The Association between Excessive Glenohumeral External Rotation and Risk for Shoulder and Elbow Injury in Left-Handed High School Baseball Pitchers: A Prospective Cohort Study.

BACKGROUND

Left-handed baseball pitchers exhibit unique throwing biomechanics, yet the risk factors for shoulder and elbow injuries in this population remain unclear.

PURPOSE: To prospectively investigate preseason risk factors for shoulder and elbow injuries in left-handed high school baseball pitchers.

STUDY

DESIGN

Cohort study; Level of evidence, 2.

METHODS

A total of 160 left-handed high school baseball pitchers were enrolled. Preseason evaluations included age, height, weight, shoulder muscle strength, and range of motion of the shoulder and elbow. Participants completed a self-recorded questionnaire on shoulder and elbow pain and associated pitching limitations during the subsequent season. Participants were categorized into the noninjured or injured group. The Mann-Whitney U test, chi-square test, logistic regression analysis, and receiver operating characteristic curve analysis were used to identify injury risk factors and cutoff values for shoulder and elbow injuries.

RESULTS

Shoulder and elbow injuries occurred in 27 participants (16.9%). The injured group had significantly greater abduction-external rotation (ABER) in the dominant shoulder (114.8°± 11.9° vs 107.5°± 13.0°; P = .008) and a greater total arc of the dominant shoulder (166.4°± 25.1° vs 156.0°± 23.4°; P = .039). Logistic regression analysis showed that ABER in the dominant shoulder was an independent risk factor for injuries (P = .031; OR, 1.04). Receiver operating characteristic curve analysis determined that an ABER ≥109° predicted injury (P = .017). Pitchers with ABER ≥109° had a 3.3 times higher incidence of injury than those with ABER <109° (P = .005).

CONCLUSION

Increased shoulder ABER was significantly associated with shoulder and elbow injuries among left-handed high school baseball pitchers. Pitchers with ABER ≥109° are at higher risk.