Magnetic resonance imaging of the throwing elbow in the uninjured, high school-aged baseball pitcher.
Hurd WJ, Eby S, Kaufman KR, Murthy NS. Am J Sports Med. 2011 Apr;39(4):722-8. Epub 2011 Jan 12.
There is no question that baseball is one of the most popular sports amongst children in America. There is also no question that with increased popularity and participation there is an inherent increase in the incidence of throwing injuries. While certain interventions have been implemented over the years in an effort to avoid injuries in the younger throwing athlete, such as limiting pitches/week and the avoidance of throwing breaking pitches, injuries can, and will, still occur often requiring diagnostic imaging. The American Journal of Sports Medicine recently published two studies by Hurd et al (https://www.ncbi.nlm.nih.gov/pubmed/21228309 and https://www.ncbi.nlm.nih.gov/pubmed/21335342) examining the elbow in high school baseball pitchers. While recent studies have shown that anatomical changes to the elbow and shoulder visible on MRI are quite common in asymptomatic elite overhead athletes, no such studies exist focusing on younger athletes. However, many of us are not working with elite level overhead athletes and knowing what tissue adaptations are occurring in the high school-aged athletes is crucial to understanding what may or may not be at the heart of elbow pain. In the first study by Hurd et al., 23 asymptomatic high school-aged pitchers (14-19 years) were recruited to determine if anatomical changes are present in the throwing elbows. All subjects completed a physical to confirm that they were asymptomatic followed by a bilateral elbow MRI utilizing the non-dominant elbow as a control. Differences in ligamentous, musculotendinous, osteoarticular and neural structures were examined. The most common findings in the subjects dominant elbows included thickening of the anterior band of the UCL (65%), ulnotrochlear subchondral sclerosis (61%) and ulnotrochlear osteophytes located on the posterior medial tip of the olecranon (35%) with 43% of the subjects presenting with multiple MRI findings.
Understanding that these degenerative findings present at an early age and are visible on MRI is of importance for ATCs. As health care providers we can begin to eliminate certain positive MRI findings as possible sources of pain and dysfunction in the high school-aged pitcher. The authors suggest that the subjects in this study presenting with multiple degenerative findings upon MRI could potentially be at an increased risk of a UCL tear and that these MRI findings could be a predictor of future elbow injury. What isn’t so clear is why the UCL thickening occurs. Currently it remains unknown if the thickened UCL is a positive or a negative finding for pitchers. It could be argued that the thicker ligament would be able to resist greater valgus forces throughout the pitching motion and potentially prevent injury. On the other hand, these changes could be construed as being degenerative eventually manifesting as a ligament tear. Either way, further investigation is necessary to evaluate the structural composition of this thickened UCL. For further insight on this topic, a SMR post detailing the author’s follow-up to this study can be found here. In it, the author examines the relationship between elbow distraction forces and UCL thickening on MRI. Are you surprised that the pitching elbow exhibits these degenerative osseous changes and UCL thickening at such an early age? What do you believe could be at the heart of the UCL thickening?
Written by: Mark Rice
Reviewed by: Stephen Thomas