Abstract

Context: Repetitive overhead throwing has been theorized to result in chronic adaptations to the capsuloligamentous restraints of the glenohumeral joint.
Objective: To compare glenohumeral joint laxity and stiffness between the throwing and nonthrowing shoulders of high school baseball pitchers. Design: Repeated measures. Setting: High school athletic training facilities. Patients or Other Participants: Twenty-two asymptomatic high school baseball pitchers (age = 16.50 ± 0.74 years, height = 178.51 ± 7.66 cm, mass = 75.43 ± 13.24 kg) from a sample of convenience. Main Outcomes Measure(s): We used computerized stress arthrometry to measure glenohumeral joint laxity and stiffness. Anterior glenohumeral joint laxity and stiffness measures were obtained with the shoulder in 90° of abduction and both neutral rotation and 90° of external rotation. Posterior laxity and stiffness measures were obtained with the shoulder in 90° of abduction and neutral rotation. Results: No clinically significant differences were found for glenohumeral laxity or stiffness between sides. However, a statistically significant main effect for position was present for both laxity and stiffness. Anterior glenohumeral joint laxity in the 90° external rotation position was significantly decreased and stiffness was increased in this position compared with the anterior at neutral and posterior at neutral positions. Conclusions: Glenohumeral joint laxity decreases and stiffness increases in the functional throwing position of 90° of abduction and 90° of external rotation. No clinically significant side-to-side differences or directional differences were found in high school baseball pitchers. Verf.-Referat