The impact of posterior epidural adipose tissue on postoperative outcomes after posterior decompression surgery for lumbar spinal stenosis: A prospectively randomized non-inferiority trial

Study design: The present study is a prospectively randomized study. Objective: The objective of the study was to evaluate the impact of posterior epidural adipose tissue (PAT) on postoperative outcome following lumbar decompression surgery for lumbar spinal stenosis (LSS) by whether PAT was removed or preserved during the surgical procedure. Summary of background data: In posterior decompression surgery for LSS, PAT is routinely removed without knowledge of its role and significance. However, considering adipose tissue has regenerative properties of damaged neighboring tissues or itself, PAT, which is adipose tissue located at peridural space, might also have a potential to regenerate the neighboring damaged tissue, including dura and nerve root in the lumbar spine, but this has not been thoroughly studied. Methods: Of the 185 eligible patients screened for the current study, 181 patients were enrolled and randomly allocated into either group A (PAT removal, n = 90) or group B (PAT retention, n = 91). The primary outcome measure was pain intensity on the lower back and lower extremity. The secondary outcome measures were functional outcome based on the Oswestry disability index (ODI) and walking distance, complications during the surgical procedure, and surgical outcomes. Results: Postoperative pain intensity on the lower back and lower extremity was greater in group A than in group B. Functional status on ODI and walking distance was also worse in group B than in group A (64.9% in group A and 66.2% in group B). The number of patients with aggravated pain intensity and deteriorated functional status in postoperative follow-up times was significantly greater in group A than in group B. There were no significant differences in surgical outcome and complications between the groups. Conclusion: Preserving epidural fat may be favorable in postoperative outcomes of posterior decompression surgery for LSS compared to removing epidural fat.