Predictors of Long-Term Outcomes after Endoscopic Spinal Decompression in Patients with Lumbar Spinal Stenosis

Background. ESD is a minimally invasive procedure to alleviate disability in LSS patients. However, long-term predictors of suboptimal surgical outcomes remain unclear. We aimed to investigate the predictors of long-term outcomes in patients with lumbar spinal stenosis (LSS) treated with endoscopic spinal decompression (ESD) surgery. Material and methods. Patients with LSS unresponsive to conservative treatment underwent ESD surgery. Disability was assessed using the Oswestry Low Back Pain (LBP) Disability Questionnaire, reported as the Oswestry Disability Index (ODI), at pre-surgery, post-surgery, and 1-year follow-up. Patients were grouped ba­sed on the presence or absence of spinal instability. Results. 93 patients (mean age 55±14, 55% female) with LSS who underwent ESD due to persistent LBP were included. Pre-surgical ODI significantly decreased post-surgery in both groups (spinal instability: 25 [IQR 19-33] vs. 3 [IQR 1-7], p<0.001; no spinal instability: 30 [IQR 24-35] vs. 2 [IQR 1-4], p<0.001). However, the spinal instability group had higher post-surgical ODI (3 [IQR 1-7] vs. 2 [IQR 1-4], p=0.018) and 1-year ODI (14 [IQR 2-24] vs. 3 [IQR 1-7], p=0.013) compared to the no spinal instability group, where ODI remained stable (2 [IQR 1-4] vs. 2 [IQR 1-4], p=0.785). Multivariable linear regression identified multilevel degenerative disc disease (β=3.357, 95% CI 0.610-6.105, p=0.017) and spinal instability (β=7.368, 95% CI 3.370-11.365, p<0.001) as independent predictors of 1-year ODI. Conclusions. 1. ESD surgery significantly improves disability, as measured by ODI, in patients with LSS, regardless of spinal instability. 2. Multilevel degenerative disc disease and spinal instability are long-term predictors of outcomes following ESD surgery.