One-third of asymptomatic youth baseball players exhibit ulnar collateral ligament sub-apophyseal avulsions

Ulnar collateral ligament sub-apophyseal avulsions are increasingly prevalent among youth baseball players, yet knowledge regarding avulsive changes in asymptomatic athletes is sparse. Ultrasound offers a minimal-risk method of assessing potential damage from repetitive valgus stress encountered during the throwing motion. The purpose of this study was to evaluate asymptomatic elbows in youth baseball players for evidence of sub-apophyseal avulsive changes and to compare sports participation characteristics, patient-reported outcomes, humeral retrotorsion angles, and elbow pain with palpation between those with and without changes. Baseball players aged <19 years were recruited at local tournaments and practices for ultrasonographic examination using a 4-20 MHz high-frequency linear transducer. The examination included the medial epicondyle and radiocapitellum as well as humeral retrotorsion. Demographics, sport participation, and perceived function were assessed via electronic surveys. Nonparametric testing and &#x3c7;analysis compared measures between those with and without avulsive changes (95% confidence interval). Sixty-five male athletes (129 elbows; 12.5 &#xb1; 1.7 years) were evaluated. Avulsive changes were observed in 23 of 64 (35.9%) dominant elbows (10 avulsions and 13 united avulsions). One dominant elbow displayed subchondral plate flattening within the radiocapitellar joint. No avulsive changes were seen in nondominant elbows, and no differences in avulsion status were identified based on athlete characteristics, self-reported function, or pain with elbow palpation. One-third of asymptomatic youth baseball players may have avulsive changes at the ulnar collateral ligament subapophysis irrespective of function or pain scores.