Buckling of Osteoporotic Lumbar: Finite Element Analysis

Abstract

The key element of the human body is the spine, which provides the main support for mechanical behavior of the body, allowing to keep its functionality during the entire life period. Consequently, evaluation of the functionality of the spine requires knowledge about the mechanical behavior of the specified particular vertebra, which could be considered by applying research methods used in mechanics of solids and structures. From a mechanical point of view, the spine may be considered as a column-like structure consisting of relatively stiffer structural bodies, i.e. vertebrae, connected by flexible intervertebral discs. Thereby, the most loaded spinal fragment is the lumbar spine, i.e. the spine fragment composed of L1-L5 vertebrae, which has to bear the essential part of the human’s induced load compared to the other spinal parts [1-3]. Specifically, compression-induced fracture of the spine usually occurs at the third vertebra of the lumbar spine (L3) [4]. Mechanical behavior largely depends on mechanical properties. Mechanical properties of biological tissues are not constant, and they may be affected by various factories and disease. One of the most widespread disease is osteoporosis, which is characterized by an overall loss of bone tissue and is a systemic disorder of the skeleton, leading to enhanced fracture risk. It is estimated that up to 50% of females (30% for males) experience at least one osteoporotic vertebral fracture during their life [5,6]. Consequently, research on osteoporotic degradation is basically focused on evaluation of the change of mechanical properties in the vertebral bone tissue [7-9]. It was found, however, that macroscopic vertebral properties strongly correlate with bone density decrease. Therewith, bone mineral density (BMD) is probably the single directly measurable physical quantity.