McQuade K J, Smidt G L
Graduate School of Health Science, New York Medical College, Valhalla 10595, USA.
J Orthop Sports Phys Ther. 1998 Feb;27(2):125-33. doi: 10.2519/jospt.1998.27.2.125.
The purpose of this study was to characterize the scapulohumeral rhythm in the normal shoulder during dynamic elevation of the arm in the scapular plane and to compare the scapulohumeral rhythm during three different states of loading: 1) arm completely unloaded and passively elevated, 2) light load consisting of active elevation against the weight of the limb, and 3) heavy loading against maximal resistance. Electromagnetic tracking was used to record three-dimensional scapular and humeral kinematics on 25 normal subjects. Cardan angles were calculated to assess the dynamic relationship of humeral elevation to scapular upward rotation. The results show that during dynamic humeral elevation the scapulohumeral rhythm changes depending on the phase of elevation and the external load on the arm. During passive range of motion, the scapulohumeral rhythm decreased from 7.9:1 to 2.1:1 as the arm was elevated. Light shoulder loads caused an increase of the scapulohumeral rhythm from 3.1:1 to 4.3:1 as the arm was elevated. Heavy shoulder loading resulted in an increasing scapulohumeral rhythm from 1.9:1 to 4.5:1 as the arm was elevated. The results suggest that the historical assumption of a simple linear 2:1 scapulohumeral rhythm ratio may be overly simplistic and may not accurately describe the scapulohumeral rhythm under varying dynamic conditions. Therapists need to understand the normal changing relationships of the scapulohumeral rhythm under different conditions for accurate interpretation of clinical observations.
本研究的目的是描述在肩胛平面内手臂动态抬高过程中正常肩部的肩肱节律，并比较三种不同负荷状态下的肩肱节律：1）手臂完全无负荷且被动抬高；2）轻负荷，即对抗肢体重量进行主动抬高；3）对抗最大阻力的重负荷。采用电磁跟踪技术记录了25名正常受试者的肩胛骨和肱骨的三维运动学数据。计算欧拉角以评估肱骨抬高与肩胛骨向上旋转的动态关系。结果表明，在肱骨动态抬高过程中，肩肱节律会根据抬高阶段和手臂上的外部负荷而变化。在被动活动范围内，随着手臂抬高，肩肱节律从7.9:1降至2.1:1。轻负荷肩部状态下，随着手臂抬高，肩肱节律从3.1:1增加到4.3:1。重负荷肩部状态下，随着手臂抬高，肩肱节律从1.9:1增加到4.5:1。结果表明，历史上关于简单线性2:1肩肱节律比的假设可能过于简单，可能无法准确描述不同动态条件下的肩肱节律。治疗师需要了解不同条件下肩肱节律的正常变化关系，以便准确解读临床观察结果。
