Research evaluating the surgical repair of femoral neck fractures in dogs is limited. This study evaluated the in vitro mechanical properties of canine femoral neck fractures stabilized with two medium Orthofix® Partially-threaded Kirschner Wires (Orthofix pins), a 2.7 mm cortical bone screw placed in lag fashion with anti-rotational Kirschner wire (K-wire), and three 1.1 mm divergent K-wires. This study compared the mean compressive pressure, compressive force and area of compression created by the insertion the Orthofix pins and a 2.7 mm cortical bone screw placed in lag fashion. Monotonic testing was used to quantify mechanical strength and pressure sensitive film was used to quantify compression. There was no significant difference in the stiffness or load to failure for the three repair methods evaluated. There was no significant difference in the compressive pressure, compressive force or area of compression in osteotomies stabilized with Orthofix pins and 2.7 mm bone screws.

A aplicação da madeira como material estrutural na construção civil é amplamente difundida em coberturas residenciais e comerciais, construção de residências ou em obras de grande porte como pontes. Freqüentemente ocorre a necessidade de ligações entre peças estruturais. Uma das possibilidades de ligação é a utilização de parafusos auto-atarraxantes solicitados por esforços de tração, diferente da maioria dos casos de ligações, nas quais pinos estão solicitados por forças laterais. Um tipo particular de parafuso auto-atarraxante é o torx, que possui rosca em toda a sua extensão, possibilitando uma outra forma de arranjo de ligação que facilita a execução das ligações entre as peças estruturais. Este parafuso possui uma grande resistência que traz à industrialização das estruturas de madeiras. O objetivo desta pesquisa é determinar, de maneira experimental, a resistência de ligações utilizando parafusos torx auto-atarraxantes submetidos a esforços axiais de tração, em peças de madeira, avaliando a influência de diversos fatores, tais como: direção de fixação dos parafusos em relação às fibras, efeito de grupo teor de umidade, massa específica da madeira e espaçamentos entre parafusos. Foram utilizadas as espécies: Pinus Taeda (Pinus taeda L.), Eucalipto Grandis (Eucalyptus grandis) e Cupiúba (Goupia glabra). / Timber as a structural material civil in construction is widely used in framework, construction of houses or larger construction as bridges. The use of connections among structural members is frequently required. One of the connection possibilities is the use of lag screws in axial withdrawal load, differently from most cases of connections in which they are laterally loaded. A peculiar type of lag screw is the torx, which possesses thread along its extension, making possible another form of connection arrangement that facilitates the execution of the connections among the structural pieces. This lag screw has a high strength and facilitates the industrialization of timber structures. The aim of this research is to determine, in an experimental way, the strength of connections using torx lag screws in withdrawal loads, evaluating the influence of several factors, such as direction of the lag screws in relation to grain, group effect, moisture content, density of wood and spacings among screws. The species used were: Pinus Taeda (Pinus taeda L.), Eucalipto Grandis (Eucalyptus grandis) and Cupiúba (Goupia glabra).

A aplicação da madeira como material estrutural na construção civil é amplamente difundida em coberturas residenciais e comerciais, construção de residências ou em obras de grande porte como pontes. Freqüentemente ocorre a necessidade de ligações entre peças estruturais. Uma das possibilidades de ligação é a utilização de parafusos auto-atarraxantes solicitados por esforços de tração, diferente da maioria dos casos de ligações, nas quais pinos estão solicitados por forças laterais. Um tipo particular de parafuso auto-atarraxante é o torx, que possui rosca em toda a sua extensão, possibilitando uma outra forma de arranjo de ligação que facilita a execução das ligações entre as peças estruturais. Este parafuso possui uma grande resistência que traz à industrialização das estruturas de madeiras. O objetivo desta pesquisa é determinar, de maneira experimental, a resistência de ligações utilizando parafusos torx auto-atarraxantes submetidos a esforços axiais de tração, em peças de madeira, avaliando a influência de diversos fatores, tais como: direção de fixação dos parafusos em relação às fibras, efeito de grupo teor de umidade, massa específica da madeira e espaçamentos entre parafusos. Foram utilizadas as espécies: Pinus Taeda (Pinus taeda L.), Eucalipto Grandis (Eucalyptus grandis) e Cupiúba (Goupia glabra). / Timber as a structural material civil in construction is widely used in framework, construction of houses or larger construction as bridges. The use of connections among structural members is frequently required. One of the connection possibilities is the use of lag screws in axial withdrawal load, differently from most cases of connections in which they are laterally loaded. A peculiar type of lag screw is the torx, which possesses thread along its extension, making possible another form of connection arrangement that facilitates the execution of the connections among the structural pieces. This lag screw has a high strength and facilitates the industrialization of timber structures. The aim of this research is to determine, in an experimental way, the strength of connections using torx lag screws in withdrawal loads, evaluating the influence of several factors, such as direction of the lag screws in relation to grain, group effect, moisture content, density of wood and spacings among screws. The species used were: Pinus Taeda (Pinus taeda L.), Eucalipto Grandis (Eucalyptus grandis) and Cupiúba (Goupia glabra).

Fracture to the neck of femur is frequently stabilised with a hip screw system, however the host bone is often weak or osteoporotic. This causes premature failure of the system, commonly by cut-out of the lag screw through the head of the femur. While augmentation of the fixation with bone cement improves the holding power and decreases failure rate, current methods of administering the cement are messy and inaccurate. This project proposes a lag screw design which allows for direct injection of the cement, via the lag screw itself, after the screw has been inserted and correctly positioned in the femur. A method is also suggested to reduce the risk of cement leakage into the joint space when the guide wire has punctured the head of the femur. The design uses a system of holes in the threaded section of a cannulated screw to allow delivery of cement to the desired area; the modified screw was also tested with and without the tip of the screw closed. These design and implantation techniques were compared to the standard design lag screw both with and without bone cement augmentation by traditional methods. Initial testing in a synthetic bone analogue looked promising. The modified screw with closed end performed better in push out tests than the standard screw alone and comparably with the standard screw with cement augmentation. A second phase of testing with the synthetic material was then conducted to more closely represent physiological loading conditions. In this case again the closed ended modified screw with cement augmentation outperformed the original screw and was comparable with the augmented original screw. However, during this phase of testing problems were observed with the synthetic testing material and it was decided to conduct further testing in paired porcine cadaveric femurs. Several further problems occurred in this phase of testing, including the bending of the test screws. It was concluded that the modified screw showed potential in being a more accurate and consistent method of cement augmentation, however neither the synthetic bone analogue or the porcine material was an adequate model of an osteoporotic human femur. If a suitable testing material could be found, continued study of this prototype may prove beneficial.

In a recent in vitro biomechanical stability study by F.J. Jacobs, a unique, patented inclined screw insertion (I.S.I.) mandibular angle, intra-oral trauma-plate was evaluated for torsion and compression stability and compared to conventional plating of simulated angle fractures in polyurethane mandibular replicas. This in vitro comparative pilot study is an extension of the above-mentioned study. Similar I.S.I. mini-plates with 45º inclined screw holes in quadrant 3 (Fig 1), were used but in the one sample 13mm-long lag screws were used to transect the fracture lines where in the other group non-lagging screws of similar length were used to fixate simulated mandibular angle fractures in polyurethane mandible replicas. A uniquely designed and manufactured jig, incorporated in a Zwick machine, was utilized to apply torsion forces within clinical relevant load values. The load-displacement values for torsion forces was determined and compared for the two groups. It was established that 5 lag screws significantly improved the torsion stability of the lag-plate group to that of the non-lag group. During the stability testing, two factors were identified, which had a critical influence on the compression generated by the lag screw between the fracture fragments. An adequate amount of bone must be maintained between the first screw hole, directly distal to the fracture line, and the fracture line. All screws must be inserted in the correct sequence in order to insure sufficient compression between the fracture fragments as a result of the lag-effect. AFRIKAANS : In `n onlangse in vitro studie deur F.J. Jacobs, is `n gepatenteerde, unieke geanguleerde miniplate, waarvan die skroefgate geanguleer is, die sg. Inklineerde Skroef Inplasing (I.S.I.) kaak-hoek, intra-orale traumaplaat geevalueer vir torsie en kompressie stabiliteit en vergelyk met konvensionele plate op gesimuleerde kaakhoek frakture in poli-uretaan mandibular replikas. In hierdie in vitro loodstudie, is I.S.I. miniplate met skroefgate wat teen 45º geanguleer is, gebruik in kombinasie met `n enkele 13mm lange grypskroef (“lag screw”) om gesimuleerde kaakhoek frakture in poli-uretaan mandibula replikas te fikseer. Deur gebruik te maak van `n spesiaal ontwerpte en vervaardigde monterings-apparaat wat binne in `n Zwick masjien geïnkorporeer word, is die I.S.I gefikseerde replikas onderwerp aan torsie kragte, binne klinies relevante ladingswaardes. Die verplasings en ladingswaardes is geregistreer en vergelyk met identiese I.S.I miniplate sonder `n grypskroef. Die loodstudie resultate het getoon dat die frakture wat gefikseerd is met die I.S.I. miniplaat-grypskroef kombinasie betekenisvol beter stabiliteit toon as die frakture wat met slegs die miniplaat, sonder `n grypskroef, gefikseerd is vir klinies relevante ladingsen verplasingswaardes. Tydens biomeganiese toetsing van die mandibula replikas, is twee faktore wat `n kardinale rol speel in die stabiliteit wat verkry word deur `n miniplaat grypskroef kombinasie te gebruik, geïdentifiseer. Voldoende hoeveelheid been tussen die eerste skroefgat, direk distaal van die fraktuurlyn, en die fraktuurlyn asook die korrekte volgorde waarin die skroewe geplaas word, moet gehandhaaf word om maksimale kompressie van die fragmente deur die grypskroef te verseker. Deur `n I.S.I miniplaat, met geanguleerde skroefgate van 45º, te kombineer met `n grypskroef, kan die stabiliteit van die gefikseerde mandibulere kaakhoek betekenisvol verbeter word en verleen dit meer stabiliteit wanneer vergelyk word met frakture gereduseer met `n I.S.I miniplaat sonder grypskroef plasing. / Dissertation (MSc)--University of Pretoria, 2010. / Maxillo-Facial and Oral Surgery / unrestricted

Master of Science / Pallets are used all over the world in the field of distribution. The strength values associated with a pallet have been thoroughly investigated by many different researchers; however, the stiffness values associated with pallet joints have not. The goal of this work was to investigate the stiffnesses associated with pallets joints made with lag screws and carriage bolts. It is important to understand that different materials, fastening methods, and design considerations can have a huge impact on the stiffness of the joint. This paper will discuss the various tests that were used to measure the actual stiffness of pallet joints and the results of those tests. Afterwards, the researchers detail their attempt to predict the stiffness using an equation created from the actual test data. Finally, by understanding the effects of these various factors, better pallet designs can be created that are both safer and stronger using the investigated alternative fasteners.