Posterior column osteotomy for spinal realignment in patients with prior lumbar fusion: illustrative case.

backgroundIatrogenic flat back syndrome following prior posterolateral fusion without interbody support is challenging, especially with adjacent segment stenosis. While pedicle subtraction osteotomy (PSO) offers strong correction, it is associated with higher morbidity. Alternative techniques with reduced risk are needed. OBSERVATIONS: The authors present the case of a 71-year-old woman with a 25-year-old L4-S1 fusion and severe sagittal deformity who underwent a Schwab grade 2 posterior column osteotomy (PCO) through the L4-5 fusion mass, with insertion of interbody cages of varying heights and lordotic angles. Preoperative parameters included C7 sagittal vertical axis (SVA) +10 cm, pelvic incidence (PI) 65°, lumbar lordosis (LL) -13°, PI-LL mismatch 79°, and pelvic tilt (PT) 43°. Postoperative improvements were C7 SVA +5.7 cm, LL 41°, PI-LL mismatch 24°, and PT 35°. The 285-minute surgery had an estimated blood loss of 1100 mL. At 1 month, the patient could walk a one-quarter mile, compared with < 50 feet before surgery. LESSONS: This modified PCO technique provides effective decompression and substantial sagittal correction for iatrogenic flat back syndrome while potentially reducing morbidity compared with PSO. By distributing correction across multiple levels, this approach offers a valuable alternative for patients with moderate to severe sagittal imbalance and concurrent stenosis above prior fusion constructs-avoiding a three-column osteotomy. https://thejns.org/doi/10.3171/CASE25251.