A comparison of glenoid morphology and glenohumeral range of motion between professional baseball pitchers with and without a history of SLAP repair

Abstract

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° 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 (α = .05).

Results: GRV was significantly greater on the dominant side (8.7° ± 5.6°) versus nondominant side (5.5° ± 5.2°) (P = .001), whereas glenoid superior inclination was equivalent (99.5° ± 4.3° for dominant side v 99.2° ± 4.4° 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° ± 12.2°) with a complementary decrease in IR (mean decrease, 5.8° ± 13.2°) and HAdd (mean decrease, 8.9° ± 13.7°) 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.