ABSTRACT
Adams in 1965' and 19662 reported on baseball pitching injuries involving the shoulder and elbow joints in the 9 to 15 year age group and documented the pathological findings resulting from such injuries. Subsequently, these injuries have become known as Little League shoulder and elbow pitching injuries. In 1968 Slocum3 described pathological changes found in elbow joints of young pitchers and correlated with these findings the stress exerted on this joint in pitching a baseball. Tulloss and King' in 1972 further described pathological changes occurring in the shoulder and elbow joints of adolescents as well as professional pitchers and correlated these findings with their excellent description of the pitching cycle. It is the purpose of this report first to confirm the pathological findings previously reported by these authors and to report eight cases, emphasizing those lesions which frequently progress to traumatic arthritis resulting in permanent impairment of normal joint function irrespective of athletic participation, as well as lesions which are completely recoverable, resulting in normal joint function with opportunity for continued pitching.
The population of metropolitan Nashville, Tennessee, is relatively stable; each year there are approximately one thousand 9- to 12-year-old youths participating in Little League and Knot-Hole programs. Also, there are some 500 boys participating in the 12- to I5-year age group in the Junior Babe Ruth and Knot-Hole programs. These programs are well organized and controlled, with regular practices and scheduled games, the entire season extends three months. In the 9-to-12-year age group a player is al-lowed to pitch six innings per week and in the older age group, seven innings. It is from this reservoir of growing athletes, that the following shoulder and elbow pitching injuries were obtained. In pitching a baseball, the goal of every pitch whether by a 9-year-old or a major leaguer, is to produce a rhythmic sequence of forces building up to a maximum velocity at the proper release angle, with as much accuracy or control as possible. The force and torque exerted on the extremity by a single pitch may be tremendous (Fig 1). The cycle of pitching begins by first cocking the arm and shoulder, followed by the delivery or acceleration phase, and finally the follow-through. The cycle begins utilizing the most powerful muscle groups first, progressing ultimately to the least powerful but most coordinate; that is, first the legs, then trunk, then shoulder girdle, arm, forearm, and finally hand. The center of gravity of the body is moved forward by the legs in throwing. In right-handed pitchers, planting of the left leg stops the initial forward movement. The trunk continues forward with an associated rotation. The shoulder then comes into the rhythm of throwing first, cocking the arm in extreme external rotation, abduction and extension. The force then continues into the arm with the elbow in valgus and forcefully thrust from the position of acute flexion into complete extension. Maximum force occurs in the delivery phase.