A Comparison of Glenoid Morphology and Glenohumeral Range of Motion Between Professional Baseball Pitchers With and Without a History of SLAP Repair

Purpose: We sought to examine the relation among glenoid morphology, glenohumeral range of motion (ROM), and history of shoulder injury in professional baseball pitchers. Methods: We studied 58 professional baseball pitchers. Internal rotation (IR) and external rotation (ER) ROM was measured at 90 degrees of abduction. Horizontal adduction (HAdd) ROM was also measured. Glenoid superior inclination and glenoid retroversion (GRV) were then measured radiographically. Separate mixed-model analyses of variance were used to compare dependent measures between the dominant and nondominant shoulders of pitchers with or without a history of SLAP repair. Significant interaction effects were interpreted by use of a test for simple main effects (alpha = .05). Results: GRV was significantly greater on the dominant side (8.7 degrees +/- 5.6 degrees) versus nondominant side (5.5 degrees +/- 5.2 degrees) (P = .001), whereas glenoid superior inclination was equivalent (99.5 degrees +/- 4.3 degrees for dominant side v 99.2 degrees +/- 4.4 degrees for nondominant side, P = .853). Post hoc analysis indicated that pitchers with a history of SLAP repair did not display an adaptive increase in dominant GRV compared with nondominant GRV (P = .016). There were no statistical differences between groups for ER (P = .29), IR (P = .39), or HAdd (P = .39). The dominant shoulder displayed greater ER (mean increase, 6.2 degrees +/- 12.2 degrees) with a complementary decrease in IR (mean decrease, 5.8 degrees +/- 13.2 degrees) and HAdd (mean decrease, 8.9 degrees +/- 13.7 degrees) compared with the nondominant side. Conclusions: Our findings suggest that the development of increased GRV in the dominant shoulder of professional baseball pitchers may be a protective adaptive change not reflected in glenohumeral ROM measures. Level of Evidence: Level IV, therapeutic case series.