Humeral head retroversion in competitive baseball players and its relationship to glenohumeral rotation range of motion.

Chant CB, Litchfield R, Griffin S, Thain LM

The objective of this study was to determine if an osseous component in the form of increased humeral head retroversion may contribute to observed differences in the amount of rotation between the throwing and nonthrowing shoulders of competitive baseball players. Maximal shoulder internal and external rotation ROM at 90 degrees abduction were measured both passively and actively for both shoulders and this was compared to bilateral computed tomography (CT) scans to determine the angle of humeral head version. The results showed that players had statistically significant side-to-side difference in humeral head version, with an average of 10.60 greater retroversion in their throwing arm compared to their nonthrowing arm. Greater humeral head retroversion was associated with greater external rotation ROM and lesser internal rotation ROM in the throwing arm of the throwers. The authors conclude that the results indicated that highly competitive baseball players do have greater humeral head retroversion in their dominant arm, which can partially explain the observed differences in side-to-side shoulder rotation ROM.

Journal of Orthopedic Sports and Physical Therapy, 2007, 37(9), 514-20

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