Little League Shoulder (Growth Plate Stress Injury)

The physis (growth plate) is a layer of cartilage near the end of bone whose cells multiply and turn into bone to lengthen the bone during growth. Most growth plates close (fuse or disappear) in girls between the ages of 14 to 16, and by age 16 to 18 in boys (although some growth plates close as late as age 25).

The growth plate is the weak link in the growing athlete during different stages of growth and is more susceptible to injury than bone, muscle, or ligaments. Little League Shoulder is characterized by stress injury to the physis (growth plate) of the proximal humerus (upper arm bone). Repetitive forces from throwing or other overhead activities like swimming, volleyball serving, and racquet sports are the most common cause.