO2 and an underground repository for nuclear waste. Shear slip can induce mechanical instability and additional fluid flow in the fracture which results in the enhanced permeability of the region. Microseismic events that occur in the aforementioned applications are also explained by the mechanisms of shear slip in small fractures. There are various reasons for shear slip at existing fractures. When injecting CO2 into a reservoir for the carbon storage, the increased pore pressure decreases the effective normal stress on the fracture, and this is expected to induce fracture shear slip. In a deep geological repository for high-level nuclear waste, heat is emitted by the nuclear waste, and thermal stress is generated due to confined nature of the rock. The thermal stress alters the stress distribution throughout the rock mass, and, therefore, the condition for shear slip changes. The phenomenon of shear displacement and dilation of fractures due to pore pressure change is termed ‘hydroshearing’ and due to thermal loading is termed ‘thermoshearing,’The main focus of this thesis is to provide systematic quantitative analysis for the hydroshearing and thermoshearing. This thesis is divided into two parts; implicit fracture shear slip analysis and explicit fracture shear slip analysis. For the implicit fracture shear slip analysis, the probability of shear slip is evaluated considering a Coulomb failure analysis and the statistical fracture distributions from In Salah and Forsmark site. The calculation of stress evolution is divided into three parts; numerical analysis at the hypothetical CO2 storage reservoir, analytic solution at the reservoir with underground injection, and numerical analysis at nuclear waste repository. For the explicit fracture shear slip analysis, TOUGH-UDEC coupled code is developed and verified. After that, numerical analysis is conducted for the hypothetical CO2 storage reservoir with pre-existing fracture to investigate the effect of fracture shear slip on the leakage of CO2. With implicit fracture shear slip analysis and explicit fracture shear slip analysis, systematic quantitative analysis for the hydroshearing and thermoshearing is conducted. Techniques of leakage and reservoir geomechanics analysis that is developed in this thesis are essential for Carbon Capture and Storage (CCS) technology in view of selection investigation. The result of this analysis can provide a guideline for performance assessment of CO2 reservoir and can help to determine the critical injection pressure at a given reservoir condition and layout of the injection wells. Also the microseismic events which are expected to occur after the injection of CO2 can be reliably predicted. The prediction of ground heave in conjunction with monitored results can improve the confidence in the performance of CO2 reservoir and nuclear waste repository.

Fracture Conductivity Behavior in Shale Formations

Guerra, Jesse Mateo Texas A&M University ProQuest Dissertations & Thes 2019 해외박사(DDOD)

The objective of this study was to further the understanding of fracture conductivity and its dependence on rock mechanical properties, mineralogy, and fracture surface attributes, as well as its impairment due to flowback, based on a systematic experimental study on several mudstone formations. As part of this objective, a practical workflow was developed to extend the measured conductivity behavior to downhole stress conditions. The experimental measurements conducted in this study used mudstone samples obtained from outcrop and downhole core segments, from the Eagle Ford, the Marcellus, the Mahantango, the Middle Bakken, and the Three Forks formations. Fracture conductivity experiments were conducted utilizing a Modified API Fracture Conductivity Cell by flowing dry nitrogen and/or saline solutions representative of flowback water. As such, undamaged and water-damaged fracture conductivity was measured. Simulated fracture conditions included unpropped and propped fractures. Natural sand proppant, with a commonly used mesh size, was used with a variety of areal concentrations. Additional experiments consisted of evaluating rock mechanical properties, mineralogy, and fracture surface attributes. A large degree of heterogeneity in properties was observed for each formation. Experimental measurements showed that fracture conductivity under increasing closure stress generally follows an exponential decline rate, which is manifested as a linear relationship on a semi-log plot that is condition-specific. These functions can be representative of the formation fracture conductivity behavior, and can be extended to additional simulated fracture conditions. Furthermore, these laboratory-based measurements can be related to downhole stress conditions predicated on poroelasticity theory. This estimated in-situ fracture conductivity can be used during the performance evaluation of a hydraulically fractured horizontal well, or during the design of a new treatment. This study provides an insight into fracture conductivity and its dependence on formation physical properties. Additionally, this study presents a practical application to the measurement of fracture conductivity in mudstones and its importance in evaluating well performance.

Correlation of microstructure and fracture toughness in two 4340 steels

이성학 Brown University 1986 해외박사

This thesis is concerned with a correlation of plane strain fracture toughnes s and microstructure in two steels corresponding to AISI 4340 composition. These steels were vacuum induction melted and then deoxidized with aluminum and titan ium-aluminum additions, respectively. In the case of the aluminum killed steel, austenitizing at temperatures above 950℃ led to large austenite grain sizes, wh ereas in the titanium steel grain sizes were maintained below about 70μm even a fter austenitizing at temperatures up to 1200℃. This allowed a comparison of va riations in plane strain fracture toughness with austenitizing temperature betwe en microstructures that underwent large increases in grain size and those that d id not. The results are interpreted using a simple fracture model which indicate d that the spacing of finer particles, e. g. carbides not dissolved in the austen itizing process, is of primary importance in controlling fracture toughness. .In quenched and tempered microstructures fracture toughness was found to scale mon otonically with plane strain tensile ductility and particle spacing. However, th e simple correlations between toughness and ductility broke down in microstructu res produced by step quenching or double austenitizing. The overall observed phe nomenology is not explainable using simple models which essentially require that either critical stresses or critical strains be achieved over distances scaling with microstructure. This finding suggests that more detailed crack tip models t han presently exist are required if the full effects of heat treatment are to be understoodand explained. In order to obtain a more complete perspective on the effects of tempering and microstructure in these two steels, the problem of temp ered martensite embrittlement (TME), which refers to the anamalous loss in tough ness, was also investigated. When the steels were tempered near 350℃, fracture toughness and Charpy impact energy data showed a trough. Since the fracture init iation of K#c specimens was primarily microvoid coalescence due to the ductile appearance near the sharp crack tip, again the spacing of undissolved alloy carb ides and/or cementite particles precipitated during the tempering treatment play ed a vital role in interpreting the TME results of fracture toughness. However, in the case of the Charpy samples fracture initiation and the first stages of c rack propagation occurred mostly by a stress assisted fracture mechanism so that the Charpy energy trough coincided very well with the intergranular fracture. T herefore, the mechanism of TME in the Charpy energy results involves a combinati on of both impurity segregation during austenitization and precipitation of ceme ntite carbides. This idea of different fracture mechanisms between the two tests may help explain the phenomenology, but quantitative interpretation is needed f or the analysis of the data.

Hydraulic Fracture Geometry Characterization Using Low-Frequency Distributed Acoustic Sensing Data: Forward Modeling, Inverse Modeling, and Field Applications

Liu, Yongzan Texas A&M University ProQuest Dissertations & Thes 2021 해외박사(DDOD)

Low-Frequency Distributed Acoustic Sensing (LF-DAS) is a promising fracture diagnostic technique for detecting fracture hits and characterizing fracture geometry. However, measured signals exhibiting various characteristics and mechanisms are not well understood, which makes the interpretation and application of LF-DAS data for hydraulic fracture monitoring and characterization very challenging. In this dissertation, a forward geomechanical model was developed based on the three-dimensional displacement discontinuity method (3D DDM) to simulate the LF-DAS strains and strain rates along horizontal wells during multistage/multicluster hydraulic fracturing treatments. The main applications of the forward model include investigating the observed strain/strain-rate responses and their corresponding fracture geometries for better understandings of LF-DAS signals and proposing guidelines for fracture-hit detection during multifracture propagation. More importantly, a Green-function-based inversion algorithm was proposed to estimate fracture geometry by direct inversion of LF-DAS strain data. The stability, accuracy, and efficiency of the proposed algorithm were tested through synthetic cases of both single fracture and multiple fractures. A few field case studies were performed to demonstrate the capability of the proposed workflow. Lastly, a two-dimensional thermoelastic model was presented to quantify the thermal effects on LF-DAS measurements.A heart-shaped extending region forms before the fracture hit on the waterfall plot of LF-DAS data. After the fracture hits the monitoring well, the extending region shrinks to a wide band, the size of which depends on the spatial resolution of field DAS measurements, and a two-wing compressing zone is observed. The size and shape of the aforementioned signatures are directly influenced by fracture geometries and fracture interactions. General guidelines for accurate fracture-hit detection were proposed based on detailed characterization of LF-DAS measurements around fracture-hit locations. The inverse modeling indicates that LF-DAS data are only sensitive to the fracture segments near the monitoring well. The developed inversion algorithm can provide the dynamic fracture widths and heights near the monitoring wells during hydraulic fracturing treatments. For the field cases from an unconventional shale oil formation, 4-5 fracture hits out of 8 perforation clusters per stage were detected. Fracturing fluid leakage into the previous fracture stage was observed in all studied stages. Fracture geometries near the monitoring well were characterized.This dissertation provides a novel workflow for quantitative hydraulic fracture geometry characterization and detection of fracture hits, which has been successfully applied to field cases. The developed workflow can play an important role in optimizing completion and fracturing designs and maximizing well performance in unconventional reservoirs.

골반이 골절된 개에서의 수술 전의 빈혈에 대한 평가

이상의 충북대학교 2018 국내석사

Pelvic fracture accounts for 20-25% of reported fractures in veterinary medicine. Life-threatening hemorrhage is a frequent complication of major pelvic fracture in human medicine, but preoperative anemia in pelvic fracture has been rarely reported in veterinary medicine. Preoperative anemia causes several perioperative problems and affects postoperative outcomes. The purpose of this study was to assess prevalence of preoperative anemia in pelvic fracture and to find factors which exacerbate anemia. General characteristics, simple radiographs of the pelvis, complete blood cell count, and medical record of patients with pelvic fracture (n = 36) were assessed. Packed cell volume, hemoglobin level, and red blood cell count of patients with pelvic fracture were compared with patients with radioulnar (n = 15), femoral (n = 10), and tibial fracture (n = 10). As one of classification method of human pelvic fracture, modified Tile classification was used to divide the fracture type. Fracture location, associated injuries or additional fractures were evaluated. The prevalence of anemia in patients with pelvic fracture was 63.9%, which is higher than that of patients with other fractures; radioulnar fracture was 13.3%, femoral fracture was 30%, and tibial fracture 0%. Young patients were susceptible to anemia and pelvic fractured patients with associated injuries and/or additional fractures were significantly anemic (p < 0.05). Many patients with preoperative anemia were unstable pelvic fracture type B and C (66.7%) and patients with iliac body fracture were more likely to have anemia (73.7%) than patients with sacroiliac luxation (63.3%). This study show high prevalence of anemia with mild to moderate severity in canine patients with pelvic fracture. To predict which patients with pelvic fractures are at the high risk of anemia, clinician focus not only on fracture itself but also on other factors, such as age, associated injury, and iliac body fracture in canine patients. Detecting and managing anemia can be challenge but it is as important as treating fractures to prevent clinical unwanted outcome caused by preoperative anemia.

Bone Material Quality, Structure, and Functional Relationships Contribute to Bone Strength and Toughness

Senwar, Bhavya University of Colorado at Boulder ProQuest Dissert 2022 해외박사(DDOD)

Fragility fractures affect 8.9 million people annually, which is characterized by low bone mineral density (BMD) and deteriorating bone microarchitecture. Clinical diagnosis of people with fracture prone bones includes assessment of BMD via DEXA. However, BMD accounts for only 60% of the variation in bone fracture risk, since bone fracture risk comprises of bone strength and toughness. In addition to BMD, strength and toughness are influenced by bone material quality and bone microarchitecture as well. Additionally, these contributors to bone fracture risk are genetically controlled and are functionally related to each other. Thus, it was hypothesized that bone material quality, structure, and their functional relationships with strength and toughness, contribute to fracture risk. In aim 1, femurs from mice subjected to skeletal unloading in microgravity had reduced fracture resistance. Microgravity disrupted the ability of osteocytes to remodel their surrounding bone matrix, resulting deteriorated bone material heterogeneity, softened mineralized collagen fibrils, and weakened extrinsic toughening mechanisms. BMD, bone strength and toughness are all correlated, and these correlations called functional relationships are governed by genetics. However, functional relationships between bone microarchitecture and material quality have not been studied for genetically diverse group of mice. Additionally, how unloading affects the functional relationships is yet to be understood. Thus, in aim 2, it was hypothesized that functional relationships exist between bone material quality, bone structure and bone fracture risk across eight strains of mice with widely varying bone traits determined by genetics (i.e., in the Diversity Outbred, DO, founder strains), and these functional relationships become weaker with unloading. In aim 2, we found that functional relationships between bone microarchitecture, material quality and bone fracture risk exist for femurs of DO founder strains. Ratio of total area and bone length called slenderness ratio, bone material quality traits such as mineral:matrix, crystallinity and their heterogeneities contributed to the functional relationships and estimation of bone fracture risk. Following unloading, the functional relationships associated with strength and toughness become separate. Additionally, functional relationships after unloading were heavily guided by bone microarchitectural changes. Fracture resistance of bone is determined by its bone strength, i.e., stiffness, yield strength and bone toughness, i.e., resisting crack initiation and propagation. Intrinsic mechanisms represent the inherent resistance of bone material to elastic and plastic deformation via generating plasticity. Ribosylation of bones increases the advanced glycation end-products (AGEs) which increases non-enzymatic crosslinks and impair bone strength and toughness. Despite numerous studies, few studies have evaluated bone material quality assisted changes to tissue toughening mechanisms and risk of bone fracture with increased AGEs. Thus, in aim 3, it was hypothesized that bone material quality measures including tissue modulus (E), hardness (H), brittleness (H3/E2), tissue scratch toughness, material composition and material heterogeneity can explain changes to tissue toughening mechanisms that ultimately influence risk of bone fracture. In aim 3, we found that bones with ribosylation had reduced scratch toughness, tissue modulus, hardness and brittleness, along with poor macro-scale strength and toughness. These results provide insight into how bone material quality changes associated with tissue toughening mechanisms contributes to increased fracture risk with increased AGEs. Collectively, work presented in this dissertation will enable better understanding of role of bone material quality in influencing bone fracture risk.