Sabe-se que a aplicação de carga influencia na consolidação óssea; e associada ao exercício podem reduzir o tempo de reparação óssea e a permanência com o fixador, que resultaria em muitas vantagens para a prática clínica. O objetivo deste trabalho foi avaliar a influência do exercício em esteira, na consolidação da osteotomia na tíbia de coelhos, tratadas com fixador externo unilateral. O trabalho foi desenvolvido no laboratório de Bioengenharia da Faculdade de Medicina de Ribeirão Preto da USP, utilizando-se 16 coelhos machos adolescentes da raça Nova Zelândia, que foram submetidos a uma osteotomia transversa no terço médio da tíbia e colocação do fixador externo unilateral para fixá-la. Após o procedimento cirúrgico os animais foram divididos em dois grupos: sedentários com n = 10 e exercitados com n = 10 (submetidos a exercícios diários em esteira, com intensidade moderada, durante 10\'). Foi realizada uma avaliação radiográfica no pós-operatório imediato e a cada 10 dias até a oitava semana, quando os animais foram eutanasiados e suas tíbias retiradas e submetidas ao ensaio mecânico de torção. Na avaliação radiográfica observou-se um percentual maior de tíbias consolidadas, num período inferior a 40 dias no grupo exercitado, enquanto que os valores médios das variáveis mecânicas: torque máximo, deformação angular e energia absorvida até a ruptura, não representaram diferença estatística significativa para p menor e igual a 0,05, apesar de ser observada uma tendência para maiores valores de torque no grupo exercitado. Estes resultados sugerem que o exercício não influencia na velocidade e no padrão de consolidação da fratura neste estudo. / It is known that a load application affects bone healing and in association with exercises, it can reduce bone healing time and fixator permanence time, what would result in several advantages in clinical practice. This article is aimed to evaluate the exercises influence on healing in osteotomised tibiae of rabbits fixed unilateral external fixator. This research was developed in the Bioengineering Laboratory of Medical School of Ribeirão Preto - USP. Sexteen young male New Zealand rabbits were submitted to transverse osteotomy in the middle third of the tibia and fixed with unilateral external fixator. After the surgical procedure, animals were divided into 2 groups: sedentary (n = 10) and exercised (n = 10), being the last group submitted to dayly exercises on a mat for 10 minutes with moderate intensity. A radiographic control was made in the immediate post-operative period and every 10 days during the first 8 weeks. After that, animals were euthanized and their tibia were removed and submitted to a torsional test. For the exercised group, there was observed a larger percentage of healed tibia in a period shorter than 40 days in respect to the radiographic control. The means of mechanical variables (maximum torque, angular displacement and energy required to failure) have shown no significant statisticall difference for p less and equal a 0.05, although it was noticed a tendency to higher values of torque in the exercised group. These results suggest no influence of exercises in relation the speed of and fracture healing in this study.

Sabe-se que a aplicação de carga influencia na consolidação óssea; e associada ao exercício podem reduzir o tempo de reparação óssea e a permanência com o fixador, que resultaria em muitas vantagens para a prática clínica. O objetivo deste trabalho foi avaliar a influência do exercício em esteira, na consolidação da osteotomia na tíbia de coelhos, tratadas com fixador externo unilateral. O trabalho foi desenvolvido no laboratório de Bioengenharia da Faculdade de Medicina de Ribeirão Preto da USP, utilizando-se 16 coelhos machos adolescentes da raça Nova Zelândia, que foram submetidos a uma osteotomia transversa no terço médio da tíbia e colocação do fixador externo unilateral para fixá-la. Após o procedimento cirúrgico os animais foram divididos em dois grupos: sedentários com n = 10 e exercitados com n = 10 (submetidos a exercícios diários em esteira, com intensidade moderada, durante 10\'). Foi realizada uma avaliação radiográfica no pós-operatório imediato e a cada 10 dias até a oitava semana, quando os animais foram eutanasiados e suas tíbias retiradas e submetidas ao ensaio mecânico de torção. Na avaliação radiográfica observou-se um percentual maior de tíbias consolidadas, num período inferior a 40 dias no grupo exercitado, enquanto que os valores médios das variáveis mecânicas: torque máximo, deformação angular e energia absorvida até a ruptura, não representaram diferença estatística significativa para p menor e igual a 0,05, apesar de ser observada uma tendência para maiores valores de torque no grupo exercitado. Estes resultados sugerem que o exercício não influencia na velocidade e no padrão de consolidação da fratura neste estudo. / It is known that a load application affects bone healing and in association with exercises, it can reduce bone healing time and fixator permanence time, what would result in several advantages in clinical practice. This article is aimed to evaluate the exercises influence on healing in osteotomised tibiae of rabbits fixed unilateral external fixator. This research was developed in the Bioengineering Laboratory of Medical School of Ribeirão Preto - USP. Sexteen young male New Zealand rabbits were submitted to transverse osteotomy in the middle third of the tibia and fixed with unilateral external fixator. After the surgical procedure, animals were divided into 2 groups: sedentary (n = 10) and exercised (n = 10), being the last group submitted to dayly exercises on a mat for 10 minutes with moderate intensity. A radiographic control was made in the immediate post-operative period and every 10 days during the first 8 weeks. After that, animals were euthanized and their tibia were removed and submitted to a torsional test. For the exercised group, there was observed a larger percentage of healed tibia in a period shorter than 40 days in respect to the radiographic control. The means of mechanical variables (maximum torque, angular displacement and energy required to failure) have shown no significant statisticall difference for p less and equal a 0.05, although it was noticed a tendency to higher values of torque in the exercised group. These results suggest no influence of exercises in relation the speed of and fracture healing in this study.

O ultra-som de baixa intensidade tem demonstrado ser um recurso acelerador do processo de consolidação óssea em fraturas. Este estudo experimental investigou a influência da estimulação ultra-sônica de baixa intensidade no processo de reparo ósseo em fraturas de tíbias tratadas por meio de fixação flexível. O estudo foi desenvolvido no laboratório de Bioengenharia da FMRP da Universidade de São Paulo Campus de Ribeirão Preto, utilizando 20 coelhos machos adolescentes da raça Nova Zelândia, que foram submetidos a uma osteotomia no terço médio da tíbia e tratados com fixador externo unilateral. Após o procedimento cirúrgico os animais foram divididos em três grupos: controle com n = 7 (membro contralateral, não fixado), grupo controle lesão com n = 7 (fixados e mantidos em gaiolas) e grupo ultra-som com n = 7, que recebeu estimulação com equipamento de ultra-som de baixa intensidade (30mW/'CM POT.2') e ciclo de trabalho de 1/5. No final de 20 dias de tratamento suas tíbias foram retiradas e submetidas a ensaio mecânico de torção. Na avaliação das propriedades mecânicas torque máximo e rigidez, não foi observada diferença significativa (p '< OU =' 0,05) entre os grupos estimulados e controle lesão. Estes resultados sugerem que a estimulação ultra-sônica de baixa intensidade aplicada ao reparo de fraturas na presença de fixação flexível não influencia a velocidade e o padrão de consolidação da fratura / The low-intensity ultrasound has demonstrated to be an accelerator device on the process of recovering of bone fractures. This experimental study investigated the influence of the low-intensity ultrasound stimulation on the process of bone repairing of fractures of tibia treated with flexible fixator. The study was developed at the FMRP Bioengineering laboratory, of the University of Sao Paulo, campus of Ribeirao Preto, using 20 teenager male rabbits from the New Zealand breed which were subjected to an osteomy in the median third of the tibia and treated with an unilateral external fixator. After the surgical procedure the animals were divided into three groups: control with n = 7 (paw contralateral, not fixed), group control injury with n = 7 (fixed and kept in cages) and group ultrasound with n = 7, that received stimulation with low-intensity ultrasound equipment (30mW/'CM POT.2') and duty cycle 1/5. At the end of 20 days of treatment, their tibia were removed and subjected to a mechanical twist test. At the evaluation of the mechanical properties: maximum torque and hardness, it was not observed significant differences (p '< OU =' 0,05) among the stimulated groups and the control injury. These outcomes suggest that the low-intensity ultrasound applied for fractures healing in the presence of flexible fixation does not have influence on the velocity nor the standard of the fracture recovering

Made available in DSpace on 2016-04-28T20:18:31Z (GMT). No. of bitstreams: 1 2008 - Carlos Otavio Jordao Moreira da Rocha.pdf: 1867760 bytes, checksum: 3392639adc640e871d82c97af23d8da8 (MD5) Previous issue date: 2008-08-29 / With the objective of testing the resistance and the biomechanical behavior of external fixators of low cost used in veterinary medicine, were created 6 prototypes la type manufactured from alternative materials, using as orthopedic implants, stainless steel screws 304 porous, and as stabilized bar the methacrylate resin or wood poles (Pinnus ellioti). The models of the fixators tested differ because they have 2, 3 or 4 implants per fractured segment. With the purpose of doing biomechanical evaluations that are closer to the real clinical situation, were selected 2 tubes of polyvinylchloride, commercially known as PVC, with 10 cm length, internal diameter of 1,27 cm and external diameter of 1,95, far 5 cm from each other, representing, this way, the bone bands and the focus of an unstable fracture. This kind of tube is like a long bone because it has an internal space that represents the medullar area and external walls that represent the two osseous cortical. To each external fixator model, were created 5 prototypes, which were submitted to mechanic tests to evaluate the axial compression strength. The device to evaluate the prototypes was the Instron model 4204, with a charge cell of 5 KN (Kilogram-Newton) and the speed of the axial compression was 2 cm/minute, according the rules ASTM D695-92. The values of rigidity, drainage point and maximum security charge were calculated, according to the methodology used by Willer et al., (1991) and by Falc?o (2004). The mechanical evaluation was done in the Instituto de Macromol?culas Elo?sa Mano in the Universidade Federal do Rio de Janeiro. We concluded that the models with the stabilized bar made of resin required a larger load than the models made of wood to suffer a plastic deformation. The model with 3 screws per segment of PVC tube and a resin stabilized bar showed to tolerate a higher weight than the others, before showing a plastic deformation, this way it s indicated to dogs that weight up to 26,5Kg with fractures in the thoracic limbs and for dogs that weight up to 44Kg that have fractures in the pelvic limbs. / Com objetivo de testar a resist?ncia e o comportamento biomec?nico de fixadores externos de baixo custo utilizados em medicina veterin?ria, foram criados 6 modelos de prot?tipos do tipo Ia confeccionados a partir de materiais alternativos, utilizando-se como implantes ortop?dicos parafusos de a?o inoxid?vel 304 porosos e totalmente rosqueados, e como barra estabilizadora a resina de metacrilato ou hastes de madeira (Pinnus ellioti). Os modelos dos fixadores testados ainda se diferenciam por apresentarem 2, 3 ou 4 implantes por segmento fraturado. Com a finalidade de realizar avalia??es biomec?nicas o mais pr?ximo poss?vel da situa??o cl?nica, optou-se pela escolha de 2 tubos de policloreto de vinila, comercialmente conhecido como PVC, apresentando 10 cm de comprimento, 1,27 cm de di?metro interno e 1,95 cm de di?metro externo, afastados 5 cm entre si, representando assim os fragmentos ?sseos e o foco de uma fratura inst?vel. Este tipo de tubo se assemelha a um osso longo por apresentar um espa?o interno que representa a ?rea medular enquanto que as paredes externas representam as duas corticais ?sseas. Para cada modelo de fixador externo foram criados 5 prot?tipos, submetidos a testes mec?nicos para avalia??o da for?a de compress?o axial. O aparelho para avalia??o dos prot?tipos foi o Instron modelo 4204, com c?lula de carga de 5 KN (Quilograma-Newton) e a velocidade da compress?o axial foi de 2 cm/minuto, seguindo as normas ASTM D695-91. Calculamos as cargas de rigidez, ponto de escoamento e carga de seguran?a m?xima. A avalia??o mec?nica foi realizada no Instituto de Macromol?culas Elo?sa Mano na Universidade Federal do Rio de Janeiro. Conclu?mos que os modelos com barra estabilizadora em resina necessitou de uma carga maior do que os modelos de madeira para sofrer deforma??o pl?stica. O modelo com 3 parafusos por segmento de tubo de PVC e barra estabilizadora de resina mostrou suportar maior peso que os demais, antes de apresentar uma deforma??o pl?stica, sendo indicado para c?es com peso corporal de at? 26,5 Kg portadores de fraturas nos membros tor?cicos e para c?es com peso de at? 44 Kg que apresentem fraturas nos membros p?lvicos.

O ultra-som de baixa intensidade tem demonstrado ser um recurso acelerador do processo de consolidação óssea em fraturas. Este estudo experimental investigou a influência da estimulação ultra-sônica de baixa intensidade no processo de reparo ósseo em fraturas de tíbias tratadas por meio de fixação flexível. O estudo foi desenvolvido no laboratório de Bioengenharia da FMRP da Universidade de São Paulo Campus de Ribeirão Preto, utilizando 20 coelhos machos adolescentes da raça Nova Zelândia, que foram submetidos a uma osteotomia no terço médio da tíbia e tratados com fixador externo unilateral. Após o procedimento cirúrgico os animais foram divididos em três grupos: controle com n = 7 (membro contralateral, não fixado), grupo controle lesão com n = 7 (fixados e mantidos em gaiolas) e grupo ultra-som com n = 7, que recebeu estimulação com equipamento de ultra-som de baixa intensidade (30mW/'CM POT.2') e ciclo de trabalho de 1/5. No final de 20 dias de tratamento suas tíbias foram retiradas e submetidas a ensaio mecânico de torção. Na avaliação das propriedades mecânicas torque máximo e rigidez, não foi observada diferença significativa (p '< OU =' 0,05) entre os grupos estimulados e controle lesão. Estes resultados sugerem que a estimulação ultra-sônica de baixa intensidade aplicada ao reparo de fraturas na presença de fixação flexível não influencia a velocidade e o padrão de consolidação da fratura / The low-intensity ultrasound has demonstrated to be an accelerator device on the process of recovering of bone fractures. This experimental study investigated the influence of the low-intensity ultrasound stimulation on the process of bone repairing of fractures of tibia treated with flexible fixator. The study was developed at the FMRP Bioengineering laboratory, of the University of Sao Paulo, campus of Ribeirao Preto, using 20 teenager male rabbits from the New Zealand breed which were subjected to an osteomy in the median third of the tibia and treated with an unilateral external fixator. After the surgical procedure the animals were divided into three groups: control with n = 7 (paw contralateral, not fixed), group control injury with n = 7 (fixed and kept in cages) and group ultrasound with n = 7, that received stimulation with low-intensity ultrasound equipment (30mW/'CM POT.2') and duty cycle 1/5. At the end of 20 days of treatment, their tibia were removed and subjected to a mechanical twist test. At the evaluation of the mechanical properties: maximum torque and hardness, it was not observed significant differences (p '< OU =' 0,05) among the stimulated groups and the control injury. These outcomes suggest that the low-intensity ultrasound applied for fractures healing in the presence of flexible fixation does not have influence on the velocity nor the standard of the fracture recovering

External fixators are used in a treatment of complicated fractures and their properties have a crucial impact on treatment quality. Therefore, this thesis is concerned with a biomechanical study of a bone (tibia) with applied external fixators via strain-stress analysis and their comparison with a state of tibia without applied fixator (physiological state). After creating the volume models of geometry of tibia and seven variants of external axial fixators, the corresponding finite element method (FEM) models are created. The analysis of tibia without applied fixator and tibia with all studied fixators is made for three states of load which correspond to characteristic load states during the first stage of treatment. The strain-stress analysis is made using finite element method. Furthermore, the methods of displacement and rotation evaluation during loading are proposed. One can conclude from the results of the strain-stress analysis how the different variants of fixators prevent the displacement and rotation of the bone during the different load states and the comparisons with the physiological state of bone are made. Bone tissue loading is determined from the distribution and the values of the first and the third principal stresses. Finally, comparing the results of all variants the influence of the fixator length, the gap between the fixation elements near the fracture, the number and the setting of the fixation elements on the fixation properties is analysed.

Bei Patienten, die auf Grund einer schweren Beckenverletzung hämodynamisch instabil sind, ist die primäre Stabilisierung des Beckens und damit die Reduktion des intrapelvinen Volumens entscheidend für den Erfolg der weiteren Therapie. Die Beckenzwinge hat sich als Notfallmaßnahme bewährt, erfordert jedoch in den meisten Fällen eine weitere operative Versorgung. Dieser Sekundäreingriff bedingt in vielen Fällen bei traumatisch geschädigten Weichteilen zusätzliche Wundheilungsstörungen. Ein weiteres Verfahren, der ventrale Fixateur externe, zeichnet sich durch einfache und schnelle Montage bei nur geringem Weichteilschaden aus. In vielen Fällen ist jedoch keine für die Mobilisierung ausreichende biomechanische Stabilisierung des vertikal instabilen dorsalen Beckenringes zu erreichen. Anhand biomechanischer Überlegungen wurde ein neuer schräg dorsaler Beckenfixateur für Becken- C-Verletzungen entwickelt, der die Vorteile des supraacetabulären Fixateur externe nutzt und dabei den hinteren Beckenring von ventral mit einer der Beckenzwinge nahe kommenden Effektivität stabilisieren kann. Er ermöglicht bereits initial eine minimal invasive sowie definitive Stabilisierung des dorsalen Beckenrings. Mehrere Variationen mit zwei unterschiedlichen Pin- Applikationsformen dieses asymmetrischen Fixateurs wurden getestet. In einer zweiten Testreihe wurde die in der ersten Testreihe favorisierte Version des neuen schräg dorsalen Fixateurs mit dem Supraacetabulärem Fixateur externe und der Beckenzwinge (ACE) verglichen. Beide Testreihen erfolgten an Kunststoff-Beckenmodellen im Einbeinstand in einer Materialprüfmaschine. Als Instabilitätsmodell dienten Verletzungen vom Typ C1.2 sowie C1.3 entsprechend der AO Klassifikation. In den Testreihen wurde kein signifikanter Unterschied des neuen verspannten schräg dorsalen Fixateurs zur Beckenzwinge gefunden. Er war jedoch deutlich stabiler als das unverspannte Modell oder der supraacetabuläre Fixateur allein. / In haemodynamically unstable patients with an unstable pelvic ring injury the primary stabilisation of the pelvis and thus reduction of pelvic volume is important for the success of the treatment. The pelvic C-clamp is an approved emergency device for these unstable pelvic ring injuries. A secondary procedure though is necessary in most of the cases with a big rate of wound problems in already traumatized soft tissue areas. The ventrally placed external fixator is a simple and quick procedure with little soft tissue damage. Though primary stability is sufficient even for C-type injuries, biomechanic stability of the posterior pelvic ring is often insufficient for mobilization. Based on biomechanic considerations, a new dorsal oblique pelvic external fixator was developed for pelvic C-type injuries. With the advantages of the supraacetabular fixator and two additional Schanz screws the ventral fixator should stabilize the posterior pelvic ring with comparable stability to the pelvic C-clamp. A primary and already definitive minimal invasive stabilization of the posterior pelvic ring was the aim. In the first series several variations of this asymmetric fixator with two different Schanz screw applications were tested biomechanically. In a second series the favourite version was tested versus the supraacetabular fixator and the pelvic C-clamp. Both of the biomechanic test series were performed with artificial pelves in the one leg stance model in the material testing machine. SI disruption and sacral fracture were the posterior instability types in 6 pelves each. There was no statistically significant difference between the dorsal oblique fixator and the pelvic C-clamp. But the new fixator was significantly more stable than the supraacetabular fixator or the new fixator without pretension.

Die Tibiaschaftfraktur ist eine häufig auftretende Verletzung. Der Fixateur externe findet bei der Versorgung von Tibiafrakturen große Verwendung. Die Variabilität und Anpassung an die individuelle Patientensituation stellen den Vorteil der Osteosynthese dar. Gleichzeitig ist unklar, ob und inwiefern die Montageebene die Frakturheilung beeinflusst. Interfragmentäre Bewegungen (IFM) bestimmen die Quantität und Qualität der Kallusbildung. IFM werden wiederum durch die Fixateurmontageebene bedingt. Diese Studie wurde vorgelegt, um den Einfluss der Montageebene auf die Frakturheilung zu bestimmen. Zwei identisch konfigurierte monolaterale Fixateurs externes mit medialer und anteromedialer Montageebene wurden bezüglich ihres Heilungspotentials an der Schafstibia verglichen. IFM und Bodenreaktionsparameter wurden während des neunwöchigen Heilungsverlaufs in vivo ermittelt. Die Knochenkonsolidierung wurde radiologisch und biomechanisch evaluiert. Allein die Änderung der Montageebene führte zu einer Modifikation der IFM. Der Unterschied der IFM war nur in der initialen Heilungsphase signifikant. Diese initialen Unterschiede beeinflussten jedoch bei nicht signifikant unterschiedlicher Gewichtsbelastung die Kallusbildung. Die Gruppe mit anteromedial montierten Fixateur zeigte initial höhere IFM und bewirkte einen radiologisch größeren Kallusdurchmesser und eine biomechanisch größere Kallussteifigkeit im Sinne einer weiter fortgeschrittenen Heilungsphase. Diese erzielten Heilungsergebnisse demonstrieren die Sensitivität der Montageebene und die Bedeutung der initialen biomechanischen Bedingungen, die den Kurs der Frakturheilung beeinflussen. Darum sollte der Montageebene und der dadurch bedingten initialen mechanischen Osteosynthesestabilität in der klinischen Frakturversorgung mehr Beachtung geschenkt werden. / Fractures of the tibia are commonly encountered problems. One of the most common osteosyntheses used to stabilise tibial fractures are external fixators. The fixator allows great freedom in configuration, especially with regard to its mounting plane. Whether and how the mounting plane influences the healing process is still unclear. Interfragmentary movements (IFM) affect the quality and quantity of callus formation. The mounting plane of monolateral external fixators may give direction to those movements. The presented study aimed to determine the influence of the fixator mounting plane on fracture healing. Identically configured fixators were mounted either medially or anteromedially on a standardised ovine tibial diastasis model with regard to their fracture healing potential. IFM and ground reaction forces were evaluated in vivo during a nine week period. Biomechanical and radiological parameters described the bone healing process. Changing only the mounting plane led to a modification of IFM in the initial healing phase. The difference in IFM between the groups was only significant during the first post-operative period. However, these initial differences in mechanical conditions influenced callus tissue formation. The group with the anteromedially mounted fixator, initially showing significantly more IFM, ended up with a radiologically bigger callus diameter and a biomechanically higher callus stiffness as a result of advanced fracture healing. This demonstrates that the initial phase of healing is sensitive to mechanical conditions and influences the course of healing. Therefore, initial mechanical stability of an osteosynthesis should be considered an important factor in clinical fracture treatment.

The overall aim of this thesis on congenital clubfoot was to estimate the incidence with a national perspective, analyse residual deformities and their management, and evaluate patient reported long-term quality of life and foot function. Paper I was a prospective, nationwide sampling of 280 children with congenital clubfoot during 1995-96. The average incidence was 1.4‰. There was regional heterogeneity but no seasonal variation. Paper II evaluated ultrasonography on 54 newborn, prospectively followed up to 12 months of age. Significant increase of medial malleolus to navicular distance (MM-N-distance) and of soft tissue thickness with increasing age was seen and with acceptable reliability. Paper III assessed 35 children (47 feet) after previous posterior release, mean age of 4.5 years, and the MM-N-distance was shorter in unilateral clubfeet (21 patients) than in contralateral normal feet. No association between navicular position and forefoot adduction (FFA) was determined. Smaller FFA yielded better subjective and functional outcome. Paper IV reviewed distraction treatment with Ilizarov External Fixator in seven patients (10 feet), 6-15 years of age, with relapsed deformities. All patients, except one, reported satisfaction with the overall result but less stiffness was experienced in only 4/10 feet. Paper V evaluated self-estimated outcome in 83 patients (63 males, 20 females), mean age of 64 years, through SF-36 and EQ-5D, and through AAOS foot and ankle score. Age and gender adjusted norm groups were used. Female patients scored worse than male patients did. Both males and females reported negative influence on foot and ankle function. Conclusion: The incidence of congenital clubfoot in Sweden is higher than in previous Scandinavian studies. Ultrasonography is reliable for describing pathoanatomy of the talo-navicular joint in clubfeet and can detect "spurious" (false) correction. Distraction treatment with the Ilizarov External Fixator yields subjective improvement but stiffness remains. Long-term influence on daily life activities is limited to foot and ankle function for both genders, but only female patients report negative influence on physical aspects of quality of life.

O fixador esquelético externo circular foi desenvolvido durante a guerra fria na Rússia, pelo Professor Gavril Abramovich Ilizarov. Esse tipo de fixação ganhou espaço como alternativa à fixação interna, devido a sua versatilidade e às suas características biomecânicas que otimizam a formação do calo ósseo. O objetivo desse estudo foi avaliar o fixador esquelético externo circular como método de fixação para fraturas metafisárias de rádio e tíbia de cães atendidos no Hospital de Clínicas Veterinárias da UFRGS. Os resultados a respeito do tipo e frequência de complicações associados a essa técnica foram documentados. No total 16 animais cumpriram os critérios para entrar no estudo sendo sete fêmeas e nove machos. A idade média dos animais foi de 50,87 ± 57,01 meses com peso médio dos animais foi de 8,6 ± 6,95kg. Três (18%) animais apresentaram fratura de tíbia e fíbula e treze (82%) fraturas de rádio e ulna. O aparelho de fixação esquelética utilizado consistiu de um aro proximal 5/8 e dois aros distais inteiros, com dois fios em cada anel. Os fios foram colocados de maneira divergente o mais próximo possível de 90°. O aparelho pesou em média 128 ± 49g, representando em média 4,09 ± 3,22% do peso do animal. O tempo médio de cirurgia foi de 115 ± 32 minutos. O tempo médio de permanência com o aparelho de fixação esquelética externa circular foi de 81,69 ± 23,14 dias. Entre as complicações encontradas estão: tratos de drenagem ao redor dos fios (37,5%), miíase (6,25%), encurtamento dos músculos flexores do antebraço (6,25%), hemorragia associada ao local de passagens dos pinos (6,25%) e quebra do fio com deslocamento do fixador levando a necessidade de sua remoção (6,25%). Não houve diferença estatística entre os tempos cirúrgicos necessários para a osteossíntese de rádio e tíbia. Não houve correlação entre as variáveis: tempo decorrido do trauma até a cirurgia e tempo de duração da cirurgia; tempo decorrido do trauma até a cirurgia e tempo de permanência com o aparelho de fixação esquelética externa circular; peso do animal e duração da cirurgia; proporção do peso do circular em relação ao peso do animal e o tempo de permanecia com o circular. Houve correlação positiva estatisticamente significativa entre as variáveis: duração da cirurgia e tempo de permanência com o aparelho de fixação esquelética externa circular. Essa modalidade de tratamento representa uma opção cirúrgica atrativa para a correção de fraturas de rádio e tíbia em cães, entretanto, devido à possibilidade complicações e necessidade de cuidados pós-operatórios intensivos uma seleção acurada dos pacientes e proprietários deve ser realizada previamente à cirurgia. / The circular external skeletal fixator was developed during the Cold War in Russia, by Professor Gavril Abramovich Ilizarov. This kind of fixation took place as an alternative to internal fixation, due to its versatility and its biomechanical characteristics that improves the formation of callus. The aim of this study was to evaluate the circular external skeletal fixator as a method of fixation for fractures of the radius and tibia of dogs treated at the Veterinary Teaching Hospital of UFRGS, corroborating the results, the type and frequency of complications associated with this technique. Sixteen animals met the criteria to participate on the study, seven females and nine males. The average age of the animals was 50.87 ± 57.01 months. The average weight of the animals was 8.6 ± 6.95 kg. Three (18%) animals showed fracture of tibia and fibula and thirteen (82%) fractures of the radius and ulna. The circular external skeletal fixation frame used consisted of a proximal ring ⅝ and two full distal rings, with two wires in each ring. The wires were placed divergently as close as possible to 90 °. The frame weighed on average 128 ± 49g, representing average 4.09 ± 3.22% of the weight of the animal. The mean time of the surgery was 115 ± 32 minutes. The average time spent with the circular was 81.69 ± 23.14 days. Among the complications found are drainage tracts around the pins (37.5%), myiasis (6.25%), shortening of the forearm flexors (6.25%), hemorrhage associated with the location of pins passages (6, 25%) and breakage of the device wire with displacement of the frame leading to its removal (6.25%). There was no statistical difference between the times required for the surgical fixation of the radius and tibia. There was no correlation between the variables: time elapsed from trauma to surgery and duration of surgery, time elapsed from trauma to surgery and time spent with the circular external skeletal fixation; animal weight and duration of surgery; the proportion of the circular weight in relation to the weight of the animal and the time remained with the circular. There was statistically significant positive correlation between the variables: duration of the surgery and the permanency with the circular external skeletal fixation. This treatment modality represents an attractive surgical option for fractures correction of the radius and tibia in dogs, however, due to possible complications and need for intensive post operative care accurate selection of patients and owners should be performed prior to surgery.