Stress distribution in 3D models of human spine with different lumbar curvature angle

The purposes of this research were to study the range of human lumbar curvature angle and to create 3D models for stress distribution studying. The research was provided with 224 MRI cases. An angle of the lumbar curvature, dimensions of vertebral bodies and intervertebral disks were measured. Computer 3D models of a human spine with different lumbar curvature angles were created. Distribution of stress and displacement for different elements of the models were received using finite‐element method with statistical analysis. The range of lumbar curvature in between 23–35 degrees was found in 58.5% of cases. It is the most optimal angle for lumbar spine since it provides balance between degree of stress in the vertebrae and the body weight support. Hyperlordosis when the angle was greater than 35 degree was noted in 21.9% of cases, while maximal registered value (68 degree) was found in 1 case only (Fig. 1). Hypolordosis when the angle was less than 23 degree was noted in 19.6% of cases, while minimal value of (5 degree) was found in 3 cases (Fig. 2). In case of the hypolordotic model the stress level is less but shock absorption does not exist, while in hyperlordosis case the stress level drastically goes up. As shown by finite‐element analysis the extreme forms of individual variability of the lumbar curvature lead to decrease of mechanical properties because of changes in geometry of lumbar spine.