Characteristics and treatment of dynamic sagittal imbalance in adult spinal deformity

Abstract

Objective: To raise the diagnostic criteria, classification and treatment strategy of dynamic sagittal imbalance (DSI). Methods: One hundred thirty-three adult spinal deformity (ASD) patients with stooping and back pain after walking were retrospectively analyzed. Based on the radiographic parameters and Oswestry Disability Index (ODI) scores, the diagnostic criteria of DSI were raised. DSI patients received nonoperative treatment and (or) surgery. Radiographic parameters and health-related quality of life (HRQOL) outcomes would be measured and compared between prewalk and postwalk and among each subgroup. Results: One hundred thirty-three ASD patients with stooping and back pain after walking were enrolled in our study. The quantitative diagnostic criteria was prewalk SVA < 40 mm and postwalk SVA-prewalk SVA ≥ 20 mm after 10-min walk. Based on the quantitative diagnostic criteria of DSI raised by our team, DSI patients could be classified into three groups: 20 mm ≤ ΔSVA < 60 mm (mild, 31.0%), 60 mm ≤ ΔSVA < 100 mm (moderate, 42.1%) and ΔSVA ≥ 100 mm (severe, 27.0%). After nonoperative treatment, the ΔSVA in mild and moderate group was prominently decreased (P < 0.001) with the significant improvement of HRQOL outcomes (P < 0.001), while there was no significant change in ΔSVA and clinical outcomes in group C (P > 0.05). Patients who received the operative treatment showed prominent improvement in ΔSVA and clinical outcomes (P < 0.001). Conclusion: Our study proposed a quantitative diagnostic criteria and novel classification of DSI. Nonoperative treatment is effective for most DSI patients with ΔSVA < 100 mm, while the majority of DSI patients with ΔSVA ≥ 100 mm need operative intervention.