Frantz T, Ramkumar PN, Frangiamore S, et al. - The epidemiology of AC joint injuries were analyzed in Major League Baseball (MLB) and Minor League Baseball (MiLB) players and ascertained the effect on time missed. Researchers applied MLB Health and Injury Tracking System to compile records of all MLB and MiLB players from 2011 to 2017 with documented acromioclavicular (AC) joint injuries. They categorized these injuries as acute (sprain or separation) or chronic (AC joint arthritis or distal clavicular osteolysis), and correlated data extracted included laterality, date of injury, player position, activity, mechanism of injury, length of the return to play, and need for surgical intervention. They reported a sum of 312 AC joint injuries (183 in MiLB players and 129 in MLB players; range, 39-60 per year). The results of this study indicated that whereas chronic AC joint injuries occur more commonly in pitchers and catchers from noncontact repetitive overhead activity, acute AC joint injuries are contact injuries occurring most commonly among infielders and outfielders while fielding that results in 3 weeks missed before return to play. The understanding of these findings can better assist expectation management in this elite population to better elucidate the prevalence of 2 common injury patterns in the AC joint.