Hospital for Special Surgery (HSS) researchers recently identified three variables—arm slot, arm speed and shoulder rotation—in throwing biomechanics that may increase risk for elbow injuries in baseball pitchers.
Baseball: Modifiable Risk Factors Identified for Elbow Injuries
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The prospective cohort study analyzed the throwing biomechanics of 81 professional pitchers wearing a Motus baseball sleeve during on-field throwing activity including structured long tosses and live game play. Combined, the pitchers took 81,999 throws.
“This study is the first comprehensive analysis of everyday on-field throwing activity of professional baseball pitchers and is to date, the largest analysis of throwing biomechanics,” Joshua Dines, M.D., sports medicine surgeon at the Hospital for Special Surgery in New York City told OTW.
“While it has already been clinically established that UCL (ulnar collateral ligament) injuries are on the rise, little is known about what impacts these elbow injuries.”
Dines added that this study is also important because it uses technology to measure natural throwing motions outside of a laboratory setting.
According to the data, arm slot, arm speed and shoulder rotation all had a strong relationship with elbow varus torque. A 1-nm increase in elbow varus torque was associated with a 13 degree decrease in arm slot, 116% increase in arm speed and 8 degree increase in shoulder rotation.
“One surprising finding was that throwing ‘long toss’ put more stress on the elbow than throwing off a mound. This ran counter to our conventional wisdom that throwing off a mound puts the most stress on an elbow. This finding may lead to changes with regards to how we rehabilitate pitchers coming off surgery or other injuries,” Dines said.
The researchers hope that their study will be a foundation for future injury prevention studies of each of these modifiable variables (arm slot, arm speed and shoulder rotation).
“There are a lot of other studies that need to be done; this was just the first step,” Dines said. “Having a device that can serve as an odometer for the elbow can ultimately help prevent injuries. While this study focused on professional pitchers, equally important work needs to be done on little leaguers, high school pitchers and college pitchers.”
The study was presented at a poster presentation at the 2017 American Academy of Orthopaedic Surgeons Annual meeting in San Diego, California.
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This is a fascinating development. In my practice we've seen similar outcomes with the revised protocol. The key differentiator seems to be patient selection criteria. Has anyone else noticed the correlation with BMI thresholds?
Great point. I'd push back slightly on the conclusion, the sample size in the cited study is too small to draw population-level inferences. That said, the directional signal is compelling and worth a larger RCT.
We implemented a similar approach last year. Early results are promising but we're still gathering 12-month follow-up data. Happy to share our protocol if anyone is interested.
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