Ironman triathletes: MRI assessment of the shoulder

The objective of this paper was to demonstrate the prevalence of shoulder magnetic resonance imaging (MRI) abnormalities, including abnormal bone marrow signal at the acromioclavicular (AC) joint in symptomatic and asymptomatic Ironman Triathletes.

The shoulders of 23 Ironman Triathletes, seven asymptomatic (group I) and 16 symptomatic (group II), were studied by MRI. A separate, non-triathlete group was evaluated specifically for AC joint marrow signal abnormalities to compare with the Ironman Triathletes.

Partial thickness tears of the rotator cuff, rotator cuff tendinopathy, and AC joint arthrosis were common findings in both groups of triathletes. Tendinopathy was the only finding that was more prevalent in the symptomatic group, but this was not a statistically significant difference (p = 0.35). There were no tears of the glenoid labrum seen in group I or II subjects. Of note is that 71% (5/7) of group I subjects and 62% (10/16) of group II subjects had increased signal changes in the marrow of the AC joint (p = 0.68). The comparison group showed a lower prevalence (35%, p = 0.06) of this finding.

No statistically significant difference was found among the findings for group 1, group 2, or the comparison group, although the difference between the comparison group and Ironman Triathletes approached statistical significance when evaluating for AC joint abnormal signal. Shoulder MRI of Ironman Triathletes should be interpreted with an appreciation of the commonly seen findings in asymptomatic subjects.