Should patients with lumbar stenosis and grade I spondylolisthesis be treated differently based on spinopelvic alignment? A retrospective, two-year, propensity matched, comparison of patient-reported outcome measures and clinical outcomes from multiple sites within a single health system.

Background: Degenerative lumbar spondylolisthesis is one of the most common pathologies addressed by surgeons. Recently, data demonstrated improved outcomes with fusion in conjunction with laminectomy compared to laminectomy alone. However, given not all degenerative spondylolistheses are clinically comparable, the best treatment option may depend on multiple parameters. Specifically, the impact of spinopelvic alignment on patient reported and clinical outcomes following fusion versus decompression for grade I spondylolisthesis has yet to be explored.

Purpose: This study assessed two-year clinical outcomes and one-year patient reported outcomes following laminectomy with concomitant fusion versus laminectomy alone for management of grade I degenerative spondylolisthesis and stenosis. The present study is the first to examine the effect of spinopelvic alignment on patient-reported and clinical outcomes following decompression alone versus decompression with fusion.

Study Design/setting: Retrospective sub-group analysis of observational, prospectively collected cohort study.

Patient Sample: 679 patients treated with laminectomy with fusion or laminectomy alone for grade I degenerative spondylolisthesis and comorbid spinal stenosis performed by orthopaedic and neurosurgeons at three medical centers affiliated with a single, tertiary care center.

Outcome Measures: The primary outcome was the change in Patient-Reported Outcome Measurement Information System (PROMIS), Global Physical Health (GPH), and Global Mental Health (GMH) scores at baseline and post-operatively at 4-6 and 10-12 months postoperatively. Secondary outcomes included operative parameters (estimated blood loss and operative time), and two-year clinical outcomes including reoperations, duration of postoperative physical therapy, and discharge disposition.

Methods: Radiographs/MRIs assessed stenosis, spondylolisthesis, pelvic incidence, lumbar lordosis, sacral slope, and pelvic tilt; from this data, two cohorts were created based on pelvic incidence minus lumbar lordosis (PILL), denoted as "high" and "low" mismatch. Patients underwent either decompression or decompression with fusion; propensity score matching (PSM) and coarsened exact matching (CEM) were used to create matched cohorts of "cases" (fusion) and "controls" (decompression). Binary comparisons used McNemar test; continuous outcomes used Wilcoxon rank-sum test. Between-group comparisons of changes in PROMIS GPH and GMH scores were analyzed using mixed-effects models; analyses were conducted separately for patients with high and low pelvic incidence-lumbar lordosis (PILL) mismatch.

Results: 49.9% of patients (339) underwent lumbar decompression with fusion, while 50.1% (340) received decompression. In the high PLL mismatch cohort at 10-12 months postoperatively, fusion-treated patients reported improved PROs, including GMH (26.61 vs. 20.75, p<0.0001) and GPH (23.61 vs. 18.13, p<0.0001). They also required fewer months of outpatient physical therapy (1.61 vs. 3.65, p<0.0001) and had lower 2-year reoperation rates (12.63% vs. 17.89%, p=0.0442) compared to decompression-only patients. In contrast, in the low PLL mismatch cohort, fusion-treated patients demonstrated worse endpoint PROs (GMH: 18.67 vs. 21.52, p<0.0001; GPH: 16.08 vs. 20.74, p<0.0001). They were also more likely to require skilled nursing/rehabilitation centers (6.86% vs. 0.98%, p=0.0412) and extended outpatient physical therapy (2.47 vs. 1.34 months, p<0.0001) and had higher 2-year reoperation rates (25.49% vs. 14.71%,p=0.0152).

Conclusions: Lumbar laminectomy with fusion was superior to laminectomy in health-related quality of life and reoperation rate at two years postoperatively only for patients with sagittal malalignment, represented by high PILL mismatch. In contrast, the addition of fusion for patients with low-grade spondylolisthesis, spinal stenosis, and spinopelvic harmony (low PILL mismatch) resulted in worse quality of life outcomes and reoperation rates.