Abstract
[Purpose] To compare 2nd rotational range of motion excluding the humeral retroversion angle of symptomatic and asymptomatic baseball pitchers. [Subjects] The subjects were 69 pitchers: 38 in the symptomatic group and 31 in the asymptomatic group. [Methods] The retroversion angle of the humeral head and the actual rotational range of motion of the shoulder joint were measured using ultrasonography. They were compared between the two groups. [Results] There were no significant differences between the two groups in the retroversion angle of the humeral head or the actual rotational angle of the non-pitching side. However, on the pitching side of the symptomatic group, the actual range of external rotation was significantly greater, and the actual range of internal rotation was significantly less than those of the asymptomatic group. [Conclusion] The changes in 2nd rotational range of motion of the symptomatic baseball pitchers were caused by soft tissue factor(s) rather than humeral retroversion.
