Surgical Management of Degenerative Lumbar Scoliosis Associated With Spinal Stenosis Does the PI-LL Matter?

Study Design. Retrospective observational cohort study. Objectives. To compare the benefits of long and short fusion treatments, and to identify factors potentially aiding surgeons' decision making about the surgical management of degenerative lumbar scoliosis associated with spinal stenosis (DLSS). Summary of Background Data. The comparative effectiveness of long and short segment fusion for the treatment of DLSS remains controversial. Methods. Fifty-three patients with symptomatic DLSS managed by posterior-only fusion surgery were enrolled in this study. Twenty patients underwent short fusion (fewer than two segments), and 33 patients had more than three segments fused. The radiological outcomes were assessed by radiography. Health-related quality of life data, including visual analog scale (VAS) and Oswestry Disability Index (ODI) scores, were collected at all preoperative and follow-up visits. Results. The short and long fusion groups showed significant differences in the change in the Cobb angle (4.2 degrees vs. 11.2 degrees), lumbar lordosis (3.9 degrees vs. 11.5 degrees), and pelvic incidence minus the lumbar lordosis angle (PI - LL; 3.2 degrees vs. 11.2 degrees). Both the short and long fusion achieved significant changes in low back pain and leg pain. Patients with PI - LLs > 10 degrees had more relief of low back pain after long fusion (VAS 4.0 +/- 2.0) than after short fusion (VAS 2.6 +/- 1.7). Patients with PI - LLs > 10 degrees showed significantly improved walking ability after long fusion (ODI 1.0 +/- 0.8). The improvement in standing ability after short fusion was greater when PI - LL +/- 10 degrees(ODI 0.9 +/- 0.6). Conclusion. Long segment fusion can relieve low back pain better and improve walking ability when PI-LL is mismatched, whereas short segment fusion is more advantageous in improving standing ability in cases of more balanced sagittal spinopelvic alignment.