Association Between Dynamic Instability and Muscle Health Change in Patients With L4-5 Degenerative Spondylolisthesis and Operative Spinal Stenosis

Introduction: Degenerative spondylolisthesis at the L4-5 level is a prevalent spinal disorder that frequently necessitates surgical intervention. While chronic low back pain is often associated with paraspinal muscle wasting, the relationship between dynamic instability and muscle health in patients with spondylolisthesis remains inadequately explored.

This study aims to examine the association between dynamic instability and muscle health changes in patients with L4-5 degenerative spondylolisthesis and concomitant spinal stenosis, thereby enhancing our understanding of the disorder's pathophysiology.

Methods: This retrospective study included patients who underwent lumbar surgery at the L4-5 level for spinal stenosis, specifically those identified with grade 1 L4-5 spondylolisthesis. Imaging assessments comprised lumbar flexion and extension radiographs and magnetic resonance imaging (MRI). Cross-sectional area (CSA) and body mass index (BMI) were analyzed using ImageJ software. Statistical analyses were performed using independent t-tests and bivariate analysis.

Results: A total of 101 patients were analyzed, with 52 classified as having grade 1 degenerative spondylolisthesis. This cohort demonstrated significantly greater L4-5 lordosis in extension (23.69 ± 10.62° vs. 20.22 ± 7.92°, p = 0.044) but exhibited worse anterolisthesis in flexion (7.21 ± 3.66 mm vs. 10.14 ± 23.53 mm, p = 0.0002). No significant differences were found in the absolute changes of lordosis or segmental angles between the groups. Bivariate analysis revealed a significant negative correlation between psoas CSA/BMI and changes in lumbar lordosis (p = 0.0038, r = -0.578) and a strong correlation with Goutallier scores and lordosis/Cobb angles (p = 0.00017, r = 0.798) in the spondylolisthesis group, while no significant correlations were observed in the non-spondylolisthesis cohort.

Conclusion : This study identifies a significant association between dynamic instability and muscle health alterations in patients with L4-5 degenerative spondylolisthesis. The findings suggest that muscle health deterioration may be integral to the pathophysiology of spondylolisthesis, warranting further research to clarify these associations and their clinical implications.