The Finite Element Analysis of Osteoporotic Lumbar Vertebral Body by Influence of Trabecular Bone Apparent Density and Thickness of Cortical Shell

Abstract

Abstract:Osteoporosis causes the bone mass loss and increased fracture risk. This paper presents the modelling of osteoporotic human lumbar vertebrae L1 by employing finite elements method (FEM). The isolated inhomogeneous vertebral body is composed by cortical outer shell and cancellous bone. The level of osteoporotic contribution is characterised by reducing the thickness of cortical shell and elasticity modulus of cancellous bone using power-law dependence with apparent density. The strength parameters are evaluated on the basis of von Mises-Hencky yield criterion. Parametric study of osteoporotic degradation contains the static and nonlinear dynamic analysis of stresses that occur due to physiological load. Results of our investigation are presented in terms of nonlinear interdependence between stress and external load.

Influence of posterior pedicle screw fixation at L4–L5 level on biomechanics of the lumbar spine with and without fusion: a finite element method

“…The L1-L5 lumbar vertebrae model in this study had a 42° lordotic angle, compatible with the mean lordotic angles of the L1-L5 lumbar segments of adolescents and adults in the literature [35]. The dimensions of the 3D model of the vertebrae were controlled according to the overall vertebral dimensions in this age range from studies in the literature [36][37][38]. The thickness of cortical bone was considered as 0.5 mm, as in the overall value of studies in the literature [36,[39][40][41], while 12,000 MPa and 0.3, also values widely used in the literature, were taken as the elastic modulus and Poisson's ratio of the cortical bone, respectively.…”

“…The dimensions of the 3D model of the vertebrae were controlled according to the overall vertebral dimensions in this age range from studies in the literature [36][37][38]. The thickness of cortical bone was considered as 0.5 mm, as in the overall value of studies in the literature [36,[39][40][41], while 12,000 MPa and 0.3, also values widely used in the literature, were taken as the elastic modulus and Poisson's ratio of the cortical bone, respectively. The inner side of the vertebra was assigned the widely used material properties of cancellous bone, which are 100 MPa elastic modulus and 0.2 Poisson's ratio [42].…”

The effects of pre-stressed rods contoured by different bending techniques on posterior instrumentation of L4-L5 lumbar spine segment: A finite element study

“…13–15 The shell thickness of cortical bone was taken as 0.5 mm considering the mean value according to previous studies. 13,16–18 Material properties were assigned for cortical bone and cancelous bone sections (Table 1). 19–21 Annulus fibrosus was achieved with membrane layers and a solid ground matrix.…”

“…20,26 Endplate sections of intervertebral discs were formed above and below the surfaces of the annulus and nucleus considering the endplate thickness (0.5 mm) with respect to previous studies in the literature. 13,16,18,27 Endplate material properties are also indicated in Table 1. 19,20 In this study, all ligament types between lumbar vertebrae were used except for the intertransverse ligament (ITL) because the reference nonlinear stiffness dataset used here for ligaments did not include ITL data.…”

“…Computed tomography (CT) image data of a healthy full human spine belonging to 45-year-old male individual were provided by TOBB ETU and a FE model of the L4-L5 lumbar spine segment containing 32,051 polygonal surfaces was generated using CATIA (Version 5.0; Dassault Systems, France) and ABAQUS (Version 2017; ABAQUS, USA) with respect to the classification of male adolescents and adults by considering the overall vertebral dimensions according to age range based on previous studies in the literature. [13][14][15] The shell thickness of cortical bone was taken as 0.5 mm considering the mean value according to previous studies. 13,[16][17][18] Material properties were assigned for cortical bone and cancelous bone sections (Table 1).…”