Department of Mechanical Engineering, Polytechnique Montréal, Downtown Station, P.O. Box 6079, Montreal, QC, H3C 3A7, Canada.
Research Center, Sainte-Justine University Hospital Center, 3175, Cote Sainte-Catherine Road, Montreal, QC, H3T 1C5, Canada.
Spine Deform. 2023 Jan;11(1):49-58. doi: 10.1007/s43390-022-00571-z. Epub 2022 Sep 9.
Assessment of sagittal lordosis distribution on mechanical proximal junctional failure-related risks through computer-based biomechanical models.
To biomechanically assess how lordosis distribution influences radiographical and biomechanical indices related to Proximal Junctional Failure (PJF). The "optimal" patient-specific targets to restore the sagittal balance in posterior spinal fusion are still not known. Among these, the effect of the lumbar lordosis correction strategy on complications such as PJF remain uncertain.
In this computational biomechanical study, five adult spinal deformity patients who underwent posterior spinal fixation were retrospectively reviewed. Their surgery, first erect posture and flexion movement were simulated with a patient-specific multibody model. Three pedicle subtraction osteotomy (PSO) levels (L3, L4, and L5) were simulated, with consistent global lordosis for a given patient and pelvic tilt adjusted accordingly to the actual surgery. Computed loads on the anterior spine and instrumentation were analyzed and compared using Kruskal-Wallis statistical tests and Spearman correlations.
In these models, no significant correlations were found between the lordosis distribution index (LDI), PSO level and biomechanical PJF-related indices. However, increasing the sagittal vertical axis (SVA) and thoracolumbar junction angle (TLJ) and decreasing the sacral slope (SS) increased the bending moment sustained by the rods at the proximal instrumented level (r = 0.52, 0.57, - 0.56, respectively, p < 0.05). There was a negative correlation between SS and the bending moment held by the adjacent proximal segment (r = - 0.71, p < 0.05).
Based on these biomechanical simulations, there was no correlation between the lordosis distribution and PJF-associated biomechanical factors. However, increasing SS and flattening the TLJ, as postural adjustment strategies required by a more distal PSO, did decrease such PJF-related factors. Sagittal restoration and PJF risks remain multifactorial, and the use of patient-specific biomechanical models may help to better understand the complex interrelated mechanisms.
通过基于计算机的生物力学模型评估矢状后凸分布与机械性近端交界区失败相关风险。
生物力学评估后凸分布如何影响与近端交界区失败（PJF）相关的影像学和生物力学指标。在接受后路脊柱融合术的患者中，仍不知道恢复矢状平衡的“最佳”患者特异性靶标。其中，腰椎前凸矫正策略对 PJF 等并发症的影响仍不确定。
在这项计算生物力学研究中，回顾性分析了 5 例接受后路脊柱固定的成人脊柱畸形患者。使用患者特异性多体模型模拟他们的手术、首次直立姿势和屈伸运动。模拟了 3 个椎弓根切除截骨术（PSO）水平（L3、L4 和 L5），对于给定的患者，整体后凸保持一致，骨盆倾斜度根据实际手术进行相应调整。使用 Kruskal-Wallis 统计检验和 Spearman 相关性分析比较分析了前柱和器械上的计算负荷。
在这些模型中，后凸分布指数（LDI）、PSO 水平与生物力学性 PJF 相关指标之间没有显著相关性。然而，增加矢状垂直轴（SVA）和胸腰椎交界角（TLJ），降低骶骨倾斜度（SS）会增加近端器械水平杆承受的弯矩（r=0.52、0.57、-0.56，分别为 p<0.05）。SS 与相邻近端节段杆承受的弯矩呈负相关（r=-0.71，p<0.05）。
基于这些生物力学模拟，后凸分布与 PJF 相关的生物力学因素之间没有相关性。然而，增加 SS 和降低 TLJ，作为更远端 PSO 所需的姿势调整策略，确实会降低此类与 PJF 相关的因素。矢状面恢复和 PJF 风险仍然是多因素的，使用患者特异性生物力学模型可能有助于更好地理解复杂的相互关联机制。
