Little Leaguer’s Shoulder is also called Proximal Humeral Epiphysitis.  It is a childhood and adolescent condition in which the growth plate located at the upper end of the humerus next to the shoulder joint is repeatedly overloaded – usually by throwing in baseball, as well as in tennis players, or participants in other throwing sports. 

Pain in, or just below the shoulder, is the most common symptom and should be treated with rest, and later with reduced pitch count so that the injury does not result in more serious compromise of the growth plate that could lead to permanent bony deformity.