MR imaging of shoulder injuries in professional baseball players.

Magnetic resonance (MR) imaging was used to evaluate the shoulders of 10 symptomatic professional baseball players and one asymptomatic player, with surgical correlation in six cases and arthrographic correlation in two cases. Seven small rotator cuff tears measuring 0.5-1 cm were identified on MR images, with arthrographic and surgical confirmation of these findings in two patients and surgical confirmation only in three patients. Cortical irregularity and/or subchondral cyst formation at the posterior aspect of the greater tuberosity near the insertion site of the infraspinatus tendon was found in five of the seven players with rotator cuff tears. Similar findings were noted in the asymptomatic volunteer and in one of the three players without cuff tear, who also had irregular thickening of the posterior capsule. These findings are believed to represent chronic avulsive changes resulting from the deceleration stresses of the follow-through motion.