Normal imaging laterality on magnetic resonance imaging of the medial epicondyle of the elbow on the dominant side of adolescent male baseball players.

Abstract

Multimodality elbow screening of adolescent baseball players shows apparent laterality in morphology and signal intensity of the medial epicondyle on dedicated magnetic resonance imaging. We aimed to elucidate actual imaging laterality in the medial epicondyle by comparing magnetic resonance images of the dominant and contradominant elbows and to clarify the clinical meaning and mechanism of this phenomenon. We used a 0.2-T dedicated magnetic resonance imaging scanner. Eighty adolescent baseball players were enrolled and divided into four age groups: 9-10years (13 patients); 11years (28 patients); 12years (24 patients) and 13-14years (15 patients). The long and short axes of the ossification center and distance of the epiphyseal plate and the cartilage of the lower pole of the medial epicondyle were measured. Signal intensity of the ossification center was visually evaluated. Owing to their age, ossification and cartilage size on the dominant side were significantly larger in all boys (P < 0.01). All age groups had larger ossification and cartilage in the dominant elbow (P < 0.01). Ossification showed an apparent lower signal intensity on the dominant side (P < 0.01). Larger ossification and cartilage size of the medial epicondyle in the dominant elbow suggested that the medial collateral ligament to the medial epicondyle induces excessive repetitive tensile stress, but without clinical symptoms. Functional or microanatomical damage of the medial epicondyle may induce a lower ossification signal in the dominant elbow, thereby decreasing fatty bone marrow and inducing sclerotic changes.