High-definition magnetic resonance images on medial elbow injuries in preadolescent Little Leaguers.

Background: The incidence of throwing-related elbow injuries is still rising. The study aimed to enhance the pathology of acute medial elbow injuries among young Little Leaguers by examining the medial elbows of symptomatic 9-10 years old Little Leaguers using High-Definition Magnetic Resonance Images (HDMRI), which uses a small-diameter surface coil on the target area, leading to greater image resolution.
Method: We identified Little Leaguers aged 9-10 years old. To minimize the detection of the chronic adaptative changes, players who experienced the medial elbow pain previously and whose HDMRI had not been taken within 4 weeks from the onset of medial elbow pain were excluded. This study considered 21 players, and the mean age was 9.4 ± 0.5 years.
Result: The fragmentation of the medial epicondyle apophysis via HDMRI was found in 15 elbows (71.4%), while the avulsion was seen in three cases. The signal hyperintensity at the medial epicondyle apophysis was observed in 2 cases. Our data showed abnormal changes to the medial epicondyle apophysis and surrounding structures, such as the ulnar collateral ligament (UCL), flexor-pronator tendons or the coronoid process of the ulna. We detected 11 abnormalities on X-ray imaging, while 20 subjects showed some abnormal findings via HDMRI.
Discussion: The current study showed that initial medial elbow injury in Little Leaguers without a history of previous elbow injury could be attributed to multi-structure injury. Over 90% of subjects were injured in the perichondrium, while 71.4% demonstrated a fragmentation of the secondary ossification center, and 14.3% experienced an avulsion of the medial epicondyle apophysis. Because the injuries were not limited to bony structures, HDMRI may be beneficial for the appropriate evaluation of medial elbow pain. The pathology of initial medial elbow injuries in young baseball players may be due to acute trauma instead of repetitive microtrauma.
Competing Interests: Declaration of competing interest This work was supported by JSPS KAKENHI Grant Number JP19K11435.
(Copyright © 2021 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)