Department of Physical Therapy, Akita University Graduate School of Health Sciences, Akita, Japan.
Johto Orthopaedic Clinic, Akita, Japan.
J Shoulder Elbow Surg. 2018 Sep;27(9):1642-1649. doi: 10.1016/j.jse.2018.05.021. Epub 2018 Jun 22.
Although the pronator teres muscle, a major dynamic stabilizer of elbow valgus stress during throwing, frequently presents stiffness, its relationship with elbow injuries in youth baseball players is unknown. This study investigated the relationship between the elasticity of the pronator teres muscle and elbow injuries in youth baseball players.
The strain ratio (SR) of 15 individuals with osteochondritis dissecans of the humeral capitellum (OCD group), 67 individuals with medial epicondylar fragmentation (medial injury group), and 115 healthy individuals (control group) was measured as the index of the elasticity of the pronator teres muscle using ultrasound strain elastography. In addition, the forearm and glenohumeral joint rotation range of motion was measured.
The SR of the throwing arm was significantly higher in the OCD and medial injury groups than in the control group (both P <.001). In the OCD group, the SR was significantly higher in the throwing arm than in the nonthrowing arm (P <.001), whereas in the medial injury group, there was no significant difference between both arms. The glenohumeral joint external rotation range of motion of the throwing arm was moderately negatively correlated with the SR (r = -0.478, P <.001).
Stiffness of the pronator teres muscle was exhibited only in the throwing arm of individuals with OCD and in both arms in individuals with medial elbow injury. These findings may contribute to an accurate evaluation and prevention of elbow injuries in youth baseball players.
尽管旋前圆肌是投掷时肘内翻应力的主要动力稳定肌，但它经常出现僵硬，但其与青年棒球运动员肘部损伤的关系尚不清楚。本研究调查了旋前圆肌弹性与青年棒球运动员肘部损伤的关系。
使用超声应变成像术测量 15 例肱骨小头骺软骨骨软骨病（OCD 组）、67 例内侧附丽末端骨折（内侧损伤组）和 115 例健康个体（对照组）的旋前圆肌弹性的应变比（SR）作为指标。此外，还测量了前臂和盂肱关节旋转活动范围。
OCD 组和内侧损伤组的投掷臂 SR 明显高于对照组（均 P<.001）。在 OCD 组中，投掷臂的 SR 明显高于非投掷臂（P<.001），而在内侧损伤组中，两臂之间没有明显差异。投掷臂的盂肱关节外旋活动范围与 SR 呈中度负相关（r=-0.478，P<.001）。
只有在 OCD 患者的投掷臂和内侧肘损伤患者的双臂中才会出现旋前圆肌僵硬。这些发现可能有助于对青年棒球运动员肘部损伤进行准确评估和预防。
