Comparative Pull-Out Performances of Cephalomedullary Nail with Screw and Helical Blade According to Femur Bone Densities

Abstract

This paper mainly examines the fixation performances of the cephalomedullary nail for the incidence of intertrochanteric (IT) fracture to guide the appropriate fixations with respect to the bone density in terms of a biomechanical perspective. It is substantially important to guide which types of fixation are applied during the operation since it tends to induce the backout or migration of the helical blade and screw according to weight and bone density. Biomedical polyurethane (PUR) foam blocks for simulating human bone are adopted with two grades of densities to simulate a normal person and an elderly person who has osteoporosis. Tensile and compression tests are conducted to analyze the tensile-compression anisotropy of PUR foams. Pull-out performances of screw and helical blades are evaluated from experimental perspectives, which are supported by comparison with the results of finite element method analysis. The clamping force of the screw is higher than the helical blade, about 177% in normal foam density and 198% in low foam density. After physical evaluation of the critical pull-out fixation force of screw and helical blade, we have suggested that stable fixation is guaranteed when the pull-out force is larger than projected force.

Biomechanical assessment of mandibular fracture fixation using finite element analysis validated by polymeric mandible mechanical testing

“…Synbone is made of polyurethane (PU) synthetic foam with varying density, mimicking cortical and trabecular bone [29][30][31] . A few studies in the literature have evaluated the material properties of Synbone and all these studies show differences in mechanical properties [29][30][31][32][33] . Therefore, to increase the accuracy of this study, it was decided to determine the mechanical material properties of the Synbone mandible.…”

Optimisation of osteosynthesis positioning in mandibular body fracture management using finite element analysis

“…The chosen mandible material properties were similar to those of the Synbone® polyurethane foam mandible to allow for a comparison with polymeric model testing. The mandible material properties were set at an elastic modulus of 2410 MPa, shear modulus of 862.2 MPa, mass density of 1.26 g/cm 3 , tensile strength of 40 MPa, and a Poisson's ratio of 0.39 [30][31][32]. The properties of the titanium miniplates and screws were as follows: an elastic modulus of 104800 MPa, mass density of 4.43 g/cm 3 , tensile strength of 1100 MPa, yield strength of 827.4 MPa, and a Poisson's ratio of 0.31 [1].…”

“…A polymeric mandible is made of polyurethane foam and is an adequate substitute for cadaveric human bone for testing purposes [30][31][32]. It has been shown to be a successful simulator for a similar sized and shaped human bone [30,[33][34].…”

Optimisation of osteosynthesis positioning in mandibular body fracture management using finite element analysis

“…The chosen mandible material properties were similar to those of the Synbone® polyurethane foam mandible to allow for a comparison with polymeric model testing. The mandible material properties were set at an elastic modulus of 2410 MPa, shear modulus of 862.2 MPa, mass density of 1.26 g/cm3, tensile strength of 40 MPa, and a Poisson's ratio of 0.39 [30][31][32]. The properties of the titanium miniplates and screws were: an elastic modulus of 104800 MPa, mass density of 4.43 g/cm3, tensile strength of 1100 MPa, yield strength of 827.4 MPa, and a Poisson's ratio of 0.31 [1].…”