Mechanical study in vitro of the resistance of axial forces of 3.5 mm cannulated and conventional screws in head and femoral neck fractures

Background: Proximal femoral fractures account for 25% of all femoral fractures in dogs and are more common in young animals. Osteosynthesis of femoral head and neck fractures is a complex procedure that can be performed using conventional screws or wires. However, proper fracture reduction and fi xation are diffi cult to achieve and, despite many advancements, such fractures remain challenging to solve. Cannulated screws have good compressive capacity and can be employed to simplify the surgical procedure while optimizing outcomes. This study was designed to compare the resistance of conventional and cannulated screws to axial loading following experimental femoral neck fracture in dogs. Materials, Methods & Results: Fourteen cadaveric canine femurs were used in this study. Femurs were collected from dogs over 20 pounds in body weight with no gross or radiographic signs of orthopedic disease. Cadaveric femurs were submitted to experimental femoral neck fracture using a Gigli saw and allocated to osteosynthesis using either conventional or cannulated screws (seven bones each). All screws were inserted below the greater trochanter of the femur from the lateral aspect of the bone and screw topography confi rmed radiographically. Test specimens were then potted in polymethylmethacrylate, coupled to a hinged device and submitted to axial loading. Data on maximum load, maximum displacement, load within the proportional limit, offset within the proportional limit and load required to produce a 3 mm displacement were collected. Mean values were calculated and compared using the Student’s t test (P < 0.05). Mean values varied greatly within groups. Maximum load and displacement correspond to the critical point from which biomechanical testing becomes destructive. Data were missing from one test specimen (conventional screw group) due to abrupt diaphyseal fracture at the start of the axial loading trial. Discussion: The canine femur was selected as an experimentalmodel in this project due to the high incidence of femoral neck fractures in dogs. Also, studies on proximal femoral fracture osteosynthesis using cannulated screws are scarce. The effectiveness of the compression osteosynthesis technique employed in this trial has been confi rmed in several canine proximal femoral fracture studies, with reported success rates between 2 and 21%. Success rate variability could be due to substantial individual differences, as suggested by the large intragroup variation in this trial. The biomechanical behaviour of conventional sliding hip screws (SHC) and cannulated screws following experimental femoral neck fracture osteosynthesis was compared. Increased stiffness was achieved with SHCs, possibly due to more effi cient transmission of compressive forces to cortical bone under the plate. Compression screws act by transmitting compressive forces to cancellous bone under the fracture line. Replication of this scenario in this trial supports the recommendation that the lowest screw be inserted as close as possible to the medial cortex of the femur, which is stiffer than the cancellous bone in the femoral head. Under the conditions studied, mean maximum load values were higher when bone screws were inserted closer to the medial cortex of the femoral shaft and the proximal aspect of the femoral head, regardless of screw type. The opposite scenario was also observed (i.e. the farther from the medial cortex of the femoral shaft, the lower the mean maximum load). In this trial, conventional and cannulated screws were equally resistant to axial loading. However, femoral neck fracture osteosynthesis using cannulated screws was easier to perfor

Use of omental flap to induce vascularization and bone healing in a dog

Este trabalho relata o caso de uma cadela da raça whippet, de 10 anos, com união retardada de tíbia e fíbula esquerdas, exposta, cotaminada e com grande perda de massa muscular e óssea e de pele causada por instabilidade óssea decorrente de duas intervenções cirúrgicas realizadas anteriormente. Foi realizado retalho de omento maior em camada simples, alcance ao foco de fratura via túnel subcutâneo e recobrimento por enxerto cutâneo em malha. O objetivo do trabalho foi avaliar a capacidade de indução vascular do omento maior para foco de fratura e consequentemente consolidação óssea, tendo como hipótese a acentuada função de angiogênese do omento maior. A tíbia e fíbula esquerdas foram estabilizadas com fixador circular externo. Após 80 dias, houve consolidação óssea da tíbia, volta do apoio do membro e retirada do implanteThis research reports the case of a whippet female dog, 10 years old, with delayed union of left tibia and fibula, exposure of the fracture focus with localized infection, and extensive loss of, muscle, bone and skin after instability caused by two surgical interventions accomplished previously. A flap was made of the greater omentum in a single layer. The fracture site was reached through the subcutaneous tunnel and the coating by mesh skin grafts. The objective of this study was to evaluate the ability of the larger omentum to induce angiogenesis to the fracture site and the subsequent bone healing, considering the strong role of angiogenesis. The left tibia and fibula were stabilized with external circular fixator. After 80 days there was bone healing of the tibia around the support member and removal of the implant. Postoperative complications included partial necrosis of the cutaneous (25%) flap and shortening of the tibia with consequent laxity ligament of the membe

Physics behind the implants used for high strain fractures: literature review

Quando fraturas ósseas ocorrem, forças externas produzem movimentação interfragmentária continuamente e um método de estabilização se faz necessário. É sabido que as condições mecânicas no local de fratura influenciam a formação de calo durante o processo de cicatrização óssea e para que cicatrização óssea primária seja obtida é necessária estabilidade absoluta no foco de fratura. O conceito de strain de Perren determina que a deformação relativa no foco de fratura estabilizado depende do tamanho da lacuna de fratura original. Fraturas redutíveis (sem cominuição) são consideradas de alto strain, pois uma pequena força aplicada a linha de fratura resulta em grande movimentação com efeito deletério ao processo de consolidação. O presente trabalho revisa a literatura disponível a respeito de fatores que influenciam a mecânica de fraturas de alto strain em medicina veterinária, seus métodos de tratamento e a física por trás dos implantes disponíveis. Cada configuração de fratura requer atenção especial e cuidado crítico na escolha do método de osteossíntese e no tipo de estabilidade necessária para que a consolidação ocorra no tempo esperado. Conhecimento da teoria do strain é mandatório para a formação de cirurgiões ortopédicos. Whenever bone fractures occur, external forces produce continuous interfragmentary motion and a stabilization method is necessary. It is known that the mechanical conditions at the fracture site influence bone callus formation during healing process. To achieve primary (direct) bone healing, absolute stability at the fracture site is necessary. Perren’s concept of strain determines that relative deformation at the fracture gap depends on the original gap’s conformation. Simple fractures (without comminution) are considered high strain fractures since a small force applied to the fracture site results in great movement with deleterious effects on the healing process. The purpose of this study is to review the available literature regarding factors that influence the mechanics of high strain fractures in veterinary medicine, its treatment methods and implants available. Each fracture configuration requires special attention and critical care in choosing the osteosynthesis method and the type of stability required for consolidation to occur within the expected time. One must know the strain theory to become an orthopedic surgeon

Avaliação bacteriológica de enxertos ósseos submetidos à técnica criogênica a -24°C em banco de ossos de cães (Canis familiaris)

The scientific basis of bone transplantation was established during the mid-nineteenth century, when the osteogenic properties of the bone and periosteum, beneficial influence of cold preservation of bones, and first conventional attempt to store bones for elective use, were described. A bone bank has several advantages, such as the immediate availability of grafts in large quantities, and different shapes and sizes, and maintenance of osteoinductive activity in grafts. In addition, it reduces patient blood loss, surgical time, and quantity of anesthetics required. Clinical applications include the correction of comminuted fractures, treatment of non-union bones, and replacement of bone loss due to infections or malignancies. The success of these procedures depends on the preservation and integrity of the graft. This study aimed to evaluate the feasibility of maintaining a canine bone bank (Canis familiaris) by quantifying the bacterial contamination of bone grafts preserved at –24°C. The samples were evaluated through a monthly assessment of bacteriological cultures over a period of 6 months. The harvest method was efficient and sterile, reducing the risk of contamination. We conclude that the techniques chosen for the implementation of a bone bank were effective and feasible (use of a common freezer reaching a temperature below –24°C). The viability of the bones was attested during a 6-month period, and the samples demonstrated a 100% sterility rate.A base científica do transplante ósseo foi estabelecida na metade do século IX quando foram descritas as propriedades osteogênicas do osso e do periósteo, a influência benéfica do frio na preservação das mesmas, e a primeira tentativa convencional para armazenar ossos para uso eletivo. As vantagens do banco de ossos são a disponibilidade imediata do enxerto em quantidade, forma e tamanhos variados, com a manutenção de sua atividade osteoindutora, e redução do tempo cirúrgico, anestésico e perda sanguínea do paciente. Dentre as aplicações clínicas cita-se a correção de fraturas cominutivas, tratamento de não união óssea e reposição de perda óssea devido a infecções ou neoplasias. O sucesso destes procedimentos depende dos parâmetros de conservação e integridade do enxerto. Este estudo teve como objetivo avaliar a viabilidade da manutenção de banco de ossos de cães (Canis familiaris) quantificando a contaminação bacteriológica dos enxertos ósseos, submetidos à técnica criogênica (-24°C) e avaliados através de realização mensal de culturas bacteriológicas por um período de seis meses. O método de coleta mostrou-se eficiente e propiciou adequada manutenção de esterilidade durante o período de coleta, diminuindo o risco de contaminação dos ossos. Concluímos que as técnicas escolhidas para implantação do banco de ossos mostraram-se eficientes e factíveis, com freezer comum de temperatura abaixo de –24°C, comprovou-se a viabilidade dos ossos por um período de 6 meses, obtendo-se taxa de esterilidade dos mesmos de 100% através das culturas bacteriológicas

Treatment of tarsal joint deformities with hinged transarticular external fixators in three young birds

Pelvic limb deformities are common in many avian species. Three young birds, including a six-week-old Cockatoo and two three-month-old goslings, were presented with tarsal joint deformities. They were treated with an experimental prototype of a hinged linear external fixator, placed in a transarticular fashion, in order to maintain joint function during treatment. All birds had close to normal leg function at six to ten weeks postoperatively. These results suggest that the hinged external fixator may be a viable treatment option for tarsal joint deformities in young bird

Results of tibial tuberosity advancement technique for treatment of insufficiency cranial cruciate ligament in 17 cases

Раздел 3 «Менеджмент. Маркетинг. Финансы и банковское дело. Экономика