Durch die Einführung der MRT-Untersuchung am stehenden sedierten Pferd ist deren Anzahl deutlich angestiegen. Hierbei stellen sich neue Fragen und Herausforderungen bezüglich der Einschätzung der Vielzahl an auftretenden Signalveränderungen. Es ergeben sich aber auch neue Möglichkeiten bezüglich der statistischen Auswertung von Befunden mit aussagekräftigen Fallzahlen. In dieser Studie sollte daher untersucht werden, wie Signalveränderungen statistisch verwendbar beschrieben und eingestuft werden können. Weiterhin sollte die Verteilung der Befunde insgesamt und bei der bilateralen Untersuchung der Vordergliedmaßen bestimmt werden. Mögliche Rückschlüsse auf deren klinische Bedeutung sollten gezogen werden. Hierzu wurden 120 bilaterale Niederfeld-MRT-Untersuchungen der Hufregion (240 Gliedmaßen) am stehenden Pferd durch zwei Tierärzte gesichtet und eine Befundbeschreibung mit einem Einstufungsschema (Grade 1-4) entsprechend dem vorgefundenen Spektrum an Signalveränderungen erstellt. Durch Anwendung und Zusammenfassung 66 wiederholte Diskussion der verschiedenen Kriterien im 1. Bewertungsdurchgang wurden die Beschreibungen und Grade auf Grundlage bestehender Literatur ausgearbeitet. In einem 2. Bewertungsdurchgang wurden die Strukturen eingestuft und die Ergebnisse statistisch ausgewertet. Hierbei wurden die generellen Häufigkeiten der Signalabweichungen erfasst und deren Zusammenhang zum Auftreten von unilateralen oder bilateralen Lahmheiten beachtet. Signalabweichungen am Strahlbein, der Tiefen Beugesehne und dem Hufgelenk standen deutlich im Vordergrund. Hierbei waren Strahlbeinveränderungen signifikant häufiger bei beidseitig lahmen Pferden zu finden, während Sehnenveränderungen deutlich häufiger bei einseitig lahmen Pferden vorgefunden wurden. Hufgelenkveränderungen wurden hingegen nicht signifikant vermehrt bei bilateralen oder unilateralen Lahmheiten festgestellt. Die Fesselbein-Strahlbein-Hufbeinbänder zeigten eine Häufung von Signalabweichungen bei lahmen Gliedmaßen, wobei diese vermehrt in Zusammenhang mit starken Veränderungen des Strahlbeins zu beobachten waren. Bei den übrigen Strukturen ließ sich kein statistisch aussagekräftiger Zusammenhang feststellen, da die Fallzahlen mit dem deutlichsten Befund an diesen Strukturen zu gering für eine Auswertung waren. Die entstandene Befundbeschreibung mit Einstufungsschema ermöglicht Vergleiche der MRT-Veränderungen z.B. mit klinischen Parametern. Signalabweichungen bestimmter Strukturen konnten statistisch eindeutig mit dem Auftreten und der Art der Lahmheit in Verbindung gebracht werden, während dies bei anderen Strukturen nicht möglich war. Hieraus ergeben sich Hinweise für die Einschätzung der Befunde und ihrer klinischen Relevanz. Insbesondere geringgradige Befunde sollten vorsichtig bewertet werden, da diese auch häufig bei nicht lahmen Gliedmaßen auftraten. Weitere statistische Vergleiche mit klinischen Parametern sind möglich und notwendig um das Krankheitsbild des „Equinen palmaren Fußsyndroms“ weiter zu untersuchen. / As a result of adopting MRI examinations for standing sedated horses their number has increased significantly. In this respect there are new questions and challenges being faced regarding estimating the huge number of occurring signal changes. New possibilities also arise regarding the statistical analysis of findings with convincing number of examined cases. In this study therefore it should be investigated how signal changes can be suitably described and classified statistically. Furthermore, the distribution of the findings as a whole and in the bilateral investigations of the forelimbs should be ascertained. Possible conclusions should be drawn regarding their clinical significance. Concerning this, 120 bilateral low-field-MRI examinations of the foot (240 limbs) on a standing horse were looked at by two veterinarians and a description of the analysis with a classification scheme (grades 1-4) corresponding to the existing spectrum of signal changes was compiled. By applying and repeatedly discussing the various Summary 68 criteria in the first evaluation round the descriptions and grades were worked out on the basis of existing literature. In a second evaluation round the structures were classified and the results statistically evaluated. In this regard the general frequency of signal deviations was recorded and its connection to the occurrence of unilateral or bilateral lameness was observed. Signal deviations at the navicular bone, deep digital flexor tendon and the coffin joint noticeably prevailed. In this respect changes to the navicular bone were found significantly more frequently in bilaterally lame horses while changes in tendons were found significantly more often in unilaterally lame horses. In contrast, changes in the coffin joint were not significantly more in bilateral or unilateral lameness. The collateral sesamoidean ligaments showed an accumulation of signal deviations at lame limbs, whereby this was observed more frequently in connection with pronounced changes of the navicular bone. In the remaining structures no statistically significant connection was found as the number of examined cases with the most significant results at these structures was too low for an evaluation. The related description of the findings with a classification scheme enables comparisons of MRI changes e.g. with clinical parameters. Signal deviations of certain structures were found to be clearly statistically associated with the occurrence and type of lameness, while this was not possible at other structures. This provides useful information for evaluating findings and their clinical relevance. Low-grade findings should be interpreted with caution since these also occurred frequently at non-lame limbs Further statistical comparisons with clinical parameters are possible and necessary in order to further examine the clinical picture of the equine palmar foot syndrome.

This thesis provides a structural and materials engineering explanation for many of the running fractures that occurred in steel structures during the destructive Kobe and Northridge earthquakes in the mid 1990s. A method is developed that allows the ductile endurance of structural steel members subjected to cyclic plastic deformation during earthquakes to be assessed and for pre-necking running fractures to be avoided. The study commenced following the 2000 World Earthquake Conference in Auckland. The conference brought together the findings of the huge research effort, in America, Japan, Europe and New Zealand, that followed the Kobe and Northridge earthquakes. The running fractures that had occurred in steel structures represented an unpredicted failure mode that structural engineers have not known how to predict or suppress through the engineering design process. A clear fundamental understanding of the causes and how to prevent the fractures did not arise from the conference. In fact apparently conflicting results were reported. Full scale cyclic tests in New Zealand on structural assemblies had not resulted in running fractures, whereas tests in American and Japan had. Structural engineers designing earthquake resistant structures rely on constructional steel to be materially homogeneous and nominally tri-linear in behaviour. Steel is expected to behave elastically under regular in-service loading, have a reliable and flat yield stress-strain characteristic, and under overload then develop predictable levels of strain-hardening in conjunction with significant plastic elongation up to its ultimate tensile strength. Steel is expected to eventually fracture after further plastic elongation and necking. Ductile design strategies and methods utilise the plastic elongation characteristics of steel to protect structures in earthquake. Plastic deformation is considered to beneficially dissipate energy generated in the structure by a severe earthquake and also dampen the structure’s response. The occurrence of running fracture without significant cyclic plastic deformation and before section necking in steelwork, therefore undermines the basis of the ductile seismic design approach. The initial part of the thesis is devoted to bringing together the fundamental aspects of materials engineering related to fracture of constructional steel. This is intended to provide a bridge of knowledge for structural engineering practitioners and researchers not fully conversant with materials engineering aspects of fracture. Fracture behaviour in steel is a broad and complex topic that developed rapidly in the twentieth century driven by the demands of technological growth. The unexpected fracture of welded liberty ships at sea in World War 2; the need for reliable long term containment for the nuclear reactors in the 1950s and 1960s; and prevention of fatigue failures in aircraft frames since the 1950s all drove engineering research into steel fracture behaviour. There are many subtle variations in definitions in the published literature on fracture that can be confusing. Therefore an attempt has been made to clarify terminology. The term brittle fracture in particular is only used in this thesis as applying to running fracture when the general or far field tensile stresses are below the yield stress of the steel. The term pre-necking or running fracture is preferred to describe the condition more broadly which may occur prior to and also after general yielding, but before section necking. Running fracture is a manifestation of pre-necking fracture in which insufficient plastic flow is available in the assembly to absorb the energy released upon fracture. The experimental studies investigated the behaviour of constructional steel commonly used in New Zealand, at various levels of plastic strain. This started with Charpy V-Notch (CVN) testing which revealed that a significant transition temperature shift and curve shape change occurs with increasing plastic strain and the associated strain-hardening. This showed that the ability of steel to avoid pre-necking or running fracture reduces as the level of plastic strain-hardening increases. Temperature controlled Crack Tip Opening Displacement (CTOD) testing was then undertaken. The setting of testing temperatures for the CTOD tests were guided by review of the CVN test results, using published CVN to fracture toughness correlation methods. However running cleavage fractures developed in the CTOD specimens at higher than predicted temperatures of 10 oC and 20 oC. These are typical service temperatures for structures in New Zealand and so are very likely to occur at the time of an earthquake. The implication from this is that there are levels of strain-hardening and conditions of material notching constraint that can lead to pre-necking and running fracture in New Zealand fabricated steel structures, under severe earthquake loading. Care was taken in the CTOD testing to monitor and maximise the capture of data electronically using a specially developed Direct Current Potential Drop method. This allowed the test results to be analysed and considered in varying ways, leading to a consistent assessment of the CTOD, crack growth, and the specific work of fracture in each test piece. While CTOD test results have sometimes been published by structural and welding engineering researchers in the wake of Kobe and Northridge, the results were typically of little use for this study as the CTOD initiation point was generally not identified effectively. The effect of remote plastic flow in the specimens was also not adequately accounted for. The CTOD test results were often simply used to help correlate other factors observed by the researchers. Side-grooving of specimens was not reported as having been used in any of the published results reviewed. When conducting CTOD test with highly ductile constructional steels it is very difficult to get useful CTOD results if the specimens are not side-grooved, as significant necking and tunnelling will otherwise occur and limit the usefulness of the results. Work by Knott and also by McRobie and Smith was seminal in terms of identifying some critical aspects of plane strain development in CTOD tests, and the links to non-metallic particle density with respect to fracture toughness and CTOD at initiation. Some of their findings with regards to the effect of pre-strain on CTOD initiation were subsequently found to confirm the experimental findings in this study. No effective methodology for prediction of pre-necking or running fracture in a structural member or assembly when subjected to gross plastic cyclic deformation was found to exist in the literature. It was concluded however that the principles of specific work of fracture, and monotonic and cyclic fracture similitude were particularly relevant. These were therefore utilised in the development of the design method proposed in this thesis. The CTOD test results were reviewed, isolating the remote plastic flow component, to determine the critical specific work of fracture property Rc of the steels tested. A meeting with Professor Kuwamura at the University of Tokyo was providential, allowing discussion of his similitude principle, and observations in person of some of the fractured specimens developed during his full scale test series’. Running fractures with cleavage were evident in the specimens, with their tell-tale chevron markings. He had predicted running fracture problems in structures in Japan ahead of the Kobe earthquake and been largely ignored. His insights were subsequently seriously considered in Japan after the earthquake. He and his colleagues developed the principle of structural similitude that relates monotonic fracture displacement ductility to cyclic fracture displacement ductility for a particular assembly. This arose from their observation that running fractures developed from ductile crack formation at blunt notches in structures. The similitude principle has echoes of the Coffin-Manson approach to ductile crack initiated low cycle fracture. The principle of similitude has a log–log relationship as does the Manson-Coffin relationship. So where notch plasticity controls the initiation of fracture in a structural assembly it is conceptually reasonable to expect that the number of cycles to initiation of fracture from a notch will have a log–log relationship to the amplitude of the cyclic strain developed in the notch. Kuwamura found that steel assemblies with lower CVN energy had reduced cyclic fracture endurance than the same assemblies made with steel with higher CVN impact energy. However no method of predicting performance of any particular assembly could be developed from his observations. The benefit of his method primarily relates to the minimising of testing necessary to assess the fracture limited cyclic displacement ductility of a structural assembly. However it doesn’t provide a means for designing a structural assembly to achieve specific levels of ductile endurance other than clearly identifying the need to use steel with good CVN characteristics. The most significant development arising from this thesis is therefore the development of a design method to assess cyclic ductile endurance. The method utilises the specific work of fracture properties obtained from CTOD specimens of the steel in conjunction with a relatively simple fracture mechanics assessment and an elasto-plastic finite element analysis (FEA). The FEA model is used to determine the displacement ductility of the assembly at the calculated onset of pre-necking fracture. The elasto-plastic stress–strain properties of the steel in various pre-strain states required for the FEA may be derived from tensile testing. Kuwamura’s similitude principle is then used to predict cyclic plastic endurance at various constant displacement ductility amplitudes. The method is extended using Miner’s rule to allow for the effects of increasing variable amplitude cyclic plastic loading. In summary the thesis explains why pre-necking and running fractures occur in steel members subjected to cyclic plastic deformation during a severe earthquake. In addition a method for consistently assessing the ability of structural steel assemblies to achieve a specified level of ductile endurance during earthquakes is proposed. The method is verified against published results for a cyclic test of a simple steel member with a crack at mid-span. / Whole document restricted, but available by request, use the feedback form to request access.

This thesis provides a structural and materials engineering explanation for many of the running fractures that occurred in steel structures during the destructive Kobe and Northridge earthquakes in the mid 1990s. A method is developed that allows the ductile endurance of structural steel members subjected to cyclic plastic deformation during earthquakes to be assessed and for pre-necking running fractures to be avoided. The study commenced following the 2000 World Earthquake Conference in Auckland. The conference brought together the findings of the huge research effort, in America, Japan, Europe and New Zealand, that followed the Kobe and Northridge earthquakes. The running fractures that had occurred in steel structures represented an unpredicted failure mode that structural engineers have not known how to predict or suppress through the engineering design process. A clear fundamental understanding of the causes and how to prevent the fractures did not arise from the conference. In fact apparently conflicting results were reported. Full scale cyclic tests in New Zealand on structural assemblies had not resulted in running fractures, whereas tests in American and Japan had. Structural engineers designing earthquake resistant structures rely on constructional steel to be materially homogeneous and nominally tri-linear in behaviour. Steel is expected to behave elastically under regular in-service loading, have a reliable and flat yield stress-strain characteristic, and under overload then develop predictable levels of strain-hardening in conjunction with significant plastic elongation up to its ultimate tensile strength. Steel is expected to eventually fracture after further plastic elongation and necking. Ductile design strategies and methods utilise the plastic elongation characteristics of steel to protect structures in earthquake. Plastic deformation is considered to beneficially dissipate energy generated in the structure by a severe earthquake and also dampen the structure’s response. The occurrence of running fracture without significant cyclic plastic deformation and before section necking in steelwork, therefore undermines the basis of the ductile seismic design approach. The initial part of the thesis is devoted to bringing together the fundamental aspects of materials engineering related to fracture of constructional steel. This is intended to provide a bridge of knowledge for structural engineering practitioners and researchers not fully conversant with materials engineering aspects of fracture. Fracture behaviour in steel is a broad and complex topic that developed rapidly in the twentieth century driven by the demands of technological growth. The unexpected fracture of welded liberty ships at sea in World War 2; the need for reliable long term containment for the nuclear reactors in the 1950s and 1960s; and prevention of fatigue failures in aircraft frames since the 1950s all drove engineering research into steel fracture behaviour. There are many subtle variations in definitions in the published literature on fracture that can be confusing. Therefore an attempt has been made to clarify terminology. The term brittle fracture in particular is only used in this thesis as applying to running fracture when the general or far field tensile stresses are below the yield stress of the steel. The term pre-necking or running fracture is preferred to describe the condition more broadly which may occur prior to and also after general yielding, but before section necking. Running fracture is a manifestation of pre-necking fracture in which insufficient plastic flow is available in the assembly to absorb the energy released upon fracture. The experimental studies investigated the behaviour of constructional steel commonly used in New Zealand, at various levels of plastic strain. This started with Charpy V-Notch (CVN) testing which revealed that a significant transition temperature shift and curve shape change occurs with increasing plastic strain and the associated strain-hardening. This showed that the ability of steel to avoid pre-necking or running fracture reduces as the level of plastic strain-hardening increases. Temperature controlled Crack Tip Opening Displacement (CTOD) testing was then undertaken. The setting of testing temperatures for the CTOD tests were guided by review of the CVN test results, using published CVN to fracture toughness correlation methods. However running cleavage fractures developed in the CTOD specimens at higher than predicted temperatures of 10 oC and 20 oC. These are typical service temperatures for structures in New Zealand and so are very likely to occur at the time of an earthquake. The implication from this is that there are levels of strain-hardening and conditions of material notching constraint that can lead to pre-necking and running fracture in New Zealand fabricated steel structures, under severe earthquake loading. Care was taken in the CTOD testing to monitor and maximise the capture of data electronically using a specially developed Direct Current Potential Drop method. This allowed the test results to be analysed and considered in varying ways, leading to a consistent assessment of the CTOD, crack growth, and the specific work of fracture in each test piece. While CTOD test results have sometimes been published by structural and welding engineering researchers in the wake of Kobe and Northridge, the results were typically of little use for this study as the CTOD initiation point was generally not identified effectively. The effect of remote plastic flow in the specimens was also not adequately accounted for. The CTOD test results were often simply used to help correlate other factors observed by the researchers. Side-grooving of specimens was not reported as having been used in any of the published results reviewed. When conducting CTOD test with highly ductile constructional steels it is very difficult to get useful CTOD results if the specimens are not side-grooved, as significant necking and tunnelling will otherwise occur and limit the usefulness of the results. Work by Knott and also by McRobie and Smith was seminal in terms of identifying some critical aspects of plane strain development in CTOD tests, and the links to non-metallic particle density with respect to fracture toughness and CTOD at initiation. Some of their findings with regards to the effect of pre-strain on CTOD initiation were subsequently found to confirm the experimental findings in this study. No effective methodology for prediction of pre-necking or running fracture in a structural member or assembly when subjected to gross plastic cyclic deformation was found to exist in the literature. It was concluded however that the principles of specific work of fracture, and monotonic and cyclic fracture similitude were particularly relevant. These were therefore utilised in the development of the design method proposed in this thesis. The CTOD test results were reviewed, isolating the remote plastic flow component, to determine the critical specific work of fracture property Rc of the steels tested. A meeting with Professor Kuwamura at the University of Tokyo was providential, allowing discussion of his similitude principle, and observations in person of some of the fractured specimens developed during his full scale test series’. Running fractures with cleavage were evident in the specimens, with their tell-tale chevron markings. He had predicted running fracture problems in structures in Japan ahead of the Kobe earthquake and been largely ignored. His insights were subsequently seriously considered in Japan after the earthquake. He and his colleagues developed the principle of structural similitude that relates monotonic fracture displacement ductility to cyclic fracture displacement ductility for a particular assembly. This arose from their observation that running fractures developed from ductile crack formation at blunt notches in structures. The similitude principle has echoes of the Coffin-Manson approach to ductile crack initiated low cycle fracture. The principle of similitude has a log–log relationship as does the Manson-Coffin relationship. So where notch plasticity controls the initiation of fracture in a structural assembly it is conceptually reasonable to expect that the number of cycles to initiation of fracture from a notch will have a log–log relationship to the amplitude of the cyclic strain developed in the notch. Kuwamura found that steel assemblies with lower CVN energy had reduced cyclic fracture endurance than the same assemblies made with steel with higher CVN impact energy. However no method of predicting performance of any particular assembly could be developed from his observations. The benefit of his method primarily relates to the minimising of testing necessary to assess the fracture limited cyclic displacement ductility of a structural assembly. However it doesn’t provide a means for designing a structural assembly to achieve specific levels of ductile endurance other than clearly identifying the need to use steel with good CVN characteristics. The most significant development arising from this thesis is therefore the development of a design method to assess cyclic ductile endurance. The method utilises the specific work of fracture properties obtained from CTOD specimens of the steel in conjunction with a relatively simple fracture mechanics assessment and an elasto-plastic finite element analysis (FEA). The FEA model is used to determine the displacement ductility of the assembly at the calculated onset of pre-necking fracture. The elasto-plastic stress–strain properties of the steel in various pre-strain states required for the FEA may be derived from tensile testing. Kuwamura’s similitude principle is then used to predict cyclic plastic endurance at various constant displacement ductility amplitudes. The method is extended using Miner’s rule to allow for the effects of increasing variable amplitude cyclic plastic loading. In summary the thesis explains why pre-necking and running fractures occur in steel members subjected to cyclic plastic deformation during a severe earthquake. In addition a method for consistently assessing the ability of structural steel assemblies to achieve a specified level of ductile endurance during earthquakes is proposed. The method is verified against published results for a cyclic test of a simple steel member with a crack at mid-span. / Whole document restricted, but available by request, use the feedback form to request access.

This thesis provides a structural and materials engineering explanation for many of the running fractures that occurred in steel structures during the destructive Kobe and Northridge earthquakes in the mid 1990s. A method is developed that allows the ductile endurance of structural steel members subjected to cyclic plastic deformation during earthquakes to be assessed and for pre-necking running fractures to be avoided. The study commenced following the 2000 World Earthquake Conference in Auckland. The conference brought together the findings of the huge research effort, in America, Japan, Europe and New Zealand, that followed the Kobe and Northridge earthquakes. The running fractures that had occurred in steel structures represented an unpredicted failure mode that structural engineers have not known how to predict or suppress through the engineering design process. A clear fundamental understanding of the causes and how to prevent the fractures did not arise from the conference. In fact apparently conflicting results were reported. Full scale cyclic tests in New Zealand on structural assemblies had not resulted in running fractures, whereas tests in American and Japan had. Structural engineers designing earthquake resistant structures rely on constructional steel to be materially homogeneous and nominally tri-linear in behaviour. Steel is expected to behave elastically under regular in-service loading, have a reliable and flat yield stress-strain characteristic, and under overload then develop predictable levels of strain-hardening in conjunction with significant plastic elongation up to its ultimate tensile strength. Steel is expected to eventually fracture after further plastic elongation and necking. Ductile design strategies and methods utilise the plastic elongation characteristics of steel to protect structures in earthquake. Plastic deformation is considered to beneficially dissipate energy generated in the structure by a severe earthquake and also dampen the structure’s response. The occurrence of running fracture without significant cyclic plastic deformation and before section necking in steelwork, therefore undermines the basis of the ductile seismic design approach. The initial part of the thesis is devoted to bringing together the fundamental aspects of materials engineering related to fracture of constructional steel. This is intended to provide a bridge of knowledge for structural engineering practitioners and researchers not fully conversant with materials engineering aspects of fracture. Fracture behaviour in steel is a broad and complex topic that developed rapidly in the twentieth century driven by the demands of technological growth. The unexpected fracture of welded liberty ships at sea in World War 2; the need for reliable long term containment for the nuclear reactors in the 1950s and 1960s; and prevention of fatigue failures in aircraft frames since the 1950s all drove engineering research into steel fracture behaviour. There are many subtle variations in definitions in the published literature on fracture that can be confusing. Therefore an attempt has been made to clarify terminology. The term brittle fracture in particular is only used in this thesis as applying to running fracture when the general or far field tensile stresses are below the yield stress of the steel. The term pre-necking or running fracture is preferred to describe the condition more broadly which may occur prior to and also after general yielding, but before section necking. Running fracture is a manifestation of pre-necking fracture in which insufficient plastic flow is available in the assembly to absorb the energy released upon fracture. The experimental studies investigated the behaviour of constructional steel commonly used in New Zealand, at various levels of plastic strain. This started with Charpy V-Notch (CVN) testing which revealed that a significant transition temperature shift and curve shape change occurs with increasing plastic strain and the associated strain-hardening. This showed that the ability of steel to avoid pre-necking or running fracture reduces as the level of plastic strain-hardening increases. Temperature controlled Crack Tip Opening Displacement (CTOD) testing was then undertaken. The setting of testing temperatures for the CTOD tests were guided by review of the CVN test results, using published CVN to fracture toughness correlation methods. However running cleavage fractures developed in the CTOD specimens at higher than predicted temperatures of 10 oC and 20 oC. These are typical service temperatures for structures in New Zealand and so are very likely to occur at the time of an earthquake. The implication from this is that there are levels of strain-hardening and conditions of material notching constraint that can lead to pre-necking and running fracture in New Zealand fabricated steel structures, under severe earthquake loading. Care was taken in the CTOD testing to monitor and maximise the capture of data electronically using a specially developed Direct Current Potential Drop method. This allowed the test results to be analysed and considered in varying ways, leading to a consistent assessment of the CTOD, crack growth, and the specific work of fracture in each test piece. While CTOD test results have sometimes been published by structural and welding engineering researchers in the wake of Kobe and Northridge, the results were typically of little use for this study as the CTOD initiation point was generally not identified effectively. The effect of remote plastic flow in the specimens was also not adequately accounted for. The CTOD test results were often simply used to help correlate other factors observed by the researchers. Side-grooving of specimens was not reported as having been used in any of the published results reviewed. When conducting CTOD test with highly ductile constructional steels it is very difficult to get useful CTOD results if the specimens are not side-grooved, as significant necking and tunnelling will otherwise occur and limit the usefulness of the results. Work by Knott and also by McRobie and Smith was seminal in terms of identifying some critical aspects of plane strain development in CTOD tests, and the links to non-metallic particle density with respect to fracture toughness and CTOD at initiation. Some of their findings with regards to the effect of pre-strain on CTOD initiation were subsequently found to confirm the experimental findings in this study. No effective methodology for prediction of pre-necking or running fracture in a structural member or assembly when subjected to gross plastic cyclic deformation was found to exist in the literature. It was concluded however that the principles of specific work of fracture, and monotonic and cyclic fracture similitude were particularly relevant. These were therefore utilised in the development of the design method proposed in this thesis. The CTOD test results were reviewed, isolating the remote plastic flow component, to determine the critical specific work of fracture property Rc of the steels tested. A meeting with Professor Kuwamura at the University of Tokyo was providential, allowing discussion of his similitude principle, and observations in person of some of the fractured specimens developed during his full scale test series’. Running fractures with cleavage were evident in the specimens, with their tell-tale chevron markings. He had predicted running fracture problems in structures in Japan ahead of the Kobe earthquake and been largely ignored. His insights were subsequently seriously considered in Japan after the earthquake. He and his colleagues developed the principle of structural similitude that relates monotonic fracture displacement ductility to cyclic fracture displacement ductility for a particular assembly. This arose from their observation that running fractures developed from ductile crack formation at blunt notches in structures. The similitude principle has echoes of the Coffin-Manson approach to ductile crack initiated low cycle fracture. The principle of similitude has a log–log relationship as does the Manson-Coffin relationship. So where notch plasticity controls the initiation of fracture in a structural assembly it is conceptually reasonable to expect that the number of cycles to initiation of fracture from a notch will have a log–log relationship to the amplitude of the cyclic strain developed in the notch. Kuwamura found that steel assemblies with lower CVN energy had reduced cyclic fracture endurance than the same assemblies made with steel with higher CVN impact energy. However no method of predicting performance of any particular assembly could be developed from his observations. The benefit of his method primarily relates to the minimising of testing necessary to assess the fracture limited cyclic displacement ductility of a structural assembly. However it doesn’t provide a means for designing a structural assembly to achieve specific levels of ductile endurance other than clearly identifying the need to use steel with good CVN characteristics. The most significant development arising from this thesis is therefore the development of a design method to assess cyclic ductile endurance. The method utilises the specific work of fracture properties obtained from CTOD specimens of the steel in conjunction with a relatively simple fracture mechanics assessment and an elasto-plastic finite element analysis (FEA). The FEA model is used to determine the displacement ductility of the assembly at the calculated onset of pre-necking fracture. The elasto-plastic stress–strain properties of the steel in various pre-strain states required for the FEA may be derived from tensile testing. Kuwamura’s similitude principle is then used to predict cyclic plastic endurance at various constant displacement ductility amplitudes. The method is extended using Miner’s rule to allow for the effects of increasing variable amplitude cyclic plastic loading. In summary the thesis explains why pre-necking and running fractures occur in steel members subjected to cyclic plastic deformation during a severe earthquake. In addition a method for consistently assessing the ability of structural steel assemblies to achieve a specified level of ductile endurance during earthquakes is proposed. The method is verified against published results for a cyclic test of a simple steel member with a crack at mid-span. / Whole document restricted, but available by request, use the feedback form to request access.

This thesis provides a structural and materials engineering explanation for many of the running fractures that occurred in steel structures during the destructive Kobe and Northridge earthquakes in the mid 1990s. A method is developed that allows the ductile endurance of structural steel members subjected to cyclic plastic deformation during earthquakes to be assessed and for pre-necking running fractures to be avoided. The study commenced following the 2000 World Earthquake Conference in Auckland. The conference brought together the findings of the huge research effort, in America, Japan, Europe and New Zealand, that followed the Kobe and Northridge earthquakes. The running fractures that had occurred in steel structures represented an unpredicted failure mode that structural engineers have not known how to predict or suppress through the engineering design process. A clear fundamental understanding of the causes and how to prevent the fractures did not arise from the conference. In fact apparently conflicting results were reported. Full scale cyclic tests in New Zealand on structural assemblies had not resulted in running fractures, whereas tests in American and Japan had. Structural engineers designing earthquake resistant structures rely on constructional steel to be materially homogeneous and nominally tri-linear in behaviour. Steel is expected to behave elastically under regular in-service loading, have a reliable and flat yield stress-strain characteristic, and under overload then develop predictable levels of strain-hardening in conjunction with significant plastic elongation up to its ultimate tensile strength. Steel is expected to eventually fracture after further plastic elongation and necking. Ductile design strategies and methods utilise the plastic elongation characteristics of steel to protect structures in earthquake. Plastic deformation is considered to beneficially dissipate energy generated in the structure by a severe earthquake and also dampen the structure’s response. The occurrence of running fracture without significant cyclic plastic deformation and before section necking in steelwork, therefore undermines the basis of the ductile seismic design approach. The initial part of the thesis is devoted to bringing together the fundamental aspects of materials engineering related to fracture of constructional steel. This is intended to provide a bridge of knowledge for structural engineering practitioners and researchers not fully conversant with materials engineering aspects of fracture. Fracture behaviour in steel is a broad and complex topic that developed rapidly in the twentieth century driven by the demands of technological growth. The unexpected fracture of welded liberty ships at sea in World War 2; the need for reliable long term containment for the nuclear reactors in the 1950s and 1960s; and prevention of fatigue failures in aircraft frames since the 1950s all drove engineering research into steel fracture behaviour. There are many subtle variations in definitions in the published literature on fracture that can be confusing. Therefore an attempt has been made to clarify terminology. The term brittle fracture in particular is only used in this thesis as applying to running fracture when the general or far field tensile stresses are below the yield stress of the steel. The term pre-necking or running fracture is preferred to describe the condition more broadly which may occur prior to and also after general yielding, but before section necking. Running fracture is a manifestation of pre-necking fracture in which insufficient plastic flow is available in the assembly to absorb the energy released upon fracture. The experimental studies investigated the behaviour of constructional steel commonly used in New Zealand, at various levels of plastic strain. This started with Charpy V-Notch (CVN) testing which revealed that a significant transition temperature shift and curve shape change occurs with increasing plastic strain and the associated strain-hardening. This showed that the ability of steel to avoid pre-necking or running fracture reduces as the level of plastic strain-hardening increases. Temperature controlled Crack Tip Opening Displacement (CTOD) testing was then undertaken. The setting of testing temperatures for the CTOD tests were guided by review of the CVN test results, using published CVN to fracture toughness correlation methods. However running cleavage fractures developed in the CTOD specimens at higher than predicted temperatures of 10 oC and 20 oC. These are typical service temperatures for structures in New Zealand and so are very likely to occur at the time of an earthquake. The implication from this is that there are levels of strain-hardening and conditions of material notching constraint that can lead to pre-necking and running fracture in New Zealand fabricated steel structures, under severe earthquake loading. Care was taken in the CTOD testing to monitor and maximise the capture of data electronically using a specially developed Direct Current Potential Drop method. This allowed the test results to be analysed and considered in varying ways, leading to a consistent assessment of the CTOD, crack growth, and the specific work of fracture in each test piece. While CTOD test results have sometimes been published by structural and welding engineering researchers in the wake of Kobe and Northridge, the results were typically of little use for this study as the CTOD initiation point was generally not identified effectively. The effect of remote plastic flow in the specimens was also not adequately accounted for. The CTOD test results were often simply used to help correlate other factors observed by the researchers. Side-grooving of specimens was not reported as having been used in any of the published results reviewed. When conducting CTOD test with highly ductile constructional steels it is very difficult to get useful CTOD results if the specimens are not side-grooved, as significant necking and tunnelling will otherwise occur and limit the usefulness of the results. Work by Knott and also by McRobie and Smith was seminal in terms of identifying some critical aspects of plane strain development in CTOD tests, and the links to non-metallic particle density with respect to fracture toughness and CTOD at initiation. Some of their findings with regards to the effect of pre-strain on CTOD initiation were subsequently found to confirm the experimental findings in this study. No effective methodology for prediction of pre-necking or running fracture in a structural member or assembly when subjected to gross plastic cyclic deformation was found to exist in the literature. It was concluded however that the principles of specific work of fracture, and monotonic and cyclic fracture similitude were particularly relevant. These were therefore utilised in the development of the design method proposed in this thesis. The CTOD test results were reviewed, isolating the remote plastic flow component, to determine the critical specific work of fracture property Rc of the steels tested. A meeting with Professor Kuwamura at the University of Tokyo was providential, allowing discussion of his similitude principle, and observations in person of some of the fractured specimens developed during his full scale test series’. Running fractures with cleavage were evident in the specimens, with their tell-tale chevron markings. He had predicted running fracture problems in structures in Japan ahead of the Kobe earthquake and been largely ignored. His insights were subsequently seriously considered in Japan after the earthquake. He and his colleagues developed the principle of structural similitude that relates monotonic fracture displacement ductility to cyclic fracture displacement ductility for a particular assembly. This arose from their observation that running fractures developed from ductile crack formation at blunt notches in structures. The similitude principle has echoes of the Coffin-Manson approach to ductile crack initiated low cycle fracture. The principle of similitude has a log–log relationship as does the Manson-Coffin relationship. So where notch plasticity controls the initiation of fracture in a structural assembly it is conceptually reasonable to expect that the number of cycles to initiation of fracture from a notch will have a log–log relationship to the amplitude of the cyclic strain developed in the notch. Kuwamura found that steel assemblies with lower CVN energy had reduced cyclic fracture endurance than the same assemblies made with steel with higher CVN impact energy. However no method of predicting performance of any particular assembly could be developed from his observations. The benefit of his method primarily relates to the minimising of testing necessary to assess the fracture limited cyclic displacement ductility of a structural assembly. However it doesn’t provide a means for designing a structural assembly to achieve specific levels of ductile endurance other than clearly identifying the need to use steel with good CVN characteristics. The most significant development arising from this thesis is therefore the development of a design method to assess cyclic ductile endurance. The method utilises the specific work of fracture properties obtained from CTOD specimens of the steel in conjunction with a relatively simple fracture mechanics assessment and an elasto-plastic finite element analysis (FEA). The FEA model is used to determine the displacement ductility of the assembly at the calculated onset of pre-necking fracture. The elasto-plastic stress–strain properties of the steel in various pre-strain states required for the FEA may be derived from tensile testing. Kuwamura’s similitude principle is then used to predict cyclic plastic endurance at various constant displacement ductility amplitudes. The method is extended using Miner’s rule to allow for the effects of increasing variable amplitude cyclic plastic loading. In summary the thesis explains why pre-necking and running fractures occur in steel members subjected to cyclic plastic deformation during a severe earthquake. In addition a method for consistently assessing the ability of structural steel assemblies to achieve a specified level of ductile endurance during earthquakes is proposed. The method is verified against published results for a cyclic test of a simple steel member with a crack at mid-span. / Whole document restricted, but available by request, use the feedback form to request access.

Prognostics and health management (PHM) is a major tool enabling systems to evaluate their reliability in real-time operation. Despite ground-breaking advances in most engineering and scientific disciplines during the past decades, reliability engineering has not seen significant breakthroughs or noticeable advances. Therefore, self-awareness of the embedded system is also often required in the sense that the system should be able to assess its own health state and failure records, and those of its main components, and take action appropriately. This thesis presents a radically new prognostics approach to reliable system design that will revolutionise complex power electronic systems with robust prognostics capability enhanced Insulated Gate Bipolar Transistors (IGBT) in applications where reliability is significantly challenging and critical. The IGBT is considered as one of the components that is mainly damaged in converters and experiences a number of failure mechanisms, such as bond wire lift off, die attached solder crack, loose gate control voltage, etc. The resulting effects mentioned are complex. For instance, solder crack growth results in increasing the IGBT’s thermal junction which becomes a source of heat turns to wire bond lift off. As a result, the indication of this failure can be seen often in increasing on-state resistance relating to the voltage drop between on-state collector-emitter. On the other hand, hot carrier injection is increased due to electrical stress. Additionally, IGBTs are components that mainly work under high stress, temperature and power consumptions due to the higher range of load that these devices need to switch. This accelerates the degradation mechanism in the power switches in discrete fashion till reaches failure state which fail after several hundred cycles. To this end, exploiting failure mechanism knowledge of IGBTs and identifying failure parameter indication are background information of developing failure model and prognostics algorithm to calculate remaining useful life (RUL) along with ±10% confidence bounds. A number of various prognostics models have been developed for forecasting time to failure of IGBTs and the performance of the presented estimation models has been evaluated based on two different evaluation metrics. The results show significant improvement in health monitoring capability for power switches. Furthermore, the reliability of the power switch was calculated and conducted to fully describe health state of the converter and reconfigure the control parameter using adaptive algorithm under degradation and load mission limitation. As a result, the life expectancy of devices has been increased. These all allow condition-monitoring facilities to minimise stress levels and predict future failure which greatly reduces the likelihood of power switch failures in the first place.

By using the technique of photogrammetry for the 3D visualization of ancient Egyptian coffins decorated with magical texts and iconography, this project aims at building up a new digital platform for an in-depth study of the ancient Egyptian funerary culture and its media. It has started in August 2015 through the support of a Mellon Fellowship for the Digital Humanities at UC Berkeley and up until now it has focused on ancient Egyptian coffins kept at the Phoebe A. Hearst Museum of Anthropology of UC Berkeley. The main outcome will be a digital platform that allows to display a coffin in 3D and where users will be able to pan, rotate, and zoom in on the coffin, clicking on areas of text to highlight them and view an annotated translation together with other metadata (transcription of the hieroglyphic text, bibliography, textual variants, museological data, provenance, etc.)

Hufgelenkerkrankungen zählen zu den häufigsten orthopädischen Verletzungen des Sportpferdes. Im Rahmen bisheriger Studien über die Therapie mit autologen Thrombozytenkonzentraten sowie mit Pentosanpolysulfat konnten positive Effekte dieser Medikamente auf die Knorpelheilung nachgewiesen werden. Allerdings gibt es bis dato keine Arbeiten, die eine vergleichende Betrachtung der Wirksamkeit dieser Substanzen unter gleichen Rahmenbedingungen vornehmen. In der vorliegenden Studie wurde daher untersucht, inwiefern sich die intraartikuläre Behandlung mit autologem konditioniertem Plasma (ACP) von der intraartikulären Therapie mit Natrium-Pentosanpolysulfat (NaPPS) bei Hufgelenkerkrankungen unterscheidet. Die erhaltenen Ergebnisse wurden weiterhin mit der konventionellen intraartikulären Therapie unter Verwendung von Hyaluronsäure und Corticosteroiden verglichen, wofür eine historische Kontrollgruppe herangezogen wurde. Als Bedingung für die Aufnahme in die Studie wurden eine gering- bis mittelgradige Vorderbeinlahmheit sowie eine positive Hufgelenkanästhesie festgelegt. Zwischen Juni 2015 und Februar 2017 wurden insgesamt 40 Pferde an der Tierärztlichen Klinik für Pferde in Brockhagen untersucht. Die Einteilung in die jeweilige Behandlungsgruppe erfolgte per Los, wobei Pferde der Gruppe I intraartikulär mit ACP und Pferde der Gruppe II intraartikulär mit NaPPS behandelt wurden. Therapiebegleitend wurde neben der Korrektur der Hufform und ggf. des Beschlages ein einheitliches Bewegungsprogramm angeordnet. Im Rahmen der Nachuntersuchungen erhielten die Pferde bei Nichterreichen der Lahmfreiheit ein bis zwei weitere Injektionen. Anhand der klinischen Lahmheitsuntersuchung erfolgte die Beurteilung der Parameter „Lahmheitsgrad“, „Ausfall der Zehenbeugeprobe“ und „Gelenkfüllung“. Der Beobachtungszeitraum betrug sechs Monate. Als Therapieziel wurde die Heilung der Patienten im Sinne einer Lahmfreiheit unter Erlangung des ursprünglichen Leistungsniveaus definiert. Dies konnte in der ACP-Gruppe bei 13 Patienten (65 %) erreicht werden. Bei zwei Pferden (10 %) war eine Verbesserung des Lahmheitsgrades feststellbar. Drei Pferde (15 %) zeigten keine Veränderung des Lahmheitsgrades und zwei Pferde (10 %) erlitten ein Rezidiv. Die NaPPS-Therapie führte bei 14 Patienten (70 %) zu einem Therapieerfolg. Bei drei Patienten (15 %) zeigte sich eine Besserung des Lahmheitsgrades, bei zwei Patienten (10 %) blieb der Lahmheitsgrad unverändert und bei einem Patienten (5 %) trat eine rezidivierende Lahmheit auf. In keiner der beiden Behandlungsgruppen traten Nebenwirkungen oder unerwünschten Reaktionen auf. Die statistische Analyse ergab hinsichtlich der Erreichung des Therapieziels keinen signifikanten Unterschied zwischen den Behandlungsgruppen. Demnach können beide Medikamente als gleichermaßen wirksam betrachtet werden. Allerdings findet sich bei Betrachtung der Nachuntersuchungen eine Tendenz zur besseren kurzfristigen Wirksamkeit von NaPPS mit 70 % lahmfreien Pferden nach vier Wochen gegenüber 50 % lahmfreien Pferden in der ACP-Gruppe. Nach drei Monaten nähern sich diese Werte wieder an (NaPPS: 75 %, ACP: 70 %). Bezüglich der Anzahl der benötigten Injektionen bis zur Erreichung der Lahmfreiheit ließ sich ein Trend zur häufigeren Injektion mit 2,23 ± 0,725 in der ACP-Gruppe gegenüber 1,71 ± 0,611 Injektionen in der NaPPS-Gruppe erkennen. Statistisch war dieser Unterschied jedoch knapp nicht signifikant (p = 0,059). Der Vergleich der Ergebnisse mit dem Therapieerfolg bei einer konventionellen intraartikulären Therapie (historische Kontrollgruppe) erwies sich ebenfalls als nicht signifikant. Die vorliegende Studie bestätigt bisherige positive Erfahrungen zur regenerativen Gelenktherapie mit autologen Thrombozytenkonzentraten und NaPPS und lässt diese Behandlungsmethoden als sinnvolle Alternativen zu konventionellen Therapieformen erscheinen. Zusammenfassend lässt sich festhalten, dass der Therapieerfolg bei der Behandlung mit NaPPS schneller eintritt, wobei eine ein- bis zweimalige Injektion als ausreichend erscheint. Die Anwendung von ACP ist längerfristig gleichermaßen wirksam; jedoch kann nach den Beobachtungen dieser Studie eine zwei- bis dreimalige Applikation notwendig sein. Die wissenschaftliche Forschung sollte sich zukünftig um ein besseres Verständnis der Wirkungsweise von autologen Thrombozytenkonzentraten bemühen. Dabei wären insbesondere neben ACP auch Produkte anderer Herstellungsart und Zusammensetzung auf Wirkungsunterschiede im Gelenk zu untersuchen. Zudem sollten das Behandlungsintervall, die Behandlungsfrequenz und der richtige Therapiezeitpunkt für die jeweiligen Medikamente (ACP und NaPPS) überprüft werden. Besonders im Hufgelenkbereich wäre bei Betrachtung dieser intraartikulären Therapieformen eine genauere Differenzierung der zugrundeliegenden Pathologie durch weiterführende Diagnosemethoden erforderlich. Schließlich sollten sich weitere prospektive, randomisierte, placebokontrollierte Studien mit größeren Patientenzahlen anschließen, um die Ergebnisse der vorliegenden Studie zu überprüfen.:Abkürzungsverzeichnis I Tabellenverzeichnis IV Abbildungsverzeichnis V 1 Einleitung 1 2 Literaturübersicht 3 2.1 Anatomie des Hufgelenks 3 2.2 Physiologie des Pferdegelenks 5 2.2.1 Gelenkkapsel 5 2.2.2 Synovia 5 2.2.3 Gelenkknorpel 6 2.3 Pathophysiologie des Pferdegelenks 8 2.3.1 Traumatische Arthritis 8 2.3.2 Osteoarthritis 8 2.4 Erkrankungen im Bereich des Hufgelenks 12 2.4.1 Aseptische Podarthritis 12 2.4.2 Podarthrose 14 2.4.3 Podotrochlose-Syndrom 14 2.4.3.1 Podotrochlose im engeren Sinne 15 2.4.3.2 Insertionsdesmopathien 15 2.4.3.3 Strahlbeinerkrankung mit Hufgelenkbeteiligung 16 2.4.4 Hufbeinfraktur 16 2.4.5 Strahlbeinfraktur 17 2.4.6 Subchondrale zystoide Defekte 17 2.4.7 Erkrankungen im Bereich des Processus Extensorius 18 2.5 Lahmheitsdiagnostik der distalen Zehe 19 2.5.1 Klinische Lahmheitsdiagnostik 19 2.5.2 Diagnostische Anästhesien 23 2.5.2.1 Leitungsanästhesien 24 2.5.2.2 Intrasynoviale Anästhesien 25 2.5.3 Direkte Druckmessung im Hufgelenk 27 2.5.4 Synoviaanalyse 27 2.5.5 Röntgenologische Untersuchung 28 2.5.5.1 Röntgenleitfaden 28 2.5.5.2 Röntgenbefunde im Hufgelenkbereich 29 2.5.5.3 Röntgenbefunde am Strahlbein 30 2.5.6 Weiterführende bildgebende Diagnostik 32 2.5.6.1 Endoskopie 32 2.5.6.2 Sonographie 32 2.5.6.3 Szintigraphie 32 2.5.6.4 Computertomographie 33 2.5.6.5 Magnetresonanztomographie 33 2.6 Therapie 34 2.6.1 Begleitende konservative Maßnahmen 34 2.6.1.1 Hufkorrektur und Beschlag 34 2.6.1.2 Bewegungsprogramm 34 2.6.2 Medikamentöse Therapie 34 2.6.2.1 NSAIDs 34 2.6.2.2 Intraartikuläre Corticosteroide 35 2.6.2.3 Hyaluronsäure (HA) 36 2.6.2.4 Kombinierte Anwendung HA/Corticosteroid 37 2.6.2.5 Polysulfatierte Glykosaminoglykane (PSGAG) 37 2.6.2.6 Pentosanpolysulfat (PPS) 38 2.6.2.7 Autologous Conditioned Plasma® (ACP) 41 2.6.2.8 Autologes Conditioniertes Serum (ACS) 44 2.6.2.9 Multipotente mesenchymale Stromazellen (MSC) 45 2.6.2.10 Polyacrylamid Hydrogel (PAAHG) 47 3 Material und Methoden 48 3.1 Therapieziel 48 3.2 Wissenschaftliche Fragestellung 48 3.3 Studienumfang 48 3.4 Untersuchungsmethodik 51 3.4.1 Einschlusskriterien 51 3.4.2 Anamnese 51 3.4.3 Klinische Untersuchung und Beurteilungskriterien 51 3.4.4 Diagnostische Anästhesien 52 3.4.5 Röntgenologische Untersuchung 53 3.4.6 Therapieplan 53 3.4.7 Nachuntersuchungen 54 3.4.8 Beurteilung des Therapieerfolges 54 3.5 Statistische Methodik 55 4 Ergebnisse 57 4.1 Vergleichbarkeit der Gruppen 57 4.1.1 Geschlechterverteilung 57 4.1.2 Altersverteilung 57 4.1.3 Rassenverteilung 58 4.1.4 Größenverteilung 58 4.1.5 Einsatzschwerpunkt und Beanspruchung 59 4.1.6 Vorerkrankungen 59 4.1.7 Vorbehandlungen 60 4.1.8 Dauer der bestehenden Lahmheit 60 4.1.9 Beginn und Verlauf der bestehenden Lahmheit 62 4.2 Befunde der Erstuntersuchung 62 4.2.1 Betroffene Gliedmaße 62 4.2.2 Art der Lahmheit 63 4.2.3 Ergebnisse der Leitungsanästhesien 63 4.2.4 Verteilung der Röntgenklassen 64 4.2.5 Lahmheitsgrad zum Zeitpunkt t0 64 4.2.6 Gelenkfüllung zum Zeitpunkt t0 65 4.2.7 Zehenbeugeprobe zum Zeitpunkt t0 65 4.2.8 Overall Clinical Severitiy Score (CSS) zum Zeitpunkt t0 65 4.3 Ergebnisse der Nachuntersuchungen 66 4.3.1 Erste Nachuntersuchung nach 14-21 Tagen (t1) 66 4.3.1.1 Lahmheitsgrad zum Zeitpunkt t1 66 4.3.1.2 CSS zum Zeitpunkt t1 68 4.3.2 Zweite Nachuntersuchung nach 21-28 Tagen (t2) 69 4.3.2.1 Lahmheitsgrad zum Zeitpunkt t2 69 4.3.2.2 CSS zum Zeitpunkt t2 70 4.3.3 Dritte Nachuntersuchung nach 3 Monaten (t3) 71 4.3.3.1 Lahmheitsgrad zum Zeitpunkt t3 71 4.3.3.2 CSS zum Zeitpunkt t3 72 4.3.4 Vierte Nachuntersuchung nach 6 Monaten (t4) 73 4.3.4.1 Lahmheitsgrad zum Zeitpunkt t4 73 4.3.4.2 CSS zum Zeitpunkt t4 75 4.4 Gesamtergebnis 77 4.4.1 Gesamtergebnis in Abhängigkeit von der Therapiemethode 77 4.4.2 Therapieergebnis in Abhängigkeit vom Erkrankungsstadium 78 4.4.3 Anzahl der benötigten Injektionen 79 4.5 Retrospektiver Vergleich mit konventioneller Therapie 79 4.6 Beurteilung der Gruppengrößen zum Abschluss der Studie 81 5 Diskussion 82 5.1 Studienumfang 82 5.2 Vergleichbarkeit der Gruppen 82 5.3 Untersuchungsmethodik 84 5.4 Nachuntersuchungen 86 5.5 Beurteilungskriterien 87 5.6 Therapieergebnisse 87 5.7 Retrospektiver Vergleich mit konventioneller Therapie 91 5.8 Schlussfolgerungen 91 5.9 Ausblick 93 6 Zusammenfassung 94 7 Summary 96 8 Literaturverzeichnis 98 9 Anhang 142 10 Danksagung 145 / Diseases related to the distal interphalangeal joint rank among the most frequently occurring orthopedic injuries in sport horses. Previous studies have shown some promising results regarding the positive influence of autologous platelet concentrates and pentosanpolysulfate sodium on cartilage healing. However, to date, there is no published scientific work comparing the efficacy of these substances under the same controlled conditions. Therefore, the present study aims at examining the differences between the intraarticular therapy using autologous conditioned plasma (ACP) and the intraarticular therapy using pentosan polysulfate sodium (PPS) in horses suffering from coffin joint related diseases. These results are further compared to the convential therapy with hyaluronic acid and betamethason by drawing on a historical control group. To be included in this study, clinical forelimb lameness (to be confirmed by a positive intraarticular analgesia of the coffin joint) had to be present in a mild to moderate form. Based on these criteria, 40 horses were selected and treated at the Brockhagen Veterinary Clinic for Horses from June 2015 to February 2017. Determined by the drawing of lots, the horses were assigned to two groups of the same size. Horses from group I received an intraarticular treatment with ACP, horses from group II were treated with PPS. Concomitant treatment included the correction of hoof conformation and, as appropriate, of the horseshoe; besides, all patients underwent a controlled and standardized exercise programm. If follow-up examinations revealed persistent lameness, the patients received one or two more intraarticular treatments. Within the clinical examination, the parameters „degree of lameness “, „response to flexion test “, and „coffin joint effusion” were evaluated (period of observation: six months). The goal of treatment was defined as the healing of the patient in terms of freedom from lameness and full recovery of the original performance. Treatment success in the ACP group was achieved in 13 patients (65 %), two patients (10 %) showed an improvement in the degree of lameness, three patients (15 %) remained unchanged and two patients (10 %) relapsed. The PPS treatment yielded a positive response in 14 patients (70 %), alleviated lameness in three patients (15 %), had no effect in two patients (10 %) and resulted in a recurrent lameness in one patient (5 %). In neither of the two groups adverse reactions or negative side effects occurred. The statistical analysis of the results showed no significant difference between ACP and PPS with regard to the goal of treatment. Accordingly, both medications can be considered as equally effective. However, when looking at the follow-up examinations, a tendency towards a higher short-term efficacy for PPS with 75 % recovered horses after four weeks versus 50 % in the ACP group became apparent. After three months, the results converged to each other (PPS: 75 %, ACP: 70 %). With regard to the number of injections required to achieve freedom of lameness, a tendency towards more frequent injections in the ACP group (2.23 ± 0.725) compared to the PPS group (1.71 ± 0.611) was found. Howevere, statistically, this difference is barely not significant (p = 0,059). Likewise, a comparison of the results with the treatment success of the conventional intraarticular therapy (historical control group) did not prove significant, as well. The present study confirms previously reported positive experience with autologous platelet concentrates and PPS in regenerative joint therapy. Accordingly, these treatment options could provide a viable alternative to conventional therapies. In summary, it can be stated that PPS shows better results in the short term, with one or two injections being sufficient. In the longer term, the application of ACP achieves similar effects; however, here two or three treatments might be necessary according to the observations of this study. Future research should focus on gaining a better understanding of the effects of autologous platelet concentrates. In doing so, other products (especially besides ACP), manufactured in different ways and with different compositions, should be examined with regard to different effects in the joint. Moreover, the treatment period, the frequency of treatment, and the time of therapy should be assessed for the different medications (including ACP and PPS). Especially in the area of the distal interphalangeal joint, a more precise differentiation of the underlying pathology through advanced diagnostic methods would be required when dealing with these intraarticular treatment methods. Finally, further prospective, randomized, and placebo-controlled studies with larger numbers of patients have to be conducted to verify the results of the present study.:Abkürzungsverzeichnis I Tabellenverzeichnis IV Abbildungsverzeichnis V 1 Einleitung 1 2 Literaturübersicht 3 2.1 Anatomie des Hufgelenks 3 2.2 Physiologie des Pferdegelenks 5 2.2.1 Gelenkkapsel 5 2.2.2 Synovia 5 2.2.3 Gelenkknorpel 6 2.3 Pathophysiologie des Pferdegelenks 8 2.3.1 Traumatische Arthritis 8 2.3.2 Osteoarthritis 8 2.4 Erkrankungen im Bereich des Hufgelenks 12 2.4.1 Aseptische Podarthritis 12 2.4.2 Podarthrose 14 2.4.3 Podotrochlose-Syndrom 14 2.4.3.1 Podotrochlose im engeren Sinne 15 2.4.3.2 Insertionsdesmopathien 15 2.4.3.3 Strahlbeinerkrankung mit Hufgelenkbeteiligung 16 2.4.4 Hufbeinfraktur 16 2.4.5 Strahlbeinfraktur 17 2.4.6 Subchondrale zystoide Defekte 17 2.4.7 Erkrankungen im Bereich des Processus Extensorius 18 2.5 Lahmheitsdiagnostik der distalen Zehe 19 2.5.1 Klinische Lahmheitsdiagnostik 19 2.5.2 Diagnostische Anästhesien 23 2.5.2.1 Leitungsanästhesien 24 2.5.2.2 Intrasynoviale Anästhesien 25 2.5.3 Direkte Druckmessung im Hufgelenk 27 2.5.4 Synoviaanalyse 27 2.5.5 Röntgenologische Untersuchung 28 2.5.5.1 Röntgenleitfaden 28 2.5.5.2 Röntgenbefunde im Hufgelenkbereich 29 2.5.5.3 Röntgenbefunde am Strahlbein 30 2.5.6 Weiterführende bildgebende Diagnostik 32 2.5.6.1 Endoskopie 32 2.5.6.2 Sonographie 32 2.5.6.3 Szintigraphie 32 2.5.6.4 Computertomographie 33 2.5.6.5 Magnetresonanztomographie 33 2.6 Therapie 34 2.6.1 Begleitende konservative Maßnahmen 34 2.6.1.1 Hufkorrektur und Beschlag 34 2.6.1.2 Bewegungsprogramm 34 2.6.2 Medikamentöse Therapie 34 2.6.2.1 NSAIDs 34 2.6.2.2 Intraartikuläre Corticosteroide 35 2.6.2.3 Hyaluronsäure (HA) 36 2.6.2.4 Kombinierte Anwendung HA/Corticosteroid 37 2.6.2.5 Polysulfatierte Glykosaminoglykane (PSGAG) 37 2.6.2.6 Pentosanpolysulfat (PPS) 38 2.6.2.7 Autologous Conditioned Plasma® (ACP) 41 2.6.2.8 Autologes Conditioniertes Serum (ACS) 44 2.6.2.9 Multipotente mesenchymale Stromazellen (MSC) 45 2.6.2.10 Polyacrylamid Hydrogel (PAAHG) 47 3 Material und Methoden 48 3.1 Therapieziel 48 3.2 Wissenschaftliche Fragestellung 48 3.3 Studienumfang 48 3.4 Untersuchungsmethodik 51 3.4.1 Einschlusskriterien 51 3.4.2 Anamnese 51 3.4.3 Klinische Untersuchung und Beurteilungskriterien 51 3.4.4 Diagnostische Anästhesien 52 3.4.5 Röntgenologische Untersuchung 53 3.4.6 Therapieplan 53 3.4.7 Nachuntersuchungen 54 3.4.8 Beurteilung des Therapieerfolges 54 3.5 Statistische Methodik 55 4 Ergebnisse 57 4.1 Vergleichbarkeit der Gruppen 57 4.1.1 Geschlechterverteilung 57 4.1.2 Altersverteilung 57 4.1.3 Rassenverteilung 58 4.1.4 Größenverteilung 58 4.1.5 Einsatzschwerpunkt und Beanspruchung 59 4.1.6 Vorerkrankungen 59 4.1.7 Vorbehandlungen 60 4.1.8 Dauer der bestehenden Lahmheit 60 4.1.9 Beginn und Verlauf der bestehenden Lahmheit 62 4.2 Befunde der Erstuntersuchung 62 4.2.1 Betroffene Gliedmaße 62 4.2.2 Art der Lahmheit 63 4.2.3 Ergebnisse der Leitungsanästhesien 63 4.2.4 Verteilung der Röntgenklassen 64 4.2.5 Lahmheitsgrad zum Zeitpunkt t0 64 4.2.6 Gelenkfüllung zum Zeitpunkt t0 65 4.2.7 Zehenbeugeprobe zum Zeitpunkt t0 65 4.2.8 Overall Clinical Severitiy Score (CSS) zum Zeitpunkt t0 65 4.3 Ergebnisse der Nachuntersuchungen 66 4.3.1 Erste Nachuntersuchung nach 14-21 Tagen (t1) 66 4.3.1.1 Lahmheitsgrad zum Zeitpunkt t1 66 4.3.1.2 CSS zum Zeitpunkt t1 68 4.3.2 Zweite Nachuntersuchung nach 21-28 Tagen (t2) 69 4.3.2.1 Lahmheitsgrad zum Zeitpunkt t2 69 4.3.2.2 CSS zum Zeitpunkt t2 70 4.3.3 Dritte Nachuntersuchung nach 3 Monaten (t3) 71 4.3.3.1 Lahmheitsgrad zum Zeitpunkt t3 71 4.3.3.2 CSS zum Zeitpunkt t3 72 4.3.4 Vierte Nachuntersuchung nach 6 Monaten (t4) 73 4.3.4.1 Lahmheitsgrad zum Zeitpunkt t4 73 4.3.4.2 CSS zum Zeitpunkt t4 75 4.4 Gesamtergebnis 77 4.4.1 Gesamtergebnis in Abhängigkeit von der Therapiemethode 77 4.4.2 Therapieergebnis in Abhängigkeit vom Erkrankungsstadium 78 4.4.3 Anzahl der benötigten Injektionen 79 4.5 Retrospektiver Vergleich mit konventioneller Therapie 79 4.6 Beurteilung der Gruppengrößen zum Abschluss der Studie 81 5 Diskussion 82 5.1 Studienumfang 82 5.2 Vergleichbarkeit der Gruppen 82 5.3 Untersuchungsmethodik 84 5.4 Nachuntersuchungen 86 5.5 Beurteilungskriterien 87 5.6 Therapieergebnisse 87 5.7 Retrospektiver Vergleich mit konventioneller Therapie 91 5.8 Schlussfolgerungen 91 5.9 Ausblick 93 6 Zusammenfassung 94 7 Summary 96 8 Literaturverzeichnis 98 9 Anhang 142 10 Danksagung 145

Durch die Einführung der MRT-Untersuchung am stehenden sedierten Pferd ist deren Anzahl deutlich angestiegen. Hierbei stellen sich neue Fragen und Herausforderungen bezüglich der Einschätzung der Vielzahl an auftretenden Signalveränderungen. Es ergeben sich aber auch neue Möglichkeiten bezüglich der statistischen Auswertung von Befunden mit aussagekräftigen Fallzahlen. In dieser Studie sollte daher untersucht werden, wie Signalveränderungen statistisch verwendbar beschrieben und eingestuft werden können. Weiterhin sollte die Verteilung der Befunde insgesamt und bei der bilateralen Untersuchung der Vordergliedmaßen bestimmt werden. Mögliche Rückschlüsse auf deren klinische Bedeutung sollten gezogen werden. Hierzu wurden 120 bilaterale Niederfeld-MRT-Untersuchungen der Hufregion (240 Gliedmaßen) am stehenden Pferd durch zwei Tierärzte gesichtet und eine Befundbeschreibung mit einem Einstufungsschema (Grade 1-4) entsprechend dem vorgefundenen Spektrum an Signalveränderungen erstellt. Durch Anwendung und Zusammenfassung 66 wiederholte Diskussion der verschiedenen Kriterien im 1. Bewertungsdurchgang wurden die Beschreibungen und Grade auf Grundlage bestehender Literatur ausgearbeitet. In einem 2. Bewertungsdurchgang wurden die Strukturen eingestuft und die Ergebnisse statistisch ausgewertet. Hierbei wurden die generellen Häufigkeiten der Signalabweichungen erfasst und deren Zusammenhang zum Auftreten von unilateralen oder bilateralen Lahmheiten beachtet. Signalabweichungen am Strahlbein, der Tiefen Beugesehne und dem Hufgelenk standen deutlich im Vordergrund. Hierbei waren Strahlbeinveränderungen signifikant häufiger bei beidseitig lahmen Pferden zu finden, während Sehnenveränderungen deutlich häufiger bei einseitig lahmen Pferden vorgefunden wurden. Hufgelenkveränderungen wurden hingegen nicht signifikant vermehrt bei bilateralen oder unilateralen Lahmheiten festgestellt. Die Fesselbein-Strahlbein-Hufbeinbänder zeigten eine Häufung von Signalabweichungen bei lahmen Gliedmaßen, wobei diese vermehrt in Zusammenhang mit starken Veränderungen des Strahlbeins zu beobachten waren. Bei den übrigen Strukturen ließ sich kein statistisch aussagekräftiger Zusammenhang feststellen, da die Fallzahlen mit dem deutlichsten Befund an diesen Strukturen zu gering für eine Auswertung waren. Die entstandene Befundbeschreibung mit Einstufungsschema ermöglicht Vergleiche der MRT-Veränderungen z.B. mit klinischen Parametern. Signalabweichungen bestimmter Strukturen konnten statistisch eindeutig mit dem Auftreten und der Art der Lahmheit in Verbindung gebracht werden, während dies bei anderen Strukturen nicht möglich war. Hieraus ergeben sich Hinweise für die Einschätzung der Befunde und ihrer klinischen Relevanz. Insbesondere geringgradige Befunde sollten vorsichtig bewertet werden, da diese auch häufig bei nicht lahmen Gliedmaßen auftraten. Weitere statistische Vergleiche mit klinischen Parametern sind möglich und notwendig um das Krankheitsbild des „Equinen palmaren Fußsyndroms“ weiter zu untersuchen. / As a result of adopting MRI examinations for standing sedated horses their number has increased significantly. In this respect there are new questions and challenges being faced regarding estimating the huge number of occurring signal changes. New possibilities also arise regarding the statistical analysis of findings with convincing number of examined cases. In this study therefore it should be investigated how signal changes can be suitably described and classified statistically. Furthermore, the distribution of the findings as a whole and in the bilateral investigations of the forelimbs should be ascertained. Possible conclusions should be drawn regarding their clinical significance. Concerning this, 120 bilateral low-field-MRI examinations of the foot (240 limbs) on a standing horse were looked at by two veterinarians and a description of the analysis with a classification scheme (grades 1-4) corresponding to the existing spectrum of signal changes was compiled. By applying and repeatedly discussing the various Summary 68 criteria in the first evaluation round the descriptions and grades were worked out on the basis of existing literature. In a second evaluation round the structures were classified and the results statistically evaluated. In this regard the general frequency of signal deviations was recorded and its connection to the occurrence of unilateral or bilateral lameness was observed. Signal deviations at the navicular bone, deep digital flexor tendon and the coffin joint noticeably prevailed. In this respect changes to the navicular bone were found significantly more frequently in bilaterally lame horses while changes in tendons were found significantly more often in unilaterally lame horses. In contrast, changes in the coffin joint were not significantly more in bilateral or unilateral lameness. The collateral sesamoidean ligaments showed an accumulation of signal deviations at lame limbs, whereby this was observed more frequently in connection with pronounced changes of the navicular bone. In the remaining structures no statistically significant connection was found as the number of examined cases with the most significant results at these structures was too low for an evaluation. The related description of the findings with a classification scheme enables comparisons of MRI changes e.g. with clinical parameters. Signal deviations of certain structures were found to be clearly statistically associated with the occurrence and type of lameness, while this was not possible at other structures. This provides useful information for evaluating findings and their clinical relevance. Low-grade findings should be interpreted with caution since these also occurred frequently at non-lame limbs Further statistical comparisons with clinical parameters are possible and necessary in order to further examine the clinical picture of the equine palmar foot syndrome.

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