Asymptomatic Medial Elbow Ultrasound Abnormality in Youth Baseball Players Is an Independent Risk Factor for Elbow Injury: A Prospective Cohort Study

BACKGROUND: Youth baseball players who experience elbow pain during the season frequently exhibit radiographic elbow abnormalities. However, it is unknown whether asymptomatic elbow abnormalities are risk factors for in-season elbow injuries. PURPOSE: To determine whether the preseason presence of asymptomatic medial epicondyle apophysitis is a risk factor for in-season elbow injuries in youth baseball players. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Youth baseball players (N = 210; age range, 7-12 years) with no pain or history of injury in their throwing arms underwent preseason evaluations that included shoulder and elbow range of motion measurements, shoulder muscle strength testing, and ultrasound elbow scans with a multifrequency 13-MHz linear array transducer. Over 1 year of play, the players and their parents maintained daily elbow pain diaries. Elbow injuries were defined as medial elbow symptoms that prevented ball throwing for ≥8 days. RESULTS: The preseason ultrasound evaluation revealed medial epicondyle apophysitis in 59 players. In the year following, elbow injuries occurred in 17 (28.8%) players with preseason medial epicondyle apophysitis and 18 (11.9%) players without apophysitis. Independent predictors of elbow injuries were preseason medial epicondyle apophysitis (odds ratio [OR], 2.488; 95% confidence interval [CI], 1.152-5.376; P = .02) and deficits of abduction (ABD) and external rotation of the dominant shoulder (OR, 0.963; 95% CI, 0.936-0.992; P = .012). CONCLUSION: Asymptomatic medial epicondyle apophysitis and ABD and external rotation deficits in the dominant shoulder were risk factors for elbow injuries in 7- to 12-year-old youth baseball players. These findings may aid in the design of programs to prevent elbow injuries in this population.