Association between Facet Fluid on Supine Axial T2-Weighted MRI and Sagittal Instability on Dynamic Standing Lateral Radiographs in Patients with Degenerative Lumbar Disease

Study Design: Prospective observational study conducted at a large tertiary care center in Karachi, Pakistan. Purpose: To examine the association between positive facet fluid on T2-weighted MRI of lumbosacral spine and the presence of instability on lateral flexion/extension radiographs, and to determine whether a correlation exists between the quantity of facet fluid on axial MRI and the degree of spinal instability on lateral standing flexion/extension radiographs. Overview of literature: The presence of increased facet fluid on axial T2-weighted magnetic resonance imaging (MRI) has been proposed as a potential marker for motion segment instability in the lumbar spine. Both facet fluid on MRI and spinal instability on dynamic x-rays are crucial in diagnosing and managing low back pain, guiding decisions on surgical interventions. Methods: We analyzed the prospectively collected data from patients meeting the inclusion criteria. Facet fluid measurements were made according to Schinnerer's criteria on axial T2-weighted images and anterior translation as a marker of instability was evaluated on dynamic radiographs for all eligible patients. Statistical analysis was performed using IBM SPSS version 23, employing cross-tabulations, chi-square tests, and Pearson correlation. The study utilized a null hypothesis to evaluate the association between facet fluid and spinal instability. Results: Our findings demonstrated a statistically significant association between positive facet fluid on MRI and the occurrence of instability on lateral flexion/extension radiographs. Moreover, we found a strong positive correlation between the volume of facet fluid on axial MRI and the level of spinal instability on standing flexion/extension radiographs. Conclusion: Based upon these outcomes, we propose that standing lateral flexion–extension radiographs should be routinely administered to patients exhibiting increased facet fluid signals on MRI, as they may provide valuable information regarding potential spinal instability. Further research will help establish the clinical utility of this approach in managing degenerative lumbar diseases.