Reverse pedicle subtraction osteotomy for iatrogenic hyperlordosis in a scoliosis patient: illustrative case.

backgroundOvercorrection of lumbar lordosis (LL) during deformity surgery can create iatrogenic hyperlordosis with negative sagittal balance, a rare but disabling complication with no standard treatment. OBSERVATIONS: A 21-year-old woman with adolescent idiopathic scoliosis had undergone T3-L5 fusion, revision L4-5 transforaminal lumbar interbody fusion (TLIF) with carbon fiber instrumentation due to a nickel allergy, and L4-S1 anterior lumbar interbody fusion with L3-pelvis fusion for pseudarthrosis. She developed severe low back and bilateral groin pain that worsened with standing. Imaging demonstrated exaggerated LL (L1-S1 82° vs pelvic incidence 52°), a negative sagittal vertical axis (-96 mm), and a PI-LL mismatch of -30°, consistent with global sagittal imbalance and hip impingement. She underwent revision L1-S1 fusion with bilateral iliac fixation, reverse pedicle subtraction osteotomy (PSO) at L4, and L3-4 TLIF. Postoperatively, LL decreased to 60° with more physiological segmental distribution and sagittal parameters improved toward neutral, with resolution of her symptoms. LESSONS: Iatrogenic lumbar hyperlordosis with negative sagittal balance can cause debilitating spinopelvic mismatch. Careful attention to patient-specific spinopelvic targets is essential during deformity correction, and reverse PSO is a useful strategy to reduce fixed hyperlordosis, restore alignment, and alleviate symptoms. https://thejns.org/doi/10.3171/CASE25944.