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Thomas Muckley - One of the best experts on this subject based on the ideXlab platform.
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biomechanical comparison of a lateral polyaxial locking plate with a posterolateral polyaxial locking plate applied to the distal fibula
Foot and Ankle Surgery, 2014Co-Authors: J Hallbauer, A Grafenstein, Sascha Rausch, Felix Wipf, Claudia Beimel, G O Hofmann, Kajetan Klos, Thomas MuckleyAbstract:Abstract Background Polyaxial locking plates are becoming popular for the fixation of distal fibula fractures. This study establishes how construct stiffness and plate loosening, measured as range of motion, differs between lateral and posterolateral plate location. Methods Seven matched pairs of cadaver fibulae were osteotomized in standardized fashion to produce a Weber type B distal fibula fracture. The fragments were fixated with an interfragmentary lag screw and polyaxial locking plates, with one fibula in each pair receiving a posterolateral anti-glide-plate, and the other a lateral neutralization-plate. In a biomechanical test, the bending and torsional stiffnesses of the constructs and the ranges of motion (ROM) were measured and subjected to a paired comparison. Results The laterally plated group had a higher median (interquartile range) bending stiffness (29.2 (19.7)N/mm) and a smaller range of motion (2.06 (1.99)mm) than the posterolaterally plated group (14.6 (20.6)N/mm, and 4.11 (3.28)mm, respectively); however, the results were not statistically significant ( p bending =0.314; p ROM =0.325). Similarly, the torsional stiffness did not differ significantly between the two groups (laterally plated: 426 (259)Nmm/°; posterolaterally plated: 248 (399)Nmm/°; p torsion =0.900). The range of motion measurements between the two groups under torsional loading were also statistically insignificant (laterally plated: 8.88 (6.30)mm; posterolaterally plated: 15.34 (12.64)mm; p ROM =0.900). Conclusion In biomechanical cadaver-model tests of Weber type B fracture fixation with polyaxial locking plates, laterally plated constructs and posterolaterally plated constructs performed without significantly difference. Therefore, other considerations, such as access morbidity, associated injuries, patient anatomy, or surgeon's preference, may guide the choice of plating pattern. Further clinical studies will be needed for the establishment of definitive recommendations. Clinical relevance : Information on the behavior of polyaxial locking plates is relevant to surgeons performing internal fixation of distal fibula fractures.
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biomechanical evaluation of plate osteosynthesis of distal fibula fractures with biodegradable devices
Foot & Ankle International, 2009Co-Authors: Kajetan Klos, Stefanie Sauer, Konrad L Hoffmeier, Florian Gras, R Frober, Gunther O Hofmann, Thomas MuckleyAbstract:Background: This study compared fixation with a titanium one-third tubular plate and one lag-screw vs. fixation with biodegradable plates with one lag-screw applied with two different plate-screw patterns. Materials and Methods: Ten pairs of fibulas were osteotomied, plated (titanium plate with one lag screw vs. absorbable 2/8 plate-screws crossing vs. 0/8 plate-screws crossing the osteotomy gap). and tested in torsion and bending to obtain stiffness and neutral-zone (NZ) data. Tests were performed using 5 load cycles. No load to failure was performed. Biodegradation was simulated by 6 week immersion in phosphate-buffered saline after which the testing protocol was repeated. The specimens were then loaded with 100 N in bending. Results: Post-implantation, there were no significant differences, in torsion and bending, regarding the NZ or the stiffness, between the 2/8 biodegradable plate and the titanium plate. The 0/8 pattern performed significantly less well in terms of stiffness and NZ in the initial to...
Hui-shen Shen - One of the best experts on this subject based on the ideXlab platform.
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Non-linear analysis of functionally graded fiber reinforced composite laminated plates, Part I: Theory and solutions
International Journal of Non-Linear Mechanics, 2012Co-Authors: Hui-shen Shen, Chen-li ZhangAbstract:This paper deals with the large amplitude vibration, non-linear bending and postbuckling of fiber reinforced composite laminated plates resting on an elastic foundation in hygrothermal environments. Two kinds of fiber reinforced laminated plates, namely, uniformly distributed and functionally graded reinforcements, are considered. The material properties of fiber reinforced laminated plates are estimated through a micromechanical model and are assumed to be temperature-dependent and moisture-dependent. The motion equations are based on a higher order shear deformation plate theory that includes plate-foundation interaction and the hygrothermal effect. A two-step perturbation technique is employed to determine the non-linear to linear frequency ratios of plate vibration, the load-deflection and load-bending moment curves of plate bending, and postbuckling equilibrium paths of laminated plates.
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Thermomechanical postbuckling of imperfect moderately thick plates on two-parameter elastic foundations
Structural Engineering and Mechanics, 1996Co-Authors: Hui-shen ShenAbstract:A postbuckling analysis is presented for a simply supported, moderately thick rectangular plate subjected to combined axial compression and uniform temperature loading and resting on a two-parameter elastic foundation. The two cases of thermal postbuckling of initially compressed plates and of compressive postbuckling of initially heated plates are considered. The initial geometrical imperfection of the plate is taken into account. The formulations are based on the Reissner-Mindlin plate theory considering the first order shear deformation effect, and including the plate-foundation interaction and thermal effect. The analysis uses a deflection-type perturbation technique to determine the buckling loads and postbuckling equilibrium paths. Numerical examples cover the performances of perfect and imperfect, moderately thick plates resting on Winkler or Pasternak-type elastic foundations. Typical results are presented in dimensionless graphical form.
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Thermomechanical Postbuckling of Imperfect Moderately Thick Plates on Nonlinear Elastic Foundations
Mechanics of Structures and Machines, 1996Co-Authors: Hui-shen ShenAbstract:A postbuckling analysis is presented for a moderately thick rectangular plate subjected to combined axial compression and uniform temperature loading, and resting on a softening nonlinear elastic foundation. The cases of (1) thermal postbuckling of initially compressed plates and (2) compressive post-buckling of initially heated plates are considered. The initial geometrical imperfections of the plates are taken into account. Formulations are based on Reissner-Mindlin plate theory, considering first-order shear deformation effects, and including plate-foundation interaction and thermal effects. The analysis uses a deflection-type perturbation technique to determine buckling loads and postbuckling equilibrium paths. Numerical examples include the performance of perfect and imperfect, moderately thick plates resting on softening nonlinear elastic foundations. Typical results are presented in dimensionless graphical form.
J Hallbauer - One of the best experts on this subject based on the ideXlab platform.
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biomechanical comparison of a lateral polyaxial locking plate with a posterolateral polyaxial locking plate applied to the distal fibula
Foot and Ankle Surgery, 2014Co-Authors: J Hallbauer, A Grafenstein, Sascha Rausch, Felix Wipf, Claudia Beimel, G O Hofmann, Kajetan Klos, Thomas MuckleyAbstract:Abstract Background Polyaxial locking plates are becoming popular for the fixation of distal fibula fractures. This study establishes how construct stiffness and plate loosening, measured as range of motion, differs between lateral and posterolateral plate location. Methods Seven matched pairs of cadaver fibulae were osteotomized in standardized fashion to produce a Weber type B distal fibula fracture. The fragments were fixated with an interfragmentary lag screw and polyaxial locking plates, with one fibula in each pair receiving a posterolateral anti-glide-plate, and the other a lateral neutralization-plate. In a biomechanical test, the bending and torsional stiffnesses of the constructs and the ranges of motion (ROM) were measured and subjected to a paired comparison. Results The laterally plated group had a higher median (interquartile range) bending stiffness (29.2 (19.7)N/mm) and a smaller range of motion (2.06 (1.99)mm) than the posterolaterally plated group (14.6 (20.6)N/mm, and 4.11 (3.28)mm, respectively); however, the results were not statistically significant ( p bending =0.314; p ROM =0.325). Similarly, the torsional stiffness did not differ significantly between the two groups (laterally plated: 426 (259)Nmm/°; posterolaterally plated: 248 (399)Nmm/°; p torsion =0.900). The range of motion measurements between the two groups under torsional loading were also statistically insignificant (laterally plated: 8.88 (6.30)mm; posterolaterally plated: 15.34 (12.64)mm; p ROM =0.900). Conclusion In biomechanical cadaver-model tests of Weber type B fracture fixation with polyaxial locking plates, laterally plated constructs and posterolaterally plated constructs performed without significantly difference. Therefore, other considerations, such as access morbidity, associated injuries, patient anatomy, or surgeon's preference, may guide the choice of plating pattern. Further clinical studies will be needed for the establishment of definitive recommendations. Clinical relevance : Information on the behavior of polyaxial locking plates is relevant to surgeons performing internal fixation of distal fibula fractures.
Mohammed Sobhy - One of the best experts on this subject based on the ideXlab platform.
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Thermal buckling of various types of FGM sandwich plates
Composite Structures, 2010Co-Authors: Ashraf M. Zenkour, Mohammed SobhyAbstract:The sinusoidal shear deformation plate theory is used to study the thermal buckling of functionally graded material (FGM) sandwich plates. This theory includes the shear deformation and contains the higher- and first-order shear deformation theories and classical plate theory as special cases. Material properties and thermal expansion coefficient of the sandwich plate faces are assumed to be graded in the thickness direction according to a simple power-law distribution in terms of the volume fractions of the constituents. The core layer is still homogeneous and made of an isotropic material. Several kinds of symmetric sandwich plates are presented. Stability equations of FGM sandwich plates include the thermal effects. The thermal loads are assumed to be uniform, linear and non-linear distribution through-the-thickness. Numerical examples cover the effects of the gradient index, plate aspect ratio, side-to-thickness ratio, loading type and sandwich plate type on the critical buckling for sandwich plates. © 2010 Elsevier Ltd.
Chen-li Zhang - One of the best experts on this subject based on the ideXlab platform.
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Non-linear analysis of functionally graded fiber reinforced composite laminated plates, Part I: Theory and solutions
International Journal of Non-Linear Mechanics, 2012Co-Authors: Hui-shen Shen, Chen-li ZhangAbstract:This paper deals with the large amplitude vibration, non-linear bending and postbuckling of fiber reinforced composite laminated plates resting on an elastic foundation in hygrothermal environments. Two kinds of fiber reinforced laminated plates, namely, uniformly distributed and functionally graded reinforcements, are considered. The material properties of fiber reinforced laminated plates are estimated through a micromechanical model and are assumed to be temperature-dependent and moisture-dependent. The motion equations are based on a higher order shear deformation plate theory that includes plate-foundation interaction and the hygrothermal effect. A two-step perturbation technique is employed to determine the non-linear to linear frequency ratios of plate vibration, the load-deflection and load-bending moment curves of plate bending, and postbuckling equilibrium paths of laminated plates.