S1 pedicle subtraction osteotomy combined with prone lateral lumbar interbody fusion for the correction of major lumbopelvic malalignment: illustrative case.

backgroundCombining lateral lumbar interbody fusion (LLIF) with open posterior surgery creates a hybrid surgical approach that can restore spinopelvic alignment by simultaneously addressing the anterior and posterior columns. The following is a case report detailing a hybrid prone LLIF with open S1 pedicle subtraction osteotomy (PSO) for correction of a major sagittal imbalance with a pelvic incidence (PI) > 100°. OBSERVATIONS: A 48-year-old female with previous L3-S1 transforaminal interbody fusion presented with severe low back pain and standing imbalance. Imaging revealed significant sagittal malalignment and a PI of 103.1°. The patient underwent revision surgery, including an L2-3 prone LLIF and an S1 PSO. There were no significant complications in the perioperative period, and her first postoperative radiographs showed a reduction in PI (103.1° to 72.1°), lumbar lordosis (LL) (87.4° to 64.2°), PI-LL mismatch (14.5° to 7.9°), and sagittal vertical axis (15.1 cm to 4.9 cm). At 1 year, she reported only minor deficits, ambulating without a cane. She has gone on to successful fusion without adjacent segment pathology. LESSONS: The prone LLIF and PSO combination offers a hybrid surgical approach utilizing the anterior and posterior columns to optimize construct and alignment goals for major sagittal deformity correction. https://thejns.org/doi/10.3171/CASE24653.