ABSTRACT
The objective of this study was to develop a locked tibial-plateau-leveling osteotomy (TPLO) plate and to compare this implant with the conventional bone fixation method using a locked plate to determine bone stabilization against torsion forces. Maximum force, angle at peak torque, and stiffness values were determined. Ten synthetic tibias were used, divided into 2 groups. The results in Group 1 (modified TPLO plate) and Group 2 (locked plate) were assessed using analysis of variance and the means were compared using Tukey's test at 5% probability. There were significant differences in the angle at peak torque and stiffness. The group Modified TPLO plate had higher mean values of stiffness compared with Group locked plate. Group locked plate showed a greater angle at peak torque compared with Group modified TPLO plate. All constructs failed due to tibial fractures distal to the plate. The modified TPLO plate presented higher stiffness indexes than conventional locked plate in torsion. The locked plate presented greater elasticity than modified TPLO plate having greater angle at the peak of torque.(AU)
O objetivo do presente estudo foi desenvolver placa de TPLO bloqueada modificada e avaliar, em ensaio de torção, a estabilização óssea proporcionada pelo implante desenvolvido comparativamente a método de fixação óssea convencional com placa reta bloqueada. As variáveis obtidas foram força máxima, ângulo no pico de torque e rigidez. Foram utilizadas 10 tíbias sintéticas, dividas em dois grupos. Os resultados obtidos do grupo 1 (placa TPLO modificada) e do grupo 2 (placa bloqueada) foram submetidos à análise de variância, e as médias comparadas entre si pelo teste de Tukey a 5% de probabilidade. Houve diferença significativa em relação às variáveis, ângulo no pico de torque e rigidez. Na variável rigidez, a média do grupo placa de TPLO modificada foi maior que a do grupo placa reta bloqueada. Em relação à variável ângulo no pico de torque, o grupo placa reta bloqueada foi superior ao grupo placa de TPLO modificada. Todas as montagens falharam devido à quebra do corpo de prova distal à placa. Conclui-se que a placa de TPLO modificada apresentou maior índice de rigidez que a placa reta convencional sob força de torção. A placa reta bloqueada apresentou maior ângulo no pico de torque, sendo, portando, mais elástica.(AU)
Subject(s)
Animals , Dogs , Prostheses and Implants/veterinary , Orthopedic Procedures/veterinary , Fracture Fixation, Internal/methods , Fracture Fixation, Internal/veterinary , TibiaABSTRACT
Pelvic fractures correspond to 20 to 30 % of the fractures observed in dogs. Complete fractures, especially with bone axis deviation should be surgically treated. The mechanical study of surgical techniques is of utmost importance to assess the best way of treating these injuries. This study compared, biomechanically, the use of a dynamic compression plate (DCP) and screws (group 1) or screws and polymethylmethacrylate (PMMA) (group 2) to stabilize an iliac fracture using a static test. Sixteen canine synthetic hemi-pelvises (test specimens) with a transverse iliac osteotomy were used. After fixation with implants, a load was applied to the acetabulum until failure. Group 1 maximal compressive load was 133.9±18.60 N, displacement at yield 21.10±3.59mm and stiffness 125.22±12.25N/mm. Group 2 maximal compressive load was 183.50±27.38N, displacement at yield 16.66±5.42mm and stiffness 215.68±33.34N/mm. The stabilization with polymethylmethacrylate was stronger than dynamic compression plate since it resisted a greater load in all test specimens.(AU)
As fraturas da pelve são frequentes em cães, correspondendo a 20-30% das fraturas encontradas na espécie. A grande maioria delas é tratada cirurgicamente, principalmente aquelas que apresentam desvio ósseo. O estudo mecânico das técnicas cirúrgicas é de extrema importância para avaliação da melhor maneira de tratamento destas lesões. O objetivo deste estudo foi comparar, do ponto de vista biomecânico, a fixação das fraturas do ílio utilizando uma placa de compressão dinâmica ou parafusos associados ao polimetilmetacrilato, por meio de um teste estático. Foram utilizadas 16 hemipelves caninas de origem sintética, nas quais uma osteotomia transversa foi realizada no corpo do ílio. As fixações foram divididas em dois grupos: fixação com placa de compressão dinâmica e parafusos (grupo1) ou parafusos associados ao polimetilmetacrilato (grupo 2). Posteriormente à fixação dos implantes foi aplicada uma carga no acetábulo de cada corpo de prova até a falha. O grupo 2 apresentou força máxima de aplicação de carga a média de 133.9±18.60N, deflexão 21.10±3.59mm e rigidez 125.22±12.25N/mm. O grupo 2 apresentou força máxima de aplicação de carga a média de 183.50±27.38N, deflexão 16.66±5.42mm e rigidez 215.68±33.34N/mm. A estabilização com o polimetilmetacrilato mostrou ser mais resistente, pois resistiu a uma maior quantidade de carga em relação à placa de compressão dinâmica, em todos os corpos de prova.(AU)
Subject(s)
Animals , Dogs , Biomechanical Phenomena , Fracture Fixation, Internal/veterinary , Internal Fixators/veterinary , Pelvis/injuries , Polymethyl Methacrylate/therapeutic use , Polyurethanes , Fractures, Bone/surgeryABSTRACT
High-impact exercise has been considered an important method for treating bone loss in osteopenic experimental models. In this study, we investigated the effects of osteopenia caused by inactivity in femora and tibiae of rats subjected to jump training using the rat tail suspension model. Eight-week-old female Wistar rats were divided into five groups (n=10 each group): jump training for 2 weeks before suspension and training during 3 weeks of suspension; jump training for 2 weeks before suspension; jump training only during suspension; suspension without any training; and a control group. The exercise protocol consisted of 20 jumps/day, 5 days/week, with a jump height of 40 cm. The bone mineral density of the femora and tibiae was measured by double energy X-ray absorptiometry and the same bones were evaluated by mechanical tests. Bone microarchitecture was evaluated by scanning electron microscopy. One-way ANOVA was used to compare groups. Significance was determined as P<0.05. Regarding bone mineral density, mechanical properties and bone microarchitecture, the beneficial effects were greater in the bones of animals subjected to pre-suspension training and subsequently to training during suspension, compared with the bones of animals subjected to pre-suspension training or to training during suspension. Our results indicate that a period of high impact exercise prior to tail suspension in rats can prevent the installation of osteopenia if there is also training during the tail suspension.
Subject(s)
Animals , Female , Bone Diseases, Metabolic/prevention & control , Hindlimb Suspension/physiology , Physical Conditioning, Animal/physiology , Biomechanical Phenomena/physiology , Bone Density/physiology , Cancellous Bone/pathology , Femur/pathology , Femur/physiology , Hindlimb Suspension/adverse effects , Models, Animal , Rats, Wistar , Tibia/pathology , Tibia/physiologyABSTRACT
Osteoporosis has become a serious global public health issue. Hence, osteoporotic fracture healing has been investigated in several previous studies because there is still controversy over the effect osteoporosis has on the healing process. The current study aimed to analyze two different periods of bone healing in normal and osteopenic rats. Sixty, 7-week-old female Wistar rats were randomly divided into four groups: unrestricted and immobilized for 2 weeks after osteotomy (OU2), suspended and immobilized for 2 weeks after osteotomy (OS2), unrestricted and immobilized for 6 weeks after osteotomy (OU6), and suspended and immobilized for 6 weeks after osteotomy (OS6). Osteotomy was performed in the middle third of the right tibia 21 days after tail suspension, when the osteopenic condition was already set. The fractured limb was then immobilized by orthosis. Tibias were collected 2 and 6 weeks after osteotomy, and were analyzed by bone densitometry, mechanical testing, and histomorphometry. Bone mineral density values from bony calluses were significantly lower in the 2-week post-osteotomy groups compared with the 6-week post-osteotomy groups (multivariate general linear model analysis, P<0.000). Similarly, the mechanical properties showed that animals had stronger bones 6 weeks after osteotomy compared with 2 weeks after osteotomy (multivariate general linear model analysis, P<0.000). Histomorphometry indicated gradual bone healing. Results showed that osteopenia did not influence the bone healing process, and that time was an independent determinant factor regardless of whether the fracture was osteopenic. This suggests that the body is able to compensate for the negative effects of suspension.
Subject(s)
Animals , Female , Bone Diseases, Metabolic/physiopathology , Fracture Healing/physiology , Tibial Fractures/physiopathology , Bone Density/physiology , Bony Callus/physiopathology , Collagen/analysis , Hindlimb Suspension/adverse effects , Hindlimb Suspension/physiology , Models, Animal , Osteotomy/adverse effects , Random Allocation , Rats, Wistar , Time Factors , Torsion, MechanicalABSTRACT
The objective of the present study was to determine to what extent, if any, swimming training applied before immobilization in a cast interferes with the rehabilitation process in rat muscles. Female Wistar rats, mean weight 260.52 ± 16.26 g, were divided into 4 groups of 6 rats each: control, 6 weeks under baseline conditions; trained, swimming training for 6 weeks; trained-immobilized, swimming training for 6 weeks and then immobilized for 1 week; trained-immobilized-rehabilitated, swimming training for 6 weeks, immobilized for 1 week and then remobilized with swimming for 2 weeks. The animals were then sacrificed and the soleus and tibialis anterior muscles were dissected, frozen in liquid nitrogen and processed histochemically (H&E and mATPase). Data were analyzed statistically by the mixed effects linear model (P < 0.05). Cytoarchitectural changes such as degenerative characteristics in the immobilized group and regenerative characteristics such as centralized nucleus, fiber size variation and cell fragmentation in the groups submitted to swimming were more significant in the soleus muscle. The diameters of the lesser soleus type 1 and type 2A fibers were significantly reduced in the trained-immobilized group compared to the trained group (P < 0.001). In the tibialis anterior, there was an increase in the number of type 2B fibers and a reduction in type 2A fibers when trained-immobilized rats were compared to trained rats (P < 0.001). In trained-immobilized-rehabilitated rats, there was a reduction in type 2B fibers and an increase in type 2A fibers compared to trained-immobilized rats (P < 0.009). We concluded that swimming training did not minimize the deleterious effects of immobilization on the muscles studied and that remobilization did not favor tissue re-adaptation.
Subject(s)
Animals , Female , Rats , Immobilization , Muscle, Skeletal/pathology , Muscular Atrophy/rehabilitation , Physical Conditioning, Animal/physiology , Swimming/physiology , Adaptation, Physiological , Muscular Atrophy/etiology , Rats, WistarABSTRACT
CONTEXTUALIZAÇÃO: O ultra-som terapêutico (UST) é um recurso comumente aplicado na aceleração do reparo tecidual de lesões musculares. A absorção das ondas ultra-sônicas é determinada pela freqüência e pela intensidade, sendo que, em uma mesma intensidade, a profundidade atingida por 1MHz é maior quando comparada a 3MHz. OBJETIVO: Analisar o comportamento das propriedades mecânicas de músculos submetidos à lesão aguda por impacto e tratados com UST, utilizando as freqüências de 1 e 3MHz. MATERIAIS E MÉTODOS: Foram utilizadas 40 ratas Wistar (200,1±17,8g), divididas em quatro grupos: (1) controle; (2) lesão muscular sem tratamento; (3) lesão muscular tratada com UST de freqüência 1MHz (0,5W/cm²) e (4) lesão muscular tratada com UST de freqüência 3MHz (0,5W/cm²). A lesão foi provocada no músculo gastrocnêmio por mecanismo de impacto. O tratamento foi de cinco minutos diários durante seis dias consecutivos. Os músculos foram submetidos a ensaios mecânicos de tração em uma máquina universal de ensaios. RESULTADOS: As médias e desvios-padrão das propriedades mecânicas dos grupos lesionados e tratados com UST foram significativamente maiores quando comparadas ao grupo lesionado sem tratamento (p<0,05). Em destaque, a propriedade de rigidez que, com a aplicação do UST, teve acréscimo de aproximadamente 38 por cento. CONCLUSÕES: A intervenção, por meio do UST, promoveu aumento das propriedades mecânicas nos músculos lesionados aproximando-as do grupo controle. Entretanto, não foi observada diferença significativa entre as propriedades mecânicas dos grupos tratados com ultra-som de freqüências 1MHz e 3MHz.
BACKGROUND: Therapeutic ultrasound is a resource commonly applied to speed up tissue repair in muscle injuries. The absorption of the ultrasound waves is determined by their frequency and intensity. For a given intensity, the depth reached by 1MHz is greater than the depth reached by 3MHz. OBJECTIVE: To analyze the mechanical properties of muscles subjected to acute impact injury treated with therapeutic ultrasound at the frequencies of 1 and 3MHz. METHODS: Forty female Wistar rats (200.1±17.8g) were used, divided into four groups: (1) control; (2) muscle injury without treatment; (3) muscle injury treated with therapeutic ultrasound at the frequency of 1MHz (0.5W/cm²); and (4) muscle injury treated with therapeutic ultrasound at the frequency of 3MHz (0.5W/cm²). The injury was produced in the gastrocnemius muscle by means of an impact mechanism. The treatment consisted of a single five-minute session per day, for six consecutive days. The muscles were subjected to mechanical traction tests in a universal test machine. RESULTS: Means and standard deviations for the mechanical properties of the injured groups that received therapeutic ultrasound were significantly greater than those of the injured group without treatment (p<0.05). The property of stiffness should be highlighted: the application of therapeutic ultrasound increased muscle stiffness by approximately 38 percent. CONCLUSIONS: Therapeutic ultrasound increased the mechanical properties of the injured muscles, and brought them to a level close to the control group. However, no significant difference in mechanical properties was observed between the groups treated with ultrasound at the frequencies of 1MHz and 3MHz.
Subject(s)
Rats , Animals , Physical Therapy Modalities , Musculoskeletal System/injuries , Ultrasonic TherapyABSTRACT
It was studied the arrangement of the collagen fibrils of the medial collateral ligament of the canine elbow joint and evaluated its diameter, when it was isolated or associated to the oblique ligament and loaded in tension until failure. Eighteen joints were divided in three groups. The first group had the medial collateral ligament collected and not loaded, the second group had the medial collateral ligament tested separately and the third group had both ligaments associately tested. Medial collateral ligament not submitted to strain presented a wavy and reticular pattern of the collagen fibers, which was not totally destroyed when it was loaded associated to the oblique ligament, and totally loses the reticular pattern when stretched separately. When the medial collateral ligament was loaded in tension separately, the mean collagen fibrils diameter increased in relation to the group not submitted to the tensile strain. Associated to the oblique ligament, the mean collagen fibrils diameter was the largest in the insertion area and the smallest in the mid-substance, in relation to the other groups. It was concluded that the oblique ligament could favor the integrity of the medial collateral ligament insertion area, facilitating its reconstruction after lesion with larger efficiency.
Foram estudados o arranjo e o diâmetro médio das fibrilas colágenas do ligamento colateral medial da articulação do cotovelo do cão, isolado ou associado ao ligamento oblíquo e tracionado até a ruptura. Dezoito articulações foram divididas em três grupos. O primeiro grupo teve o ligamento colateral medial coletado, mas não tracionado; o segundo grupo teve o ligamento colateral medial tracionado isoladamente; o terceiro grupo teve os ligamentos colateral medial e oblíquo tracionados associadamente. O ligamento colateral medial não submetido ao ensaio de tração apresentou um padrão ondulado das fibras colágenas, o qual não foi totalmente destruído quando foi tracionado, associado ao ligamento oblíquo, e perdeu totalmente o padrão reticular das fibras colágenas quando testado isoladamente. Quando o ligamento colateral medial foi submetido à tensão isoladamente, o diâmetro médio das fibrilas colágenas aumentou em relação ao grupo não submetido à tensão. Associado ao ligamento oblíquo, o diâmetro médio das fibrilas colágenas foi o maior na região de inserção e o menor na região média, em relação aos outros grupos. Concluiu-se que o ligamento oblíquo pode favorecer a integridade da região de inserção do ligamento colateral medial, aumentando a eficácia de sua reconstrução após a lesão.
Subject(s)
Animals , Male , Female , Elbow Joint/anatomy & histology , Fibril-Associated Collagens/adverse effects , Dogs , Collateral Ligaments/anatomy & histology , Collateral Ligaments/injuriesABSTRACT
The aim of this study was to evaluate the effect of snake venom derived fibrin glue on the strength of tendon healing in dogs. The deep digital flexor tendon of the 5th digit of 24 thoracic limbs was partially sectioned for adhesive application. On the 7th, 15th, and 30th postoperative day tendons segments were removed for the clinical and biomechanical study. Results indicated that 62.5% of the tendons showed stump retraction and 20.8% moderate to excessive adherence, which affected gliding. The biomechanical evaluation showed that, over time, tendon healing gained progressive resistance for maximum traction and permanent deformations with satisfactory results on the 15th day for rigidity and resilience compared to the other two studied periods. Snake venom derived fibrin glue promotes healing in dog flexor tendon
Subject(s)
Animals , Dogs , Fibrin Tissue Adhesive/therapeutic use , Dogs , Snake Venoms , Tendons , Biomechanical PhenomenaABSTRACT
Costicosteroides sistemicos em altas doses podem causar miopatia metabolica. O Objetivo deste estudo foi valiar, por meio de ensaios de tracao, os efeitos da miopatia induzida por corticosteroides nas propriedades mecanicas do musculo gastrocnemio medial de coelhos. Foram estudados dois grupos de 15 coelhas da raca Nova Zelandia: grupo experimental (GE), que recebeu injecoes subcutaneas de metil-prednisolona (2mg/kg/dia), e grupo-controle (GC), que recebeu solucao fisiologica por via subcutanea. Os grupos foram tratados por 21 dias. Foram feitos ensaios de tracao nos musculos gastrocnemios mediais esquerdos. Resultados: o peso final dos animais do GE foi 3,6+-0,1kg e do GC, 40+-0,1kg. O peso final do gastrocnemio do GE foi 5,6+-1,0g e do GC, 7,0+-1,3g. Os valores de area, largura e espessura do gastrocnemio...
Subject(s)
Adrenal Cortex Hormones , Biomechanical PhenomenaABSTRACT
Healing is a complex process with many interfering factors. The objective of this work was to evaluate regeneration strenght of non-pregnant adult dog uterus when snake venom derived fibrin adhesive is used to reinforce hysterorrhaphy. Maximum limit and rigidity were analyzed. Twenty uterine horns from 10 dogs were hysterotomized and distributed into 2 groups. Hysterorrhaphy was performed using the Shimieden-Cushing double layer suture. In one group, animals received snake venom derived fibirn adhesive as reinforcement. Although neither variable was significantly different, our results showed higher rigidity values in the adhesive group. This can be attributed to the adhesive's effect on organ elasticity or to more granulation tissue formed in the uterine scar
Subject(s)
Animals , Female , Dogs , Fibrin Tissue Adhesive/therapeutic use , Wound Healing , Hysterectomy/veterinary , Snake Venoms , Biomechanical PhenomenaABSTRACT
The study of the effects of the immobilization on the muscular tissue is a very important issue and the measurement of the biomechanics properties provides relevant knowledgement about adaptations occurred from functional demands...
Subject(s)
Biomechanical Phenomena , Immobilization , Muscle Rigidity , Muscle, Skeletal , Rats, Wistar , Musculoskeletal SystemABSTRACT
The purpose of this study was to investigate the influence of physical training and sedentarism on the mechanical properties of striated muscle...
Subject(s)
Biomechanical Phenomena , Motor Activity , Muscle, Skeletal , Rats, Wistar , Swimming , Musculoskeletal SystemABSTRACT
A medida da forca de preensao palmar tem sido um dos meios uteis para a avaliacao das caracteristicas fisicas, a evolucao durante a reabilitacao e o grau de incapacidade. Na pratica clinica o fisioterapeuta se depara com a dificuldade em selecionar o protocolo mais adequado e eficiente para o fortalecimento muscular. O objetivo deste trabalho foi comparar dois protocolos de regimes isotonicos buscando evidenciar qual deles seria o mais indicado para o fortalecimento musculos responsaveis pela preensao. As medidas da forca de preensao pre e pos-treinamento foram realizadas com um dinamometro mecanico da marca Jamar, em 22 mulheres com idade entre 18 e 21 anos (media de 19 anos). As voluntarias foram separadas em 2 grupos, DeLorme (carga crescente) e Oxford (carga decrescente), para a aplicacao dos protocolos. Para o treinamento foi utilizado um exercitador de mao e dedos da marca Digi-flex, e o programa foi realizado duas vezes por semana, com duracao de 20 minutos cada sessao em um total de 8 sessoes. Posteriormente, foram comparadas as forcas pre e pos-treinamentos e foi observado que, para as amostras dependentes (pre e pos-treinamentos), houve diferenca significativa tanto no grupo DeLorme quanto no Oxford, ja para as amostras independentes (pos-DeLorme e pos-Oxford) nao houve diferenca significativa
Subject(s)
Disability Evaluation , Physical Education and Training , Physical Therapy Specialty , RehabilitationABSTRACT
Foi analisando o efeito da aplicaçäo do ultra-som terapêutico em lesäo muscular aguda. Foi realizada uma lesäo por esmagamento no músculo reto da coxa direita e esquerda em 26 coelhos (52 músculos) da raça Nova Zelândia, com peso médio de 2,2 kg. Após 3dias da lesäo, os animais foram tratados em um lado com ultra-som terapêutico com tipo de onda pulsada, razäo 1:5, frequência de 1 MHz e intensidade de 0,5 W/cm2 por 5 minutos, durante 10 dias consecutivos. O músculo contralateral serviu como controle e sofreu apenas esmagamento. Após 3 dias do término da aplicaçäo, os animais foram sacrificados e os músculos submetidos a ensaios de traçäo na máquina universal de ensaio, com célula de carga de 2000 kgf e velocidade de 4,5 mm/minuto. Foram analisados os resultados dos ensaios de 36 músculos (18 animais), mostrando que os músculos tratados pelo ultra-som apresentaram diferença significativa na deformaçäo máxima, carga e deformaçäo no limite de proporcionalidade, e na energia na fase de deformaçäo elástica. Estes resultados sugerem que a aplicaçäo do ultra-som terapêutico possa melhorar a qualidade da reparaçäo da lesäo muscular aguda.
Subject(s)
Animals , Female , Rabbits , Muscles/injuries , Ultrasonic Therapy/adverse effects , Clinical Trials as Topic , Tensile Strength/radiation effects , Thigh/injuriesABSTRACT
Inúmeras moléstias, tais como neoplasias, traumatismos, abscessos, nódulos parasitários, podem comprometer a funçäo normal de um órgäo. Isto torna necessária, muitas vezes, a correçäo cirúrgica com a utilizaçäo de implantes, entre eles, as membranas biológicas. A finalidade deste trabalho foi testar e analisar a influência da glicerina na resistência à traçäo e na elasticidade de peritônios de bovino, eqüino, suíno e canino, assim como estabelecer uma comparaçäo entre as membranas das espécies citadas, e suas alteraçöes histológicas. Para isso, após o sacrifício dos animais, foram retiradas amostras de peritônio, padronizadas para cada espécie. Foram obtidos, entäo, os corpos de prova, padronizados nas dimensöes de 6 mm de largura e 50 mm de comprimento. Os ensaios de traçäo foram realizados em corpos e prova a fresco e em outros mantidos em glicerina durante 15, 30 e 60 dias. Os testes foram realizados em Máquina Universal de Ensaio. Após o teste mecânico de traçäo, os corpos de prova foram fixados, e cortes histológicos, corados pelo método de Hematoxilina-Eosina, foram obtidos e analisados. Os resultados da traçäo do peritônio a fresco bovino, eqüino, suíno e canino, quando analisados os alongamentos em funçäo das cargas aplicadas, mostraram comportamentos heterogêneos, e o ponto de ruptura das membranas foi bastante diferente entre as espécies