Humeral Head Retroversion in Competitive Baseball Players and Its Relationship to Glenohumeral Rotation Range of Motion
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Bibliographic record
Abstract
Design Prospective case series. Objective 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. Background Differences in side-to-side shoulder rotation range of motion (ROM) are seen in throwing athletes. In the past, these differences have been attributed to adaptive changes to the surrounding soft tissue structures, including attenuation of the anteroinferior capsule and ligaments, and tightening of the posterior capsule. Recent studies, however, suggest that a possible osseous adaptation in the form of increased humeral head retroversion may be the cause of this side-to-side ROM difference. Methods and Measures Twenty-five individuals (19 competitive baseball players, 6 controls with no history of specific overhead sports activity) with no previous shoulder surgery and free of any symptomatic shoulder pathology at the time of testing participated. All subjects underwent bilateral computed tomography (CT) scans to determine the angle of humeral head version. Maximal shoulder internal and external rotation ROM at 90° abduction were measured both passively and actively for both shoulders. Results Players had statistically significant (P<.001) side-to-side difference in humeral head version, with an average of 10.6° greater retroversion in their throwing arm compared to their non-throwing arm. A significant side-to-side difference was not observed in the control group (average difference, 2.3°; P = .197). Greater humeral head retroversion was associated with greater external rotation ROM and lesser internal rotation ROM in the throwing arm of the throwers. Conclusions Our 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. J Orthop Sports Phys Ther 2007;37(9):514–520. doi:10.2519/jospt.2007.2449
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it