Background:

Thoracic outlet syndrome is more common in overhead athletes. The anterior and middle scalene muscles have been associated with thoracic outlet syndrome; however, the relationship between the elastic moduli of the scalene muscles and the overhead-throwing position has not been evaluated.

Purpose:

To investigate the elastic moduli of the anterior and middle scalene muscles in simulated throwing positions using shear wave elastography.

Study Design:

Descriptive laboratory study.

Methods:

We enrolled collegiate baseball players who underwent preseason medical checkups in January and February 2020. The anterior and middle scalene muscles were visualized in the short-axis view using ultrasound. In this view, the elastic moduli of the anterior and middle scalene muscles were measured using shear wave elastography in the following arm and neck positions: (1) adduction and neutral rotation of the shoulder (neutral), (2) 90° of abduction and external rotation of the shoulder (ABER), and (3) ABER with neck rotation toward the nonthrowing side (ABER+NR). Repeated-measures analysis of variance and a paired t test were used to compare the elastic modulus values among the 3 positions and between the 2 muscles, respectively.

Results:

Overall, 30 baseball players were included. In both scalene muscles, the elastic moduli were significantly greater in the ABER versus neutral position (anterior scalene: 14.4 ± 3.8 vs 9.4 ± 2.0 kPa, respectively [P < .001]; middle scalene: 15.8 ± 5.0 vs 10.9 ± 3.4 kPa, respectively [P < .001]). In the neutral position, the elastic modulus was significantly greater in the middle scalene than the anterior scalene (10.9 ± 3.4 vs 9.4 ± 2.0 kPa, respectively; P = .03). In the ABER+NR position, the elastic modulus was significantly greater in the anterior scalene than the middle scalene (18.1 ± 4.6 vs 15.8 ± 2.6 kPa, respectively; P = .03).

Conclusion:

Because the ABER position was a simulation of the throwing position, these results indicate that this position could be associated with high elastic moduli of the scalene muscles, and both the anterior and middle scalene muscles may be involved.

中文翻译：

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大学棒球投手斜角肌的弹性使用剪切波弹性成像

背景：

胸廓出口综合征在头顶运动员中更为常见。前斜角肌和中斜角肌与胸廓出口综合征有关；然而，尚未评估斜角肌的弹性模量与头顶投掷姿势之间的关系。

目的：

使用剪切波弹性成像研究模拟投掷姿势中前斜角肌和中斜角肌的弹性模量。

学习规划：

描述性实验室研究。

方法：

我们招募了在 2020 年 1 月和 2020 年 2 月接受季前体检的大学棒球运动员。使用超声波在短轴视图中可视化了前斜角肌和中斜角肌。在这个视图中，前斜角肌和中斜角肌的弹性模量是在以下手臂和颈部位置使用剪切波弹性成像测量的：（1）肩部的内收和中性旋转（中性），（2）外展 90° 和肩部外旋 (ABER)，和 (3) ABER 颈部向非投掷侧旋转 (ABER+NR)。重复测量方差分析和配对t检验分别用于比较 3 个位置和 2 个肌肉之间的弹性模量值。

结果：

总共包括30名棒球运动员。在两种斜角肌中，ABER 与中立位的弹性模量显着更大（前斜角肌：分别为 14.4 ± 3.8 对 9.4 ± 2.0 kPa [ P < .001]；中斜角肌：15.8 ± 5.0 对 10.9 ± 3.4 kPa，分别[ P < .001]）。在中立位，中斜角肌的弹性模量显着大于前斜角肌（分别为 10.9 ± 3.4 vs 9.4 ± 2.0 kPa；P = .03）。在 ABER+NR 位置，前斜角肌的弹性模量显着大于中斜角肌（分别为 18.1 ± 4.6 和 15.8 ± 2.6 kPa；P = .03）。

结论：

由于 ABER 姿势是投掷姿势的模拟，这些结果表明该姿势可能与斜角肌的高弹性模量有关，并且可能涉及前斜角肌和中斜角肌。