Reliability of facet fluid on preoperative MRI for prediction of segmental instability after decompression surgery for degenerative lumbar spinal stenosis.

Abstract

The purpose of this study is to determine whether preoperative facet fluid on MRI can help predict segmental instability (SI) after decompression surgery. We analyzed 34 patients (14 men and 20 women, a total of 37 segments) who underwent decompression for degenerative lumbar spinal stenosis from June 2011 to August 2019 at a single institution. Mean age at the time of operation was 67.8. Postoperative assessment was performed uniformly 12 months (11~15 months) after the surgery. Preoperative facet fluid on MRI, pre- and postoperative slip percentage and segmental motion on lumbar lateral neutral and flexion-extension (LFE) radiographic images were measured. Visual analog scale (VAS) and necessities of interventional procedure or medication was also assessed for clinical outcomes. No significant association was found between preoperative facet fluid indices and pre- or post-operative slip percentage (P=0.134) and segmental motion (p=0.936). There were no significant association also between facet fluid indices and VAS of back or leg (p=0.997 and p=0.437 respectively). Preoperative facet fluid is not a predictive index of postoperative segmental instability or clinical outcome. Without segmental instability on LFE radiographic images, the presence of facet fluid in MRI is not an absolute indication for fusion.