Estudo biomecânico do comportamento de diferentes espessuras de capa de cimento ósseo em novo modelo de prótese modular diafisária femoral em cão submetidas a ensaio de torção / Biomechanical Analysis in the Use of Different Cement Layers in a New Model of Modular Diaphyseal Femoral Implant Relative to Torsion Forces

Background: The feasibility of modular cemented prosthesis in the femoral diaphysis was demonstrated in dogs, but several authors report loosening of bone-cement-implant interface as a major complication and have yet to reach a consensus on the ideal cement layer thickness for reducing postoperative morbidity. The objective of this study was to evaluate the stabilization of the prosthesis using different thicknesses of cement layer, subjected to torsion forces. Materials, Methods & Results: For this study 48 femurs from 24 dogs weighing over 15 kg were used. The animals used did not have any prior diagnosis of bone or nutritional diseases, which was an exclusion criteria for this study. All biological materials were obtained immediately after death or euthanasia of the animal, and then subjected to conventional storage in a freezer at a temperature of - 24°C. The prosthesis was composed of a cylindrical part with rods for attachment to the intramedullary canal, made of alloy steel 316L. After thawing the femurs and subsequent stabilization at room temperature we performed osteotomies of the femoral diaphysis with an oscillating saw and the installation of the prosthesis. As preparatory measures for prosthesis fixation with cement, the intramedullary canals were cleaned, washed with saline and aspirated. They were separated in four groups, the first group with eight femurs used a cement mantle of 1.0 to 1.5 mm, the second group, with eight femurs, used a cement mantle of 2.0 to 2.5 mm and the third group, with eight femurs, used a cement layer of 3.0 to 3.5 mm. The femurs were submitted to destructive torsion tests using a universal testing machine with a load cell of 981 N (100 kg) and an essay speed of 22 mm / min. They were evaluated due to the values of torsional rigidity and maximum torque shown by the implant, bone and bone cement interface. The fourth group consisted of the remaining intact femurs, they were evaluated using the same torsion test used on the other groups. The results were analyzed using the Statistical Analysis System (SAS, 2001) and the normality of residuals was previously verified by the Shapiro-Wilk test. It was established to conduct the testing using an external rotation protocol in order to standardize, assuming a situation where the dog was in movement during a uniform curvilinear motion, trying to mimic a situation where the rotational forces were acting more significantly on the femur. Discussion: In our study the importance of cleaning up the intramedullary canal for proper bone cement penetration, a good reaming of the intramedullary canal and drying the area before the cement implantation was made clear. Statistical analysis showed that the thicknesses of the cement layer ranging from 1 mm to 2.5 mm, although bringing a gradual increase in maximum torque and torsional rigidity, are not sufficient to be statistically significant and may be considered equal in their biomechanical behavior assessed by this study. A similar result was found when we compared the 2 mm to 3.5 mm layers. The comparison that was statistically significant and can be considered in relation to the different biomechanical behavior of the cement layer was seen between the group I of 1 mm to 1.5 mm, and group III of 3 mm to 3.5 mm. Although some results were not statistically significant we must remember that, in absolute values, the torsional rigidity and maximum torque increased linearly with the increasing of the cement layer. From these results we can infer about the real advantage of using a thicker cement layer over an increment in the diameter of the intramedullary component, giving greater resistance to the prosthesis.

Artrodese parcial tarsometatársica com uso de fixador esquéletico externo circular em cão / Tarsometatarsal Partial Arthrodesis with Use of Circular Skeletal Fixator on a Dog

Background: Trauma to the canine foot may result in injury to soft tissue or bone or both. Foot injury often results in fractures and joint instability because of disruption to carpal or tarsal ligaments. Several fixation methods have been described for stabilizing tarsometatarsal arthrodesis. The aim of this paper is to report the case of a unilateral tarsometatarsal arthrodesis with use of circular skeletal fixator on the left pelvic limb of a dog. Case: A 5-year-old intact male dog weighting 25 kg was referred to the veterinary hospital with a left tarsal degloving injury. The previous history revealed that the dog had been bitten by another dog seven days prior to the referral. On physical exam it had swelling and severe pain on the left foot, crepitus of the intertarsal/tarsometatarsal region, instability, bone exposure and myiasis larvae on the wound. The dog was non-weight-bearing on the affected limb. No other abnormalities were found. Radiographs revealed it to be an open fracture of the left tarsal distal line with tarsometatarsal luxation. Adherent dressings were changed for seven days to minimize the contamination before surgery. The dog was treated by open reduction and internal fixation using a circular skeletal fixator. After general anesthesia was induced, a lateral approach to the tarsometatarsal joint was made. The tarsometatarsal joint then was exposed. Articular cartilage was removed with a pneumatic burr. Manual reduction was performed. There were placed two rings proximal to the fracture and one distal with Kirschner wires were angled 45° between them through the bone. One of them was a semi-ring in the shape of a horseshoe. The 1,5 mm Kirschner wires were tensioned by a dynamometer loaded at 30 kg. For wound closure a free skin graft from the thorax was used. Articular anchylosis was reached in three months but the implant removal was posterior to that time due to the owner's choice. Discussion: Traumatic injury is the most important cause for fracture and instability of the tarsometatarsal joint and was the cause of injury for this case. Partial arthrodesis is considered the treatment of choice for tarsal instabilities with ligament disruption. Implant problems following union can complicate arthrodeses stabilized with internal fixation, and they may require a second surgery for implant removal. In this case the size of the rings conformed well to the proximal tarsus, and allowed sufficient space for wire placement in the metatarsal bones and did not interfere with ambulation. The dog recovered good limb function soon after the surgery and articular anchylosis was reached within three months as expected. In a study three of ten dogs undergoing tarsometatarsal arthrodesis due to continued lameness after bony union, using a laterally applied plate required a second surgery for implant removal. Implant failure is a common complication of tarsocrural and tarsometatarsal arthrodeses stabilized with bone screws, Steinmann pins or plate fi xation. Tarsometatarsal partial arthrodesis with use of circular skeletal fixator is a proper option for contaminated wounds without enough skin for closure. The limiting factor is the surgeon experience for this choice of fixation, material availability and the owner's commitment with the treatment.

Resultados clínicos e radiográficos de placas ósseas bloqueadas em 13 casos / Clinical and radiographics results of locking plates in 13 cases

A Placa Óssea Bloqueada (POB) consiste em um novo sistema de fixação interna, onde a placa apresenta orifícios duplos, um liso para compressão e outro rosqueado para fixação do parafuso que se fixa à placa. Promove grande estabilidade à fratura, sendo possível associar parafusos neutros e compressivos. Parafusos tradicionais comprimem a placa ao osso, nas placas bloqueadas não existe esta força e o encaixe da cabeça do parafuso à placa resulta em menores danos ao suporte vascular periosteal. Treze cães com distúrbios ortopédicos diversos foram tratados cirurgicamente com placa bloqueada com resultados satisfatórios. A placa bloqueada pode ser utilizada na medicina veterinária, porém, é técnica que requer cuidado e planejamento pré-operatório, especialmente na sequência de aplicação dos diferentes tipos de parafusos. Apresenta custo elevado, mas confere estabilidade rígida do foco de fratura e minimiza a possibilidade de perda prematura da interface parafuso e osso, diminuindo a possibilidade de instabilidade precoce e soltura do implante.(AU)

Locking plate is a new internal fixation system where the plate features has double holes, one smooth for compression and other threaded for screw fixing that attaches the plate. It leads to greater stability to the fracture being possible to associate neutral and compressive screws. Traditional screws compress the plate to the bone, in the locking plates there are no such strength and the fit of the screw head to the plate results in less damage to the vascular periosteal support. Thirteen dogs with various orthopedic disorders were treated surgically by locking plate with satisfactory results. The locking plate can be used in veterinary medicine, however, it is a technique that requires care and preoperative planning, especially in the order of applying different types of screws. It is expensive, but provides rigid stability of the fracture site and minimizes the likelihood premature loss of the screw and bone interface, reducing the possibility of instability and early loosening of the implant.(AU)

Resultados clínicos e radiográficos de placas ósseas bloqueadas em 13 casos / Clinical and radiographics results of locking plates in 13 cases

A Placa Óssea Bloqueada (POB) consiste em um novo sistema de fixação interna, onde a placa apresenta orifícios duplos, um liso para compressão e outro rosqueado para fixação do parafuso que se fixa à placa. Promove grande estabilidade à fratura, sendo possível associar parafusos neutros e compressivos. Parafusos tradicionais comprimem a placa ao osso, nas placas bloqueadas não existe esta força e o encaixe da cabeça do parafuso à placa resulta em menores danos ao suporte vascular periosteal. Treze cães com distúrbios ortopédicos diversos foram tratados cirurgicamente com placa bloqueada com resultados satisfatórios. A placa bloqueada pode ser utilizada na medicina veterinária, porém, é técnica que requer cuidado e planejamento pré-operatório, especialmente na sequência de aplicação dos diferentes tipos de parafusos. Apresenta custo elevado, mas confere estabilidade rígida do foco de fratura e minimiza a possibilidade de perda prematura da interface parafuso e osso, diminuindo a possibilidade de instabilidade precoce e soltura do implante.

Locking plate is a new internal fixation system where the plate features has double holes, one smooth for compression and other threaded for screw fixing that attaches the plate. It leads to greater stability to the fracture being possible to associate neutral and compressive screws. Traditional screws compress the plate to the bone, in the locking plates there are no such strength and the fit of the screw head to the plate results in less damage to the vascular periosteal support. Thirteen dogs with various orthopedic disorders were treated surgically by locking plate with satisfactory results. The locking plate can be used in veterinary medicine, however, it is a technique that requires care and preoperative planning, especially in the order of applying different types of screws. It is expensive, but provides rigid stability of the fracture site and minimizes the likelihood premature loss of the screw and bone interface, reducing the possibility of instability and early loosening of the implant.

Avaliação do uso de haste bloqueada e bloqueio transcortical no reparo de fraturas diafisárias de fêmur em felinos / Evaluation of the use of interlocking nail and transcortical blockade for the repair of diaphyseal fractures of the femur in cats

As hastes bloqueadas além de permitirem estabilização rígida de fraturas, possuem vantagens biomecânicas quando comparadas a outras técnicas de imobilização, por atuar ao longo do eixo mecânico central do osso, além de preservar os conceitos de padrões biológicos de osteossíntese . O uso limitado de hastes bloqueadas em gatos se atribui ao fato da cavidade intramedular ser pequena, limitando o tamanho e diâmetro dos pinos. Relatam-se casos de 10 felinos que apresentavam fraturas fechadas simples ou múltiplas da diáfise femoral. Os animais pesavam entre 3,5 e 5 kg, o que permitiu a utilização de hastes de 4,0mm e 4,7mm de diâmetro. Para inserção da haste, adotou-se a via retrógrada ou a normógrada e foram realizados bloqueios com quatro parafusos de titânio de 2,0 mm de diâmetro. Complicações intra-operatórias não ocorreram, entretanto um animal sofreu fratura de colo femoral e fratura transversa distal ao implante, três dias após o ato cirúrgico, devido a novo trauma. Os animais foram submetidos a exames radiográficos até quatro meses após a intervenção, evidenciando-se formação de calo ósseo secundário e consolidação óssea em período de 61-89 dias. Clinicamente, ocorreu esporadicamente alteração na marcha por leve claudicação de apoio definida por escala de claudicação, entretanto os animais iniciaram o apoio adequado entre três e oito dias após o ato operatório. Complicações pósoperatórias ocorreram referentes ao animal que sofreu novo trauma, entretanto notou-se consolidação do foco primário tratado pelo implante com 61 dias e consolidação da nova fratura num período total de 150 dias do início do tratamento conservativo por penso esparadrapado e tala. Conclui-se que o uso de haste bloqueada em felinos foi adequado uma vez que houve consolidação óssea em todos os casos, com retorno precoce da função do membro, permitindo a deambulação.

Interlocking nails allow rigid fracture stabilization and present biomechanical advantages when compared to other immobilization techniques. It acts along the central mechanical axis of the bone and preserves biological concept standards for osteosynthesis. The use of interlocking nail in cats is limited because the intramedullary space is relatively small for the available nail sizes. We reported 10 cases of cats that had simple or multiple closed fractures of the femoral diaphysis. The animals weighed 3.5 to 5 kg , which allowed using nails of 4.0mm and 4.7mm in diameter. For the nail insertion, retrograde and normograde routs were used, and four 2mm titanium screws were used to lock all the perforations. No trans-surgical complication occurred, however, due to a new trauma, one of the animals suffered femoral neck fracture and transversal distal fracture to the nail, three days after surgery. Radiographies were made up to four months after surgery, and in most cases secondary bone formation was seen, showing bone consolidation in 61-89 days, excluding the animal who suffered new trauma, who presented bone healing in 150 days. Clinically, occasional lameness occurred; however, except for the animal that had new trauma, all animals initiated adequate limb support in 3 to 8 days after surgery. In conclusion, the use of 4.0mm and 4.7mm interlocking nails in felines was adequate, with bone healing in all cases, and also return of good limb function after surgery.

Avaliação do uso de haste bloqueada e bloqueio transcortical no reparo de fraturas diafisárias de fêmur em felinos / Evaluation of the use of interlocking nail and transcortical blockade for the repair of diaphyseal fractures of the femur in cats

As hastes bloqueadas além de permitirem estabilização rígida de fraturas, possuem vantagens biomecânicas quando comparadas a outras técnicas de imobilização, por atuar ao longo do eixo mecânico central do osso, além de preservar os conceitos de padrões biológicos de osteossíntese . O uso limitado de hastes bloqueadas em gatos se atribui ao fato da cavidade intramedular ser pequena, limitando o tamanho e diâmetro dos pinos. Relatam-se casos de 10 felinos que apresentavam fraturas fechadas simples ou múltiplas da diáfise femoral. Os animais pesavam entre 3,5 e 5 kg, o que permitiu a utilização de hastes de 4,0mm e 4,7mm de diâmetro. Para inserção da haste, adotou-se a via retrógrada ou a normógrada e foram realizados bloqueios com quatro parafusos de titânio de 2,0 mm de diâmetro. Complicações intra-operatórias não ocorreram, entretanto um animal sofreu fratura de colo femoral e fratura transversa distal ao implante, três dias após o ato cirúrgico, devido a novo trauma. Os animais foram submetidos a exames radiográficos até quatro meses após a intervenção, evidenciando-se formação de calo ósseo secundário e consolidação óssea em período de 61-89 dias. Clinicamente, ocorreu esporadicamente alteração na marcha por leve claudicação de apoio definida por escala de claudicação, entretanto os animais iniciaram o apoio adequado entre três e oito dias após o ato operatório. Complicações pósoperatórias ocorreram referentes ao animal que sofreu novo trauma, entretanto notou-se consolidação do foco primário tratado pelo implante com 61 dias e consolidação da nova fratura num período total de 150 dias do início do tratamento conservativo por penso esparadrapado e tala. Conclui-se que o uso de haste bloqueada em felinos foi adequado uma vez que houve consolidação óssea em todos os casos, com retorno precoce da função do membro, permitindo a deambulação.(AU)

Interlocking nails allow rigid fracture stabilization and present biomechanical advantages when compared to other immobilization techniques. It acts along the central mechanical axis of the bone and preserves biological concept standards for osteosynthesis. The use of interlocking nail in cats is limited because the intramedullary space is relatively small for the available nail sizes. We reported 10 cases of cats that had simple or multiple closed fractures of the femoral diaphysis. The animals weighed 3.5 to 5 kg , which allowed using nails of 4.0mm and 4.7mm in diameter. For the nail insertion, retrograde and normograde routs were used, and four 2mm titanium screws were used to lock all the perforations. No trans-surgical complication occurred, however, due to a new trauma, one of the animals suffered femoral neck fracture and transversal distal fracture to the nail, three days after surgery. Radiographies were made up to four months after surgery, and in most cases secondary bone formation was seen, showing bone consolidation in 61-89 days, excluding the animal who suffered new trauma, who presented bone healing in 150 days. Clinically, occasional lameness occurred; however, except for the animal that had new trauma, all animals initiated adequate limb support in 3 to 8 days after surgery. In conclusion, the use of 4.0mm and 4.7mm interlocking nails in felines was adequate, with bone healing in all cases, and also return of good limb function after surgery.(AU)

Comparação de osteossíntese com placa e osteossíntese com placa associada a enxerto de proteína morfogenética óssea em fratura bilateral distal de rádio e ulna em cão - Relato de Caso / Comparison between bone plate osteosinthesis and bone plate associated to bone morphogenetic protein in a bilateral distal fracture of radius and ulna in a dog - Case Report

Os cuidados e dificuldades em reparação de fraturas de rádio-ulna de cães de porte pequeno são conhecidos, com a ocorrência freqüente de não-união óssea, principalmente no que tange as fraturas distais, relacionadas a características anatômicas inerentes, como pouco recobrimento de tecido muscular, canal medular de diâmetro reduzido, e pouca vascularização. Tendo em vista esta realidade, descreve-se a comparação entre o tratamento com placa e parafuso e placa e parafuso com adição de proteína morfogenética óssea em fratura completa transversa de terço distal bilateral de rádio-ulna, de semelhante apresentação em cão da raça Pinscher, atendido no Serviço de Cirurgia de Pequenos Animais do HOVET / USP. Avaliou-se, comparativamente, o tempo de formação de calo ósseo, por exames radiográficos, aos 30, 60, 90 e 120 dias de pós-operatório, onde foi encontrado tempo de cicatrização de 90 dias no membro controle enquanto que, no membro tratado com a proteína morfogenética óssea, o tempo de cicatrização foi de 30 dias, demonstrando a possibilidade de incremento que o uso de fatores de crescimento podem trazer ao tratamento de fraturas em cães de pequeno porte.(AU)

The aims and difficulties in small breed dogs radius and ulna fracture repair are known, frequently occurring cases of nonunionn principally in distal part of these bones, by their inherent anatomical characteristics, as poor muscular recovering, small medullar channel and less vascular aport, that are the principal causes of complication in post surgical or conservative procedures. By this reallty, the comparison between treatment with bone plate and screws, with and without addition of bone morphogenetic protein (BMP), in distal fracture of radius and ulna in a Doberman Pinscher, cared in HOVET surgical area is described. It was evaluated the bone callus formation, by radiographic examination in 30th ,60th ,90th and 120th day of surgical procedure, being visualized total consolidation after 90 days in the control member and after 30 days in the BMP member, showing all the beneficial possibilities of the BMP use in cases of distal fractures in small breed dogs.(AU)

Comparação de osteossíntese com placa e osteossíntese com placa associada a enxerto de proteína morfogenética óssea em fratura bilateral distal de rádio e ulna em cão: relato de caso / Comparison between bone plate osteosinthesis and bone plate associated to bone morphogenetic protein in a bilateral distal fracture of radius and ulna in a dog: case report

Os cuidados e dificuldades em reparação de fraturas de rádio-ulna de cães de porte pequeno são conhecidos, com a ocorrência freqüente de não-união óssea, principalmente no que tange as fraturas distais, relacionadas a características anatômicas inerentes, como pouco recobrimento de tecido muscular, canal medular de diâmetro reduzido, e pouca vascularização. Tendo em vista esta realidade, descreve-se a comparação entre o tratamento com placa e parafuso e placa e parafuso com adição de proteína morfogenética óssea em fratura completa transversa de terço distal bilateral de rádio-ulna, de semelhante apresentação em cão da raça Pinscher, atendido no Serviço de Cirurgia de Pequenos Animais do HOVET / USP. Avaliou-se, comparativamente, o tempo de formação de calo ósseo, por exames radiográficos, aos 30, 60, 90 e 120 dias de pós-operatório, onde foi encontrado tempo de cicatrização de 90 dias no membro controle enquanto que, no membro tratado com a proteína morfogenética óssea, o tempo de cicatrização foi de 30 dias, demonstrando a possibilidade de incremento que o uso de fatores de crescimento podem trazer ao tratamento de fraturas em cães de pequeno porte.

The aims and difficuIties in small breed dogs radius and ulna fracture repair are known, frequently occurring cases of nonunionn principally in distal part of these bones, by their inherent anatomical characteristics, as poor muscular recovering, small medullar channel and less vascular aport, that are the principal causes of complication in post surgical or conservative procedures. By this reallty, the comparison between treatment with bone plate and screws, with and without addition of bone morphogenetic protein (BMP), in distal fracture of radius and ulna in a Doberman Pinscher, cared in HOVET surgical area is described. It was evaluated the bone callus formation, by radiographic examination in 30th ,60th ,90th and 120th day of surgical procedure, being visualized total consolidation after 90 days in the control member and after 30 days in the BMP member, showing all the beneficial possibilities of the BMP use in cases of distal fractures in small breed dogs.