Change in MRI findings of medial collateral ligament injury in adolescent baseball players with no clinical symptoms over time
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Elbow screening of adolescent baseball players began in 2014 using ultrasound, palpation, and dedicated magnetic resonance imaging (MRI). We frequently encountered subjects showing MCL injury on MRI but no clinical symptoms. We assessed variations in asymptomatic MCL injury findings at follow-up MRI, and clarified the pathogenesis of these findings.
Materials and methods
Using a 0.2-T-dedicated MRI, 30 subjects with asymptomatic MCL injury at initial MRI who agreed to follow-up MRI were included. We classified the findings at repeat MRI as follows: (a) disappeared, (b) better, and (c) worse.
There were 6, 16, and 8 subjects in groups a, b, and c, respectively. The average age at follow-up was 14.0, 12.1, and 12.4 years in groups a, b, and c, respectively. There were significant differences between groups a and b and between groups a and c. Average height at follow-up of groups a, b, and c was 1.64, 1.52, and 1.57 cm, respectively, with a statistically significant difference between groups a and b. The average size of the short axis of the MCL of subjects in group a was 2.0 cm on the dominant side and 1.5 cm on the contradominant side (P < 0.04).
Players with asymptomatic MCL injury can continue to play baseball with no limitations, as these findings usually disappear around the age of 14.0 years, when the growth spurt occurs. This finding may be a precursor of ‘adaptation’, which is generally observed in high school baseball players, suggesting that the MCL adapts as growth occurs.
KeywordsDedicated MRI Asymptomatic MCL injury Elbow screening Adaptation Medial epicondyle
I would like to express my greatest appreciation to Akito Kawasaki and Masashi Maruyama for their useful discussion and ideas regarding this work.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Informed consent was obtained from all individual participants included in the study.
All procedures involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
- 2.The Japanese Orthopaedic Association. 2016. https://www.joa.or.jp/media/comment/pdf/2016_survey_childrensbaseball.pdf. Accessed 17 June 2016.