MacEwen Matthew R, Abbott Rebecca E, Barocas Victor H, Ellingson Arin M
Department of Biomedical Engineering University of Minnesota Minneapolis Minnesota USA.
Department of Physical Medicine and Rehabilitation School of Medicine, University of Colorado Anschutz Medical Campus Aurora Colorado USA.
JOR Spine. 2025 Jun 19;8(2):e70088. doi: 10.1002/jsp2.70088. eCollection 2025 Jun.
This study introduces the helical compliance vector (HCV), a novel measuring parameter that quantifies the orientation and magnitude of joint compliance (inverse of stiffness) by integrating kinetic and kinematic data within the helical axis framework. The HCV provides high temporal and spatial resolution, enabling detailed analysis of compliance and stiffness throughout motion, surpassing the limitations of traditional static or end-range metrics, which often fail to capture transient variations in stiffness and multiplanar interactions that occur during movement.
Eight cadaveric lumbar segments (L4-L5) were tested under pure moment loading (up to 7 Nm) in lateral bending, flexion/extension, axial rotation, and a multiplanar (Kemp's) test.
The findings revealed distinct moment-specific compliance trends, with the highest compliance during low-moment flexion and the lowest during axial rotation. The Kemp's test demonstrated the HCV's ability to capture complex coupled motions, combining lateral bending and axial rotation motion. Across all loading scenarios, compliance decreased significantly near the end range of motion, illustrating its evolution throughout motion.
By simultaneously characterizing the magnitude and directionality of compliance, the HCV framework offers a comprehensive, high-resolution approach to understanding joint mechanics. This method establishes a foundation for investigating multiplanar joint behaviors and can be extended to in vivo applications using advanced imaging and musculoskeletal modeling technologies.
本研究引入了螺旋柔顺度向量（HCV），这是一种新型测量参数，通过在螺旋轴框架内整合动力学和运动学数据来量化关节柔顺度（刚度的倒数）的方向和大小。HCV具有高时间和空间分辨率，能够在整个运动过程中对柔顺度和刚度进行详细分析，克服了传统静态或终末范围测量指标的局限性，这些指标往往无法捕捉运动过程中刚度的瞬态变化和多平面相互作用。
对八个尸体腰椎节段（L4-L5）在侧屈、屈伸、轴向旋转和多平面（肯普氏）试验中进行纯力矩加载（高达7 Nm）测试。
研究结果揭示了特定力矩下不同的柔顺度趋势，低力矩屈曲时柔顺度最高，轴向旋转时最低。肯普氏试验证明了HCV捕捉复杂耦合运动的能力，即结合了侧屈和轴向旋转运动。在所有加载情况下，运动接近终末范围时柔顺度显著降低，说明了其在整个运动过程中的变化。
通过同时表征柔顺度的大小和方向性，HCV框架为理解关节力学提供了一种全面、高分辨率的方法。该方法为研究多平面关节行为奠定了基础，并可利用先进的成像和肌肉骨骼建模技术扩展到体内应用。
