Shoulder Range of Motion Measures as Risk Factors for Shoulder and Elbow Injuries in High School Softball and Baseball Players

Background: Range of motion deficits in shoulder external rotation (ER), internal rotation (IR), total rotation range of motion (ER + IR), and horizontal adduction (HA) have been retrospectively associated with overhand athletes' arm injuries. Hypothesis: The authors expected the incidence of upper extremity injury in high school softball and baseball players with side-to-side shoulder range of motion deficits to be greater than the incidence of upper extremity injury in players with normal shoulder range of motion. Study Design: Cohort study (prognosis); Level of evidence, 2. Methods: High school softball and baseball players (N = 246) participated. Before the start of the season, passive shoulder ER, IR, and HA were assessed at 90 degrees of abduction with the scapula stabilized. Relative risk (RR) was calculated to examine range of motion measure, by categorical criteria, and risk of upper extremity injury. Results: Twenty-seven shoulder and elbow injuries (9 softball, 18 baseball) were observed during the season. The dominant shoulder of all injured players and baseball players displayed a significant decrease in HA (P = .05) and IR (P = .04). The dominant shoulder total rotation of injured baseball players displayed a significant decrease (mean difference = 8.0 degrees +/- 0.1 degrees; P = .05) as compared with the dominant shoulder of uninjured baseball players. Players who displayed a decrease of >= 25 degrees of IR in the dominant shoulder were at 4 times greater risk of upper extremity injury compared with players with a < 25 degrees decrease in IR, especially for baseball players. While we observed a 1.5 to 2 times increased risk of injury for the 10 degrees to 20 degrees loss in rotational range of motion for the overall sample and baseball, the risk estimates were not statistically significant (P > .05). Conclusion: There are large mean deficits in shoulder IR and HA between injured and noninjured players, but not in ER or total rotation. Passive shoulder IR loss >= 25 degrees as compared bilaterally was predictive of arm injury. Shoulder range of motion deficits differed between sports and appeared more predictive of injury for baseball players.