Ultrasonography has high positive predictive value for medial epicondyle lesions among adolescent baseball players.

<bold>Purpose: </bold>Only few studies have investigated medial epicondyle (MEC) lesions, particularly in the 12-18 age group. To the best of our knowledge, no study has compared ultrasonography (US), radiography and magnetic resonance imaging (MRI) in detecting MEC lesions. The aims of this study were to examine the value of US for detecting MEC lesions and to investigate correlations among diagnostic tools.<bold>Methods: </bold>A prospective, comparative study was performed. Young baseball players from southern Taiwan were recruited, and basic characteristics, as well as passive range of motion (pROM) of the upper extremities, were recorded. Screening US was performed to identify MEC lesions, and players with MEC lesions received follow-up plain radiography and MRI.<bold>Results: </bold>A total of 299 young baseball players were screened using US, and 28 of 299 players with possible MEC lesions were identified with a positive predictive value (PPV) of 88% according to MRI findings. The MEC lesions were primarily comprised of unfused ossicles and bony fragmentation. Other diagnoses, including UCL strain and medial epicondylitis, were also found by MRI in players with abnormal US screening results. The pROM of shoulder external rotation (ER) of the throwing hand was significantly reduced in players with MEC lesions (p = 0.006).<bold>Conclusions: </bold>Bony cortical discontinuity or fragmentation over the MEC warrants further research, and US provides good PPV for types of MEC lesions. Decreased shoulder ER may relate to MEC lesions and should be taken into consideration. The use of US may facilitate early detection and intervention.<bold>Level Of Evidence: </bold>IV, Cross-sectional study. [ABSTRACT FROM AUTHOR]