Three-Dimensional Finite Element Model of the Cervical Spinal Cord Preliminary Results of Injury Mechanism Analysis

Study Design. A three-dimensional finite element investigation. Objectives. To create a three-dimensional finite element model of the cervical spinal cord enlargement and to simulate a hyperextension injury of the cervical cord. Summary of Background Data. Experimental studies are difficult to simulate the complex mechanism of spinal cord injuries. The introduction of three-dimensional modeling technique into neurotrauma studies is essential to further understand mechanical behavior of the nerve tissue during traumatic injuries. Methods. Geometrical reconstruction of cervical spinal cord enlargement was developed based on the morphologic features of each segment of the fresh human cervical cord. After the validation of the model, the pinching condition in the hyperextension injuries was simulated with compressive and extension forces applied on the cervical enlargement model. The average von Mises stress of the 9 anatomic regions, such as anterior funiculus, lateral part of the lateral funiculus, medial part of the lateral funiculus, lateral part of the posterior funiculus, medial part of the posterior funiculus, anterior horn, the bottom of anterior horn, the apex of posterior horn, the cervix cornu posterioris, and caput cornu posterioris was recorded. Results. The force-displacement response of the spinal cord under compression and axial tension loading was close to the experimental results reported in the literature. The stress distribution of the spinal cord according to the numerical simulation and the morphologic features of the in vivo experiment were also in close agreement. Hyperextension injury simulation showed high localized stress at the anterior and posterior horn in the gray matter. Conclusion. The finite element method as a three-dimensional modeling technique can improve the understanding of the biomechanical behavior of the spinal cord. The results of hyperextension injury simulation of the cervical spinal cord probably account for the predominance of the hand weakness in patients with central cord injury.