Humeral retroversion and its relationship to glenohumeral rotation in the shoulder of college baseball players.
BACKGROUND
Previous studies have documented changes in musculature, bony anatomy, and glenohumeral rotation in the dominant shoulder of baseball players.


OBJECTIVE
In a group of asymptomatic college baseball players the total range of motion in the dominant and nondominant shoulders will be similar. Any measured increase in external rotation and decrease in internal rotation occurring between the two sides will be consistent and directly correlate with an increased angle of humeral retroversion in the dominant extremity.


METHODS
Descriptive anatomic study.


METHODS
Fifty-four asymptomatic college baseball players were examined. Standard measurements of glenohumeral range of motion were made and humeral retroversion was determined radiologically.


RESULTS
Total rotational motion, measured at 90 degrees of glenohumeral abduction, was 159.5 degrees for the dominant shoulders and 157.8 degrees for the nondominant shoulders. Mean differences in external and internal rotation in the dominant versus nondominant extremities were 9.7 degrees and 8.2 degrees, respectively. Humeral retroversion measured 36.6 degrees +/- 9.8 degrees in the dominant and 26 degrees +/- 9.4 degrees in the nondominant extremity. The mean difference in retroversion correlated significantly by Pearson's product moment with the difference in external (P = 0.001) and internal (P = 0.003) rotation measurements.


CONCLUSIONS
There is a pattern of increased external rotation and decreased internal rotation in the dominant extremity that significantly correlates with an increase in humeral retroversion. The loss of internal rotation and gains in external rotation may be more strongly related to adaptive changes in proximal humeral anatomy than to changes in the soft tissues.
Reagan
K M
KM
Department of Exercise and Sport Sciences, College of Health and Human Performance, University of Florida, 200-B SW 62nd Boulevard, Gainesville, FL 32607, USA.
Meister
Keith
K
Horodyski
Mary Beth
MB
Werner
Dave W
DW
Carruthers
Cathy
C
Wilk
Kevin
K
D000293:Adolescent; D000328:Adult; D001484:Baseball / Q000502:physiology*; D001696:Biomechanical Phenomena; D006801:Humans; D006811:Humerus / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D008297:Male; D011859:Radiography; D016059:Range of Motion, Articular; D012016:Reference Values; D012399:Rotation; D012785:Shoulder Joint / Q000000981:diagnostic imaging / Q000502:physiology*; D014495:Universities