An experimental-numerical method for the calibration of finite element models of the lumbar spine

We present a systematic and automated stepwise method to calibrate computational models of the spine. For that purpose, a sequential resection study on one lumbar specimen (L2-L5) was performed to obtain the individual contribution of the IVD, the facet joints and the ligaments to the kinematics of the spine. The experimental data was prepared for the calibration procedure in such manner that the FE model could reproduce the average motion of the 10 native spines from former cadaveric studies as well as replicate the proportional change in ROM after removal of a spinal structure obtained in this resection study. A Genetic Algorithm was developed to calibrate the properties of the intervertebral discs and facet joints. The calibration of each ligament was per-formed by a simple and novel technique that requires only one simulation to obtain its mechanical property. After calibration, the model was capable of reproducing the experimental results in all loading directions and resections.

Automated summary

We propose a systematic and automated method to calibrate computational models of the spine. By conducting a sequential resection study, we determine the individual contribution of the intervertebral discs, facet joints, and ligaments to the kinematics of the spine. Using a Genetic Algorithm, we calibrate the properties of the discs and facet joints, and develop a simple technique to calibrate each ligament. The calibrated model can accurately reproduce experimental results.