Title: A three-dimensional finite element stress analysis of L4-L5 vertebra in a bending posture

Authors: Titov Banerjee, Santanu Majumder, Jayanta K. Chakraborty

Addresses: Mechanical Engineering Department, Birbhum Institute of Engineering and Technology, Suri 731101, West Bengal, India. ' Department of Applied Mechanics, Bengal Engineering and Science University, Shibpur, Howrah 711103, West Bengal, India. ' Department of Applied Mechanics, Bengal Engineering and Science University, Shibpur, Howrah 711103, West Bengal, India

Abstract: The lumbar inter-vertebral joint (L4-L5) performs a very important role in transferring load from the upper portion of the body to the lower part, especially during bending activities. Failure such as bone fracture, tissue damage, disc rupture, etc. occurs very often in this region. Stress distribution patterns are very useful for evaluation of such failure. A three-dimensional finite element model of lumbar vertebral joint (L4-L5) along with an intervertebral disc was created. The geometry was based on standard literature and compared physically. For meshing cortical bone, 8-noded shell elements were used and 10-noded tetrahedra were used for meshing cancellous bone and intervertebral disc. The finite element model contained different isotropic material properties for different regions. The finite element model contained 105,876 elements, connected through 136,974 nodes. Stress analyses were done for different loading conditions such as axial compression of 2,000 N, bending moments for flexion with magnitudes of 5, 10, 15 and 20 Nm and lifting weight in hand with varying magnitude (20-80% of the body weight) and inclination (15°-90°) of the body with the vertical axis (0° for vertical body and 90° for horizontal body). The results were compared with previous similar type of studies, carried out by different researchers. This finite element model may be useful in clinical application for fracture assessment and spinal instrumentation.

Keywords: finite element analysis; FEA; flexion; inter-vertebral disc; lumbar vertebra; stress distribution; stress analysis; bending posture; fracture assessment; spinal instrumentation.

DOI: 10.1504/IJVS.2008.022217

International Journal of Vehicle Safety, 2008 Vol.3 No.2, pp.182 -193

Published online: 23 Dec 2008 *

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