Mid-term changes in spinopelvic sagittal alignment in lumbar spinal stenosis with coexisting degenerative spondylolisthesis or scoliosis after minimally invasive lumbar decompression surgery: minimum five-year follow-up

Recently, the number of patients with lumbar spinal stenosis (LSS) who present with a coexisting spinal deformity such as degenerative spondylolisthesis (DS) and scoliosis (DLS) has been increasing. Lumbar decompression without fusion can lead to a reactive improvement in the lumbar and sagittal spinopelvic alignment, even if a sagittal imbalance exists preoperatively. However, the mid- to long-term impact of the coexistence of DS and DLS on the change in sagittal spinopelvic alignment and clinical outcomes after decompression surgery remains unknown.This study aimed to investigate whether the coexistence of DS or DLS in patients with LSS is associated with differences in radiological and clinical outcomes after minimally invasive lumbar decompression surgery.A retrospective analysis of prospectively collected data.A total of 169 patients who underwent minimally invasive lumbar decompression surgery and follow-up >5 years postoperatively.Self-report measures: Low back pain (LBP) and/or leg pain and/or leg numbness visual analog scale (VAS) scores and the Japanese Orthopedic Association scores.Standing sagittal spinopelvic alignment.In total, 81 patients with LSS, 50 patients with LSS and DS (≥3 mm anterior slippage), and 38 patients with LSS and DLS (≥15° coronal Cobb angle) were included in the current study. Clinical and radiological outcome results before surgery and at 2 and 5 years after surgery were compared among the groups.In patients with LSS with coexisting DS, the clinical outcomes at 2, and 5 years after surgery were similar to those of patients with only LSS. In patients with LSS with coexisting DLS, the VAS LBP and leg pain at 2 years after surgery was significantly higher (34.7 vs. 27.8, p=0.014; 27.8 vs. 14.7, p=0.028) and the achievement rate of the minimal clinically important difference in VAS LBP and leg pain was significantly lower than that of the LSS group (36.1% vs. 54.2%, p=0.036; 58.3% vs. 69.9%, p=0.10). The clinical outcomes except VAS leg numbness at 5 years after surgery were similar to those of patients with only LSS. The reoperation rate of the DS group was significantly lower than that of the LSS group (4.0% vs. 14.8%; p=0.01); however, the reoperation rate of the DLS group was comparable to that of the LSS group (15.8% vs. 14.8%; p=0.493). Lumbar lordosis (LL), sacral slope, pelvic tilt, and pelvic incidence-LL had significantly improved and been maintained for 5 years after the surgery in both the DS and the DLS groups. The sagittal vertical axis had improved at two-year follow-up; however, no significant difference was observed at the 5-year follow-up in both the DS, and the DLS groups.Mid-term clinical outcomes in patients with LSS with and without deformity were comparable. Lumbar decompression without fusion can result in a reactive improvement in the lumbar and sagittal spinopelvic alignment, even with coexisting DS or DLS. Minimally invasive surgery could be considered for most patients with LSS.