Radial Shaft Stress Fracture in a Major League Pitcher.

Upper extremity injuries are associated with significant morbidity in throwing athletes, and prevention and diagnosis of overuse injuries in these athletes are increasingly being emphasized. Although stress fractures are common overuse injuries, stress fractures of the upper extremity are relatively rare. To our knowledge, a stress fracture of the radial shaft has not been reported in a throwing athlete. In this article, we describe the case of a Major League Baseball pitcher who presented with a stress fracture of the lateral cortex of the radius, likely caused by contractile forces of the supinator muscle, arising after his attempt to develop a new pitch.