Investigation of site and frequency of asymptomatic injury in medial structures of the elbow in adolescent baseball players using dedicated magnetic resonance imaging

Abstract

Medial epicondyle (ME) and elbow joint proximal (UCL-p) and distal ulnar collateral ligament (UCL-d) asymptomatic injuries are frequently observed using magnetic resonance imaging (MRI). However, the injury rates vary among these structures in elbow screening of adolescent baseball players, despite being adjacent medial structures of the elbow. This study aimed to retrospectively determine the actual injury site and rate, and investigate the underlying reason for discrepancies anatomically and biomechanically. Forty-four male adolescent baseball players were scanned using MRI. Two interpreters independently and retrospectively assessed the ME, UCL-p, and UCL-d injuries using the gradient echo axial, sagittal, and coronal planes. The injury prevalence was significantly higher in the ME and UCL-p (> 50% of the participants) than in the UCL-d (22.7%), P < 0.01 and P < 0.01, respectively. Additionally, there was a tendency toward a high-frequency injury rate of the ME or UCL-p. The injury site of the medial structures tended to be proximal. The ME and UCL-p were observed to be more frequently injured compared to the UCL-d in adolescent baseball players according to the dedicated MRI findings in this study.