FE modeling and analysis of L4-L5 lumbar segment under physiological loadings

BACKGROUND: Because of the complexity and construction, the failure rate of lumbar surgery is still high. It is necessary to find a solution to help improve the accuracy and safety of surgery. OBJECTIVE: Construction and stress analysis of lumbar spine. METHODS: The generated FE model based on CT scan images was validated and used to investigate the motion, and stress/strain of the vertebrae under different physiological loadings. A degenerated model was also simulated by changing the materials properties (E and Poisson's Ratio) of the intervertebral disc nucleus and annulus fibers from 1.0 N/mm(2) to 3.0 N/mm(2), and 0.42 to 0.45, respectively. RESULTS: When annulus fibrosis is degenerating or under ictal external loadings, the annulus fibrosis will be in a state of protrusion and there will potential for other pathological changes, such as herniation of the nucleus pulpous. CONCLUSION: The effects of these changes in the corresponding motion and stress/strain of the spinal motion segments were investigated with some conclusions drawn in relation to the normal model for future application of medical diagnosis and surgical treatment.