Department of Orthopaedics, University of Utah, Salt Lake City, UT, United States; Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States.
Department of Orthopaedics, University of Utah, Salt Lake City, UT, United States; Department of Physical Therapy and Athletic Training, University of Utah, Salt Lake City, UT, United States.
Gait Posture. 2021 Jul;88:28-36. doi: 10.1016/j.gaitpost.2021.05.004. Epub 2021 May 8.
Based on Euler/Cardan analysis, prior investigations have reported up to 80° of glenohumeral (GH) external rotation during arm elevation, dependent on the plane of elevation (PoE). However, the subtraction of Euler/Cardan angles does not compute the rotation around the humerus' longitudinal axis (i.e. axial rotation). Clinicians want to understand the true rotation around the humerus' longitudinal axis and rely on laboratories to inform their understanding of underlying shoulder biomechanics, especially for the GH joint since its motion cannot be visually ascertained. True GH axial rotation has not been previously measured in vivo, and its difference from Euler/Cardan (apparent) axial rotation is unknown.
What is the true GH axial rotation during arm elevation and external rotation, and does it vary from apparent axial rotation and by PoE?
Twenty healthy subjects (10 M/10 F, ages 22-66) were recorded using biplane fluoroscopy while performing arm elevation in the coronal, scapular and sagittal planes, and external rotation in 0° and 90° of abduction. Apparent GH axial rotation was computed using the xz'y'' and yx'y'' sequences. True GH axial rotation was computed by integrating the projection of GH angular velocity onto the humerus' longitudinal axis. One-dimensional statistical parametric mapping was utilized to compare apparent versus true axial rotation, axial rotation versus 0°, and detect differences in axial rotation by PoE.
In contrast to apparent axial rotation, true GH axial rotation does not differ by PoE and is not different than 0° during arm elevation at higher elevation angles. The spherical area between the sequence-specific and actual humeral trajectory explains the difference between apparent and true axial rotation.
Proper quantification of axial rotation is important because biomechanics literature informs clinical understanding of shoulder biomechanics. Clinicians care about true axial rotation, which should be reported in future studies of shoulder kinematics.
基于 Euler/Cardan 分析，先前的研究报告称，在手臂抬高过程中，盂肱关节（GH）的外旋角度可达 80°，具体取决于抬高平面（PoE）。然而，Euler/Cardan 角度的相减并不能计算围绕肱骨长轴的旋转（即轴向旋转）。临床医生希望了解围绕肱骨长轴的真实旋转，并依赖实验室来了解其对肩部生物力学的理解，尤其是对于 GH 关节，因为其运动无法通过肉眼确定。GH 关节的真实轴向旋转以前从未在体内进行过测量，其与 Euler/Cardan（表观）轴向旋转的差异尚不清楚。
在手臂抬高和外旋过程中，GH 关节的真实轴向旋转是多少，它与表观轴向旋转和 PoE 有关吗？
对 20 名健康受试者（10 名男性/10 名女性，年龄 22-66 岁）进行双侧荧光透视检查，让他们在冠状面、肩胛骨平面和矢状面进行手臂抬高，在 0°和 90°外展位进行外旋。使用 xz'y'' 和 yx'y'' 序列计算表观 GH 轴向旋转。通过将 GH 角速度在肱骨长轴上的投影进行积分，计算真实 GH 轴向旋转。使用一维统计参数映射比较表观和真实轴向旋转、轴向旋转与 0°，以及检测 PoE 对轴向旋转的差异。
与表观轴向旋转不同，真实 GH 轴向旋转不受 PoE 影响，在较高抬高角度的手臂抬高过程中，与 0°时无差异。序列特异性和实际肱骨轨迹之间的球形区域解释了表观和真实轴向旋转之间的差异。
正确量化轴向旋转很重要，因为生物力学文献为肩部生物力学的临床理解提供了依据。临床医生关心真实的轴向旋转，在未来的肩部运动学研究中应报告真实轴向旋转。
