Lower degrees of dominant humeral torsion results in severe upper extremity injuries for pitchers
Major League Baseball pitchers with lower degrees of dominant humeral torsion had more severe upper extremity injuries, and pitchers with lower side-to-side differences in torsion experienced more severe dominant upper extremity injuries, according to results of this recently published study.
In the study, 25 professional pitchers from a single Major League Baseball organization underwent CT on dominant and nondominant humeri. Image data were processed with a 3-D volume-rendering post-processing program. Researchers then modified the software program to model a simplified throwing motion to measure potential internal impingement distances in number of days missed from pitching as a measure of injury severity and incidence.
Overall, the mean dominant humeral torsion was 38.5°, while the mean nondominant humeral torsion was 27.6°. Overall, 45% of pitchers were injured during follow-up. Five players had shoulder injuries, seven players had elbow injuries and two players had finger injuries.
According to the study results, dominant humeral torsion was a statistically significant predictor of severe injuries, but not of milder injuries. Researchers found a strong correlation between a high number of days missed because of injury and lower degrees of dominant humeral torsion and smaller differences between dominant and nondominant humeral torsions. Study results showed no significant association between the incidence of shoulder injury and minimum glenoid-tuberosity distance in the dominant or nondominant shoulder or degree of dominant glenoid version.
As these results show, the interplay of dominant humeral torsion, torsion difference and shoulder injury is complex,” the researchers wrote.