Differences in humeral retroversion in dominant and nondominant sides of young baseball players

Our findings indicated that humeral retroversion decreased with age in the nonthrowing side but not in the throwing side and that the side-to-side difference of humeral retroversion in the baseball players became obvious from the fourth grade. We assume that the repetitive throwing motion restricts the physiologic humeral derotation process and the difference became apparent from the fourth grade when the growth spurt begins in boys.