Department of Physical Therapy Faculty Articles
PubMed Identifier
27852593
Humeral Retrotorsion and Glenohumeral Motion in Youth Baseball Players Compared With Age-Matched Nonthrowing Athletes.
Publication Title
The American Journal of Sports Medicine
Publisher
Sage Publications
ISSN
1552-3365
Publication Date
2-1-2017
Keywords
adolescent, age factors, baseball, bone retroversion, child, cross-sectional studies, humans, humeral head, male, Pennsylvania, range of motion, articular, rotation, shoulder, shoulder joint
Abstract
Background: Baseball players exhibit a more posteriorly oriented humeral head in their throwing arm. This is termed humeral retrotorsion (HRT) and likely represents a response to the stress of throwing. This adaptation is thought to occur while the athlete is skeletally immature, however currently there is limited research detailing how throwing activity in younger players influences the development of HRT. In addition, it is presently unclear how this changing osseous orientation may influence shoulder motion within young athletes.
Purpose: To determine the influence of throwing activity and age on the development of side-to-side asymmetry in HRT and shoulder range of motion (ROM).
Study Design: Cross-sectional study; Level of evidence, 3.
Methods: Healthy athletes (age range, 8-14 years) were categorized into 2 groups based upon sports participation; throwers (n = 85) and nonthrowers (n = 68). Bilateral measurements of HRT, shoulder external rotation (ER), internal rotation (IR), and total range of motion (TROM) at 90° were performed using diagnostic ultrasound and a digital inclinometer. Side-to-side asymmetry (dominant minus nondominant side) in HRT and in shoulder ER, IR, and TROM were assessed. Statistical analysis was performed with 2-way analysis of variance and Pearson correlation coefficients.
Results: Throwers demonstrated a larger degree of HRT on the dominant side, resulting in greater asymmetry compared with nonthrowers (8.7° vs 4.8°). Throwers demonstrated a gain of ER (5.1°), a loss of IR (6.0°), and no change in TROM when compared with the nondominant shoulder. Pairwise comparisons identified altered HRT and shoulder ROM in all age groups, including the youngest throwers (age range, 8-10.5 years). A positive correlation existed between HRT and ER ROM that was stronger in nonthrowers (r = 0.63) than in throwers (r = 0.23), while a negative correlation existed with IR that was stronger in throwers (r = −0.40) than in nonthrowers (r = −0.27).
Conclusion: Throwing activity causes adaptive changes in HRT and shoulder ROM in youth baseball players at an early age. Other factors in addition to HRT influence shoulder motion within this population.
DOI
10.1177/0363546516676075
Volume
45
Issue
2
First Page
454
Last Page
461
Disciplines
Medicine and Health Sciences | Physical Therapy | Rehabilitation and Therapy
NSUWorks Citation
Greenberg, Elliot M.; Lawrence, J. Todd R.; Fernandez-Fernandez, Alicia; and McClure, Philip, "Humeral Retrotorsion and Glenohumeral Motion in Youth Baseball Players Compared With Age-Matched Nonthrowing Athletes." (2017). Department of Physical Therapy Faculty Articles. 168.
https://nsuworks.nova.edu/hpd_pt_facarticles/168
