Effect of Morphologic Changes in the Posterior Glenoid Rim on Rotator Cuff Impingement in Baseball Players

Abstract

Abstract Background: The larger area of rotator cuff tendons pinched within the glenohumeral joint may lead to rotator cuff injury with an internal impingement in the late cocking phase. However, a few other previous studies have examined the relationship between the area of impingement (AOI) of the rotator cuff tendon and morphologic changes, such as the slanting appearance in the posterior glenoid rim. Therefore, this study aimed to clarify whether morphologic changes in the posterior glenoid rim is associated with the AOI in college baseball players. Methods: Fifteen asymptomatic male college baseball players (15 throwing and 15 non-throwing shoulders) participated in this study. The AOI and posterior glenohumeral distance (PGHD) were measured using magnetic resonance imaging (MRI) to quantitatively assess the impingement area of the rotator cuff tendon within the glenohumeral joint and the morphologic change in the posterior glenoid rim. These MRI assessments were measured at 90° shoulder abduction with an external rotation of 110°. Simple regression analysis was performed to identify the predictors of the AOI among the PGHD. Results: The results of the simple regression analysis showed that the PGHD was a predictor of the AOI (β-coefficient=0.613, R2=0.38, and p=.015). Conclusions: This study found that AOI was associated with PGHD. Therefore, these findings may support that complex shoulder joint morphologic changes result in a disabled throwing shoulder.