Analysis of the impact responses in a degenerated spinal motion segment FE model

• Published in: Journal of mechanical science and technology Vol. 23; no. 1; pp. 19 - 25
• Main Authors: Kim, YoungEun, Choi, Haewon
• Format: Journal Article
• Language: English
• Published: Heidelberg Korean Society of Mechanical Engineers 01.01.2009; Springer Nature B.V; 대한기계학회
• Subjects: Biological and medical sciences; Bones; Computer simulation; Control; Degeneration; Dynamical Systems; Engineering; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Fundamental areas of phenomenology (including applications); Industrial and Production Engineering; Mathematical models; Mechanical Engineering; Nuclei; Physics; Segments; Skeleton and joints; Solid mechanics; Static elasticity (thermoelasticity...); Stress concentration; Stresses; Structural and continuum mechanics; Vertebrates: osteoarticular system, musculoskeletal system; Vibration; 기계공학; Poroelastic model; Finite element model; Degeneration; Spine; Impact loading; Stress concentration; Stress analysis; Diseases of the osteoarticular system; Multiple layer; Mechanical properties; Durability; Porous material; Modeling; Biomechanics; Finite element method; Osteoporosis; Morphology; Von Mises criterion; Vertebral column; Spongious bone; Porosity; Non linear effect; Mechanical shock
• ISSN: 1738-494X; 1976-3824
• DOI: 10.1007/s12206-008-0923-6

A three-dimensional non-linear poroelastic finite element model of an L3/L4 motion segment was used to analyze the biomechanical effects of degeneration under impact loading on the spinal segment. A previously developed degeneration algorithm was applied to generate a degenerated disc model. Regional variation in intact vertebral body bone morphology was simulated by assigning different void ratios of 4.0–5.02, which were assessed for 27 regions of vertebral cancellous bone. For the osteoporotic structure of the vertebral body, the body was divided into 5 regions with 10–24 void ratios. Different material properties were assigned to the annulus fibers; hereupon our annulus model reflected variation in tensile behavior of multiple layer annulus samples. The impact load applied to the top of the L3 vertebral body was assumed to be a triangular impulsive force with a maximum compressive impact load of 3 kN and 20ms impact duration time. Calculated results indicated that the effect of the degeneration was predominant at the center of the vertebral body. The maximum von Mises stress was found at the region of near the endplate. The degeneration increased the averaged stress at the center of the vertebral body of L3 from 1.54 MPa to 1.69 MPa, the stress remaining relatively small at L4. Decreased fluid volume ratio of the degenerated nucleus tended to increase pressure slightly at the nucleus, and the averaged stress at the nucleus was almost doubled compared to the intact case. The innermost layers of the anterior annulus showed the highest stress concentration, followed by outermost anterior and posterior regions, for both the degenerated and the intact models. Despite an irregular stress distribution in the degenerated model, pore pressure showed relatively uniform distribution.