Cervical Ossification of the Posterior Longitudinal Ligament: Biomechanical Analysis of the Influence of Static and Dynamic Factors.

Abstract

Cervical myelopathy of ossification of the posterior longitudinal ligament（OPLL）is induced by static factors, dynamic factors or a combination of both. We used a 3-dimensional finite element method to analyze the stress distributions of spinal cord of compression by OPLL. Experimental condition for spinal cord, lamina and OPLL with ossification. To simulate static compression, 10%, 20% and 30% anterior static compression of the AP diameter of the spinal cord was applied to the spinal cord by OPLL. To simulate dynamic compression, OPLL is rotationed 5°, 10°and 15°to the flexion direction. To simulate static and dynamic compression, under 10% and 20% anterior static compression, OPLL is rotationed 5°, 10°and 15°to the flexion direction. The stress distribution in the spinal cord increased following static compression and dynamic compression. In both of static compression and dynamic compression, more than static compression increases, more than stress distribution increases even mild range of motion. There is possibility that the symptoms appear just static compression and dynamic compression only. However, under static compression, the stress distribution increases with ROM of the responsibility level and this makes it very likely that symptoms will worsen.