Schmid Stefan, Burkhart Katelyn A, Allaire Brett T, Grindle Daniel, Bassani Tito, Galbusera Fabio, Anderson Dennis E
Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Boston, MA, United States.
Department of Orthopaedic Surgery, Harvard Medical School, Boston, MA, United States.
Front Bioeng Biotechnol. 2020 Mar 3;8:159. doi: 10.3389/fbioe.2020.00159. eCollection 2020.
The pathomechanisms of curve progression in adolescent idiopathic scoliosis (AIS) remain poorly understood and biomechanical data are limited. A deeper insight into spinal loading could provide valuable information toward the improvement of current treatment strategies. This work therefore aimed at using subject-specific musculoskeletal full-body models of patients with AIS to predict segmental compressive forces around the curve apex and to investigate how these forces are affected by simulated load carrying. Models were created based on spatially calibrated biplanar radiographic images from 24 patients with mild to moderate AIS and validated by comparing predictions of paravertebral muscle activity with reported values from studies. Spinal compressive forces were predicted during unloaded upright standing as well as standing with external loads of 10, 15, and 20% of body weight (BW) applied to the scapulae to simulate carrying a backpack in the regular way on the back as well as in front of the body and over the shoulder on the concave and convex sides of the scoliotic curve. The predicted muscle activities around the curve apex were higher on the convex side for the erector spinae (ES) and multifidi (MF) muscles, which was comparable to the EMG-based measurements from the literature. In terms of spinal loading, the implementation of spinal deformity resulted in a 10% increase of compressive force at the curve apex during unloaded upright standing. Apical compressive forces further increased by 50-62% for a simulated 10% BW load and by 77-94% and 103-128% for 15% and 20% BW loads, respectively. Moreover, load-dependent compressive force increases were the lowest in the regular backpack and the highest in the frontpack and convex conditions, with concave side-carrying forces in between. The predictions indicated increased segmental compressive forces during unloaded upright standing, which could be ascribed to the scoliotic deformation. When carrying loads, compressive forces further increased depending on the carrying mode and the weight of the load. These results can be used as a basis for further studies investigating segmental loading in AIS patients during functional activities. Models can thereby be created using the same approach as proposed in this study.
青少年特发性脊柱侧凸（AIS）中脊柱侧凸进展的病理机制仍未得到充分理解，生物力学数据也很有限。对脊柱负荷的更深入了解可为改进当前治疗策略提供有价值的信息。因此，这项研究旨在使用AIS患者的个体化肌肉骨骼全身模型来预测脊柱侧凸顶点周围的节段性压缩力，并研究这些力如何受到模拟负荷的影响。基于24例轻度至中度AIS患者的空间校准双平面放射图像创建模型，并通过将椎旁肌活动的预测结果与先前研究报告的值进行比较来进行验证。预测了无负荷直立站立以及在肩胛骨上施加体重（BW）10%、15%和20%的外部负荷时的脊柱压缩力，以模拟以常规方式在背部、身体前方以及脊柱侧凸曲线凹侧和凸侧的肩部背包的情况。在脊柱侧凸顶点周围，竖脊肌（ES）和多裂肌（MF）在凸侧的预测肌肉活动较高，这与文献中基于肌电图的测量结果相当。在脊柱负荷方面，脊柱畸形的存在导致无负荷直立站立时脊柱侧凸顶点处的压缩力增加10%。对于模拟的10%BW负荷，顶点压缩力进一步增加50 - 62%，对于15%和20%BW负荷，分别增加77 - 94%和103 - 128%。此外，负荷依赖性压缩力增加在常规背包情况下最低，在前背包和凸侧负荷情况下最高，凹侧负荷力介于两者之间。预测结果表明，在无负荷直立站立时节段性压缩力增加，这可能归因于脊柱侧凸变形。负重时，压缩力会根据负重方式和负荷重量进一步增加。这些结果可作为进一步研究AIS患者在功能活动期间节段性负荷的基础。因此，可以使用本研究中提出的相同方法创建模型。
