Department of Orthopaedic Surgery, University of California, San Francisco, USA.
Department of Electrical Engineering and Computer Science, University of California, Berkeley, USA.
Eur Spine J. 2019 May;28(5):905-913. doi: 10.1007/s00586-019-05925-2. Epub 2019 Mar 2.
A longitudinal cohort study.
To define a set of objective biomechanical metrics that are representative of adult spinal deformity (ASD) post-surgical outcomes and that may forecast post-surgical mechanical complications. Current outcomes for ASD surgical planning and post-surgical assessment are limited to static radiographic alignment and patient-reported questionnaires. Little is known about the compensatory biomechanical strategies for stabilizing sagittal balance during functional movements in ASD patients.
We collected in-clinic motion data from 15 ASD patients and 10 controls during an unassisted sit-to-stand (STS) functional maneuver. Joint motions were measured using noninvasive 3D depth mapping sensor technology. Mathematical methods were used to attain high-fidelity joint-position tracking for biomechanical modeling. This approach provided reliable measurements for biomechanical behaviors at the spine, hip, and knee. These included peak sagittal vertical axis (SVA) over the course of the STS, as well as forces and muscular moments at various joints. We compared changes in dynamic sagittal balance (DSB) metrics between pre- and post-surgery and then separately compared pre- and post-surgical data to controls.
Standard radiographic and patient-reported outcomes significantly improved following realignment surgery. From the DSB biomechanical metrics, peak SVA and biomechanical loads and muscular forces on the lower lumbar spine significantly reduced following surgery (- 19 to - 30%, all p < 0.05). In addition, as SVA improved, hip moments decreased (- 28 to - 65%, all p < 0.05) and knee moments increased (+ 7 to + 28%, p < 0.05), indicating changes in lower limb compensatory strategies. After surgery, DSB data approached values from the controls, with some post-surgical metrics becoming statistically equivalent to controls.
Longitudinal changes in DSB following successful multi-level spinal realignment indicate reduced forces on the lower lumbar spine along with altered lower limb dynamics matching that of controls. Inadequate improvement in DSB may indicate increased risk of post-surgical mechanical failure. These slides can be retrieved under Electronic Supplementary Material.
纵向队列研究。
定义一组代表成人脊柱畸形（ASD）术后结果的客观生物力学指标，这些指标可能预测术后机械并发症。目前，ASD 手术规划和术后评估的结果仅限于静态放射学对齐和患者报告的问卷。对于 ASD 患者在功能运动中稳定矢状平衡的代偿生物力学策略知之甚少。
我们在无辅助坐站（STS）功能运动期间从 15 名 ASD 患者和 10 名对照者中收集门诊运动数据。关节运动使用非侵入性的 3D 深度映射传感器技术进行测量。数学方法用于实现生物力学模型的高保真关节位置跟踪。这种方法为脊柱、髋关节和膝关节的生物力学行为提供了可靠的测量。这些包括 STS 过程中矢状垂直轴（SVA）的峰值，以及各个关节的力和肌肉力矩。我们比较了术前和术后动态矢状平衡（DSB）指标的变化，然后分别将术前和术后数据与对照组进行比较。
经重新对线手术后，标准放射学和患者报告的结果显著改善。从 DSB 生物力学指标来看，术后 SVA 峰值和下腰椎的生物力学负荷和肌肉力显著降低（-19%至-30%，均 p<0.05）。此外，随着 SVA 的改善，髋关节力矩减小（-28%至-65%，均 p<0.05），膝关节力矩增加（+7%至+28%，p<0.05），表明下肢代偿策略发生变化。手术后，DSB 数据接近对照组的值，一些术后指标在统计学上与对照组等效。
成功的多节段脊柱重新对线后 DSB 的纵向变化表明下腰椎的力降低，同时下肢动力学与对照组相匹配。DSB 改善不足可能表明术后机械失败的风险增加。这些幻灯片可在电子补充材料中检索。
