Objective      To establish an accurate finite element (FE) model of complete lumbar spine with complicated lumbar spinal stenosis (LSS)

then compare and analyze with normal model.       Methods      A woman with diagnosed complicated LSS was enrolled in this study after her agreement of informed consent. Her CT scan data were collected. By using specially designed modeling system

a complete FE model of the lumbar with complicated LSS was generated

as well as comparing lumbar model with normal material and geometry. Then

same boundary conditions were applied to do comparison.        Results      The results demonstrated that the complicated LSS model was stiffer

and its active movement range decreased

by 25.4% compared to normal model. Generally

the stress in the complicated LSS model intended to increase. There were stress concentration around the endplate and disk at the degenerative intervertebral disc L

4

-L

5

and adjacent disc L

3

-L

4

. And the maximum Mises stress of the anulus fibrosus was increased by 129%.       Conclusion      The lumbar spine with complicated LSS has less range of motion and is stiffer compared to normal model

and there are stress concentration at the degenerative intervertebral disc and adjacent intervertebral disc. The analysis result is useful to practical clinical diagnosis of lumbar spine with LSS.