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

A critical study about the treatment of 196 cases of diphiseal radial

Fraturas diafisárias de rádio e ulna em cães são freqüentes dentro dos quadros mórbidos ortopédicos em Medicina Veterinária, e seu tratamento merece especial atenção, face aos muitos quadros de insucesso observados. Foram comparados neste estudo os resultados de três métodos de osteossíntese, sendo estes a fixação esquelética externa, o uso de placas e parafusos e a imobilização externa, em quadros de fraturas de terço proximal, médio e distal de rádio e ulna em cães. Os dados demográficos e referentes à distribuição e classificação das fraturas, bem como o método utilizado para osteossíntese e suas conseqüências foram tabulados e os dados comparados estatisticamente. Como resultados, das 196 fraturas acompanhadas, pacientes com até 6,0 kg foram os mais acometidos (46,4%) com lesões principalmente no terço distal (64,93% das fraturas). Animais que foram operados com intervalo menor entre a ocorrência da fratura e a cirurgia demonstraram melhores resultados. Houve diferença significativa entre as osteossínteses por fixadores externos e placas parafusadas, quando comparados à imobilização externa, independentemente da região fraturadaThe results from three osteosynthesis methods in cases of proximal, mid and distal fractures of radio and ulna in dogs were compared: the skeletal external fixation, plates and screws and the external immobilization. Shaft fractures of radius and ulna in dogs are frequent among the orthopedic morbid cases in Veterinary Medicine and their treatment deserves special attention, due to the high number of unsuccessful cases observed. The demographic data with reference to distribution and classification of fractures, as well as the method used for osteosynthesis and its consequences, were tabulated and the data were statistically compared. As results, from the 196 fractures observed, patients with up to 6.0 kilograms were the most affected (46.4%) with lesions mainly in the distal third (64.93% of the fractures). Animals that have been operated with smaller interval between the fracture occurrence and the surgery showed better results. There was a significant difference between osteosynthesis by external fixators and screwed plates when compared to external immobilization, independent on the fracture sit

Avaliação radiográfica da absorção de parafusos de osso cortical bovino com bone morphogenetic protein (BMP) inseridos em úmero de cão

Allografts are produced from natural sources and have been used in orthopedic repair procedures for a long time in humans and animals. Since 1952, hundreds of orthopedic surgeries have been performed with success using donated tissues and materials from bone banks. The purpose of the present study was to verify the absorption time of xenografts screws made of bovine cortical bone, inserted in the greater tubercule. The humerus of seven dogs in comparison with stainless steel screws. The results showed that screws made from bovine cortical bone used in the humerus of dogs were incorporated within a period of 30 to 60 days with no severe periosteum reaction.Os aloenxertos, são retirados de fontes naturais e são utilizados em cirurgias ortopédicas em humanos e em animais há muitos anos. Desde 1952 centenas de cirurgias ortopédicas foram realizadas com sucesso usando-se tecidos e materiais doados de banco de ossos. O propósito do presente estudo é verificar o tempo de absorção, através de exames radiográficos, de parafusos confeccionados com cortical óssea bovina, inserida no tubérculo maior do úmero de sete cães, em comparação com parafusos de aço. Os resultados demonstraram que o parafuso de cortical bovino foi incorporado entre um período de 30 a 60 dias sem reação periostal exuberante

Mechanical study &quot;in vitro&quot; of the resistance of axial forces of 3.5mm cannulated screws in comparison with conventional screws of the same diameter, in head and femoral neck fractures

Em razão da complexidade da osteossíntese nas regiões de colo e cabeça femorais, aliado à dificuldade da boa redução e fixação da fratura, objetivou-se estudar comparativamente os efeitos das cargas com forças axiais nos conjuntos osso-parafuso convencional e osso-parafuso canulado. O parafuso canulado possui eficiente capacidade compressiva e por possuir uma cânula central é capaz de simplificar a técnica cirúrgica se comparado aos parafusos ósseos convencionais. Foram utilizados dois parafusos dispostos paralelamente, inseridos da porção lateral do fêmur, abaixo do trocânter maior, em direção à cabeça femoral em 14 fêmures de cães acima de 20 kilos de peso, subdivididos em 2 grupos de 7 fêmures com parafusos convencionais e 7 fêmures com parafusos canulados , sem sinais macroscópicos ou radiográficos de moléstias ósseas. Os resultados obtidos mostraram que não houve diferenças estatísticas na força máxima e na rigidez nos dois grupos, e em todos os ensaios, os implantes não sofreram deformação, portanto conclui-se que as resistências dos parafusos convencional e canulado, utilizados na osteossíntese de fraturas de cabeça e colo de fêmur, são semelhantes.Because of the complexity of osteosynthesis of femoral head and neck fractures and the difficulty of good reduction and fixation of the fractures, we studied comparatively the effects of load and axial forces of bone-conventional screws and bone-cannulated screws. The cannulated screw presents efficient compressive capacity and it presents a central cannula capable of simplifying the surgical technique if compared to conventional bone screws. We used two screws placed parallel, inserted in the lateral aspect of the femur, beneath the greater trocanter, directed to the femoral head, in fourteen femurs of dogs over 20Kg, subdivided in two groups of seven femurs each, the first with conventional screws and the second with cannulated screws, with no macroscopic or radiographic signs of bone diseases. The results didn´t show any statistical differences in maximum strength and rigidity of both groups and the implants didn´t suffer deformities in any essays, therefore we conclude that the resistances of conventional and cannulated screws, used in of femoral heads and necks fracture repairs, are similar

Plasma rico em plaquetas combinado a hidroxiapatita na formação do calo ósseo em fraturas induzidas experimentalmente no rádio de cães Platelet-rich plasma combined with hydroxyapatite on bone callus formation in experimental radii fractures in dogs

Avaliou-se, no presente estudo, os efeitos do plasma rico em plaquetas (PRP) autógeno combinado a hidroxiapatita não-absorvível na formação do calo ósseo em fraturas diafisárias induzidas experimentalmente em rádio de cães e fixadas com placas e parafusos ósseos. Foram utilizados oito cães adultos sem raça definida, machos ou fêmeas, com pesos compreendidos entre 5 e 15kg. Induziu-se na diáfise de ambos os rádios defeito ósseo correspondente a 25% do diâmetro do mesmo. No rádio direito (grupo HA/PRP), implantou-se plasma rico em plaquetas combinado a hidroxiapatita. No rádio esquerdo (grupo HA), implantou-se somente a hidroxiapatita. Para a obtenção do PRP, empregou-se protocolo simplificado utilizando centrífuga laboratorial comum. Comparou-se entre os grupos a evolução clínica dos animais, o tempo de formação e a densidade do calo ósseo por exames radiográficos simples e pela técnica de densitometria óptica aos 15, 30, 45 e 60 dias de pós-operatório. Tanto na avaliação radiográfica como densitométrica não se observou diferença estatisticamente significante na evolução do calo ósseo entre os grupos (P>0,05). No presente estudo, o PRP autógeno combinado à hidroxiapatita não-absorvível não acelerou o processo de formação do calo ósseo, comparado à hidroxiapatita somente.<br>The present study was aimed at evaluating the effects of autologous platelet-rich plasma (PRP) in combination with unabsorbable hydroxyapatite on bone callus formation in an experimental canine diaphyseal radius fracture stabilized with bone plate. Eight mature, male and female mongrel dogs were selected weighed 5 to 15kg. Bone defects were created, bilateral, in both radii diaphysis, corresponding to 25% of bone diameter. On the right radius (group HA/PRP), the defect was filled with PRP and hydroxyapatite. On the left radius (group HA), was placed hydroxyapatite alone. PRP was obtain by a simplified technique using a laboratory centrifuge. Clinical evaluations, bone formation and bone density by use of radiographic and optical densitometry, were compared between group HA/PRP and group HA after 15, 30, 45 and 60 days post surgery. The radiographic and densitometric study did not indicate a significant difference in the bone callus formation between the groups (P>0.05). In the present study the autologous PRP in combination with unabsorbable hydroxyapatite could not accelerated the bone callus in comparison with hydroxyapatite alone