Por meio deste estudo objetivou-se avaliar a viabilidade de um novo acesso artroscópico para o recesso palmar da articulação interfalângica distal em eqüinos pela bainha sinovial comum aos tendões flexores digitais, com as finalidades de proporcionar segurança e eficiência durante a artrocentese, permitir visualização efetiva das estruturas anatômicas, além de criar condições para manipulação de instrumentos artroscópicos. Foram utilizadas 20 peças anatômicas, correspondentes aos membros torácicos de 10 eqüinos. Os conjuntos de um a cinco formaram o Grupo I, cujo o acesso cirúrgico foi medial, e os conjuntos seis a 10 formaram o Grupo II, onde o acesso cirúrgico foi lateral. Posteriormente, avaliou-se o procedimento em animais de experimentação com a aplicação da técnica artroscópica proposta em seis articulações interfalângicas distais dos membros torácicos de três eqüinos (GIII), sem enfermidade previamente diagnosticada através de exames físicos e radiográficos. Os procedimentos no Grupo III foram efetuados sob anestesia geral, em decúbito lateral, e todos animais foram observados durante seis semanas. Neste período, além da avaliação dos parâmetros físicos, foram efetuados controles radiográficos contrastados, visando a avaliar a recuperação e o tempo necessário para oclusão da membrana divisória entre a bainha digital e o interior da articulação interfalângica distal. A técnica proposta alcançou os objetivos propostos, oferecendo nova alternativa para o acesso ao recesso palmar da articulação interfalângica distal nos eqüinos / This study was carried out in order to evaluate the viability of a new arthroscopic approach of the palmar recess of the the interphalangeal joint in horses through the synovial sheath that involves the digital flexor tendon. The purposes of the study were to provide safety and efficiency during arthrocentesis, to allow effective visualization of the anatomical structures and provide means for the manipulation of arthroscopic instruments. Initially, 20 anatomic parts corresponding to the forelimbs of 10 horses were used. Sets numbers 1 through 5 formed Group I in wich a medial surgical approach was performed. Sets numbers 6 through 10 formed Group II, in which there was a lateral surgical approach. Later, the procedure in experimental animals was analyzed. This analysis was done using the proposed arthroscopic technique in 6 distal interphalangeal joints of the forelimbs of three horses (GIII). There was no previously disease diagnosed through physical and radiographic exams. The procedures in Group III were done under put general anesthesia in the lateral recumbence position and all the animals were under observation during six weeks. In the post-operative period a physical and contrasted radiographic exams were done to evaluate the recovery as well as the necessary healing time of the membrane between the digital sheath and distal interphalangeal joint. The technique responded positively to its objectives offering a new alternative to the approach of the palmar recess in the distal interphalangical joint in horses

Os tendões são tecidos de transição das forças contráteis geradas pelos músculos e as transferindo para os ossos, podendo assim gerar movimento. A região em que o tecido tendíneo se insere ao ósseo é chamada de junção osteotendínea ou entese. Estas junções podem ser classificadas como fibrosas ou fibrocartilaginosas, as fibrosas são aquelas em que os tendões e/ou ligamentos se inserem no eixo (diáfise) dos ossos longos e as fibrocartilaginosas a inserção ocorre nas epífises dos ossos longos ou nos ossos curtos. Este estudo tem como propósito analisar as fibras colágenas e as células presentes na junção osteotendínea, utilizando microscopia de luz com as colorações de Hematoxilina-eosina, Azocarmim, Picro-sírius e Tricromo de Masson e os aspectos ultraestruturais empregando os métodos de microscopia eletrônica de varredura e de transmissão. Foram utilizados 30 ratos Wistar machos, sendo 15 adultos com idade de 4 meses (grupo A) e 15 idosos com idade de 18 meses (grupo B), sendo utilizados 5 ratos de cada grupo para microscopia de luz, 5 para microscopia eletrônica de varredura e 5 para microscopia eletrônica de transmissão. Os membros posteriores dos ratos foram retirados, dissecados e desmineralizados com EDTA a 7% para microscopia de luz e EDTA 0,15M pH 7,4 para microscopia eletrônica de transmissão durante 4 semanas, não foi necessário desmineralizar as amostras para microscopia eletrônica de varredura. Cortes de 6 m foram realizados e montados em lâminas histológicas para análise em microscópio de luz, a técnica de criofratura em nitrogênio líquido foi realizada para análises em microscópio eletrônico de varredura e cortes de 60 nm foram realizados, montados em telas de cobre de 200 mesh (EMS) para análises em microscópio eletrônico de transmissão. O processo de envelhecimento mostrou alterações das fibrilas colágenas, em que o tipo I predomina no grupo adulto e o tipo III no idoso, diminuição na quantidade de células de fibrocartilagem, processos citoplasmáticos destas células curtos e em número reduzido e uma diminuída capacidade de síntese devido a aparelhos de Golgi menores, poucas cisternas de retículo endoplasmático granular e escassas mitocôndrias. / Tendons are transition tissues of contractile forces generated by muscles and transferring to bone, generating this way move. The region where tendon attach to bone is called bone-tendon junction or enthesis. These junctions can be classified as fibrous or fibrocartilaginous, the fibrous are those in which tendons/ligaments are attached in the shaft (diaphysis) of the long bones and fibrocartilaginous attachment occur in the epiphyses of the long bones or short bones. This study aims to analyze collagen fibers and the cells present in the bone-tendon junction, using light microscope with Hematoxylineosin, Azocarmine, Picrosirius red and Masson\'s trichrome staining and ultrastructural aspects using scanning electron microscope, transmission electron microscope methods. Thirty male Wistar rats were using, 15 adults rats at 4 months-old (A group) and 15 old rats at 18 months-old (B group), were used 5 rats of each group to light microscopy, 5 rats to scanning electron microscopy and 5 rats to transmission electron microscopy. The hind limbs of the rats were removed, dissected and demineralized using 7% EDTA solution to light microscopy and 0,15M pH 7,4 EDTA solution to transmission electron microscopy for 4 weeks, was not necessary demineralize the samples to scanning electron microscopy. Cut in slices 6 m thickness were made and mounted on histological slides to analyze in light microscope, freeze-fracture technique with liquid nitrogen was performed to analysis in scanning electron microscope and cuts in slices 60 nm thickness were made, mounted on copper grids (200-mesh - EMS) to analysis in transmission electron microscope. The aging process showed changes of the collagen fibrils, in which type I predominates on adult groups and the type III on the old group, decrease in the amount of the fibrocartilage cells, few and short cytoplasmic processes of this cells and a decreased synthesis capacity due a small Golgi apparatus, a few cisternae of rough endoplasmatic reticulum and few mitochondria.

Para avaliar a eficácia do laser de arsenito de gálio em acelerar a cicatrização tendínea em cavalos PSI de corrida com lesão no tendão flexor digital superficial, foram realizados dois experimentos, primeiro (E1) com 14 casos clínicos onde as lesões foram decorrentes do esporte em um dos membros torácicos, o segundo (E2) com cinco casos experimentais, onde as lesões foram induzidas com colagenase em ambos os membros torácicos. No E1, após a detecção da lesão no tendão flexor digital superficial por exame ultra-sonográfico, todos os animais receberam antiinflamatório não esteróide associado à dimetilsulfóxido por via intravascular, crioterapia no local da lesão, e caminharam ao passo duas vezes ao dia por 15 minutos durante os 30 dias de acompanhamento. Os membros tratados pertenceram a onze animais que receberam uma sessão diária de laser de arsenito de gálio na dose de 20 J/cm2, realizadas durante 10 dias consecutivos, após término do antiinflamatório e da crioterapia. Os membros controle pertenceram a três animais, os quais não foram tratados com laser. No E2, após identificação das lesões, foram escolhidos aleatoriamente um membro torácico controle e outro a ser tratado por laser em cada animal. Da mesma forma, estes animais foram mantidos a passo e receberam o mesmo protocolo de laserterapia que os membros tratados do E1. Todos os membros foram avaliados através de exames ultra-sonográficos, utilizando-se como parâmetros o paralelismo das fibras tendíneas em corte longitudinal; a ecogenicidade, a área do tendão, a área da lesão e a porcentagem de ocupação da lesão em corte transversal. No E1, os membros controle não apresentaram diferença significativa (P>0,05) nos parâmetros avaliados entre os dias 0 e 30. Nos membros tratados, a área do tendão também não apresentou diferença significativa (P>0,05) entre os dias analisados, porém houve diminuição muito significativa nos escores de ecogenicidade e paralelismo (P<0,001), assim como diminuição no tamanho da lesão (P<0,05) e na porcentagem de ocupação da lesão (P<0,05). No E2 também não houve diferença significativa entre os dias em todos os critérios avaliados nos membros controles (P>0,05). Nos membros tratados a ecogenicidade, o paralelismo e o tamanho do tendão, não sofreram alterações significativas (P>0,05) entre os dias avaliados, porém o tamanho da lesão (P<0,05) e a porcentagem de ocupação da lesão (P<0,01) apresentaram diminuição significativa. O laser de arsenito de gálio na dose de 20 J/cm2 mostrou-se eficaz em acelerar a reparação da lesão tendínea nos membros tratados em relação aos membros controle, tanto no grupo de casos clínicos quanto no grupo experimental, quando comparados aos 30 dias do aparecimento da lesão. Esses resultados sugerem a participação positiva do laser de arsenito de gálio nos resultados e a validação do mesmo no tratamento da tendinite do flexor digital superficial de cavalos Puro Sangue Inglês de corrida. / This study conducted two trials to evaluate the efficacy of Gallium Arsenide Laser in the speed of the healing process of superficial digital flexor tendon (SDFT) lesions in thoroughbred horses. One trial group (T1) comprises 14 horses with lesions, which resulted from the sport, in the SDFT in one of the front limbs. The other trial group (T2) was formed by five horses that had lesions induced in both front limbs by collagenase injection. In the T1, after the detection of the lesion in the SDFT by ultrasonography all horses were treated by intravenous injection, once a day, over five days, with an association of two AINS: phenylbutazone and dimethylsulfoxide. Cryotherapy was also applied on the affected tendon (three times a day over five days) and the horses were kept in stalls and allowed controlled exercise (hand-walked twice daily for 15 minutes) during the 30 days of the study. The treated limbs belong to 11 horses that received laser sessions once a day for ten days at a dosage of 20J/cm2. These sessions started after the AINS association and cryotherapy. The control limbs belong to the other three horses that received the same treatment, except by the laser sessions. In the T2, after the detection of the lesion, a limb from each horse was randomly chosen to be the control limb and the other limb was treated by laser. These horses were also kept in stall under controlled exercise and the treated limb was under the same laser protocol that T1. All horses were evaluated by two ultrasonographic exams with a 30-day interval. The parameters evaluated were: the fiber alignment, the echogenicity, the tendon area, the lesion area and the proportion of the cross sectional area involved. In the T1, the control limbs showed no significant difference (p>0,05) in the echogenicity, the fiber alignment, the tendon area, the lesion area or the proportion of the cross sectional area involved, between the day 0 and 30. The treated limb, didn´t show any significant difference of the tendon area, but showed a significant difference on the echogenicity (P<0,001), the fiber alignment (P<0,001), the lesion area (P<0,05) and the proportion of the cross sectional area involved (P<0,05). In the T2, only one limb received the laser treatment, the other limb acted as a control. The control limbs showed no significant difference (P>0,05) in the echogenicity, the fiber alignment, the tendon area, the lesion area and the proportion of the cross sectional area involved between the day 0 and 30. The treated limbs showed no significant difference (P>0,05) in the echogenicity, the fiber alignment and the tendon area, but showed significant difference in the lesion area (P<0,05) and the proportion of the cross sectional area involved (P<0,01). The treatment dose of 20J/cm2 of gallium arsenide laser was efficient in speeding the healing process of SDFT lesions of the laser treated limbs in both groups (T1 and T2), when compared with the control limbs, at 30 days of the onset of the lesion. The group which lesions occurred due to the sport (T1) had a better response to the treatment than the group which lesions were induced by collagenasis (T2). The limbs treated by laser showed a positive response which validates the use of the Gallium Arsenide laser for the treatment of tendinitis in the Superficial Digital Flexor in race horses.

Tendões são descritos como tecido conjuntivo denso modelado que inserem os músculos aos ossos. Sua principal função é servir como tecido de transição das forças contráteis geradas pelos músculos aos ossos, podendo assim gerar movimentos. Entre todos os tendões, o calcâneo é um dos mais frequentemente lesados. As lesões ocorrem principalmente em homens e são mais frequentes entre a terceira e quarta década de vida. Dentre os vários métodos de sutura existentes, do ponto de vista clínico, a de Kessler-Tajima com os nós entre os cotos é muito utilizada por evitar o estrangulamento da microcirculação. Após a cirurgia o paciente retorna ao trabalho após 85 dias, em média, podendo atingir até 270 dias. O objetivo do presente estudo foi testar a eficiência da aplicação da proteína biocompatível F1, uma proteína extraída a partir do látex natural da Hevea brasiliensis, sobre tendões lesados, buscando uma melhora no reparo, assim como, a influência da sutura-U e de Kessler-Tajima. Alterações musculares decorrentes da lesão no tendão também foram avaliadas. Para isso, utilizamos ratos Sprague Dawley machos de 3 meses, que foram submetidos a tenotomia completa, a lesão foi corrigida com ambas as suturas, seguido da aplicação da proteína e avaliados após duas e quatro semanas. As técnicas utilizadas para análises no tendão foram as de microscopia de luz, microscopia eletrônica de varredura e transmissão, bem como, a síntese de colágeno tipos I e III, TIMP-1 e 2, MMP-2 e 9 por western blot. Para analisar as alterações musculares, a expressão dos genes MuRF1 e Atrogin1 foram quantificadas por RT-qPCR, seguido de análises de contração muscular máxima e teste de fadiga. Os resultados sugerem uma melhora no reparo do tendão no grupo que utilizamos a sutura-U associada à proteína após quatro semanas, devido ao aumento na síntese de colágeno tipo I e a diminuição de MMP-9, assim como, a capacidade de contração muscular máxima retorna aos níveis do grupo controle. A sutura-U também influencia menos na fadiga muscular. / Tendons are described as dense modeled connective tissue which insert the muscles to the bones. Its main function is to serve as transition tissue of the contractile forces generated by muscles to the bones, and thus generate movements. Among all the tendons, the calcaneal is the most frequently injured one. The lesions occur mainly in men and are more frequent between the third and fourth decade of life. Among the several existing suture methods, from a clinical point of view, the Kessler-Tajima with the nodes between the stumps is used to a great extent in order to avoid the microcirculations strangling. After surgery, the patient returns to work after 85 days, on average, and can reach up to 270 days. The objective of this study was to test the efficiency of the application of biocompatible F1 protein, a protein extracted from natural latex from the Hevea brasiliensis, on injured tendons, seeking an improvement in the repair, as well as the influence of the suture-U and Kessler-Tajima. Muscle changes arising from the tendon injury were also evaluated. For this reason, Sprague Dawley male rats at 3 mounths-old were used, which underwent complete tenotomy, the lesion was corrected with both sutures, followed by the application of protein and evaluated after two and four weeks. The techniques used for analyzes in the tendon were the light microscopy, scanning electron microscopy and transmission, as well as the synthesis of collagen types I and III, TIMP-1, -2, MMP-2, and -9 by Western blot. In order to analyze the muscular alterations, the expression of genes MuRF1 and Atrogin1 were quantified by RT-qPCR, followed by analysis of maximum muscle contraction and fatigue testing. The results suggest an improvement in the tendon repair in the group that the suture-U was used associated with protein after four weeks, due to the increase in the synthesis of collagen type I and the decrease of MMP-9, as well as the ability of maximum muscle contraction to return to the levels of the control group. The suture-U also influences on less muscle fatigue.

O crescente aumento do interesse no desenvolvimento em técnicas cirúrgicas menos invasivas, como nas reconstruções tendíneas e ligamentares, tem levado ao aumento das pesquisas referentes ao uso de aloenxertos esterilizados por radiação ionizante. O processamento por radiação ionizante é um método seguro e não deixa resíduos, sendo utilizado como esterilização final. O presente estudo teve como proposta avaliar os efeitos da aplicação de radiação ionizante, produzida por fonte de 60Co, em amostras de tendões humanos pré processados de doadores multiorgãos obtidas por meio de colaboração com Bancos de Tecidos. O pré-processamento das amostras deu-se por métodos químicos e preservação por congelamento em -80 °C. As doses aplicadas no processamento por radiação foram de 12,5 kGy, 15,0 kGy e 25,0 kGy, cada uma com seu respectivo controle não irradiado. As amostras foram avaliadas por meio de testes histológicos, ópticos e biomecânicos, com o objetivo de analisar possíveis modificações morfológicas e estruturais. Os resultados apresentados demonstraram que o processamento por ultrassom e peróxido de hidrogênio causaram alterações na morfologia dos tecidos, o que ocasionou danos à sua estrutura, inviabilizando as amostras. Nas amostras processadas por álcool e antibiótico não foram observados danos na rede de colágeno pela aplicação da radiação. Os resultados dos testes biomecânicos apresentaram diferenças significativas entre os métodos aplicados. As amostras processadas com álcool e antibiótico apresentaram perda pouco significativa no módulo de elasticidade, comparadas às amostras processadas por ultrassom e peróxido de hidrogênio que mantiveram a propriedade viscoelástica. Contudo na dose de 12,5 kGy foi observado um aumento no módulo elástico e na viscoelasticidade. Com base nas análises, podemos concluir que o método de processamento com álcool, antibiótico e irradiação demonstrou menor dano, tanto na biomecânica quanto na esterilização, sendo que as amostras irradiadas a 15,0 e 25,0 kGy apresentaram características semelhantes ao controle não irradiado. / The increasing interest of development in less invasive surgical techniques, such as reconstructions of ligament tendon, has led to the increase of the research concerning the use of Allografts sterilized by ionizing radiation. Processing by ionizing radiation is a safe method and leaves no residues, being used as final sterilization. The present study was to evaluate the effects of proposed application of ionizing radiation, produced by 60Co source in human tendon pre-samples processed multiorgans donors obtained through collaboration with tissue banks. The pre-processing of samples given by chemical methods and preserved by freezing at -80 °C. The doses applied in radiation processing were 12.5, 15.0 and 25.0 kGy, each with your corresponding non-irradiated control. The samples were evaluated by means of histological and biomechanical testing, with the purpose of analyzing possible structural and morphological changes. The results showed that the ultrasound processing and hydrogen peroxide caused changes in the morphology of the tissues, which caused damage to the structure, making your samples. In the samples processed by alcohol and antibiotics were not observed damage on the network of collagen by the application of radiation. The results of biomechanical tests showed significant differences between the methods used. The samples processed with alcohol and antibiotics showed negligible loss in modulus of elasticity compared with the samples processed by ultrasound and hydrogen peroxide which kept the viscoelastic property, however in 12.5 kGy dose was observed an increase in elastic modulus and viscoelasticity. Based on the analysis we can conclude that the method of processing with alcohol, antibiotics and irradiation showed less damage, both in biomechanics and sterilization, in the samples irradiated with 15.0 and 25.0 kGy, showing results similar to the non-irradiated control.

INTRODUÇÃO: A ultrassonografia (US) e a ressonância magnética (RM) representam os principais métodos de diagnósticos por imagem na avaliação do mecanismo extensor do joelho. Há carência de trabalhos que avaliem por US e RM a presença de alterações no mecanismo extensor de jogadores de futebol assintomáticos. OBJETIVO: Avaliar, por meio de RM e US, o tendão quadríceps e o ligamento patelar de jogadores de futebol assintomáticos e dos participantes do grupo-controle. Identificar se há alterações de imagens ou lesões. Determinar se essas sofrem influências pelos seguintes critérios: canhoto ou destro, quanto à dominância ao chute, posição em campo, idade do atleta e tempo de prática esportiva. MÉTODO: Foram avaliados um total de 248 joelhos: 112 eram de 56 de jogadores de futebol assintomáticos e 136 eram do grupo-controle. O grupo composto por jogadores de futebol apresentava idades entre 14 e 34 anos. Já o grupo-controle era composto por indivíduos com idade também entre 14 e 34 anos, principalmente, universitários e funcionários do hospital, com gênero igual aos dos jogadores selecionados, mas sem atividades físicas de impacto, como vôlei, futebol e salto, por exemplo. RESULTADO: Constatou-se a presença de alterações de imagens ou de lesões em nove ligamentos patelares e apenas duas nos tendões quadríceps de jogadores de futebol assintomáticos, tanto pela US quanto pela RM, e nenhum caso alterado no grupo-controle. Houve concordância significativa entre RM e US quanto aos resultados obtidos. Além disso, os jogadores de futebol apresentaram anormalidades (alterações de imagens ou lesões) no tendão quadríceps ou no ligamento patelar significativamente (p<0,05) maior do que no grupo-controle; a idade média dos jogadores com alguma anormalidade é significativamente menor do que a dos jogadores sem lesão (p<0,003); o tempo médio de prática desportiva dos jogadores que apresentam anormalidade é menor do que o tempo médio dos jogadores que não têm anormalidade (p<0,001); os jogadores destros apresentaram anormalidades, enquanto que os jogadores canhotos não (p<0,05). Dentre os jogadores, há correlação entre mais alterações de imagem ou lesão de joelho e menor tempo como jogador e menor idade (R² de Nagelkerke = 0,700). Destros têm risco aumentado de ter anormalidade nas referidas estruturas (Razão de Chances = 15,204) quanto menor for o tempo como jogador de futebol. Os jogadores da defesa têm 4,76 vezes mais chance de desenvolver anormalidade do que atacantes e goleiros (p<0,04). CONCLUSÃO: Os jogadores de futebol assintomáticos apresentam anormalidades no tendão do quadríceps e ligamento patelar detectadas pela RM e US. As alterações estão relacionadas a menor idade, menor tempo de prática desportiva, ser destro e ser jogador de defesa / INTRODUCTION: Ultrasonography (US) and magnetic resonance imaging (MRI) are the main diagnostic imaging methods used in evaluation of the extensor mechanism of the knee. Theres a scarcity of works assessing alterations on the extensor mechanism of the knee of asymptomatic soccer players using US and MRI. OBJECTIVE: To assess, by means of MRI and US imaging, the quadriceps tendon and patellar ligament of asymptomatic soccer players and healthy control group; identify abnormal imaging findings or injuries; ascertain whether these are affected by leg dominance (left or right), field position, age, and time spent practicing the sport. METHOD: A total of 248 knees were evaluated: 112 of 56 asymptomatic soccer players and 136 of healthy controls. The players ages ranged from 14 to 34 years. The control group was composed mostly of college students and hospital staff members, also with ages between 14 and 34, matched for gender to the selected soccer players, and who did not engage in high-impact activities such as volleyball, soccer, or jumping. RESULTS: Abnormal imaging findings or injuries were detected, by US and MRI alike, in nine patellar ligaments and two quadriceps tendons of asymptomatic soccer players. No abnormal findings were detected in the control group. CONCLUSION: There was significant consistency between MRI and US findings. Soccer players were much more likely (p<0.05) to have abnormal imaging findings or injuries of the quadriceps tendon and patellar ligament as compared with the control group; the average age of players presenting some abnormality is significantly lower than of those without injuries (p<0.003); the average time spent practicing the sport for players presenting abnormalities is lower than those who dont present injuries (p<0.001); a correlation between the dominant leg and the affected knee was observed, with the players with a dominant right leg presenting injuries while the ones with a dominant left leg not showing abnormalities (p<0.05). Amongst the players there is a correlation between more abnormal imaging findings or injuries on the knee and less professional practicing time and age (Nagelkerke R² = 0.700).Players with a dominant right leg have an increased chance of presenting abnormalities on the quadriceps tendon and patellar ligament (Odds Ratio = 15.204) with a lower average time spent practicing the sport. Defense players have 4.76 times more chance to develop abnormalities than forward players and goalkeepers (p<0.04). CONCLUSION: The asymptomatic soccer players present abnormalities on the quadriceps tendon and patellar ligament identified using ultrasonography (US) and magnetic resonance imaging (MRI). The alterations are related with less age, less time of professional practice, right leg dominance and defense field position

Li Chi Kei. / Thesis (M.Phil.)--Chinese University of Hong Kong,1995. / Includes bibliogrpahical references (leaves 54-68). / Abstract --- p.1 / Acknowledgments --- p.4 / Lists of Figures --- p.5 / List of Tables --- p.8 / Chapter Chapter 1 --- Introduction --- p.9 / Chapter 1.1 --- Ligamental Injury --- p.9 / Chapter 1.2 --- ACL Injury --- p.10 / Chapter 1.3 --- Patellar Tendon and Anterior Cruciate Ligament --- p.11 / Chapter 1.4 --- Patellar Tendon Bone Graft --- p.13 / Chapter 1.41 --- Strength of the Patellar Tendon Bone Graft --- p.13 / Chapter 1.42 --- Use of the Patellar Tendon Bone Graft --- p.14 / Chapter 1.5 --- Patellar Tendon Bone Graft in Anterior Cruciate Ligament Reconstruction --- p.14 / Chapter 1.6 --- Complications of Anterior Cruciate Ligament Reconstruction after the Use of Patellar Tendon Bone Graft --- p.16 / Chapter 1.7 --- Healing of the Patellar Tendon Donor Site --- p.17 / Chapter 1.8 --- Objective of the Study --- p.22 / Chapter 1.9 --- Significance of the Study --- p.22 / Chapter Chapter 2 --- Material & Method --- p.24 / Chapter 2.1 --- Animal Model --- p.24 / Chapter 2.2 --- Grouping --- p.24 / Chapter 2.3 --- Operative Procedure --- p.24 / Chapter 2.4 --- Method of Assessment --- p.26 / Chapter 2.41 --- Gross Morphology --- p.26 / Chapter 2.42 --- Biomechanical Testing --- p.27 / Chapter 2.43 --- Biochemical Assay --- p.28 / Chapter 2.43.1 --- Water Content --- p.29 / Chapter 2.43.2 --- Collagen Content --- p.29 / Chapter 2.44 --- Histology --- p.30 / Chapter 2.45 --- Immunohistochemistry --- p.31 / Chapter 2.5 --- Statistics --- p.32 / Chapter Chapter 3 --- Results --- p.33 / Chapter 3.1 --- Operation Complications --- p.33 / Chapter 3.2 --- Gross Morphology --- p.33 / Chapter 3.21 --- Dimension of the Patellar Tendon --- p.33 / Chapter 3.22 --- Dimension of the Patellar Tendon Bone Graft --- p.33 / Chapter 3.23 --- Dimension of the Remain Patellar Tendon --- p.34 / Chapter 3.24 --- Gross Appearance of the Patellar Tendon Donor Site --- p.35 / Chapter 3.3 --- Biomechanical Testing --- p.36 / Chapter 3.31 --- Failure Load --- p.36 / Chapter 3.32 --- Ultimate Stress --- p.37 / Chapter 3.33 --- Stiffness --- p.37 / Chapter 3.34 --- Energy Absorbed before Failure --- p.38 / Chapter 3.4 --- Biochemical Assay --- p.38 / Chapter 3.41 --- Water Content --- p.38 / Chapter 3.42 --- Collagen Content --- p.39 / Chapter 3 .5 --- Histology & Immunohistochemistry --- p.39 / Chapter 3.51 --- Morphology of Control Tendon --- p.40 / Chapter 3.52 --- Morphology of Experimental Tendon with 'Open' Procedure --- p.40 / Chapter 3.53 --- Morphology of Experimental Tendon with 'Close' Procedure --- p.41 / Chapter 3.54 --- Healing at the Patellar and Tibial Insertion Site --- p.41 / Chapter 3.55 --- Morphology of the Cartilage Surface --- p.42 / Chapter Chapter 4 --- Discussion & Conclusion --- p.43 / Chapter 4.1 --- Gross Morphology --- p.43 / Chapter 4.2 --- Biomechanical Testing --- p.45 / Chapter 4.3 --- Biochemical Assay --- p.47 / Chapter 4.4 --- Histology & Immunohistochemistry --- p.49 / Chapter 4.5 --- Conclusion --- p.51 / References --- p.54 / Figures / Tables / Appendix

肌腱損傷發生率高，並且癒合結果很不理想，因為少量的肌腱細胞缺乏有效的修復能力，僅僅通過瘢痕形成來癒合, 肌腱瘢痕癒合難以恢復原本的肌腱組織結構及力學特性。目前，國內外臨床上治療肌腱損傷的方法很多，包括藥物、物理治療、手術等，這些並不能獲得滿意的療效。因此，如何採用肌腱組織工程技術迅速、安全、有效的修復肌腱損傷已成為運動醫學領域急需解決的重要問題。 / 有研究表明，骨髓間充質幹細胞、表皮成纖維細胞、肌腱細胞和胚胎幹細胞通過肌腱組織工程技術用於肌腱修復及再生取得了不錯的療效。但是，這些來源的細胞存在分化效率低，形成畸胎瘤和異位骨化等風險。近來，有研究報導可從人、小鼠、大鼠和兔的肌腱組織中分離培養出幹細胞，可作為肌腱組織工程種子細胞的一種新選擇，用於肌腱修復和再生。對於間充質幹細胞的成肌腱分化，有研究報導結締組織生長因子（CTGF）和抗壞血酸（維生素C的一種形式）在膠原及細胞外基質合成、調節細胞成肌腱分化方面扮演者重要的角色。 / 本研究的旨在：（1）在大鼠髕腱損傷模型中，證實肌腱幹細胞可作為一種新的幹細胞來源用於肌腱修復；（2）檢驗結締組織生長因子和抗壞血酸能在體外促進肌腱幹細胞的成肌腱分化；（3）嘗試通過肌腱幹細胞的成肌腱分化過程在體外構建不含外源性支架的肌腱樣組織；（4）探索該肌腱樣組織在大鼠髕腱損傷模型中是否可以促進肌腱癒合。 / 在大鼠急性髕腱損傷動物模型中，與對照組相比，肌腱幹細胞組具有更好的膠原排列，顯著增高的最大張力和楊氏模量，表明肌腱幹細胞可作為一種新的幹細胞來源用於肌腱損傷的修復。結締組織生長因子和抗壞血酸體外誘導肌腱幹細胞2周後，可顯著增加Tenomodulin, Scleraxis, Thbs4, I型膠原等肌腱相關基因的表達以及膠原蛋白的合成，說明結締組織生長因子和抗壞血酸可促進肌腱幹細胞的成肌腱分化。被結締組織生長因子和抗壞血酸誘導兩周後，肌腱幹細胞可形成了細胞膜樣結構，將這種細胞膜纏繞在迴紋針上，構建成肌腱樣組織，其具有相對疏鬆的細胞外基質和雜亂排列其中的肌腱幹細胞，以及表達Tenomodulin，I型膠原和III型膠原。將該肌腱樣組織移植到裸鼠體內8周和12周可形成新生肌腱組織，梭形細胞縱行分佈在平行的膠原纖維之間，並表達Tenomodulin，I型膠原和III型膠原蛋白。在大鼠髕腱損傷動物模型中，與對照組相比較，該肌腱樣組織可通過恢復肌腱組織結構及生物力學特性來促進肌腱癒合。 / 總的來說，本研究證實肌腱幹細胞可作為一種新的幹細胞來源用於肌腱組織工程促進肌腱再生。結締組織生長因子和抗壞血酸可調控肌腱幹細胞的成肌腱分化，並形成細胞膜結構。該細胞膜結構可在體外構建出不含外源性支架的肌腱樣組織，進而在裸鼠體內形成新生肌腱，並且在大鼠髕腱損傷模型中可有效的促進損傷肌腱的癒合。這種不含外源性支架的肌腱樣組織有希望成為肌腱組織工程技術的新手段，在肌腱再生和肌腱修復的臨床應用及基礎研究方面有廣泛的前景。 / Tendon injuries are common and tendon healing outcome is poor, because tendon contains few cells with limited capacities for self-repair/regeneration. The current treatments on tendon injuries including drugs, physiotherapy, and surgery are not ideal and there is a need for the development of novel tissue-engineering strategies for tendon repair. / Previous studies have shown positive effects of bone marrow-derived mesenchymal stem cells (BMSCs), dermal fibroblast, tenocytes, and embryonic stem cells-derived MSCs for tendon repair/regeneration. However, these cells have limitations including insufficient differentiation; risk of teratoma and ectopic bone formation etc. Recently, stem cells have been isolated from tendons of human, mouse, rat and rabbit and considered as a new alternative cell source for tendon tissue engineering (TDSCs). For tenogenic differention of MSCs, connective tissue growth factor (CTGF) and ascorbic acid (one form of vitamin C) are reported to play important roles in promoting collagen and other extracellular matrixes (ECM) production, and regulating the MSCs differentiation towards tenogenic pathway. / The aims of the current study are: (1) To investigate the use of TDSCs in tendon repair in a rat acute patellar tendon injury model; (2) To test the effects of CTGF and ascorbic acid on tenogenic differentiation of TDSCs in vitro; (3) To construct scaffold-free tendon-like tissues in vitro using tenogenically differentiated TDSCs; (4) To promote tendon healing by engineered tendon-like tissues in a rat acute patellar tendon injury model. / In the rat acute patellar tendon injury model, in contract to control group, TDSCs treated group showed better alignment of collagen fibers and the significantly higher ultimate stress and Young’s modulus, indicating TDSCs may be an alternative cell source for tendon repair. The effects of CTGF and ascorbic acid on tenogenic differentiation of TDSCs were also confirmed with higher expression of tendon related markers such as Tenomodulin, Scleraxis, Thbs4, Type I Collagen, etc; with higher production of collagenous proteins. After treatment with CTGF and ascorbic acid for 2 weeks, TDSCs can form cell sheets, which can be harvested, rolled up on a U-shaped spring to form tendon-like tissues in culture, which had loose extracellular matrices and randomly distributed TDSCs and also expressed Tenomodulin, Type I & III collagen. Following transplantation of the engineered tendon-like tissue in nude mice for 8 and 12 weeks, neo-tendon tissues were formed, with thin and parallel collagen fibrils and extracellular matrices of Tenomodulin, Type I & III collagen. Finally in the rat patellar tendon window injury model, data suggested that the engineered tendon-like tissue could promote tendon healing with significantly improved histological features and biomechanical properties comparing to the control group. / In conclusion, our study has indicated that TDSCs can be an alternative cell source in tendon tissue engineering for tendon regeneration. The tenogenic differentiation of TDSCs, induced by CTGF and ascorbic acid in vitro, produces cell sheets, which can be constructed tendon-like tissues in vitro; to form neo-tendon and repair tendon injuries in vivo. The use of engineered scaffold-free tendon tissue for tendon tissue engineering has potentials in clinical application for tendon repair/regeneration. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Ni, Ming. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 107-126). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / DEDICATION --- p.I / ACKNOWLEDGEMENT --- p.II-III / TABLE OF CONTENTS --- p.IV-IX / PUBLICATIONS --- p.X-XII / ABBREVIATION --- p.XIII-XV / ABSTRACT (ENGLISH) --- p.XVI-XVIII / ABSTRACT (CHINESE) --- p.XIX-XX / Chapter CHAPTER 1 --- Introduction --- p.1 / Chapter 1.1 --- Epidemiology of tendon injury --- p.1 / Chapter 1.2 --- Healing process of tendon injury --- p.1 / Chapter 1.3 --- Tendon tissue engineering for tendon repair --- p.2 / Chapter 1.4 --- Stem cells in tendon repair --- p.2 / Chapter 1.5 --- Tenogenic differentiation of tendon derived stem cells --- p.7 / Chapter 1.6 --- Growth factors for tenogenic differentiation --- p.8 / Chapter 1.7 --- Vitamin C for tenogenic differentiation --- p.9 / Chapter 1.8 --- Summary --- p.10 / Chapter CHAPTER 2 --- Hypothesis, Objectives and Study Design --- p.11 / Chapter 2.1 --- Hypothesis --- p.11 / Chapter 2.1.1 --- Overall hypothesis --- p.11 / Chapter 2.1.2 --- Specific hypothesis --- p.11 / Chapter 2.2 --- Objectives --- p.12 / Chapter 2.3 --- Study design --- p.12 / Chapter 2.3.1 --- Study I --- p.12 / Chapter 2.3.2 --- Study II --- p.14 / Chapter 2.3.3 --- Study III --- p.14 / Chapter 2.3.4 --- Study IV --- p.17 / Chapter CHAPTER 3 --- Tendon-derived Stem Cells (TDSCs): A New Cell Source for Tendon Repair (Study I) --- p.19 / Chapter 3.1 --- Materials and Methods --- p.19 / Chapter 3.1.1 --- Isolation and characterization of rat GFP-TDSCs --- p.19 / Chapter 3.1.2 --- Animal surgery --- p.20 / Chapter 3.1.3 --- Ultrasound imaging --- p.25 / Chapter 3.1.4 --- Histology --- p.27 / Chapter 3.1.5 --- Biomechanical test --- p.27 / Chapter 3.1.6 --- Ex vivo fluorescence imaging --- p.28 / Chapter 3.1.7 --- Data analysis --- p.29 / Chapter 3.2 --- Results --- p.29 / Chapter 3.2.1 --- Gross observation of the injured knee and patellar tendon --- p.29 / Chapter 3.2.2 --- Histology of regenerated tendon tissue --- p.30 / Chapter 3.2.3 --- Biomechanical test of regenerated tendon tissue --- p.32 / Chapter 3.2.4 --- Ex vivo fluorescence imaging of GFP-TDSCs --- p.33 / Chapter 3.2.5 --- Ultrasound imaging of wound gap volume --- p.34 / Chapter 3.3 --- Discussion --- p.35 / Chapter 3.4 --- Conclusion --- p.50 / Chapter CHAPTER 4 --- Tenogenic Differentiation of Tendon-derived Stem Cells (TDSCs) (Study II) --- p.51 / Chapter 4.1 --- Materials and Methods --- p.51 / Chapter 4.1.1 --- Tenogenic differentiation of tendon-derived stem cells (TDSCs) --- p.51 / Chapter 4.1.2 --- Quantification of collagenous proteins --- p.51 / Chapter 4.1.3 --- Quantitative Real Time PCR (qRT-PCR) --- p.52 / Chapter 4.1.4 --- Data analysis --- p.54 / Chapter 4.2 --- Results --- p.55 / Chapter 4.2.1 --- Quantification of collagenous proteins --- p.55 / Chapter 4.2.2 --- Tenogenic, osteogenic and chondrogenic markers mRNA expression --- p.57 / Chapter 4.2.3 --- Tendon extracellular matrix markers mRNA expression --- p.57 / Chapter 4.3 --- Discussion --- p.59 / Chapter 4.4 --- Conclusion --- p.66 / Chapter CHAPTER 5 --- Engineered Scaffold-free Tendon Tissue Produced by Tendon-derived Stem Cells (TDSCs) Cell Sheet (Study III) --- p.67 / Chapter 5.1 --- Materials and Methods --- p.67 / Chapter 5.1.1 --- In vitro engineered scaffold-free tendon tissue by TDSCs cell sheet --- p.67 / Chapter 5.1.2 --- In vivo neo-tendon formation using engineered scaffold-free tendon tissue in nude mouse model --- p.67 / Chapter 5.1.3 --- Histology and immunohistochemistry staining --- p.68 / Chapter 5.1.4 --- In vivo fluorescence imaging --- p.69 / Chapter 5.1.5 --- Data analysis --- p.70 / Chapter 5.2 --- Results --- p.70 / Chapter 5.2.1 --- Gross observation of TDSCs cell sheet and engineered scaffold-free tendon tissue --- p.70 / Chapter 5.2.2 --- Histological and immunohistochemical characteristics in engineered scaffold-free tendon tissue --- p.71 / Chapter 5.2.3 --- Gross observation and in vivo fluorescence imaging of neo-tendon tissue --- p.74 / Chapter 5.2.4 --- Histology of neo-tendon tissue --- p.75 / Chapter 5.2.5 --- Immunohistochemistry staining in neo-tendon tissue --- p.76 / Chapter 5.3 --- Discussion --- p.78 / Chapter 5.4 --- Conclusion --- p.82 / Chapter CHAPTER 6 --- Use of Engineered Scaffold-free Tendon Tissue for Tendon Repair (Study IV) --- p.83 / Chapter 6.1 --- Materials and methods --- p.83 / Chapter 6.1.1 --- Animal surgery --- p.83 / Chapter 6.1.2 --- Ex vivo fluorescence imaging --- p.84 / Chapter 6.1.3 --- Histology and immunohistochemistry staining --- p.85 / Chapter 6.1.4 --- Biomechanical test --- p.86 / Chapter 6.1.5 --- Ultrasound imaging --- p.87 / Chapter 6.1.6 --- Data Analysis --- p.87 / Chapter 6.2 --- Results --- p.88 / Chapter 6.2.1 --- Gross observation of the injured knee and patellar tendon --- p.88 / Chapter 6.2.2 --- Histology of regenerated tendon tissue --- p.89 / Chapter 6.2.3 --- Tendon specific and ECM markers expression in regenerated tendon tissue --- p.91 / Chapter 6.2.4 --- Osteogenic and chondrogenic specific markers expression in neo-tendon tissue --- p.93 / Chapter 6.2.5 --- The fate of the transplanted engineered scaffold-free tendon tissue --- p.93 / Chapter 6.2.6 --- Biomechanical test of regenerated tendon tissues --- p.94 / Chapter 6.3 --- Discussion --- p.96 / Chapter 6.4 --- Conclusion --- p.102 / Chapter CHAPTER 7 --- General Conclusions --- p.103 / Chapter 7.1 --- General discussion --- p.103 / Chapter 7.2 --- General conclusions --- p.105 / FUNDING --- p.106 / REFERENCES --- p.107 / APPENDIX --- p.127

Research applications of nuclear magnetic resonance (NMR) span a broad range of fields and disciplines. The work presented in this dissertation attests to this fact. Specifically, the research topics discussed in the body of this work employ NMR spectroscopy and imaging to characterize the water diffusion and NMR relaxation times ex vivo in rabbit Achilles tendon and, in a clinical setting, employ functional magnetic resonance imaging (fMRI) to investigate the behavior of different neural networks over a period of sustained activity. In the ex vivo rabbit Achilles tendon work, a series of studies were performed. First, the diffusion-time dependence of the water apparent diffusion coefficient (ADC) was characterized in a spectroscopic mode with the samples subjected to different states of tensile loading. The results of this study demonstrated: (1) the anisotropy of the diffusion of water through tendon; (2) the ADC is diffusion-time dependent; (3) the values of the ADC(tdif) curve increased with tensile loading; (4) a change at the short diffusion-time points that is consistent with the interpretation of a load-induced increase in the collagen fibril packing density; and (5) an increase in the water ADC at long diffusion times is hypothesized to be due to T1 editing. To further investigate these issues, another series of ex vivo rabbit Achilles tendon experiments was performed that employed NMR imaging to spatially characterize the water ADC, T1 and T2 relaxation time constants. As with the spectroscopic work, these studies were also conducted with the tendon samples subjected to different states of tensile loading. The results from these imaging experiments demonstrate: (1) two regions with distinct differences in signal intensity across the tendon: a thin region of high signal intensity at the peripheral rim of the tendon that encircles a region of low signal intensity in the central core of the tendon; (2) a higher diffusion anisotropy ratio in the tendon central core relative to the peripheral rim; (3) upon tensile loading, significant increases in the ADC of water in the peripheral rim region and a corresponding increase in a measure of the change in proton density in the rim region, consistent with the hypothesis that tensile loading causes extrusion of water from the core to the rim region of the tendon; (4) this water extrusion is not uniformly distributed throughout the tendon rim region; and (5) the long-diffusion-time ADC behavior is consistent with the T1 spin editing hypothesis of the spectroscopic work. From the clinical fMRI studies, an analysis method was presented for observing dynamic changes in brain regions involved in different neural network processes during a period of sustained activity. The results from these studies are consistent with the idea that over time, brain regions adapt to the given task demands through either recruitment or discharge of adjacent areas of tissue. These results also indicate that traditional analysis of block design fMRI studies may underestimate dynamic changes in brain regions during a sustained task. The analysis method may be useful as an exploratory tool to observe region specific variations in activation that may allow inferences to be made regarding how different brain regions adapt to and interact with one another during periods of extended activity.

A cadência de pedalada é um importante componente na produção de potência, sendo responsável pelas mudanças na velocidade de encurtamento muscular, a qual influencia diretamente o desempenho no ciclismo. Ainda não está claro se a redução na ativação muscular e o menor torque no pedivela estão associados com a redução na contribuição dos tecidos ativos e/ou passivos em diferentes velocidades de pedalada. O objetivo da presente dissertação foi investigar o efeito de diferentes cadências de pedalada (70 e 90 rpm) sobre a arquitetura muscular do vasto lateral (VL) e comprimento da unidade músculo-tendão (UMT). Além de dados adicionais, da unidade músculo-tendão, força e a atividade elétrica dos músculos vasto medial, reto femoral e bíceps femoral, do torque muscular, força, ângulo do joelho, assim como a força resultante no pedal durante a pedalada. A amostra foi composta por 19 atletas (11 ciclistas e 8 triatletas) experientes em ciclismo. As características dos atletas avaliados foram (média±DP): 29 ± 7,4 anos de idade, 72 ± 8,3 kg de massa corporal, 178 ± 8,9 cm de altura, 382 ± 62 km por semana de treinamento de ciclismo, POMAX = 381 ± 37 W da potência máxima aeróbica e 62 ± 6 ml/kg/min de consumo máximo de oxigênio. Os atletas realizaram um teste preliminar para determinação da potência máxima aeróbica durante carga máxima de trabalho, enquanto no segundo teste eles pedalaram na potência referente ao segundo limiar ventilatório (POLV2 = 324±37 W) a 90 e 70 rpm em ordem randomizada por sorteio. A força aplicada no pedal direito, a ativação muscular do membro inferior, a cinemática da articulação do joelho e a arquitetura muscular foram coletadas durante os últimos 20 segundos de cada teste. Esses dados foram utilizados em um modelo biomecânico para verificação da variação do comprimento da unidade músculo-tendão nas respectivas cadências. Comparações estatísticas foram realizadas utilizando testes t de Student entre as duas cadências (70 e 90 rpm) para todas as variáveis do estudo, assumindo uma diferença significativa quando p≤0,05. Para o teste utilizamos o software SPSS 17.0 para Windows. Foi observada uma diminuição significativa no torque extensor do joelho (70 rpm = 108±13% vs. 90 rpm = 97±13%; p<0,01), na força resultante no pedal (70 rpm = 107±11% vs. 90 rpm = 94±7%; p<0,01) e na força do quadríceps (70 rpm = 107±17% vs. 90 rpm = 98±13%; p<0,01) na cadência de 90 rpm comparado a cadência de 70 rpm. Foram observadas ainda similaridade para o ângulo do joelho entre as cadências (100±20% em 70 rpm vs. 99±6% em 90 rpm; p=0,92), e similaridade na espessura do músculo vasto lateral (70 rpm = 101±5%, 90 rpm = 99±6%; p=0,14), enquanto o comprimento do fascículo (70 rpm = 74±33%, 90 rpm = 86±35%; p=0,01) aumentou e o ângulo de penação diminuiu da cadência de 70 para a de 90 rpm (70 rpm = 115±45%, 90 rpm = 96±34%; p<0,01). O comprimento da UMT do quadríceps (70 rpm = 99±2%, 90 rpm = 100±2%; p≤0,05) e o comprimento da UMT do vasto lateral (70 rpm = 98±4%, 90 rpm = 100±4%; p=0,02) apresentaram um aumento na cadência de 70 para a cadência de 90 rpm. Para os músculos reto femoral (70 rpm = 100±1%, 90 rpm = 100±1%; p=0,08) e bíceps femoral (70 rpm = 100±1%, 90 rpm = 100±1%; p=0,16) não houveram diferenças significativas para o comprimento da UMT. A ativação muscular do vasto medial em 90 rpm apresentou um diminuição comparada à cadência de 70 rpm (70 rpm = 114±34% vs. 90 rpm = 83±19%; p≤0,05), enquanto a ativação dos músculos bíceps femoral e reto femoral não apresentaram diferença significativa entre as cadências. Em conclusão, a mudança na cadência de pedalada de 70 para 90 rpm em carga constante de trabalho reduz a produção de força dos extensores do joelho à 90 rpm, provavelmente decorrente de uma menor ativação do vasto medial e de um trabalho do fascículo em um maior comprimento e em um menor ângulo de penação do vasto lateral nessa cadência mais elevada. / Cycling cadence is an important component in power production, where changes muscle shortening velocity can affect cycling performance. It is not yet clear if the reduction in muscle activation and the lower crank torque are associated with decreases in contribution from active and/or passive tissues in different cycling cadences. The propose of this master thesis was to investigated the influence of two cycling cadences (70 and 90 rpm) on muscle architecture of the vastus lateralis and muscle-tendon unit length. As well, addictional data was analyzed as muscle-tendon unit, force, and the muscle activation of vastus medialis, rectus femoris and biceps femoris, muscular torque, force, knee angle and resultant force during pedaling. Nineteen athletes (11 cyclists and 8 triathletes) experienced in cycling have taken part in this study. The characteristics of cyclists/triathletes were(mean ±SD): 29 ±7.4 years of age, 72 ±8.3 kg of body mass, 178 ±8.9 cm of height, 382 ±62 km per week of cycling training, 381 ±37 W of maximal aerobic power output, and 62 ±6 ml/kg/min of maximal oxygen uptake. The athletes performed an incremental cycling test to determinate their maximal workload. In a second they pedalled in their maximal workload and at the workload of their second ventilatory threshold (POVT2 = 324±37 W) at 90 and 70 rpm in random order. The force applied to the right pedal, lower limb muscles’ activation, lower limb kinematics and the ultrasound images from vastus lateralis were collected during the last 20 seconds of each test. This data was used in a biomechanical model to assess the influence of muscle-tendon unit in the two cadences. Student t tests were used to compare effects from pedalling cadences (70 and 90 rpm) in this study, assuming a significant difference when p≤0.05 using a statistical package (SPSS 17.0 for windows). A significant decrease in knee extensor torque (70 rpm = 108±13% vs. 90 rpm = 97±13%; p<0.01), in crank torque (70 rpm = 107±11% vs. 90 rpm = 94±7%; p<0.01) and in quadriceps force (70 rpm = 107±17% vs. 90 rpm = 98±13%; p<0.01) were found at 90 rpm compared to 70 rpm. No differences were found for the knee angle between cadences (100±20% at 70 rpm vs. 99±6% at 90 rpm; p=0.92). Muscle thickness was not significantly different between cadences (70 rpm = 101±5%, 90 rpm = 99±6%; p=0.14), however the fascicle length significantly increased (70 rpm = 74±33%, 90 rpm = 86±35%; p=0.01) and pennation angle decreased (70 rpm = 115±45%, 90 rpm = 96±34%; p<0.01) from 70 rpm to 90 rpm. Muscle-tendon unit length of quadriceps showed a significant increase (70 rpm = 99±2%, 90 rpm = 100±2%; p≤0.05) followed by a significant increase in muscle-tendon unit length of vastus lateralis (70 rpm = 98±4%, 90 rpm = 100±4%; p=0.02) from 70 rpm to 90 rpm. Rectus femoris (70 rpm = 100±1%, 90 rpm = 100±1%; p=0.08) and biceps femoris (70 rpm = 100±1%, 90 rpm = 100±1%; p=0.16) did not differ between the two cadences. Muscle activation of vastus medialis at 90 rpm showed a decrease compare to70 rpm (70 rpm = 114±34% vs. 90 rpm = 83±19%; p≤0.05), whistle biceps femoris and rectus femoris muscle did not differ between the two cadences. In conclusion, changes in cycling cadence from 70 rpm to 90 rpm at constant workload reduced force production at 90 rpm, resulting in a lower activation of the vastus medialis while fascicles worked at longer lengths and at smaller pennation angles.