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Animal Models of Spinal Instability and Spinal Fusion
Published in Yuehuei H. An, Richard J. Friedman, Animal Models in Orthopaedic Research, 2020
Harvinder S. Sandhu, Linda E. A. Kanim, Federico Girardi, Frank P. Cammisa, Edgar G. Dawson
Lumbar intervertebral fusions were performed on Spanish goats. Spines implanted with the carbon-fiber reinforced polymer implant containing autogenous bone graft achieved a quicker and more reliable fusion than those with ethylene oxide-sterilized allograft bone.107
Reduction and Fixation of Sacroiliac joint Dislocation by the Combined Use of S1 Pedicle Screws and an Iliac Rod
Published in Kai-Uwe Lewandrowski, Donald L. Wise, Debra J. Trantolo, Michael J. Yaszemski, Augustus A. White, Advances in Spinal Fusion, 2003
Kai-Uwe Lewandrowski, Donald L. Wise, Debra J. Trantolo, Michael J. Yaszemski, Augustus A. White
During the past 15 years we have described a number of cases in which we successfully reconstructed failed pedicle screw constructs with carbon fiber fusion cages and new screws of the exact same type that had previously failed when used alone [20]. We carried out laboratory validation of these principles with mechanical testing in cadaver spines [21] and with a 2-year animal study in the Spanish goat [22]. We have completed a 2-year investigational device study [23], which has resulted in FDA approval of these devices. Other surgeons have reported favorable clinical series [24,25]. This is the first approved and widely used application of carbon fiber-reinforced polymer as an implant material. Additional CFRP “cage” implants have been designed to meet the anatomical requirements of various spinal areas, including a large oval ALIF cage, a cervical cage, and stackable corpectomy cages for thoracolumbar tumors and fractures. The polymer material — currently PEEK-Optima (Invibio Inc., Greenville, SC) — is from the family of plastics known as polyaryletherketones. The purpose of this chapter is to
A validated computational framework to evaluate the stiffness of 3D printed ankle foot orthoses
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
Alessio Ielapi, Nicolas Lammens, Wim Van Paepegem, Malcolm Forward, Jan Patrick Deckers, Miguel Vermandel, Matthieu De Beule
In this study, four patients (both children and adults) were selected and the pathologies considered were trauma, neuro-muscular disorder and cerebral palsy. Consequently, four patient-specific FE models were created: one model with the full shell design and three models with the modular design. The EU foot size of the full shell AFO was 40, defined as AFO A, while the modular AFOs, defined as AFO B, C and D, have 35, 37 and 38 EU foot size. For every modular AFO, the rods (thickness = 6 mm) are made of carbon fiber reinforced polymer (CFRP). The foot and the calf part of the AFOs were realized in Polyamide 12 (PA 12). The full shell AFO, instead, is completely realized in PA 12. Since this polymer owns complex visco-elasto-plastic properties, the virtual implementation was realized through a parallel rheological framework (PRF) model in the FE software Abaqus: the framework is based on the superposition of viscoelastic and elastoplastic networks in parallel, so to have an additive total stress response. In particular, the framework is intended for polymers and elastomeric materials which exhibit a nonlinear viscous behavior, implying hysteresis effects and undergoing large deformations (Hurtado et al. 2013; Lapczyk and Hurtado 2014), which makes it suitable for PA 12. The nonlinear viscous effects were modeled using the power law model formulation, while the plasticity was expressed with the stress values at the corresponding plastic strain (Tables 1 and 2). The elastic response was specified using hyperelastic neo-hookean material coefficients (Table 3). All the parameters were derived from experimental tests carried out on samples of the material (Lammens et al. 2017) and they are suitable for describing the behavior of PA 12 during a static analysis. The material properties of the CFRP rods were also obtained experimentally (Table 4).
An insight into Transfemoral Prostheses: Materials, modelling, simulation, fabrication, testing, clinical evaluation and performance perspectives
Published in Expert Review of Medical Devices, 2022
K. Amudhan, A. Vasanthanathan, J. Anish Jafrin Thilak
Composites are durable and light in weight and are fabricated by joining layers of reinforcement fibers like fiberglass, nylon or carbon. The fibers are tough, malleable, and brittle. Fiber and resin mixture is vacuum-molded onto residual limb models. Wet laminations are made by mixing resins and hardeners and pouring them over the fibers. High heat hardens thermosets. These acrylic, epoxy and polyester composites can be manufactured in various thicknesses for use in sockets. Unlike thermoplastics, thermoset polymers are difficult to reshape after manufacture. The kind, quantity, and combination of fibers and resins can be tailored to a patient’s weight and activity level. Polymer matrix composites are simpler, less expensive alternatives to steel, high-grade Aluminum, Titanium, and Magnesium, especially for applications that require less weight without compromising strength [59,60]. Ionomeric polymer metal composites (IPMC) [61] are cationic capacitive actuators and sensors. They are operated actively due to ionic redistribution in response to imposed electric field or physical deformation. In a prosthetic limb, IPMC material works as an artificial muscle, with actuation controlled by electric impulses. Large electrically induced bending, mechanical flexibility, low excitation voltage, low density and ease of production make IPMC appealing electro-active polymer actuation materials. The most crucial advancement in patient comfort is in socket material technology. Silicone and urethane are used to cushion sockets and prevent skin irritation. Gel liners preserve and cushion the residual limb’s bony prominence [32,34]. Silicone gel, Silicone elastomers, and urethane are the most common materials utilized for liners [33]. Extra-long silicone and PVC gloves are supplied for a smooth transition over the proximal socket brim. Table 1 shows the common reinforcement and matrix materials in polymer matrix composites to fabricate lower limb prosthetic components. All of these papers use respective American Society for Testing and Materials standards (ASTM) to study mechanical parameters including tensile strength, Young’s modulus, and fatigue strength. The number of layers, thickness, layer placement, and volume fraction determines the characteristics of fiber reinforced composites. In fact, most research focuses on producing the socket component using composites and most prosthetic foot components rely on Carbon fiber reinforced polymers (CFRP) composites for their excellent mechanical qualities. Carbon fibers were created in the twentieth century while seeking for a lighter load bearing material. It is known for its high specific strength, specific modulus, high stiffness, and tensile strength. It was determined that it could support a hefty amputee. The specific modulus of Carbon fiber reinforced composites is roughly three times higher than common materials used for prosthetics [62,63]. CFRP also offer high specific tensile and compressive strengths, as well as excellent elastic deformation responsiveness.