A COMPARISON OF THE VISCOELASTIC BEHAVIOR OF THE LUMBAR INTERVERTEBRAL DISC BEFORE AND AFTER THE IMPLANTATION OF A PROSTHETIC DISC NUCLEUS

摘要

A prosthetic disc nucleus device has been designed to replace the degenerated lumbar intervertebral disc (IVD) nucleus. In this study, we measured the creep response of a lumbar motion segment in the intact condition, after a nucleotomy, and after implantation with the device. The creep behavior was modeled with a three parameter standard linear solid to determine the elastic (E_1, E_2) and viscous (#eta#) constants that describe the behavior of the disc. The average elastic damping constant (E_1), and the viscous constant (#eta#) were significantly lower after the nucleotomy than in the intact state. There were no significant differences between the intact motion segment and the device-implanted motion segment. This study demonstrates that the prosthetic disc nucleus device restores the viscoelastic behavior of the intact spine after nucleotomy.