Bone and Joint Center, Dept. of Orthopaedic Surgery, Henry Ford Health, Detroit, MI, USA; Program in Physical Therapy, Washington University School of Medicine in St. Louis, St. Louis, MO, USA.
Bone and Joint Center, Dept. of Orthopaedic Surgery, Henry Ford Health, Detroit, MI, USA.
J Biomech. 2022 Dec;145:111385. doi: 10.1016/j.jbiomech.2022.111385. Epub 2022 Nov 14.
Several scapular anatomical coordinate systems have been reported in the literature to describe shoulder kinematics. Unfortunately, the use of different conventions hinders comparison across studies. Further, inconsistencies between a coordinate system and the scapula's 3D axis of motion means that scapular motion will be incorrectly attributed to axes about which it did not rotate. The objectives of this study were to: 1) determine the extent to which the axes of four common scapular coordinate system conventions correspond to the 3D axis of scapular motion (i.e., instantaneous helical axis, IHA), and 2) report the prevalence of scapulothoracic gimbal lock for each convention. Shoulder kinematics were tracked during scapular plane abduction in 45 participants using biplane videoradiography. Scapulothoracic kinematics were described using the original convention proposed by van der Helm, the convention recommended by the International Society of Biomechanics (ISB), a glenoid-based coordinate system, and a glenoid-oriented coordinate system. The 3D angle was calculated between the IHA and each axis of the four conventions (IHA-axis angular deviations). A repeated measures ANOVA was used to compare IHA-axis angular deviations between conventions. The glenoid-oriented and ISB conventions resulted in the smallest and largest IHA-axis angular deviations, respectively (21.7°±3.6° vs. 30.5°±5.2°, p < 0.01). Gimbal lock was approached in 17.8% of participants when using the original convention, 2.2% when using the ISB convention, and 0% when using the glenoid-based or -oriented conventions. These findings suggest the glenoid-oriented coordinate system may be worthy of further consideration when investigating shoulder kinematics during scapular plane abduction.
几种肩胛骨解剖坐标系已在文献中报道，用于描述肩部运动学。不幸的是，不同约定的使用阻碍了研究之间的比较。此外，坐标系与肩胛骨三维运动轴之间的不一致意味着肩胛骨运动将错误地归因于它没有旋转的轴。本研究的目的是：1）确定四个常见肩胛骨坐标系约定的轴与肩胛骨运动的三维轴（即瞬时螺旋轴，IHA）之间的对应程度，以及 2）报告每个约定的肩胛骨胸锁关节万向节锁定的发生率。在 45 名参与者的肩胛骨平面外展过程中，使用双平面 X 射线摄影术跟踪肩部运动学。肩胛骨胸锁关节运动学使用 van der Helm 提出的原始约定、国际生物力学学会（ISB）推荐的约定、基于关节盂的坐标系和关节盂定向坐标系来描述。计算了 IHA 与四个约定的每个轴之间的三维角度（IHA 轴角度偏差）。使用重复测量方差分析比较了约定之间的 IHA 轴角度偏差。关节盂定向和 ISB 约定分别导致最小和最大的 IHA 轴角度偏差（21.7°±3.6°对 30.5°±5.2°，p<0.01）。当使用原始约定时，17.8%的参与者接近万向节锁定，当使用 ISB 约定时为 2.2%，当使用基于关节盂或关节盂定向的约定时为 0%。这些发现表明，在研究肩胛骨平面外展期间的肩部运动学时，关节盂定向坐标系可能值得进一步考虑。
