Purpose: Vertebral body tethering (VBT) for lumbar curves may have wider application than for thoracic curves due to greater growth potential than thoracic spine and benefits of preserved flexibility. Predicting long-term correction remains challenging, with high revision rates and complications (14-32%) including under-/over-correction, tether breakage, adding-on. This study aimed to validate a planning tool for lumbar VBT using a patient-specific finite element model (FEM) integrating mechanobiological growth modulation as a function of preoperative skeletal maturity.

Methods: Thirty-five retrospective idiopathic scoliosis patients who underwent lumbar VBT, with or without concomitant thoracic VBT, were included. A personalized FEM calibrated to preoperative spine deformity, flexibility and weight was created using 3D radiographic reconstructions. The FEM was linked to an algorithm integrating spine growth and mechanobiological growth modulation, calibrated using preoperative Sanders score. VBT surgery was simulated to replicate immediate postoperative correction and predict two-year correction. Simulated Cobb angles, sagittal curves, and apical axial rotation were compared to actual two-year radiographic measurements.

Results: Preoperative Cobb angles averaged 37 ± 12° (thoracic) and 48 ± 9° (thoraco-lumbar/lumbar). Immediate postoperative correction was 38 ± 15% and 59 ± 16%, with two-year corrections of 44 ± 24% and 73 ± 21%, respectively. Simulated postoperative correction was accurate within 3° (Cobb angles), while simulated 2-year outcomes were accurate within 3° (Cobb), 2° (kyphosis), 4° (lordosis), and 3° (axial rotation), showing no significant differences from reference results (p < 0.05; statistical power 90%).

Conclusion: The patient-specific FEM and growth modulation algorithm accurately predicted two-year correction. This tool can support preoperative planning, reduce surgeon variability, and potentially improve VBT outcomes by providing a predictive tool to help surgical planning.

Keywords: Biomechanics; Finite element modeling; Growth modulation; Idiopathic scoliosis; Vertebral body tethering.

© 2025. The Author(s), under exclusive licence to Scoliosis Research Society.

目的：腰椎曲度的椎体牵拉术（VBT）可能比胸椎曲度有更广泛的应用，因为腰椎的增长潜力更大，并且可以保留灵活性。预测长期矫正仍然具有挑战性，高修订率和并发症（14-32%），包括矫枉过正或矫治不足、牵拉带断裂、叠加效应等问题。本研究旨在通过使用患者特异性有限元模型（FEM）验证腰椎VBT的规划工具，并结合术前骨骼成熟度的机理生物学生长调节功能。

方法：回顾性纳入了35例接受腰椎VBT手术的特发性脊柱侧弯患者，其中一些伴有胸椎VBT。使用三维放射重建技术创建个性化的有限元模型，并校准以匹配术前脊柱畸形、灵活性和体重。该FEM与一个算法相连接，该算法结合了脊柱生长和机理生物学生长调节功能，并通过术前Sanders评分进行校准。模拟VBT手术以复制即刻术后矫正效果并预测两年后的矫正情况。将模拟的Cobb角、矢状位曲线及顶点轴向旋转与实际两年后放射测量结果进行比较。

结果：术前平均Cobb角为37 ± 12°（胸椎）和48 ± 9°（胸腰段/腰椎）。即刻术后矫正率为38 ± 15% 和 59 ± 16%，两年后的矫正率分别为44 ± 24% 和 73 ± 21%。模拟的术后矫正在Cobb角上准确度为±3°，而预测的两年结果在Cobb角（±3°）、驼峰角（±2°）、腰椎前凸角（±4°）和轴向旋转角度（±3°）上的准确性均与参考结果无显著差异（p

结论：患者特异性的FEM及生长调节算法能够准确预测两年后的矫正情况。该工具可以支持术前规划，减少外科医生的变量，并通过提供预测性工具来帮助手术规划，从而可能改善VBT的结果。

关键词：生物力学；有限元建模；生长调节；特发性脊柱侧弯；椎体牵拉术。

© 2025. The Author(s), under exclusive licence to Scoliosis Research Society.