Effect of a prosthetic disc nucleus on the mobility and disc height of the L4–5 intervertebral disc postnucleotomy

Abstract

Compared with the intact state (100%), the nucleotomy increased the ROM in flexion-extension to 118%, lateral bending to 112%, and axial rotation to 121%; once the device was implanted the ROM was reduced to 102%, 88%, and 90%, respectively. The NZ increased the ROM to 210%, lateral bending to 173%, and axial rotation to 107% after nucleotomy, and 146%, 149%, 44%, respectively, after device implantation. A 200-N preload reduced the intact and postnucleotomy disc heights by approximately 1 mm and 2 mm, respectively. The original intact disc height was restored after implantation of the device. The results of the cadaveric L4-5 flexibility testing indicate that the device can potentially restore ROM, NZ, and disc height to the denucleated segment.