RESUMO
The purpose of this study is to evaluate the characteristics of posterior glenoid lesion (PGL) on magnetic resonance imaging (MRI) in adolescent baseball players. Seventy-two adolescent baseball players (mean age, 15.1 years) who underwent MRI scan for dominant shoulder pain were enrolled and the location and morphologic features of PGLs were assessed on MRI. All players were divided into three groups based on the physeal status of proximal humerus: group I, open; group II, partial closure; and group III, complete closure. Of the 72 players, posterior glenoid rim rounding (69%) and periosteal thickening (88%) were the main PGL on axial imaging. Osteochondritis dissecans (OCD) of glenoid (10%), Bennett lesion (6%), and posterior labral tear (21%) were also identified. On oblique sagittal imaging, bony PGL including OCD involves mid-portion of posterior glenoid consistent with the level of the infraspinatus muscle, but Bennett lesion was located relatively lower than PGL. Posterior glenoid rim rounding was more prevalent in younger players (group I, 86%; group II, 78%; group III, 43%; p=0.015), and posterior labral tears were in older players (group I, 0%; group II, 19%; group III, 38%, p=0.027). Factors related with prevalence of posterior glenoid rim rounding were increased body mass index (p=0.016), pitchers (p=0.024), and players with posterior shoulder tightness (p=0.023), but career length was not statistically significant (p=0.089). Decreasing the rate of posterior glenoid rim rounding with skeletal growth implies that it may be recovered through the remodeling process, and labral tears are increasing internal impingement lesion after physeal closure.