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Pitchers’ injuries linked to degree of dominant humeral torsion
There was a strong correlation between lower degrees of dominant humeral torsion and more severe upper extremity injuries in professional baseball pitchers, according to recent study results.
In a case-control study, researchers prospectively recruited 25 pitchers from a single Major League Baseball organization. They conducted computed tomography (CT) on dominant and nondominant humeri. A 3-D volume-rendering postprocessing program generated image data. Researchers modified the software to display a simplified throwing motion and to measure any internal impingement distances in a subset of pitchers. Follow-up was 2 years after CT, with injury severity and incidence defined as the number of days missed from pitching.
The pitchers’ mean dominant humeral torsion was 38.5 degrees ± 8.9 degrees and a mean nondominant torsion of 27.6 degrees ± 8 degrees (P<.0001 for difference). During follow-up, 11 pitchers were injured (five shoulder injuries, seven elbow injuries and two finger injuries).
“Dominant humeral torsion was a statistically significant predictor of severe injuries (at least 30 missed days; P=.048),” the researchers reported.
For the injured pitchers, lower degrees of dominant humeral torsion and smaller differences between dominant and nondominant humeral torsions were strongly correlated with a higher number of injury days (r=–0.78, P=.005; r=–0.59, P=.055; respectively). Incidence of shoulder injury displayed no significant association with minimum glenoid-tuberosity distance in the dominant or nondominant shoulder or degree of dominant glenoid version.
“A strong relationship was found between lower degrees of dominant humeral torsion and more severe upper extremity injuries, as well as a trend relating lower side-to-side differences in torsion with more severe dominant upper extremity injuries,” the researchers concluded. “In addition, there was a higher incidence of severe injuries in players with lower degrees of dominant torsion. If future studies confirm these results, humeral torsion measurements could play a role in risk assessment in pitchers.”
Disclosure: The study was supported by grant funding from Major League Baseball.