Proximal Lumbar Anterior Column Realignment for Iatrogenic Sagittal Plane Adult Spinal Deformity Correction: A Retrospective Case Series.

Background: Anterior column realignment (ACR) is a powerful minimally invasive surgery technique to restore sagittal alignment in adult spinal deformity (ASD). This can accomplish similar segmental lordosis restoration as 3-column osteotomy with less blood loss and comparable complication rates. ACR can be performed at adjacent disease segments in the proximal lumbar spine in revision cases. However, two thirds of physiologic lordosis occurs between L4-S1, and concerns remain about altered lumbar morphology. We evaluated patients who underwent proximal lumbar ACR for iatrogenic flatback deformity.

Methods: A total of 19 consecutive patients who underwent L1-2 or L2-3 ACR were retrospectively analyzed. All patients were treated with lateral minimally invasive surgery interbody technique, followed by posterior reconstruction with Smith-Peterson osteotomy. Preoperative and postoperative radiographic and clinical outcomes were obtained.

Results: Mean follow-up was 19 months. All but 1 patient had a history of prior lumbar or lumbo-sacral fusion. Sagittal vertical axis and pelvic incidence-lumbar lordosis decreased from 11.9 cm to 6.1 cm (P < 0.0001) and 34.2° to 12.8° (P < 0.0001). Segmental lordosis increased from -2.7° to 21.9° (P < 0.0001). Proximal lumbar lordosis increased from -0.4° to 22.6° (P < 0.0001), and lordosis distribution index decreased from 79.5% to 48.9% (P < 0.0001). Mean Oswestry Disability Index and numeric pain rating scale back pain scores decreased from 58.0 to 36.2 (P = 0.0041) and 7.9 to 3.4 (P < 0.0001), respectively. Patient-Reported Outcomes Measurement Information System Physical and Mental Health T-scores increased from 34.1 to 43.3 (P = 0.0049) and 40.4 to 45.0 (P = 0.0993), respectively. Major complication rate was 15.8%. One patient required revision for mechanical failure. There were no permanent neurological or vascular injuries.

Conclusions: Proximal lumbar ACR plus Smith-Peterson osteotomy can achieve sagittal correction with low major complication rates in patients with ASD and prior distal fusion. Differentially increasing proximal lumbar lordosis and lowering lumbar distribution index did not have deleterious effects on radiographic or clinical outcomes. Further work is needed to understand the effect of proximal ACR in the surgical management of ASD.