Breaking Down Instability: The Associations Between Muscle Health, Facet Joint Morphology, Spinopelvic Alignment, and Stability Status in Degenerative Lumbar Spondylolisthesis.
Academic Article
Overview
abstract
STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To compare muscle health and imaging markers in patients with 1-level L4-L5 stable versus unstable degenerative lumbar spondylolisthesis (DLS). BACKGROUND: DLS may be stable or unstable. It is unknown how muscle health and other imaging markers are associated with DLS stability. MATERIALS AND METHODS: Patients 18 years or older with 1-level L4-L5 DLS and preoperative flexion/extension radiographs were included. Normalized total psoas area (NTPA), body mass index (BMI)-normalized paralumbar [PL; multifidus (MF)+erector spinae (ES)] cross-sectional area (PL-CSA/BMI), and Goutallier were assessed. Other L4-L5 markers included: facet orientation, slip percentage, pelvic incidence (PI), tilt (PT), sacral slope (SS), lumbar lordosis (LL), and PI-LL. Instability was defined as >3 mm translation or >10° endplate change on flexion-extension. Low versus normal muscle health was defined as NTPA or PL-CSA/BMI below the lowest sex-specific quartile. Multivariate logistic regression was used to determine variables associated with instability. RESULTS: Two hundred fifty-one patients (unstable = 50; stable = 201) were included. There were no significant differences in muscle health at L3, L4, or L5 or Goutallier on univariate analysis. The stable cohort had smaller slip percentage (19 ± 9% vs . 15 ± 8%, P = 0.007) and PI-LL (13.56 ± 12.75 vs . 5.81 ± 14.46, P = 0.001). The stable cohort had more patients with MF and ES total Goutallier ≤2 ( P = 0.031, P = 0.002, respectively) at L3-L4 versus L4-L5 and more patients with MF and ES total Goutallier ≤2 ( P = 0.013, P = 0.004, respectively) at L4-L5 versus L5-S1. On regression, low L4-L5 MF Goutallier was associated with instability [OR: 2.50 (95% CI: 1.01-6.20), P = 0.047]. CONCLUSION: Patients with unstable L4-L5 spondylolisthesis have lower multifidus Goutallier at the slip level, greater slip percentage, and greater PI-LL mismatch. Patients with stable L4-L5 spondylolisthesis have greater Goutallier of the caudal paralumbars. LEVEL OF EVIDENCE: Level III.
