Quantitative Assessment of Glenohumeral Translation in Baseball Players

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° external rotation to 68° internal rotation, and it was 100° external rotation to 85° 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.