RESUMEN
Ti6Al4V alloy was shot peened by using stainless-steel shots with different sizes (0.09-0.14 mm (S10) and 0.7-1.0 mm (S60)) for two durations (5 and 15 min) using a custom-designed peening system. The shot size was the main parameter modifying the roughness (0.74 µm for S10 vs. 2.27 µm for S60), whereas a higher peening time slightly increased roughness. Hardness improved up to approximately 35% by peening with large shots, while peening time was insignificant in hardness improvement. However, longer peening duration with large shots led to an unwanted formation of micro-cracks and delamination on the peened surfaces. After dry sliding wear tests, the mass loss of peened samples (S60 for 15 min) was 25% higher than that of un-peened samples, while the coefficient of friction decreased by 12%. Plastically deformed regions and micro-scratches were observed on the worn surfaces, which corresponds to mostly adhesive and abrasive wear mechanisms. The present study sheds light on how surface, subsurface and tribological properties of Ti6Al4V vary with shot peening and peening parameters, which paves the way for the understanding of the mechanical, surface, and tribological behavior of shot peened Ti6Al4V used in both aerospace and biomedical applications.
RESUMEN
OBJECTIVE: The aim of the present study was to determine whether the side of application of the plate itself affects the mechanical stability of the fixation. The specific question addressed is whether or not a lateral or medial plate application is biomechanically better, for the treatment of distal diaphysis fractures of the femur. METHODS: Stability and stiffness of medial sided plating relative to the conventional lateral sided plating in distal diaphysis of the femur were measured by analyzing axial loading forces leading to implant failure. Sixty synthetic femurs were tested in physiological bending, to calculate the yield and ultimate load to displacement following fixation of distal diaphysis fractures of the femur by either medial or lateral sided plating. Axial loading was applied to samples using a uniaxial testing machine. RESULTS: There was more implant deformation in the lateral sided plating group - a difference with statistical significance. CONCLUSION: Medial sided plating was found to be as stiff as lateral plating. Medial plating may be a reasonable treatment option that can be used safely in selected cases. Level of Evidence I, Therapeutic Studies Investigating the Results of Treatment.
OBJETIVO: O objetivo deste estudo foi determinar se o lado de aplicação da placa em si afeta a estabilidade mecânica da fixação. A questão específica abordada é se a aplicação da placa lateral ou medial é melhor ou não em termos biomecânicos para o tratamento das fraturas da diáfise distal do fêmur. MÉTODOS: A estabilidade e a rigidez da placa medial com relação à lateral, convencional na diáfise distal do fêmur, foram medidas pela análise das forças de carga axial que levam à falha do implante. Sessenta fêmures sintéticos foram testados em flexão fisiológica, para calcular a tolerância e a carga final para o deslocamento após a fixação das fraturas diafisárias distais do fêmur com placa medial ou lateral. A carga axial foi aplicada às amostras usando máquina de teste uniaxial. RESULTADOS: Verificou-se maior deformação do implante no grupo de placa lateral diferença com significância estatística. CONCLUSÃO: Constatou-se que a placa medial era tão rígida quanto a lateral. A placa medial pode ser uma opção de tratamento razoável e segura em casos selecionados. Nível de evidência I, Estudos terapêuticos - Investigação dos resultados do tratamento.
RESUMEN
ABSTRACT Objective: The aim of the present study was to determine whether the side of application of the plate itself affects the mechanical stability of the fixation. The specific question addressed is whether or not a lateral or medial plate application is biomechanically better, for the treatment of distal diaphysis fractures of the femur. Methods: Stability and stiffness of medial sided plating relative to the conventional lateral sided plating in distal diaphysis of the femur were measured by analyzing axial loading forces leading to implant failure. Sixty synthetic femurs were tested in physiological bending, to calculate the yield and ultimate load to displacement following fixation of distal diaphysis fractures of the femur by either medial or lateral sided plating. Axial loading was applied to samples using a uniaxial testing machine. Results: There was more implant deformation in the lateral sided plating group - a difference with statistical significance. Conclusion: Medial sided plating was found to be as stiff as lateral plating. Medial plating may be a reasonable treatment option that can be used safely in selected cases. Level of Evidence I, Therapeutic Studies Investigating the Results of Treatment
RESUMO Objetivo: O objetivo deste estudo foi determinar se o lado de aplicação da placa em si afeta a estabilidade mecânica da fixação. A questão específica abordada é se a aplicação da placa lateral ou medial é melhor ou não em termos biomecânicos para o tratamento das fraturas da diáfise distal do fêmur. Métodos: A estabilidade e a rigidez da placa medial com relação à lateral, convencional na diáfise distal do fêmur, foram medidas pela análise das forças de carga axial que levam à falha do implante. Sessenta fêmures sintéticos foram testados em flexão fisiológica, para calcular a tolerância e a carga final para o deslocamento após a fixação das fraturas diafisárias distais do fêmur com placa medial ou lateral. A carga axial foi aplicada às amostras usando máquina de teste uniaxial. Resultados: Verificou-se maior deformação do implante no grupo de placa lateral - diferença com significância estatística. Conclusão: Constatou-se que a placa medial era tão rígida quanto a lateral. A placa medial pode ser uma opção de tratamento razoável e segura em casos selecionados. Nível de evidência I, Estudos terapêuticos - Investigação dos resultados do tratamento.
RESUMEN
Thermal, viscoelastic and mechanical properties of polyphenylene sulfide (PPS) were optimized as a function of extrusion and injection molding parameters. For this purpose, design of experiments approach utilizing Taguchi's L27 (37) orthogonal arrays was used. Effect of the parameters on desired properties was determined using the analysis of variance. Differential scanning calorimeter (DSC) tests were performed for the analysis of thermal properties such as melting temperature (Tm) and melting enthalpy (ΔHM). Dynamic mechanical analysis (DMA) tests were performed for the analysis of viscoelastic properties such as damping factor (tan δ) and glass transition temperature (Tg). Tensile tests were performed for the analysis of mechanical properties such as tensile strength and modulus. With optimized process parameters, verification DSC, DMA and tensile tests were performed for thermal, viscoelastic and mechanical properties, respectively. The Taguchi method showed that 'barrel temperature' and its level of '340°C' were seen to be the most effective parameter and its level; respectively. It was suggested that PPS can be reinforced for further improvement after optimized thermal, viscoelastic and mechanical properties.
RESUMEN
PURPOSE: Pedicle screw fixation of osteoporotic bone in the elderly is a challenge. Various augmentation methods have been studied by many authors. Although polymethylmethacrylate (PMMA) augmentation is believed to be a standard method, its usage is fraught with complications. Butyl-2-cyanoacrylate is an alternative to PMMA as it is bioresorbable, biocompatible, inexpensive, and noninfective. The objective of the current study was to determine the pullout strength of the pedicle screws when butyl-2-cyanoacrylate is used for augmentation. METHODS: Fresh calf lumbar vertebrae were obtained from male calves weighing 100-120 kg and implanted with pedicle screws. The screws were placed in native, unaugmented bone (group 1), butyl-2-cyanoacrylate-augmented bone (group 2), and PMMA-augmented bone (group 3). Axial pullout tests were done by an Instron 4411 universal testing machine. Statistical analysis was performed using the SPSS 9.0 for Windows program. Paired samples t test was used, and P < 0.05 was considered significant. RESULTS: The mean bone mineral density of the vertebrae was 1.6 +/- 0.1 g/cm2. The mean pullout strengths were 1.55 +/- 0.23 kN for group 1, 1.62 +/- 0.42 kN for group 2, and 2.55 +/- 0.22 kN for group 3. There was no statistically significant difference between groups 1 and 2. PMMA augmentation increased the pullout strength significantly when compared with butyl-2-cyanoacrylate augmentation and native bone (P = 0.002 and P = 0.001, respectively). CONCLUSIONS: The results of this study show that butyl-2-cyanoacrylate has no contribution to the augmentation of pedicle screw fixation in a calf model when compared with native bone or PMMA augmentation. Further studies are required to evaluate the effectiveness of butyl-2-cyanoacrylate in osteoporotic specimens and under cyclic loading in calf vertebra and animal and cadaver models before dispensing with its utility as an augmentation method in the clinical setting.