Discectomy decreases facet joint distance and increases the instability of the spine: A finite element study

Maria Prado; Caroline Mascoli; Hugo Giambini

doi:10.1016/j.compbiomed.2022.105278

Discectomy decreases facet joint distance and increases the instability of the spine: A finite element study

Comput Biol Med. 2022 Apr:143:105278. doi: 10.1016/j.compbiomed.2022.105278. Epub 2022 Feb 1.

Authors

Maria Prado¹, Caroline Mascoli², Hugo Giambini³

Affiliations

¹ Department of Biomedical Engineering and Chemical Engineering, University of Texas at San Antonio, San Antonio, TX, USA.
² Biomedical Engineering Department, University of Connecticut, Storrs, CT, USA.
³ Department of Biomedical Engineering and Chemical Engineering, University of Texas at San Antonio, San Antonio, TX, USA. Electronic address: hugo.giambini@utsa.edu.

PMID: 35124438
DOI: 10.1016/j.compbiomed.2022.105278

Abstract

The L4-L5 spinal segment is mostly associated with the development of lumbar back pain (LBP). Lumbar disc herniation (LDH), intervertebral disc degeneration (IVDD), or degeneration of the facet joints (FJs) can lead to LBP. Although the surgical gold standard for treating LDH is well established, consequences from this surgery on the biomechanics of the spine are still a matter of discussion. Using a finite element model of the L4-L5 spinal segment, this study aimed (1) to determine the changes in FJ distance during physiological motions of a lumbar spine in a healthy-normal condition, after conservative and aggressive percutaneous transforaminal endoscopic discectomy (PTED) to correct LDH, and during mild and severe IVDD; (2) to determine spine instability and endplate stresses under various physiological motions. Aggressive-PTED in a healthy disc decreased facet distances in axial rotation, lateral bending, and flexion by ∼25%, ∼10%, and 8%, respectively. Mild and severe disc degeneration increased the stiffness of the spine, resulting in a decrease in the range of motion (ROM) for all conditions. Severe disc degeneration decreased ROM as high as 57% for lateral bending, while a 13% decrease was observed for mild degeneration. High and abnormal endplate stress distributions were observed due to PTED and IVDD. PTED and IVDD, individually and collectively, change spine kinematics potentially leading to LBP and other associated negative outcomes. An increase in spine instability and a decrease in distance between superior and inferior facets resulting from PTED might lead to facet degeneration.

Keywords: Biomechanics; Disc degeneration; Discectomy; Facet joint degeneration; Finite element.