Image Correlation Between Facet Effusion and Lumbar Instability

Abstract

Objective To assess the incidence of facet effusion in lumbosacral spine magnetic resonance imaging (MRI) and the relationship with radiographic segmental instability in patients submitted to spinal surgery. Methods Retrospective cohort study of patients submitted to lumbosacral spine surgery over a period of three years, through the evaluation of dynamic radiographs (X-ray) motion and facet effusion in axial section of MRI. Instability was defined as vertebral translation > 3 mm or intervertebral angle > 10º, and facet effusion as fluid in the facet joints > 1.5 mm. Results The total number of patients that fulfilled the criteria for analysis was 244, of which 47 presented movement (≤ 3 mm) and 31 presented excessive movement (> 3 mm), 115 had facet effusion (≤ 1.5 mm) and 46 presented excessive fluid (> 1.5 mm). Statistical analysis did not demonstrate a significant association between increased segmental movement and facet effusion (p = 0.150). Conclusions The total incidence of facet effusion was 47.1% and the excessive fluid was 18.9%.There was no association between facet effusion in MRI and instability in dynamic X-ray. MRI does not replace dynamic X-ray in flexion and extension in the evaluations of lumbar instability. Level of evidence III; Retrospective Cohort.

Important controversies in lumbar spine surgery: which patients benefit from lumbar spinal fusion and who should be fused?

“…Use of imaging like X-rays in flexion-extension and side-bending, standardised lumbo-sacral X-rays along with lateral flexion and extension radiographs -defining spinal instability as sagittal plane translation of 4 mm or more (13)( 14), fluoroscopy, MRI(standard and dynamic) and CT scans can provide useful information. Dynamic X-rays in flexion and extension should not be replaced by MRI and CT scans in the assessment of spinal instability (16). Radiological documentation of instability should be performed preop, at 6 months and 3 years post op to demonstrate evidence of progressive segmental instability (2).…”