The purpose of this project is to quantify the effects of increasing spinal ligament fidelity on the mechanics of the human lumbar spine using finite element analysis (FEA). In support of this goal, a material characterization study was completed to provide anisotropic, nonlinear material parameters for the human anterior longitudinal ligament. (ALL). Cadaveric samples of the human ALL were tested using a punch test technique. Multi- axial force-deformation data were gathered and fit to a commonly used transversely isotropic material model using an FEA system identification routine. The resulting material parameters produced a curve that correlated well with the experimental curve (R2≥0.98). Recently published material data on several major spinal ligaments have been incorporated into an existing finite element model of the human lumbar spine. This data includes the results from the above mentioned material characterization, similar material characterizations of the supraspinous (SSL) and interspinous (ISL) ligaments, localized material properties of the SSL and pre-strain data for the ISL, SSL and ALL. These results have been incorporated both separately and compositely into the finite element model and each configuration has been simulated in spinal flexion, extension, axial rotation and lateral bending. Results suggest that the effects of increased ligament model fidelity on bone strain energy were moderate and the effects on disc pressure were slight, and do not justify a change in modeling strategy for most clinical applications. There were significant effects on the ligament stresses of the ligaments that were directly modified, suggesting that these phenomenon should be included in FE models where ligament stresses are the desired metric.



College and Department

Ira A. Fulton College of Engineering and Technology; Mechanical Engineering



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