Dissertations / Theses on the topic 'Biomechanics of the proximal tibia'

In this study, trabecular architecture is considered as a cellular solid structure, including both intact and damaged bone models. ??Intact?? bone models were constructed based on ideal versions of 25, 60 and 80-year-old specimens with varying trabecular lengths and orientations to 5%, and 10% covariance of variation (COV). The models were also flipped between longer transverse and longer longitudinal trabeculae. With increasing COV of lengths and orientations of trabecular bone, the apparent modulus is linearly decreased, especially in the longer transverse trabeculae lengths. ??Damaged?? bone models were built from the 25 year old model at 5% COV of longer transverse trabeculae, and with removing trabeculae of 5% and 10% of trabecular volume in transverse and longitudinal directions, respectively, as well as in combination to total 10% and 15%. With increasing percent of trabeculae missing, the apparent modulus decreased, especially dramatically when removal was only in the transverse direction. The trabecular bone models were also connected to a cortical shell and it was found that the apparent modulus of an entire slice was increased in comparison to the modulus of trabecular bone alone. We concluded that the architecture of trabecular bone, especially both lengths and percent of trabecular missing in the longitudinal direction, significantly influences mechanical properties.

Orientador: João Batista de Miranda<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas<br>Made available in DSpace on 2018-08-15T13:23:10Z (GMT). No. of bitstreams: 1 Zorzi_AlessandroRozim_M.pdf: 2318090 bytes, checksum: 67428e73d40fe1ff0a25f4c17e78e4f8 (MD5) Previous issue date: 2010<br>Resumo: Introdução: A técnica de abertura de cunha medial apresenta vantagens em relação às outras de osteotomia valgizante da tíbia, o que a tem tornado muito popular. Sua desvantagem é a criação de uma falha óssea na tíbia proximal, o que poderia possibilitar perda de correção ou retardo de consolidação. O uso de enxerto ósseo autólogo da crista ilíaca tem sido preconizado para diminuir o risco destas complicações. Entretanto, nenhum estudo clínico comparou a evolução clínica entre pacientes com e sem o uso do enxerto ósseo. Hipótese: Não há necessidade de enxerto ósseo na osteotomia de abertura medial, fixada com placa-calço igual ou menor que 12,5 mm. Desenho do estudo: Estudo clínico controlado, duplo-cego, randomizado. Métodos: Foram realizadas 46 osteotomias entre Abril de 2007 e Novembro de 2008. As osteotomias foram divididas aleatoriamente por um programa de computador em dois grupos de 23 joelhos cada. No grupo A, foi usado enxerto autólogo da crista ilíaca para preencher o espaço. No grupo B, o espaço foi deixado sem preenchimento. O enxerto foi coletado nos dois grupos, para garantir o mascaramento tanto dos pacientes quanto dos avaliadores. Avaliações clínicas foram realizadas a cada duas semanas até que sinais clínicos de consolidação estivessem presentes. Resultados: As varáveis demográficas foram similares nos dois grupos. A média de tempo para consolidação no grupo A foi de 12,4 semanas (IC 11,2 - 13,6), e no grupo B foi de 13,7 semanas (IC 12,5-14,9), sem diferença estatística (p=0,130). Perda de correção ocorreu em um paciente no grupo A (4,35%) e em dois pacientes no grupo B (8,7%). Conclusão: Nesta amostra, o tempo de consolidação das osteotomias foi similar nos grupos com e sem enxerto ósseo<br>Abstract: Background: Medial opening-wedge has gained popularity among other techniques of high tibial osteotomy with many advantages. The disadvantage of this method is the creation of a gap, with the possibility of collapse or delayed bone healing, and the need to harvest iliac crest bone graft. The filling of the gap is recommended, but no reports have compared grafted and ungrafted osteotomies. Hypothesis: There is no need for graft to achieve bone union in medial opening-wedge high tibial osteotomy when 12,5 mm or less spacer plate is used. Study design: Double-blinded randomized controlled clinical trial. Methods: Forty-six opening-wedge high tibial osteotomies were carried out. They were randomly divided by software in two groups of 23 knees: group A filled with autologous bone graft and group B unfilled. Bone graft was taken in all cases to ensure blindness of patients and investigators. Clinical evaluations were performed each two weeks until signs of bone union were achieved. Results: Demographic variables were similar in both groups. Mean time to bone union in group A was 12.4 weeks (CI 11.2-13.6) and in group B was 13.7 weeks (CI 12.5-14.9), without significant difference (p=0.130). Signals of loosening of screws occurred in one patient (4,35%) in group A, against two patients (8,7%) in group B. Conclusion: In this series both groups achieved bone union in similar times<br>Mestrado<br>Cirurgia<br>Mestre em Cirurgia

Introduction: Une procédure fréquente pour la prévention de l’arthrose de la cheville est une ostéotomie corrective du tibia distal (SMOT). Le Distal Tibia Nail (DTN ; Mizuho®), a été développé pour la réduction des fractures du tibia distal. L’objectif de ce projet était d’analyser la faisabilité du DTN pour des procédures SMOT effectuées avec une ouverture médiale (MWO). Méthodes : Au total 16 Sawbones® ont été instrumentés par un DTN ou une plaque (MDTP, Synthes®), suivi par la simulation d’une MWO. Quatre phases d’expérimentation étaient définies : Phase-0, Sawbones sans implant ni MWO ; Phase-1, échantillons avec un implant et MWO. Phase-2, les échantillons de la Phase-1 avec le cortex latéral fracturé ; Phase-3, simulation d’une fracture de type A3. La raideur et le mouvement inter-fragmentaire (IFM) étaient analysés. Des tomographies des échantillons ont été prises à Phases 0 et 1. Résultats : Jusqu’à 80% de différence était présente enter les Sawbones® de Phase-0 ; dans les Phases 1 et 2, des différences importantes se sont montrées entre des implants mais équivalent à &lt;2 mm d’IFM. Le DTN a démontré une résistance très élevée aux charges appliquées en comparaison avec le MDTP pour la fixation des fractures A3. Des facteurs expérimentaux tels que la raideur initiale des Sawbones®, l’axe de chargement, et le positionnement de l’échantillon dans la machine d’essai, peuvent tous avoir une influence importante sur la raideur mesurée. Conclusion : Le DTN peut être considéré comme option pour la fixation des SMOT effectués avec un MWO. Des études futures doivent faire attention aux conditions limites ayant un effet sur des critères d’évaluation et des conclusions tirées<br>Introduction: Supra-malleolar corrective osteotomies (SMOT) are a common surgical procedure for the prevention of early onset of ankle arthritis. The Distal Tibia Nail (DTN; Mizuho®), was previously developed for the reduction of distal tibia fractures. The aim of this project was to identify error sources in biomechanical testing, and to test the feasibility of the DTN for SMOT performed using the medial wedge opening (MWO) technique. Methods: A total of 16 Sawbones® were each implanted with either a DTN or medial distal tibia plate (MDTP; Synthes®), and a MWO simulated. Four testing phases were defined: Phase-0, testing of Sawbones® without implant/osteotomy; Phase-1, samples with MWO and implant; Phase-2, Phase-1 samples with lateral cortex fractured; Phase-3, samples with an A3 type fracture. Stiffness construct and interfragmentary movement (IFM) were analysed. CT scans were taken of the samples at Phases 0 and 1. Results: Up to 80% difference was noticed between Sawbones® samples in Phase-0; in Phases 1 and 2 significant differences were found between stiffness constructs of the implant groups but this amounted to &lt;2 mm IFM. The DTN was significantly more resistant to compression and torsion when supporting an A3 fractures (Phase-3). Elements such as original Sawbones® stiffness construct, implant position, potting material, loading axis, and sample positioning can have a high influence on measured stiffness and bias the results. Conclusion: The DTN is a viable option for the fixation of SMOT performed with a MWO technique. Future studies should pay careful attention to boundary conditions affecting outcomes measures and drawn conclusions

Osteoporosis is a metabolic bone disease that needs to be properly diagnosed. The current diagnosing procedure of osteoporosis is based on the mineral density of bones measured by common methods such as dual energy X-ray absorptiometry (DXA). However, due to the deficiencies and limitations of these common methods, investigations on the utilization of other non-invasive diagnosing methods have been executed. For instance, using vibration measurements seems to be a promising technique in diagnosing metabolic bone diseases such as osteoporosis and also in monitoring fracture healing. Throughout this study, bone structural modal parameters obtained from vibrations experiments with decreasing mineral density are examined and therefore, it is aimed to find a new approach to detect osteoporosis or progressing osteoporosis by investigating a relation between structural dynamic properties and mineral density of bone. The main advantage of this study is that loss factor, which is an inherit property of bone, is investigated since in the previous studies mainly the changes in natural frequency of bones with the state of osteoporosis is examined. In this thesis, both in vitro and in vivo experiments are carried out on human tibia specimens. The measured frequency response functions (FRFs) are analyzed using modal identification techniques to extract the modal parameters of the human tibia. The results obtained from in vitro experiments show that loss factor may be a powerful tool in diagnosing osteoporosis, however due to the difficulties encountered in the case of in vivo experiments makes the use of this parameter as a diagnosing tool difficult. It is also seen from in vivo experiments that there is a weak correlation between the natural frequencies of tibia and BMD measurements of patients. Therefore, in order to investigate the parameters affecting the natural frequencies of tibia, finite element (FE) model of human tibial bone is constructed. Using this FE model tibia, the effect of boundary conditions of experiments and geometry of the bone on natural frequencies of bone is examined. These analyses show that the effect of both boundary conditions and geometry of tibia is very high. Therefore, it is concluded that if the necessary conditions are satisfied, the using natural frequency information of tibia seems to be a possible and practical method that can be used to detect progressing osteoporosis. Also, using the FE model of tibia, the changes of natural frequencies of tibia with the variation in elastic modulus are investigated.

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No. of bitstreams: 1 sembenelli_g_me_jabo.pdf: 2565740 bytes, checksum: d9b68e8304088478cada8ab56efa1c00 (MD5) Previous issue date: 2017-05-30<br>Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)<br>O objetivo do presente estudo foi desenvolver placa de TPLO bloqueada modificada e avaliar a eficácia da estabilização óssea proporcionada pelo implante desenvolvido comparativamente a outros dois métodos convencionais de fixação óssea (placa bloqueada e placa bloqueada associada a pino intramedular). Por meio de estudos biomecânicos, avaliaram-se as construções às forças de torção, flexão craniocaudal, flexão mediolateral e compressão axial. Foram utilizadas sessenta tíbias sintéticas dividas em três grupos. O Grupo 1 (placa TPLO modificada), o Grupo 2 (placa bloqueada) e o Grupo 3 (placa bloqueada associada a pino intramedular) foram qsubdivididos em quatro grupos de cinco tíbias. Os ensaios foram realizados até a falha da montagem (implantes e/ou tíbia) e os resultados obtidos comparados entre os grupos. As variáveis estudadas foram analisadas sob delineamento inteiramente casualizado no esquema fatorial 3 por 4 com 5 repetições para cada combinação do esquema fatorial. Os resultados foram submetidos à análise de variância e as médias comparadas entre si pelo teste de Tukey a 5% de probabilidade. No ensaio de compressão axial houve diferença significativa em relação a variável força máxima em que o Grupo 3 obteve maior média, não havendo diferença significativa entre os Grupos 1 e 2. Todas as montagens falharam devido à flexão da placa na região de falha no corpo de prova. No ensaio de flexão em três pontos craniocaudal houve diferença significativa em relação às três variáveis estudas. Na variável força máxima G2>G3=G1, na variável deflexão G3>G1=G2 e na variável rigidez G3=G2, G2=G1 G3>G1. Todas as montagens falharam devido à quebra do corpo de prova. No ensaio de flexão mediolateral houve diferença significativa em relação a variável rigidez em que G3>G2=G1. Todas as montagens falharam devido à flexão da placa na região de falha no corpo de prova. No ensaio de torção houve diferença significativa em relação às variáveis ângulo no pico de torque e rigidez. Na variável ângulo no pico de torque G2>G1=G3. Na variável rigidez G1=G3>G2. Todas as montagens falharam devido à quebra do corpo de prova distal a placa. Conclui-se a placa de TPLO modificada apresentou semelhança biomecânica com a placa reta convencional na maioria das variáveis estudadas. O grupo, da associação placa e pino, obtive maiores índices de rigidez comparativamente aos outros dois grupos, exceto no teste de torção em que o grupo da placa de TPLO modificada apresentou o mesmo índice de rigidez que o da associação placa e pino.<br>The aim of this study was to develop modified TPLO locked plate and to evaluate the effectiveness of stabilization provided by the implant developed compared to two other conventional methods of stabilization (locked plate and plate-rod). Through biomechanical studies the constructions were evaluated to craniocaudal and mediolateral bending, axial compression and torsional forces. Sixty synthetic tibias were used divided into three groups. Group 1 (modified TPLO plate), Group 2 (locked plate) and Group 3 (plate-rod) were subdivided into four groups of five tibiae. The tests were perfomed until failure of the construction (implants / tibia) and the results compared between the groups. The variables studied were analyzed under a completely randomized design in the factorial scheme 3 by 4 with 5 replicates for each combination of the factorial scheme. The results were submitted to analysis of variance and the means compared to each other by the Tukey test at 5% probability. In the axial compression test there was a significant difference in relation to the variable maximum force in which Group 3 obtained higher mean, not having significant difference between Groups 1 and 2. All constructions failed due to plate bending in the gap region of the synthetic tibia. In the three-point craniocaudal flexion test there was a significant difference in relation to the three variables studied. In the variable force maximum G2> G3 = G1, in the variable deflection G3> G1 = G2 and in the variable stiffness G3 = G2, G2 = G1 G3> G1. All constructions failed because of the breaking of the synthetic tibia. In the three-point craniocaudal flexion test there was a significant difference in relation to the three variables studied. In the variable force maximum G2> G3 = G1, in the variable deflection G3> G1 = G2 and in the variable stiffness G3 = G2, G2 = G1 G3> G1. All constructions failed because of the breaking of the synthetic tibia. In the mediolateral flexion test there was a significant difference in relation to the stiffness variable in which G3> G2 = G1. All constructions failed due to plate bending in the gap region of the synthetic tibia. In the torsion test there was a significant difference in relation to the variables angle at peak torque and stiffness. In the variable angle at the torque peak G2> G1 = G3. In the stiffness variable G1 = G3> G2. All constructs failed due to the breaking of the synthetic tibia distally to the plate. It is concluded that the modified TPLO plate presented biomechanical similarity with the conventional plate in most of the studied variables. The groups of locking plate an plate-rod constructions obtained higher stiffness indices compared to the other two groups, except for the torsion test in which the modified TPLO plate group had the same stiffness index as the plate and plate-rod.<br>FAPESP: 2015/14602-8

This thesis explores form variation in the knee joint of thirteen geographically and economically distinct populations of modern Homo Sapiens from different ancestral backgrounds. Shape differences are interpreted within the context of the size of the knee joint and against size differences in the femur and tibia. Three dimensional coordinate data are taken from the distal femur and proximal tibia and statistical shape analysis is conducted using geometric morphometric techniques. Results from initial intra-population analyses using a restricted number of samples determine the data that are submitted for inter-population analyses using the full dataset. Three series of intra-population analyses test for asymmetry, sexual dimorphism and age. Significant shape asymmetry exists in all samples examined. Results therefore preclude the use of both right- and left- sided specimens within any single sample in subsequent analyses. Results indicate the existence of a significant degree of sexual dimorphism in all samples, but that the nature and degree of variation is population specific. For both sexual dimorphism and shape variation with ageing, differences are of lesser significance relative to inter-population variation. Using the full dataset, results indicate the existence of size and (particularly) shape differences between samples at a high level of statistical significance. Morphological variation between populations arises from a number of influential factors, including climate and more specifically, cold temperature. The powerful influence of additional factors, including working practices, disease and nutrition is examined in greater depth in relation to the Spitalfields sample from London, which shows a distinctive pattern of form variation relative to the other population samples.

Stage IV cancer is characterized by a cancer’s ability to metastasize, or spread throughout the body. Metastatic disease in bone is a devastating condition affecting hundreds of thousands of people each year. Stage IV cancer patients suffering from metastatic disease in the proximal femur are at high risk of catastrophic pathologic fracture, an event which severely impacts patient health. Although metrics have been created to assess the risk of impending fracture, they lack specificity in the proximal femoral region. Shortcomings of these metrics further complicate clinical decision making related to prophylactic fixation in these medically compromised individuals. Fortunately, by using computational modeling to study this at-risk patient population, the likelihood of fracture due to metastatic lesions in the proximal femur can be more accurately assessed to improve clinical decision making. Finite element analysis (FEA) is a computational modeling technique that can non-invasively provide mechanics information to better assess true fracture risk of a given metastatic lesion. Although FEA has previously been utilized to study metastatic disease, lesions were always modeled as spheres or ellipsoids, while true lesion shapes are far more amorphous. It was the focus of this study to validate FEA’s ability to predict fracture location in cadaveric femora with realistically shaped experimental metastatic lesions. Off-set torsion, or load applied off-set from the fixed long bone axis, was applied to cadaveric specimens with mechanically induced metastatic lesions, and the resultant fracture location was compared to specimen-specific FEA models replicating the mechanical test. FEA was able to correctly predict fracture locations in five models. Determining fracture risk based on objective mechanical data may more accurate and effective in this patient population.

Introduction: The forearm is a complex biological unit, which has allowed man's evolution. This PhD commenced with an analysis of the normal biomechanical functioning of the key components of the forearm: notably the distal radioulnar joint (DRUJ), interosseous ligament (IOL) and proximal radioulnar joint (PRUJ). Understanding normal forearm physiology, a clinical study followed to delineate the pathophysiology of a new clinical entity, related to DRUJ dysfunction. Methods: Biomechanical Study: A biomechanical testing jig was developed to facilitate collection of data about normal functioning of the DRUJ, IOL and PRUJ in both unloaded and loaded states. This permitted testing throughout the range of forearm pronosupination. Thawed fresh frozen cadaveric upperlimbs were mounted into the jig. Using Microstrain® strain gauges and Tekscan™ pressure sensors, the functional anatomy of the key components of the forearm was delineated, both with the forearm flexed at 90° and maximally extended at the elbow. Clinical Study: A series of 3-Tesla MRI scans was undertaken on patients symptomatic of an intermittent ulnar neuropathy. The causative pathophysiology was determined using 3D qualitative and quantitative analyses. Results: Biomechanical Study: Reproducible patterns of force transmitted and joint contact area have been determined for the DRUJ, and for the first time, the PRUJ. With the exception of PMax and P60 for the PRUJ, application of load increases contact areas and transmitted forces across the joints (P<0.05). The converse is true for PMax and P60 in the PRUJ. The IOL is lax during pronation, strain gradually increasing as the arm moves to neutral. In neutral the middle-portion of the IOL (m-IOL) demonstrates most strain, this decreasing again in supination, whilst the distal and proximal portions (d- & p-IOL) exhibit more strain (P<0.05). Axial loading consistently increases strain in all ligaments (P<0.05). Observed behaviour patterns across the joints and in the ligaments alter with elbow extension (P<0.05). Clinical Study: Salient symptoms of the new syndrome were described. Displacement of the ulnar nerve from its normal course was seen with compression/distraction in the distal forearm and Guyon’s canal. This was considered causative of the syndrome. As a by-product of the research, a new clinical device was also developed, which improves the patient pathway when investigating DRUJ dysfunction. Conclusions and Outcomes: This research has analysed normal forearm biomechanics determining that the PRUJ is a load-bearing joint, interrelated with the DRUJ and IOL. Elbow extension has been shown to alter the normal biomechanics of the forearm. A clinical entity of a dysfunctional forearm has been defined, called subluxation-related ulnar neuropathy or SUN syndrome. Finally, a new clinical device has been developed, which it is anticipated will translate into visible improvements in patient care.

Introdução: A busca por um substituto ósseo que faça prescindível a obtenção de enxerto autólogo é uma necessidade do cirurgião ortopédico. O aspirado de medular óssea possui células tronco do sistema mesenquimal capazes de se diferenciarem em osteoblastos, sendo assim considerado um material osteogênico. O plasma rico em plaquetas possui os chamados fatores plaquetários de crescimento, que possuem a capacidade de promover e estimular a diferenciação de células tronco do sistema mesenquimal em osteoblastos, acelerando o processo de consolidação óssea. Objetivo: O objetivo deste estudo foi avaliar a ocorrência de consolidação e o tempo para tal nas osteotomias de cunha de abertura na tíbia, comparando o enxerto autólogo de ilíaco, ao plasma rico em plaquetas associado a medular óssea. Métodos: Foram estudados 25 pacientes submetidos a osteotomia tibial de cunha de abertura medial. Os pacientes foram divididos em dois grupos, de forma randomizada. O grupo controle formado por 14 pacientes submetidos à osteotomia com a utilização de enxerto autólogo do ilíaco, e o grupo de estudo formado por 11 pacientes submetidos à osteotomia com utilização de um composto de plasma rico em plaquetas e medular óssea. Resultados: Quanto à ocorrência de consolidação da osteotomia, as Introdução: A busca por um substituto ósseo que faça prescindível a obtenção de enxerto autólogo é uma necessidade do cirurgião ortopédico. O aspirado de medular óssea possui células tronco do sistema mesenquimal capazes de se diferenciarem em osteoblastos, sendo assim considerado um material osteogênico. O plasma rico em plaquetas possui os chamados fatores plaquetários de crescimento, que possuem a capacidade de promover e estimular a diferenciação de células tronco do sistema mesenquimal em osteoblastos, acelerando o processo de consolidação óssea. Objetivo: O objetivo deste estudo foi avaliar a ocorrência de consolidação e o tempo para tal nas osteotomias de cunha de abertura na tíbia, comparando o enxerto autólogo de ilíaco, ao plasma rico em plaquetas associado a medular óssea. Métodos: Foram estudados 25 pacientes submetidos a osteotomia tibial de cunha de abertura medial. Os pacientes foram divididos em dois grupos, de forma randomizada. O grupo controle formado por 14 pacientes submetidos à osteotomia com a utilização de enxerto autólogo do ilíaco, e o grupo de estudo formado por 11 pacientes submetidos à osteotomia com utilização de um composto de plasma rico em plaquetas e medular óssea. Resultados: Quanto à ocorrência de consolidação da osteotomia, asIntrodução: A busca por um substituto ósseo que faça prescindível a obtenção de enxerto autólogo é uma necessidade do cirurgião ortopédico. O aspirado de medular óssea possui células tronco do sistema mesenquimal capazes de se diferenciarem em osteoblastos, sendo assim considerado um material osteogênico. O plasma rico em plaquetas possui os chamados fatores plaquetários de crescimento, que possuem a capacidade de promover e estimular a diferenciação de células tronco do sistema mesenquimal em osteoblastos, acelerando o processo de consolidação óssea. Objetivo: O objetivo deste estudo foi avaliar a ocorrência de consolidação e o tempo para tal nas osteotomias de cunha de abertura na tíbia, comparando o enxerto autólogo de ilíaco, ao plasma rico em plaquetas associado a medular óssea. Métodos: Foram estudados 25 pacientes submetidos a osteotomia tibial de cunha de abertura medial. Os pacientes foram divididos em dois grupos, de forma randomizada. O grupo controle formado por 14 pacientes submetidos à osteotomia com a utilização de enxerto autólogo do ilíaco, e o grupo de estudo formado por 11 pacientes submetidos à osteotomia com utilização de um composto de plasma rico em plaquetas e medular óssea. Resultados: Quanto à ocorrência de consolidação da osteotomia, as Introdução: A busca por um substituto ósseo que faça prescindível a obtenção de enxerto autólogo é uma necessidade do cirurgião ortopédico. O aspirado de medular óssea possui células tronco do sistema mesenquimal capazes de se diferenciarem em osteoblastos, sendo assim considerado um material osteogênico. O plasma rico em plaquetas possui os chamados fatores plaquetários de crescimento, que possuem a capacidade de promover e estimular a diferenciação de células tronco do sistema mesenquimal em osteoblastos, acelerando o processo de consolidação óssea. Objetivo: O objetivo deste estudo foi avaliar a ocorrência de consolidação e o tempo para tal nas osteotomias de cunha de abertura na tíbia, comparando o enxerto autólogo de ilíaco, ao plasma rico em plaquetas associado a medular óssea. Métodos: Foram estudados 25 pacientes submetidos a osteotomia tibial de cunha de abertura medial. Os pacientes foram divididos em dois grupos, de forma randomizada. O grupo controle formado por 14 pacientes submetidos à osteotomia com a utilização de enxerto autólogo do ilíaco, e o grupo de estudo formado por 11 pacientes submetidos à osteotomia com utilização de um composto de plasma rico em plaquetas e medular óssea. Resultados: Quanto à ocorrência de consolidação da osteotomia, as Introdução: A busca por um substituto ósseo que faça prescindível a obtenção de enxerto autólogo é uma necessidade do cirurgião ortopédico. O aspirado de medular óssea possui células tronco do sistema mesenquimal capazes de se diferenciarem em osteoblastos, sendo assim considerado um material osteogênico. O plasma rico em plaquetas possui os chamados fatores plaquetários de crescimento, que possuem a capacidade de promover e estimular a diferenciação de células tronco do sistema mesenquimal em osteoblastos, acelerando o processo de consolidação óssea. Objetivo: O objetivo deste estudo foi avaliar a ocorrência de consolidação e o tempo para tal nas osteotomias de cunha de abertura na tíbia, comparando o enxerto autólogo de ilíaco, ao plasma rico em plaquetas associado a medular óssea. Métodos: Foram estudados 25 pacientes submetidos a osteotomia tibial de cunha de abertura medial. Os pacientes foram divididos em dois grupos, de forma randomizada. O grupo controle formado por 14 pacientes submetidos à osteotomia com a utilização de enxerto autólogo do ilíaco, e o grupo de estudo formado por 11 pacientes submetidos à osteotomia com utilização de um composto de plasma rico em plaquetas e medular óssea. Resultados: Quanto à ocorrência de consolidação da osteotomia, as porcentagens de consolidação foram de 100% no grupo Ilíaco e 91% no grupo PRP (p=0,440). Em relação ao tempo para consolidação não se observou diferença entre os grupos (p=0,129). Conclusão: Nas osteotomias proximais por cunha de adição medial a utilização do plasma rico em plaquetas associado ao aspirado de medular óssea foi efetiva no que se refere à ocorrência de consolidação e no tempo necessário para a ocorrência de tal evento, quando estudamos e comparamos este enxerto ao enxerto autólogo do ilíaco<br>Introduction: The search for a bone substitute that makes unnecessary the harvest of autologous bone graft is a necessity of the orthopaedic surgeon. Bone marrow aspirate is rich in mesenquimal stem cells. The bone marrow aspirate contain mesenquimal stem cells that can differenciate in osteoblasts, being considered an osteogenic material. Platelet rich plasma contain several growth factors that have the capacity to promote and stimulate the differenciation of mesenquimal stem cells in osteoblasts improving the bone healing process, in other words platelet rich plasma has osteoinductive property. Objective: The aim of this study was to compare the occurrence of consolidation and the time taken to achieve this in cases of opening wedge osteotomy of the tibia, between autologous iliac grafts and platelet rich plasma with bone marrow aspirate. Methods: Twenty-five patients who underwent opening wedge osteotomy were studied. They were randomly divided into two groups: a control group of 14 patients wich received autologous iliac grafts and a study group of 11 patients wich received a compound of platelet rich plasma and bone marrow aspirate. Results: The consolidation rates achieved were 100% in the iliac group and 91% in the platelet-rich plasma group (p = 0.440). There was no difference in the time taken to achieve consolidation between the groups (p = 0.129). Conclusion: The use of platelet rich plasma with bone marrow aspirate as a bone substitute was shown to be effective in achieving consolidation in tibial osteotomies and in the time necessary to achieve this when compared to autologous iliac graft .

Orientador: Luis Gustavo Gosuen Gonçalves Dias<br>Banca: Antonio Carlos Shimano<br>Banca: Bruno Watanabe Minto<br>Resumo: O objetivo do presente estudo foi desenvolver placa de TPLO bloqueada modificada e avaliar a eficácia da estabilização óssea proporcionada pelo implante desenvolvido comparativamente a outros dois métodos convencionais de fixação óssea (placa bloqueada e placa bloqueada associada a pino intramedular). Por meio de estudos biomecânicos, avaliaram-se as construções às forças de torção, flexão craniocaudal, flexão mediolateral e compressão axial. Foram utilizadas sessenta tíbias sintéticas dividas em três grupos. O Grupo 1 (placa TPLO modificada), o Grupo 2 (placa bloqueada) e o Grupo 3 (placa bloqueada associada a pino intramedular) foram qsubdivididos em quatro grupos de cinco tíbias. Os ensaios foram realizados até a falha da montagem (implantes e/ou tíbia) e os resultados obtidos comparados entre os grupos. As variáveis estudadas foram analisadas sob delineamento inteiramente casualizado no esquema fatorial 3 por 4 com 5 repetições para cada combinação do esquema fatorial. Os resultados foram submetidos à análise de variância e as médias comparadas entre si pelo teste de Tukey a 5% de probabilidade. No ensaio de compressão axial houve diferença significativa em relação a variável força máxima em que o Grupo 3 obteve maior média, não havendo diferença significativa entre os Grupos 1 e 2. Todas as montagens falharam devido à flexão da placa na região de falha no corpo de prova. No ensaio de flexão em três pontos craniocaudal houve diferença significativa em relação às três vari... (Resumo completo, clicar acesso eletrônico abaixo)<br>Abstract: The aim of this study was to develop modified TPLO locked plate and to evaluate the effectiveness of stabilization provided by the implant developed compared to two other conventional methods of stabilization (locked plate and plate-rod). Through biomechanical studies the constructions were evaluated to craniocaudal and mediolateral bending, axial compression and torsional forces. Sixty synthetic tibias were used divided into three groups. Group 1 (modified TPLO plate), Group 2 (locked plate) and Group 3 (plate-rod) were subdivided into four groups of five tibiae. The tests were perfomed until failure of the construction (implants / tibia) and the results compared between the groups. The variables studied were analyzed under a completely randomized design in the factorial scheme 3 by 4 with 5 replicates for each combination of the factorial scheme. The results were submitted to analysis of variance and the means compared to each other by the Tukey test at 5% probability. In the axial compression test there was a significant difference in relation to the variable maximum force in which Group 3 obtained higher mean, not having significant difference between Groups 1 and 2. All constructions failed due to plate bending in the gap region of the synthetic tibia. In the three-point craniocaudal flexion test there was a significant difference in relation to the three variables studied. In the variable force maximum G2> G3 = G1, in the variable deflection G3> G1 = G2 and in the varia... (Complete abstract click electronic access below)<br>Mestre

Abstract Hip fracture is a significant problem in health care incurring major costs to society. Therefore, it is necessary to study fracture mechanisms and develop improved methods to estimate individual fracture risk. In addition to conventional bone density measurements, computational finite element (FE) analysis has been recognized as a valuable method for studying biomechanical characteristics of a hip fracture. In this study, computed tomography (CT) based finite element methods were investigated and simulation models were developed to estimate experimental femoral fracture load and hip fracture type in a sideways fall loading configuration. Cadaver femur specimens (age 55–100 years) were scanned using a CT scanner and dual-energy X-ray absorptiometry (DXA), and the femurs were mechanically tested for failure in a sideways fall loading configuration. CT images were used for generating the FE model, and DXA was used as a reference method. FE analysis was done for simulation models of the proximal femur in a sideways fall loading configuration to estimate the experimentally measured fracture load and fracture type. Statistical analyses were computed to compare the experimental and the FE data. Cervical and trochanteric hip fractures displayed characteristic strain patterns when using a FE model mainly driven by bone geometry. This relatively simple FE model estimation provided reasonable agreement for the occurrence of experimental hip fracture type. Accurate assessment between experimental and finite element fracture load (r2&#160;= &#160;0.87) was achieved using subject-specific modeling, including individual material properties of trabecular bone for bilinear elastoplastic FE models. Nevertheless, the study also showed that proximal femoral fracture load can be estimated with reasonable accuracy (r2&#160;= &#160;0.73) by a relatively simple FE model including only cortical bone. The cortical bone FE model was more predictive for fracture load than DXA and slightly less accurate than the subject-specific FE model. The accuracy and short calculation time of the model suggest promise in terms of effective clinical use<br>Tiivistelmä Lonkkamurtuma on huomattava ongelma terveydenhuollossa aiheuttaen merkittäviä kustannuksia yhteiskunnalle. Tämän vuoksi on tärkeää tutkia ja kehittää uusia yksilöllisen murtumariskin arviointimenetelmiä. Elementtimenetelmä on tehokas laskennallinen työkalu lonkkamurtuman biomekaanisten ominaisuuksien tutkimisessa. Tässä työssä tutkittiin ja kehitettiin tietokonetomografiaan perustuvia reisiluun simulaatiomalleja kokeellisten murtolujuuksien ja lonkkamurtumatyyppien arviointiin. Reisiluunäytteet (ikä 55–100 vuotta) kuvattiin tietokonetomografialaitteella ja kaksienergisellä röntgenabsorptiometrialla, jonka jälkeen reisiluut kuormitettiin kokeellisesti murtolujuuden ja murtumatyypin määrittämiseksi sivuttaiskaatumisasetelmassa. Tietokonetomografialeikekuvia käytettiin simulaatiomallien luomiseen, ja kaksienergistä röntgenabsorptiometriaa käytettiin vertailumenetelmänä. Reisiluun simulaatiomallit analysoitiin elementtimenetelmän avulla kokeellisten murtolujuuksien ja murtumatyyppien arvioimiseksi. Tilastoanalyysiä käytettiin verrattaessa kokeellista aineistoa ja simulaatioaineistoa. Reisiluun muotoon perustuva simulaatiomalli osoitti, että reisiluun kaulan ja sarvennoisen murtumilla on tyypilliset jännitysjakaumat. Tämän suhteellisen yksinkertaisen mallin murtumatyyppi oli lähes yhdenmukainen kokeellisen murtumatyypin kanssa. Reisiluun kokeellinen murtolujuus pystyttiin arvioimaan tarkasti (r2&#160;= &#160;0.87) käyttäen yksityiskohtaista simulaatiomallia, joka sisältää yksilölliset hohkaluun materiaaliominaisuudet. Toisaalta murtolujuus pystyttiin arvioimaan kohtuullisella tarkkuudella (r2&#160;= &#160;0.73) melko yksinkertaisellakin mallilla, joka käsittää ainoastaan kuoriluun. Kuoriluuhun perustuva malli oli tarkempi arvioimaan reisiluun kokeellista murtolujuutta kuin kaksienerginen röntgenabsorptiometria ja lähes yhtä tarkka kuin yksityiskohtaisempi simulaatiomalli. Mallin tarkkuus ja lyhyt laskenta-aika antavat lupauksia tehokkaaseen kliiniseen käyttöön

Longitudinal growth of long bone occurs at growth plates by a process called endochondral ossification. Endochondral ossification is affected by both biological and mechanical factors. This thesis focuses on the mechanical modulation of femoral bone growth occurring at the proximal growth plate, using mechanobiological theories reported in the literature. Finite element analysis was used to simulate bone growth. The first study analyzed the effect of subject-specific growth plate geometry over simplified growth plate geometry in numerical prediction of bone growth tendency. Subject-specific femur finite element model was constructed from magnetic resonance images of one able- bodied child. Gait kinematics and kinetics were acquired from motion analysis and analyzed further in musculoskeletal modelling to determine muscle and joint contact forces. These were used to determine loading on the femur in finite element analysis. The growth rate was computed based on a mechanobiological theory proposed by Carter and Wong, and a growth model in the principal stress direction was introduced. Our findings support the use of subject- specific geometry and of the principal stress growth direction in prediction of bone growth. The second study aimed to illustrate how different muscle groups’ activation during gait affects proximal femoral growth tendency in able-bodied children. Subject-specific femur models were used. Gait kinematics and kinetics were acquired for 3 able-bodied children, and muscle and joint contact forces were determined, similar to the first study. The contribution of different muscle groups to hip contact force was also determined. Finite element analysis was performed to compute the specific growth rate and growth direction due to individual muscle groups. The simulated growth model indicated that gait loading tends to reduce neck shaft angle and femoral anteversion during growth. The muscle groups that contributes most and least to growth rate were hip abductors and hip adductors, respectively. All muscle groups’ activation tended to reduce the neck shaft and femoral anteversion angles, except hip extensors and adductors which showed a tendency to increase the femoral anteversion. The third study’s aim was to understand the influence of different physical activities on proximal femoral growth tendency. Hip contact force orientation was varied to represent reported forces from a number of physical activities. The findings of this study showed that all studied physical activities tend to reduce the neck shaft angle and anteversion, which corresponds to the femur’s natural course during normal growth. The aim of the fourth study was to study the hypothesis that loading in the absence of physical activity, i.e. static loading, can have an adverse effect on bone growth. A subject-specific model was used and growth plate was modeled as a poroelastic material in finite element analysis. Prendergast’s indicators for bone growth was used to analyse the bone growth behavior. The results showed that tendency of bone growth rate decreases over a long duration of static loading. The study also showed that static sitting is less detrimental than static standing for predicted cartilage-to-bone differentiation likelihood, due to the lower magnitude of hip contact force. The prediction of growth using finite element analysis on experimental gait data and person- specific femur geometry, based on mechanobiological theories of bone growth, offers a biomechanical foundation for better understanding and prediction of bone growth-related deformity problems in growing children. It can ultimately help in treatment planning or physical activity guidelines in children at risk at developing a femur or hip deformity.<br><p>QC 20170616</p>

<i>AIMS:</i> The primary aim of this thesis was to determine what effect modular intramedullary stems of differing lengths have on the initial stability experienced by the tidial tray and the strain magnitude experienced within the proximal tibia due to the differing modular stems in a primary and revision TKA. <i>NULL HYPOTHESIS: </i>Increasing the length of the implant stem has no affect on the micromotion of the tibial tray relative to the bone surface. Adding a modular stem does not affect the strain distribution within the proximal tibia. <i>CONCLUSIONS:</i> A 40mm or 80mm press-fit modular stem does not enhance initial fixation with hybrid or cementless implantation in either primary or T2A revision TKA. The addition of a modular stem when implanting an uncemented tibial tray may well increase the instability of the construct. Cemented implants with no modular stem have better initial fixation compared to all uncemented implants tested. In a primary and revision T2A TKA scenario the addition of a press-fit or fully cemented 80mm modular stem offers no added translational or rotational stability. In the bone impaction grafting group a fully cemented tibial tray with an 80mm modular stem significantly increased the migrational and inducible displacement stability. The use of cemented modular stems in primary TKA and simple revision TKA reduces the strains experienced in the proximal tibia and causes excessive strains within the distal cancellous bone at the stem tip. Press-fit stems do not cause significant stress shielding but do cause localised areas of high strain at the stem tip, (which may be linked to patient pain and discomfort). A cemented long modular stem provided the best strain distribution within the proximal graft in the T1 models.

INTRODUCCION La patología degenerativa del compartimento interno de la rodilla por desalineación en varo es un problema frecuente. La osteotomía valguizante proximal de tibia (OTV) de adición (OTV-A) o sustracción (OTV-S) son el tratamiento quirúrgico habitualmente más utilizado. Ambos procedimientos presentan buenos resultados clínicos y funcionales aunque con otro tipo de efectos que debemos analizar. OBJETIVO A través del estudio comparativo de la osteotomía proximal valguizante de tibia de adición y sustracción, analizar la influencia de las variaciones de la pendiente tibial posterior, altura rotuliana y corrección del eje mecánico en los resultados clínicos y funcionales obtenidos al año. MATERIAL Y MÉTODO Se trata de un estudio multicéntrico, retrospectivo, descriptivo, no aletorizado de un total de 172 pacientes que se distribuyeron en 2 grupos: uno de 85 casos a los que se realizó una OTV-S y otro de 87 casos a los que se realizó una OTV-A. Los pacientes fueron intervenidos en 3 centros diferentes. Se valoraron los parámetros clínicos y radiológicos preoperatoriamente y al año de la cirugía. Se incluyeron pacientes con grados de artrosis de hasta grado II de la clasificación de Ahlbäch y hasta grado III de Kellgren-Lawrence con un máximo de edad de 65 años. Los resultados clínicos y funcionales se valoraron según la escala de la American Knee Society. Se valoró el estado condral preoperatorio tras visión artroscópica atendiendo a la clasificación de Outerbridge y el índice de masa corporal (IMC). El cálculo de la corrección se realizó con el método de la línea de carga en el punto de Fujisawa. Los parámetros radiográficos estudiados fueron el ángulo femorotibial mecánico (AFT), altura rotuliana medida con el índice de Caton-Deschamps (ICD) y la pendiente tibial posterior de tibia medida con el eje anatómico de la tibia proximal. Se utilizó la escala de calidad de vida SF-36 para valorar el estado postoperatorio al año. RESULTADOS Predominaba el sexo masculino (71’51%). La edad media de ambas series fue de 52’65 ± 8’2 años. El grado de lesión condral preoperatorio mostró lesión grado I en el 0’6% del total de ambos grupos, grado II en el 31’6%, grado III en el 41’6% y grado IV en el 26’1% del total de casos, no observando diferencias significativas entre ambas series. El IMC mostró 61’6% de pacientes normales, 27’9% con sobrepeso, y 10’4% con obesidad tipo I, según la clasificación de la OMS, no observando tampoco diferencias entre ambos grupos. Se observó que a mayor IMC mayor era la lesión condral preoperatoria. El AFT mejoró en la serie de adición 10’06º±3’6º y 7’28º±4’24º en la serie de sustracción. La pendiente tibial aumentó y el ICD disminuyó en la serie de adición y al contrario en las de sustracción. Los resultados funcionales y clínicos mejoraron en ambas series aunque fue mejor significativamente en la serie de adición. Se encontró relación directa entre la mejoría entre el AFT y los resultados clínicos. Y, solo en la serie de adición, los resultados funcionales empeoraban con la edad. No se encontraron diferencias entre ambas series en valores postoperatorios al año en la escala del SF-36. Se obtuvo la consolidación de 170 casos sobre 172. CONCLUSIONES La OTV es una técnica efectiva para corregir la desalineación en varo, obteniendo resultados funcionales y clínicos óptimos, mayores cuanto más corrección se obtiene, siendo la OTV-A la técnica que consigue significativamente mejores resultados. No obstante se producen alteraciones en los parámetros de altura rotuliana y pendiente tibial con ambas técnicas que pueden modificar las propiedades biomecánicas de la rodilla, aunque en nuestro estudio, estas alteraciones no influyeron en los resultados funcionales y clínicos al año de la cirugía.<br>INTRODUCTION Degenerative disease in the internal compartment of the knee with varus malaignment is a common problem. Opening (OTV-A) and closing (OTV-S) wedge high tibial osteotomy are the usual surgical treatments used. Both methods have good clinical and functional outcomes, although other effects must be analyzed. OBJECTIVE A comparative study after opening and closing wedge high tibial osteotomy. Analysis and influence of slope tibial, patellar height and mechanical axis changes in postoperative outcomes at one year. MATERIALS AND METHODS This is a multicenter, retrospective and descriptive study, not aleatorized. A total of 172 patients were divided into 2 groups: one of 85 cases that underwent an OTV-S and another 87 cases to which it was performed OTV-A. The patients were operated on 3 different centers. Clinical and radiological parameters, preoperatively and one year after surgery, were assessed. Patients with up to grade II osteoarthritis of the Ahlbach classification and up to grade III of Kellgren-Lawrence classification with a maximum age of 65 years were included. Clinical and functional results were evaluated according to the scale of the American Knee Society. The chondral status was examined arthroscopically preoperatively and assessed using the Outerbridge classification and the body mass index (BMI). The correction calculation was performed using the weight bearing line method at the Fujisawa point. The radiographic parameters studied were mechanical tibiofemoral angle (AFT), patellar height as the Caton-Deschamps index (ICD) and the posterior tibial slope measured with the anatomical axis of the proximal tibia. The scale of quality of life SF-36 was used to assess the postoperative condition at one year from surgery. RESULTS Males predominated (71.51%). The average age of both series was 52.65 ± 8.2 years. The degree of chondral lesion in both groups showed preoperative grade I lesion in 0.6% of cases, grade II in 31.6%, grade III in 41.6% and grade IV in 26.1% of cases, not observing significant differences between the two series. BMI showed 61.6% of normal patients, 27.9% overweight and 10.4% with type I obesity, according to the WHO classification, significant differences not observed between the two groups. It was observed that patients with higher BMI had greater preoperative chondral injury. The AFT improved in OTV-A 10.06º±3.6º and in OTV-S 7.28º±4.24º. The tibial slope increased and ICD decreased in opening group and vice-versa in closing group. The functional and clinical results improved in both series but were significantly better in the opening group. A direct relationship was observed between the level of the AFT improvement and the clinical outcome. In the opening group, worse functional outcomes were observed with increasing age of the patient. This was not observed with the closing group. No differences were found between the two series in the postoperative value on the scale of the SF-36 at one year. Consolidation was achieved in 170 of the 172 cases. CONCLUSIONS The high tibial osteotomy is an effective technique for correcting varus malalignment. Although both groups showed clinical and functional improvement, the best results were observed in the OTV-A group, where the greater level of correction was achieved. However, alterations in patellar height parameters and tibial slope with both techniques are produced, and this can change the biomechanical properties of the knee. In our study , these changes did not influence the functional and clinical outcomes one year after surgery.

Les variations de contraintes mécaniques appliquées sur l'os entrainent des modifications du métabolisme osseux. La diminution des contraintes mécaniques telle qu'elle existe dans le modèle du rat suspendu, induit une perte osseuse rapide dès le début de la suspension qui se stabilise par la suite. L'augmentation des contraintes par un exercice de type dynamique (la course sur tapis roulant) induit un gain osseux. Les mécanismes cellulaires responsables de ces modifications sont encore mal connus. Grâce à la mise au point d'une méthode d'isolement des cellules ostéoformatrices à partir du tibia de rat, nous avons pu isoler les cellules des facteurs environnementaux et les maintenir en culture primaire. Les études in vitro sur les différents modèles animaux précités, ont permis de montrer que la diminution de contrainte entraine une inhibition de la maturation des ostéoblastes conduisant à une perte osseuse, qui cesse dès que les contraintes sur l'os se retrouvent au niveau initial. Inversement, l'exercice stimule la différenciation des ostéoblastes en ostéoblastes matures aboutissant à un gain osseux qui diminue les contraintes mécaniques de l'os. Nous avons pu étudier l'effet direct de la microgravité sur les cellules ostéoblastiques grâce au développement d'un module de culture et de techniques d'investigations adaptées aux conditions expérimentales du vol spatial biocosmos x. Les résultats de cette expérience ont montré que la cellule ostéoblastique est capable de s'adapter à son nouvel environnement physique en modifiant son activité cellulaire et l'organisation de son cytosquelette. Nous pensons que les contraintes mécaniques pourraient avoir une influence sur le cytosquelette des ostéoblastes qui modifierait l'activité cellulaire, permettant à l'os de s'adapter à son nouvel environnement

This thesis deals with stress analysis strain proximal end of tibia with total joint replacements. The analysis is done on the basis of deformation characteristics of voltage, through the finite element method (FEM). We have developed two-dimensional models of the proximal end of tibia with tibial components total endoprosthesis (TEP), without loss and bone loss. Geometry model is created based on data obtained from computerized tomography, which were further processed in the program, Rhinoceros 3.0 and SolidWorks 2009th Computational solution was carried out by finite element method in Ansys Workbench 12.0. The model without loss of bone tissue was tested the hypothesis that the deformation is very small and there is no violation of the shank prosthesis. Due to loss of bone tissue is lost support to the tibial pulse in the proximal tibia and by a progressive increase in stress, which can lead to a breach of the shank total joint replacement. The analysis results show that, if the loss of bone tissue, so that the tibial part of the TEP will lose support, there is a crack stem total hip replacement due to stress.

O autor estudou as propriedades biomecânicas dos tendões dos músculos tibial anterior e tibial posterior congelados a -20°C e a -86°C extraídos de cadáveres humanos frescos. Foram realizados ensaios mecânicos de tração até a ruptura e determinadas as seguintes propriedades: resistência máxima, coeficiente de rigidez, módulo de elasticidade e alongamento máximo relativo. Os dados obtidos foram comparados aos existentes na literatura relativos ao ligamento cruzado anterior, ligamento da patela e aos tendões dos músculos grácil e semitendíneo<br>The author studied the mechanical properties of the anterior and posterior tibialis muscle tendons frozen at -20°C and -86°C obtained from fresh-frozen human cadavers. The tendons were submitted to axial traction until failure and the following properties were determined: ultimate load, stiffness, modulus of elasticity and relative strain. Data obtained were compared to those from the literature related to the anterior cruciate ligament, patellar tendon, gracilis and semitendinous tendons

Advancements in computational capabilities have allowed researchers to turn towards modeling as an efficient tool to replicate and predict outcomes of complex systems. Computational models of the musculoskeletal system have gone through various iterations with early versions employing dramatic simplifications. In this work, a three-dimensional computational model of the wrist joint was developed. It accurately recreated the skeletal structures of the hand and wrist and represented the constraints imposed by soft tissue structures like ligaments, tendons, and other surrounding tissues. It was developed to function as a tool to investigate the biomechanical contributions of structures and the kinematic response of the wrist joint. The model was created with the use of a commercially available computer-aided design software employing the rigid body modeling methodology. It was validated against three different cadaveric experimental studies which investigated changes in biomechanical response following radioscapholunate fusion and proximal row carpectomy procedures. The kinematic simulations performed by the model demonstrated quantitatively accurate responses for the range of motions for both surgical procedures. It also provided some understanding to the trends in carpal bone contact force changes observed in surgically altered specimens. The model provided additional insight into the importance of structures like the triangular fibrocartilage and the capsular retinacular structures, both of which are currently not very well understood. As better understanding of components of the wrist joint is achieved, this model could function as an important tool in preoperative planning and generating individualized treatment regiments.

碩士<br>國立成功大學<br>醫學工程研究所碩博士班<br>95<br>Abstract Tibial fractures are the third most common fracture type following femur and radius/ulna fractures. The tibia has one third area, which is only covered by skin and lack of blood and nutrient supply with poor bone healing. The Less Invasive Stabilization System (LISS) for proximal tibial fractures provides a locking mechanism of the screw in the plate which offers angular stability and is suitable for patients with osteopenia or osteoporosis. LISS proximal tibia plate has been clinically efficacy on the fixation of proximal tibial fractures for bone healing. However, the biomechanics of the fixation of LISS on tibital fractures are still not clear. The purpose of this research was to apply finite element method to characterize the biomechanical performance of the proximal tibia plate to stabilize the proximal tibia fracture. Finite element method was used to analyze the stresses distribution on the fixation of the plate to three different sites of, two common types of proximal tibial fractures and different screw positions. In addition, a fractured plate after clinical use was investigated by using material testing to determine fracture characteristics and to validate through the outcomes of finite element analysis. The analytical results illustrate that (1) the higher stress are occurring in the plate, while the tibia fracture site is more closer to the distal region of tibia; (2) the fixation of oblique fracture has led to higher stress in the plate than the fixation of transverse fracture; (3) a change of screw position to increase the working length of plate is led to the reduction of stress in the plate. In all conditions, the stress concentration are occurred around the screw hole of the plate, which may lead to fatigue failure of the bone plate. This may also lead to the delay of fracture healing. The results of this research have suggested the following two designs to the improved bone plate: (1) smooth the curvature in the proximal region of the plate to fit the bone contour of domestic people and to reduce the stress; (2) improve the manufacture process to enhance fatigue strength of the plate.

碩士<br>國立成功大學<br>生物醫學工程學系<br>101<br>Tibia fractures account for 1% of all fractures in human beings. The main features of the tibia joint surface is to support our body weight, hence, it is extremely important to us and so there is a vital necessity to understand the biomechanical performance of proximal tibia fractures. In clinical treatment, using a locking plate to stabilize and treat the proximal tibia fractures has shown good results. However, there are still examples of failed cases, such as those in which bone plate breakage occur. The aim of this study is to determine the best of three different brands of proximal tibia plates which are commonly used to fix the fracture site, under the simulation of the worst conditions, when using the finite element method, as well as assessing the biomechanics effects of the bone plate when used on a proximal tibia fracture. The results show that the maximum stress value of the bone plates of different brands is located at the position of the screw holes; the stress concentration sites are located on both sides of the fracture fragments. However, increasing the working length of the bone plate can effectively reduce the phenomenon of stress concentration. Compared with the bone plates of the other two brands, the bone plate made by the United Orthopedic Corporation not only has better mechanical properties, but is also able to obtain the same effect as the other brands regarding the promotion of callus formation in the bone healing process.

In the past few decades, an area of skeletal research focusing on shape analyses has gained popularity in the field of physical anthropology, and subsequently forensic anthropology. Known as geometric morphometrics, this type of analysis allows the researcher to place the morphological shape of bones into a statistical framework to answer questions on a variety of topics, including sexual dimorphism. Sex assessment from the long bones has been traditionally conducted using traditional morphometric methods (Iscan and Miller-Shaivitz 1984; Steyn and Iscan 1997), and as a result, relies mainly on size differences and has not considered how joint morphology and shape affect sex. For this project, a geometric morphometric analysis of the proximal tibia in a modern Caucasian American population was conducted using a sample of 100 male and 100 female tibiae from the William M. Bass Donated Skeletal Collection at the University of Tennessee at Knoxville. The proximal tibia's effectiveness as an indicator of sex in a modern American population was evaluated via generalized Procrustes, principal components, and discriminant function analyses. Principal components revealed a lack of separation between males and females in terms of proximal tibia shape. The discriminant function analysis was successful at discriminating males from females, but cross-validation yielded a low total accuracy rate of 58%. The shape of the proximal tibia contributes to sexual dimorphism in a Caucasian American population, but is only slightly useful in a discriminant function. Further research should be conducted on different populations and using different skeletal landmarks.

碩士<br>義守大學<br>生物醫學工程學系<br>101<br>Tibial fractures were often seen in the car accidents, especially open fractures. These fractures were still challenges to clinical surgeons. Open fractures with severe soft tissue damage were treated by external fixators in early stage, then followed by internal fixation. Previous studies reported that locking plate could be applied as external fixation and this treatment received good prognosis. However, no biomechanical study was performed to validate that locking plate as external fixators has sufficient structural stability. This study was to compare the biomechanical stability of the internal and external locking plate used in the tibial fractures. Fatigue test was excuted to evaluate the stability of both constructs. In addition, finite element analysis was adopted to figure out the effect of the distance from the plate to the bone surface. The results showed that, although the axial stiffness of external locking plate was less than internal one, it could provide sufficient stiffness for bone healing. The results of finite element analysis showed that 6-cm distance from the plate to the bone surface was acceptable. Other loading modes and the screw configuration of external locking plate still need further investigation.

碩士<br>國立陽明大學<br>醫學工程研究所<br>94<br>Good coverage of tibial component and proximal resected tibial surface can improve the strength of component fixation and thus avoid component subsidence and loosening. Most prostheses in Taiwan are imported from USA or Europe. The tibial components don’t have good coverage for Taiwanese in our previous study. Especially in revision knee surgery, the shape is varied in different cutting thicknesses of the tibia. It’s difficult to have a good coverage of revision tibial component and resection surface. The purpose of this study was to investigate the proximal tibial morphology of Taiwanese. The results can be applied for geometric designs of tibial baseplate and augmentation. Fifty osteoarthritis knees were collected for analysis. Three- dimensional proximal tibia was constructed from Computed-Tomography slices for measuring morphologic data. Five cutting depths of 4, 7, 10, 13, and 16mm below tibial plateau were measured. The parameters included the dimensions of anteroposterior length (AP), mediolateral width (ML) of resected surface and four radii as anterolateral radius (AL), posterolateral radius (PL), anteromedial radius (AM), and posteromedial radius (PM). The results showed that mean AP was 47.4mm (40.4-52.9), mean ML was 69.0mm (59.6-79.1), AL was 30.0mm (18-38), PL was 20.0mm (10-25), AM was 28.7mm (18-36), and PM was 17.9mm (11-23). Comparing the results with commercial tibial components, the imported implants of PFC sigma and Zimmer Nexgen could provide better coverage for Taiwanese. Body height and dimensions of AP and ML present high dependence, and American and European is relatively taller than Taiwanese. The factor of body height may highly influence the covering rate of tibial components. This study suggested 5 sizes of tibial components for Taiwanese. They can improve the rate of coverage, and reduce the rate of implant subsidence.

碩士<br>國立臺灣科技大學<br>機械工程系<br>94<br>The gamma nail and sliding screw plate have been popularly used to the treatment of proximal femoral fracture. In the clinical point of view, the implants may be failed and cause loss of fracture fixation in impairment of fracture healing. In addition, the femoral head may be cut out by those implants especially for the patients with osteoporosis. In this study, two types of commercial available implants (gamma nail and sliding screw plate) and a newly designed implant (double screw nail) were assessed by finite element analyses and biomechanical tests. The purposes of this study were to evaluate the mechanical performances of these fracture fixators and to verify the rationality of finite element analyses by using biomechanical tests. In finite element analysis, in accordance with the bone structures and geometry gained from a computed tomography (CT) scan, the anatomical shape for femur was created. Then the CT scan models were transformed into three-dimensional solid models by image processing and Boolean operation. A joint reaction force which was applied at the center of femoral head and an abductor muscle force which was applied at the greater trochanter were used and the end of distal femur was fully constrained. Three kinds of fractures were discussed including femoral neck fracture, subtrochanter fracture, and subtrochanteric fracture with gap. The von Mises stress, displacement, total strain energy, and strain energy density were obtained. In biomechanical tests, three kinds of proximal femoral fracture were created and three kinds of implants were implanted into the artificial femur. The loading and boundary conditions were similar to the finite element models. The load and displacement were measured and the stiffness was calculated. The results of biomechanical tests were compared with the results of finite element analyses. From the results of finite element simulation, the strain energy density is a good predictor as compared with the von Mises stress in this study. The results of finite element analyses were closely related to those of biomechanical tests with high correlation coefficient (>0.72). The double screw nail can eliminate the stress concentration at the femoral shaft as compared with the gamma nail and decrease the risk of bone cut out as compared with sliding screw plate. Developing the finite element models in this study could be used to reflect the clinical observation. This study could assist the engineers to design new orthopedics implants and help the surgeons to select suitable implants for their patients.

Background: Osteoarthritis (OA) is a debilitating joint disease marked by cartilage and bone changes. Morphological and mechanical changes to bone, which are thought to increase overall bone stiffness, result in distorted joint mechanics and accelerated cartilage degeneration. Using a parametric finite element (FE) model of the proximal tibia, the primary objective of this study was to determine the relative and combined effects of OA-related osteophyte formation, and morphological and mechanical alterations to subchondral and epiphyseal bone on overall bone stiffness. The secondary objective was to assess how simulated bone changes affect load transmission in the OA joint. Methods: The overall geometry of the model was based on a segmented CT image of a cadaveric proximal tibia used to develop a 2D, symmetric, plane-strain, FE model. Simulated bone changes included osteophyte formation and varied thickness and stiffness (elastic modulus) in subchondral and epiphyseal bone layers. Normal and OA related values for these bone properties were based on the literature. “Effective Stiffness (K)” was defined as the overall stiffness of the proximal tibia, calculated using nodal displacement of the loaded area on the subchondral cortical bone surface and the load magnitude. Findings: Osteophyte formation and thickness or stiffness of the subchondral bone had little effect on overall bone stiffness. Epiphyseal bone stiffness had the most marked effect on overall bone stiffness. Load transmission did not differ between OA and normal bone. Interpretation: Results suggest that epiphyseal (trabecular) bone is a key site of interest in future analyses of OA and normal bone. Results also suggest that observed OA-related alterations in epiphyseal bone may result in OA bone being more flexible than normal bone.

碩士<br>國立臺灣大學<br>醫學工程學研究所<br>89<br>The purpose of this study is to find the cross-sectional geometry and the dimension of distal femur, proximal tibia and patella in Chinese population for the basis of designing the total knee prosthesis. Fifty consecutive CT scan images of osteoarthritic knee were collected. We designed a semiautomatic program to detect the bony contour and a semiautomatic program to measure the width and depth of distal femur, proximal tibia and patella. The measured data along with patient’s information such as sex, age, height, body weight, and the distance from joint line were analyzed using multiple regression method to find out the relation among these factors. The results show there are variations along the anatomic axis of femur. In distal femur, the variations in depth are more obvious than those in width. There is no significant difference in the allometry along the anatomic axis of proximal tibia (P<0.05). The results of regression analysis show that there is no relation between sex, age and the dimension of knee joint. Several best fitted models using Minitab statistical software were established to predict parameters of knee dimension.

During landing, the human body is required to absorb impact forces throughout its tissues. Muscle and connective tissue is able to dissipate much of this force, however, a portion of the impact is delivered to the bones. Forces acting on the human skeleton can cause microscopic fractures which may lead to stress fracture. The present study seeks to calculate changes in the magnitude of strain using noninvasive methods. A musculoskeletal model representing a healthy male subject (22 years, 78.6 kg, 1.85 m) was created. A flexible tibia, created from a computed tomography scan of the subject’s right tibia, was included in the model. Motion capture data were collected while the subject performed drop landings from three separate heights (26, 39, and 52 cm) and used to compute simulations in LifeMOD. Surface electromyography and joint angle data were compared to their simulated counterparts using a cross correlation. Maximum magnitudes of principal and maximum shear strain were computed. The model had reasonable agreement between joint angle curves. A large Cohen’s d effect size showed that our subject had increased tibial strain and strain rate as the drop height increased. This study demonstrates a valid method of simulating tibial strain during landing movements. Future studies should focus on recruiting a larger sample and applying this method.<br>School of Physical Education, Sport, and Exercise Science

Dissertação de Mestrado Integrado em Engenharia Mecânica apresentada à Faculdade de Ciências e Tecnologia<br>O objetivo principal deste trabalho é a avaliação do comportamento biomecânico de uma placa de contenção (TPC- Trochanteric Plate of Contention) de fraturas do fémur na zona trocantérica. Neste estudo é ainda analisada a influência da qualidade do osso trabecular no comportamento final da TPC. O dispositivo TPC é um sistema de fixação interna que visa eliminar alguns dos problemas biomecânicos apresentados pelos outros dispositivos e, simultaneamente, cumprir as linhas de orientação da norma ASTM (American Standard Specifications and Test Methods) F384-12. Assim, neste trabalho, as condições de fronteira e carregamentos foram definidos tendo em conta a informação descrita na referida norma e foi utilizado o programa comercial de elementos finitos ADINA® para avaliar numericamente o seu desempenho biomecânico. Os modelos geométricos do conjunto fémur/TPC foram gerados utilizando o modelo #3403 do fémur da marca Sawbones® e a geometria do dispositivo TPC existente no DEM/UC. Atendendo a que o modelo CAD original é de um fémur íntegro, foi necessário criar dois modelos diferentes para o conjunto fémur/TPC: um modelo íntegro e um fraturado. No modelo fraturado foi gerada uma fratura intertroncatérica de obliquidade reversa, com as faces de corte distanciadas de 1mm, de forma a simular uma situação pós-operatória. Recorrendo ao software ADINA® e importando os modelos geométricos do conjunto fémur/TPC, foram feitos estudos numéricos para quatro situações diferentes, isto é, foram feitas combinações de fémur fraturado ou íntegro e osso trabecular saudável ou não saudável (tentando aproximar o comportamento de um osso osteoporótico).Os resultados obtidos permitem concluir que a TPC não é sensível às alterações das propriedades do osso, mantendo os valores de tensão e deslocamento próximos em ambas as condições. O mesmo não pode ser dito do tipo de osso trabecular na zona proximal do fémur, que apresentou variações significativas nas deformações principais.<br>The main objective for this assignment is to assess the biomechanical performance of a plate for contention (TPC – Trochanteric Plate of Contention) of trochanteric femoral fractures. In this study, the influence of trabecular bone quality on the TPC’s performance is also analysed.The TPC device is an internal fixation system that aims to eliminate some of the biomechanical problems that affect other devices and, simultaneously, comply with the guidelines of ASTM (American Standard Specifications and Test Methods) F384-12. Thus, in this work, the boundary conditions and loadings were defined taking into account the information described in said standard and was used the finite element commercial program ADINA® to numerically assess its biomechanical performance.The geometric models of the femur/TPC assembly were generated using the Sawbones® fémur model #3403 and the existing TPC geometry at DEM/UC. Given that the original CAD model is an intact femur, it was necessary to create two different models for the femur / TPC assembly: an intact model and a fractured one. In the fractured model a reverse obliquity intertrochanteric fracture was generated, with the cut faces distanced of 1mm, in order to simulate a postoperative situation. Using the ADINA® software and importing the geometric models of the femur / TPC assembly, numerical studies were done for four different situations, that is, a combination of fractured or intact models and healthy or unhealthy trabecular bone (attempting to simulate the behaviour of osteoporotic bone)The results obtained able the confirmation that the TPC is not sensitive to changes in bone properties, maintaining similar tension and displacement values on both conditions. The same can not be said about the trabecular bone on the proximal femur, which showed significant variations in the principal deformations.

A Dissertation submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Medicine, 2018<br>Intrauterine alcohol exposure is detrimental to fetal and postnatal development. Fetal Alcohol Syndrome (FAS) is the most severe effect of prenatal alcohol exposure. Of the abnormalities that are characteristic of FAS, there are relatively few research studies on the effects of gestational alcohol exposure on skeletal development. Hence, we aimed at investigating the effects of prenatal alcohol consumption on the proximal growth plate of the tibia in 3 week old rats. Time mated pregnant Sprague Dawley dams were assigned into either the ethanol (n=6), saline (n=6) control and untreated control groups (n=3). These rat dams were treated with 0.015 ml/kg of 25.2% ethanol and 0.9% saline by oral gavage during the 19 days of gestation respectively. While the untreated control group remained untreated. Two pups from each dame were selected from the three groups (n=60) and reared for three weeks. These pups were then terminated by intraperitoneal anesthetic injection of sodium pentobarbital. Following an abdominal incision the carcasses were fixed in 10% buffered formalin prior to the dissection of limbs. Bilateral tibiae were harvested, soft tissue was cleaned off the tibiae and then these fixed in 10% buffered formalin. The proximal end of the left tibiae, was subjected to histological and immunohistochemical staining analysis. The, epiphyseal plate area, proliferative zone and hypertrophic zone length, number of cells, area, and number of proliferative cells where evaluated. For osteometric analysis bilateral tibiae were subjected to three-dimensional micro-focus computed tomography investigations.<br>XL2018

Αναδρομική μελέτη των 13 ασθενών με σηπτική ψευδάρθρωση κάτω πέρατος μηριαίου που αντιμετωπίστηκαν με ευρύ χειρουργικό καθαρισμό και με τη μέθοδο Ilizarov. Κατά την έναρξη της τελικής αντιμετώπισης όλοι οι ασθενείς είχαν σημαντικό περιορισμό της κίνησης της άρθρωσης του γόνατος. Ο μέσος όρος προηγούμενων χειρουργικών επεμβάσεων ήταν τρεις. Ο μέσος όρος οστικού ελλείμματος ήταν 8.3 εκ. Ο μέσος χρόνος εξωτερικής οστεοσύνθεσης ήταν 309.8 ημέρες. Σύμφωνα με τα κριτήρια Paley σε οκτώ ασθενείς είχαμε άριστο οστικό αποτέλεσμα, ενώ το λειτουργικό αποτέλεσμα ήταν σε τρεις περιπτώσεις άριστο, σε τέσσερις καλό. Πώρωση του κατάγματος, εκρίζωση της λοίμωξης και αποκατάσταση της στηρικτικής ικανότητας του σκέλους επιτεύχθηκε σε όλους τους ασθενείς. Η αύξηση του χρόνου εξωτερικής οστεοσύνθεσης παρατηρήθηκε: 1) η οριστική αντιμετώπιση εφαρμόστηκε 6 μήνες μετά από τον αρχικό τραυματισμό. 2) ο ασθενής υποβλήθηκε σε 4 τουλάχιστον προηγούμενες χειρουργικές επεμβάσεις 3) η αρχική αντιμετώπιση συμπεριλάμβανε ανοικτή ανάταξη και εσωτερική οστεοσύνθεση. Με την μέθοδο Ilizarov επιτυγχάνεται πλήρη εκρίζωση της οστικής λοίμωξης, υψηλό ποσοστό πώρωσης και αποκατάσταση της στηρικτικής ικανότητας του σκέλους. Ωστόσο συχνά η δυσκαμψία του γόνατος και η χωλότητα αποτελούν χρόνιο πρόβλημα για αρκετούς ασθενείς.<br>We retrospectively reviewed 13 patients with infected nonunion of the distal femur, which had been treated by radical surgical debridement and Ilizarov method. All had severely restricted movement of the knee and a mean of 3.1 previous operations. The mean bone defect was 8.3 cm and no patient was able to bear weight. The mean external fixation time was 309.8 days. According to the Paley’s grading system, eight patients had an excellent bone result and seven excellent and good functional results. Bone union, the ability to bear weight fully, and eradication of infection were achieved in all the patients. The external fixation time was increased when the definitive treatment started six months or more after the initial trauma, the patient had been subjected to more than four previous operations and the initial operation had been ORIF. The treatment of infected defect pseudarthrosis of the distal femur using the Ilizarov device is a salvage procedure, as it offers complete eradication of infection, high union rate and ability for full weight bearing. Nevertheless problems such as, impaired knee joint motion and limping bother the patients permanently.