Quantitative assessment of glenohumeral translation in baseball players: a comparison of pitchers versus nonpitching athletes

Abstract

Background: Objective data quantifying differences in glenohumeral range of motion in baseball pitchers versus position players are established. There is limited information objectively comparing glenohumeral laxity in this same population.

Hypothesis: Baseball pitchers have greater difference in side-to-side anteroposterior translation of their throwing shoulders compared with position players.

Study design: Prospective cross-sectional study.

Methods: Cutaneous electromagnetic sensors quantified anteroposterior shoulder translation of college and professional baseball players. Range of motion was measured.

Results: Nineteen position players and 37 pitchers were studied. Pitchers had a significant increase in external rotation of the dominant arm as compared with the nondominant arm (P = .02); the difference was not significant in position players (P = .34). The mean range of motion for pitchers' dominant arm was 110 degrees external rotation to 68 degrees internal rotation, and it was 100 degrees external rotation to 85 degrees internal rotation for position players (P = .278). The mean anteroposterior translation in pitchers' dominant arm was 33.30 mm and 29.84 mm in the nondominant side (P = .0001). This difference was not present in position players (P = .88). One of 19 position players had a side-to-side shoulder translation difference greater than 3 mm, compared with 22 of 37 pitchers (P = .0001).

Conclusions: Pitchers have a greater amount of glenohumeral translation in the dominant arm. This difference is not seen in position players. These differences make the side-to-side comparison less useful in pitchers and should be considered when making therapeutic decisions.