Long-Term Spinopelvic Alignment Following Unilateral Laminotomy with Bilateral Decompression for Lumbar Spinal Stenosis: A Retrospective Analysis Using Surgimap Digital X-Ray Imaging.

BACKGROUND Lumbar spinal stenosis (LSS) is a common cause of disability in the elderly. This retrospective study from a single center included 92 patients with LSS and aimed to evaluate long-term sagittal spinopelvic alignment following multi-level unilateral laminotomy with bilateral decompression using digital X-ray image analysis with Surgimap software. MATERIAL AND METHODS A retrospective analysis was conducted on 117 patients who underwent ULBD between 2016 and 2019, with 92 patients meeting inclusion criteria. Preoperative and postoperative sagittal balance parameters, including lumbar lordosis (LL), pelvic tilt (PT), sacral slope (SS), pelvic incidence (PI), and pelvic incidence-lumbar lordosis (PI-LL) mismatch, were measured using digital X-ray image analysis via Surgimap software, Version 2.3.0.1 (New York, 2019). Patients were divided into single-level (n=48) and multi-level (n=44) groups, and long-term radiological outcomes were compared over a mean follow-up period of 5.5 years. RESULTS Sagittal alignment parameters were preserved in most patients, with minimal increases in LL (+0.58° in single-level, +3.82° in multi-level) and PT, and decreases in PI-LL mismatch (-1.79° in single-level, -3.38° in multi-level). Multi-level patients showed better long-term preservation of spinal parameters, with 84.6% maintaining favorable PI-LL alignment (<10°), compared with 75% of single-level patients. Additionally, 40.9% of multi-level patients and 35.7% of single-level patients with preoperative sagittal alignment disorder achieved normal alignment postoperatively. CONCLUSIONS ULBD surgery effectively preserves and modestly improves sagittal spinopelvic alignment, particularly in multi-level cases. The findings from this study support the use of digital X-ray image analysis in evaluating long-term sagittal spinopelvic alignment following laminotomy and decompression.