Dynamic US of the Anterior Band of the Ulnar Collateral Ligament of the Elbow in Asymptomatic Major League Baseball Pitchers

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Abstract
To determine whether dynamic ultrasonography (US) can reveal abnormalities of the anterior band of the ulnar collateral ligament (UCL) of the elbow in asymptomatic major league professional baseball players. US was performed in 26 asymptomatic major league professional baseball pitchers before spring training. Images were obtained in both pitching and nonpitching arms with a multifrequency 13-MHz linear-array transducer. The thickness of the anterior band of the UCL and the width of the joint it spans (the ulnohumeral joint) were measured with the elbow at 30 degrees of flexion, both at rest and with valgus stress. The thickness of the anterior band of the UCL and the width of the joint space were compared for pitching and nonpitching arms by using the Student t test. The prevalence of hypoechoic areas and calcifications within the anterior band of the UCL in pitching and nonpitching arms was compared by using the McNemar test. The average time of the US examinations was recorded. At rest, the mean thickness (+/- 1 SD) of the anterior band of the UCL was 6.3 mm +/- 1.1 in pitching arms and 5.3 mm +/- 1.0 in nonpitching arms. This difference was statistically significant (P <.01). With stress, the anterior band thickness was 6.3 mm +/- 1.4 in the pitching arms and 4.8 mm +/- 0.9 in the nonpitching arms (P <.001). The joint space width at rest was 2.8 mm +/- 1.0 in the pitching arms and 2.5 mm +/- 0.7 in the nonpitching arms (not statistically significant). When stress was applied, however, the joint space width was significantly greater in the pitching arms than in the nonpitching arms (4.2 mm +/- 1.5 vs 3 mm +/- 1.0, respectively; P <.01). Hypoechoic foci within the anterior band of the UCL were seen in 18 of 26 (69%) pitching arms and three of 26 (12%) nonpitching arms (P <.001). Calcifications were detected in nine of 26 (35%) pitching arms but in none of the nonpitching arms (P <.001). The average time for bilateral US was 10.4 minutes. Dynamic US provides a rapid means for evaluating the anterior band of the UCL in professional baseball pitchers. In pitching arms, this band is thicker, is more likely to have hypoechoic foci and/or calcifications, and demonstrates more laxity with valgus stress.

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