Yang Yangyang, Hu Xiangjun, Cheng Rongshan, Liang Zhihao, Lv Xiaolong, Zheng Nan, Mabel Ong Xuan Yi, Zhao Jie, Tsai Tsung-Yuan
School of Biomedical Engineering and Med-X Research Institute, Shanghai Jiao Tong University, Shanghai 200030, China; Engineering Research Center of Digital Medicine and Clinical Translation, Ministry of Education, Shanghai 200030, China; Department of Orthopedics, Shanghai Ninth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China.
Department of Rehabilitation Medicine, Shanghai Institute of Rehabilitation with Integrated Western and Chinese Traditional Medicine, Zhongshan Hospital, Fudan University, Shanghai 200032, China; Shanghai Baoshan District Wusong Central Hospital, Shanghai 200940, China.
Spine J. 2025 Jul 8. doi: 10.1016/j.spinee.2025.07.016.
In-vitro spinal testing often relies on passive and static loading, causing discrepancies in kinematic and mechanical behaviors compared to in-vivo performance. These constrain the reliability of biomechanical evaluations.
In-vitro biomechanical study.
A musculoskeletal loading platform was developed to replicate global (active and passive) and local muscle loads. Global muscle forces were simulated via active and passive loading modules, while local muscle stabilization was mimicked utilizing a follower load (FL) that applies a compressive force along the lumbar curvature. Four loading protocols were designed and applied using a novel platform for forward flexion tests on 7 porcine lumbar specimens (L3-L5). The protocols included: 1) DynWoFL: dynamic active and dynamic passive muscle loading without FL as a preload, 2) StaPass: dynamic active and static passive muscle forces with a FL as preload, 3) StaLdg: static active and static passive muscle loading with a FL, and 4) DynLdg: dynamic active and dynamic passive muscle loading combined with a FL. Kinematics assessed range of motion (ROM), vertebral translation, and center of rotation (COR) distribution. Mechanical assessments covered intradiscal pressure (IDP) changes and disc surface strain.
Under loading protocols with FL (StaPass, StaLdg, DynLdg), the ROMs of L3/L4 and L4/L5 increased to about 4°. FL reduced the COR distribution range, thereby enhancing spinal movement stability. However, FL had minimal effect on surface strain between DynWoFL and DynLdg groups. Compared to DynLdg, the static passive loading group (StaPass) exhibited additional extension of 3° and posterior translation of 2 mm, with greater medial-lateral and cranial-caudal translations. The COR distribution was also located lower. Although no significant difference in IDP increase was found, StaPass showed significantly higher disc strain. The kinematic performance and disc surface strain of StaLdg were similar to StaPass, and static active and passive muscle loading (StaLdg) underestimated IDP increase by 6.95%-14.70%.
Among the musculoskeletal loading procedures, DynLdg produced ROM, vertebral translation, and disc strain values that closely matched published in-vivo data, supporting its substitutes for related studies. For research focusing on COR distribution and IDP changes, they were more suitable for providing qualitative rather than quantitative insights.
The dynamic musculoskeletal loading protocol enables porcine lumbar spines to replicate biomechanical responses similar to human in-vivo behaviors, establishing it as a reliable alternative for in-vitro biomechanical research in the future.
体外脊柱测试通常依赖于被动和静态加载，与体内性能相比，这会导致运动学和力学行为上的差异。这些限制了生物力学评估的可靠性。
1）建立一个脊柱肌肉骨骼加载平台，并评估在各种加载方案下的生物力学响应。2）基于这个主动动态加载平台提出一种最佳加载方案。
体外生物力学研究。
开发了一个肌肉骨骼加载平台来模拟整体（主动和被动）以及局部肌肉负荷。通过主动和被动加载模块模拟整体肌肉力量，同时利用一个随动载荷（FL）来模拟局部肌肉稳定，该随动载荷沿着腰椎曲度施加压缩力。设计并使用一个新颖的平台对7个猪腰椎标本（L3-L5）进行前屈测试，应用了四种加载方案。这些方案包括：1）DynWoFL：无FL作为预载的动态主动和动态被动肌肉加载，2）StaPass：有FL作为预载的动态主动和静态被动肌肉力量，3）StaLdg：有FL的静态主动和静态被动肌肉加载，4）DynLdg：动态主动和动态被动肌肉加载结合FL。运动学评估了运动范围（ROM）、椎体平移和旋转中心（COR）分布。力学评估涵盖椎间盘内压力（IDP）变化和椎间盘表面应变。
在有FL的加载方案（StaPass、StaLdg、DynLdg）下，L3/L4和L4/L5的ROM增加到约4°。FL减小了COR分布范围，从而增强了脊柱运动稳定性。然而，FL对DynWoFL和DynLdg组之间的表面应变影响最小。与DynLdg相比，静态被动加载组（StaPass）表现出额外3°的伸展和2mm的后向平移，以及更大的内外侧和头尾向平移。COR分布也更低。虽然在IDP增加方面未发现显著差异，但StaPass显示出明显更高的椎间盘应变。StaLdg的运动学性能和椎间盘表面应变与StaPass相似，并且静态主动和被动肌肉加载（StaLdg）使IDP增加低估了6.95%-14.70%。
在肌肉骨骼加载程序中，DynLdg产生的ROM、椎体平移和椎间盘应变值与已发表的体内数据密切匹配，支持其可替代相关研究。对于关注COR分布和IDP变化的研究，它们更适合提供定性而非定量的见解。
动态肌肉骨骼加载方案使猪腰椎能够复制类似于人类体内行为的生物力学响应，使其成为未来体外生物力学研究的可靠替代方法。
