Assessment of posterior shoulder muscle stiffness related to posterior shoulder tightness in college baseball players using shear wave elastography

摘要

During release to follow-through phases of throwing motion in baseball, significant distraction force is generated in the posterior shoulder. It is reported that this force generation causes glenohumeral internal rotation deficit (GIRD) and/or glenohumeral horizontal adduction deficit (GHAD) in their throwing arm of the baseball players. These limi- tations of range of motion (ROM) could be caused by the reduction of soft tissue flexibility in the posterior shoulder region, and have been reported to be at high risk for development of shoulder disorders in baseball players. Recent researches reported that the posterior and posteroinferior capsules were stiffer as well as thicker in the throwing shoulder than the non- throwing shoulder, and that posterior capsule elasticity had a greater effect on GIRD than posterior capsule thickness did. However, there is no report about the relationship between posterior shoulder muscle stiffness and posterior shoulder tightness. In this study, we assessed the posterior shoulder muscle stiffness using quantitative shear wave elastography inthe baseball players with/without posterior shoulder tightness. The pur- pose of this study was to investigate the effect of posterior and inferior shoulder muscles on posterior shoulder tightness. Materials and Background: During release to follow-through phases of throwing motion in baseball, significant distraction force is generated in the posterior shoulder. It is reported that this force generation causes glenohumeral internal rotation deficit (GIRD) and/or glenohumeral horizontal adduction deficit (GHAD) in their throwing arm of the baseball players. These limitations of range of motion (ROM) could be caused by the reduction of soft tissue flexibility in the posterior shoulder region, and have been reported to be at high risk for development of shoulder disorders in baseball players. Recent researches reported that the posterior and posteroinferior capsules were stiffer as well as thicker in the throwing shoulder than the non-throwing shoulder, and that posterior capsule elasticity had a greater effect on GIRD than posterior capsule thickness did. However, there is no report about the relationship between posterior shoulder muscle stiffness and posterior shoulder tightness. In this study, we assessed the posterior shoulder muscle stiffness using quantitative shear wave elastography in the baseball players with/without posterior shoulder tightness. The purpose of this study was to investigate the effect of posterior and inferior shoulder muscles on posterior shoulder tightness.