Sports Rehab Write-Up: RHP Dustin May
With a 2.63 ERA, 0.94 WHIP, and 34 strikeouts, Dodgers pitcher Dustin May was off to a really solid start to the season – even leading qualified National League pitchers with the lowest hits & home runs per nine innings to that point. Unfortunately, he left the team’s May 18th matchup against the Twins after the first inning with reports of elbow & forearm pain. We would later find out that May suffered a flexor-pronator strain.
A flexor-pronator strain is exactly what it sounds like: a strain of the wrist flexors & a little muscle called pronator teres! So, somewhere between the medial epicondyle & the wrist a few muscle fibers have torn.
Stick your hand out in front of you with your palm face up. Now, flip it face down; that’s pronation. Curl your palm down towards your body; that’s wrist flexion. As you’d imagine, this is a very important movement for a professional baseball pitcher. Similarly, we see a good number of injuries in the muscles involved.
So what does this injury typically entail, from a sports rehab perspective? Well, we can take notes from May’s outing against the Twins...
According to Dodgers manager Dave Roberts:
“Coming out of his last start, he felt that there was just normal soreness like any starting pitcher has… obviously, he felt good enough to make the start. And then after that first inning, the velocity wasn't there and I saw him kind of moving his hand and those are the signs that something's not right.”
Translation: More pain, less pitching power.
A simple flexor-pronator strain typically resolves within about 6 weeks with a little physical therapy & some feel-good modalities. Though it seems there’s a little more going on with this one.
The Dodgers ended up placing May on the 60-day injured list, indicating a possible set-back. May is eligible to return to sport on July 17th; though, that timeline for a return seems pretty ambitious. According to the most recent reports, May has not even returned to playing catch yet. So what’s going on?
When we look back to the 2021 & ’22 seasons, we can see that Dustin missed a good amount of time following his Tommy John surgery, also known as an Ulnar Collateral Ligament (UCL) Reconstruction. The UCL runs a similar path to some of the flexor-pronator muscle fibers, originating from the same point. It isn’t far-fetched to think that there may be some lingering instability in May’s medial elbow complex. The dynamic stabilizers, the flexor-pronator muscles, are just as important to the stability of the medial elbow as the static UCL is; they work in concert. Hard to say if the chicken or the egg came first here!
It's important to highlight, that according to the literature, the Flexor Digitorum Superficialis (FDS), Pronator Teres, & Flexor Carpi Ulnaris (FCU) play the biggest roles in dynamic medial elbow stability (Cinque et al., 2020). The FDS’s ulnar insertion has been shown to overlap with the UCL insertion for 46% of its path, the FCU’s ulnar insertion overlaps 21%, & Pronator Teres’s ulnar insertion runs between the brachialis muscle and the anterior bundle of the UCL (Frangiamore et al., 2018).
A good rehab protocol for May would focus on maximizing the strength & integrity of those dynamic stabilizers. Luckily for May, not much changes in his rehab approach, whether it’s a UCL or flexor-pronator injury. Therapeutic exercises targeting the wrist flexors & pronator teres muscle are still the way to go. Specifically, it makes sense to work a ton of finger flexion & ulnar deviation while we’re at it!
If you’re dealing with a similar injury, consult a trusted medical professional to build you a good exercise program to re-establish the integrity of your medial elbow complex!
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References & Works Cited
Cinque, M. E., Schickendantz, M., & Frangiamore, S. (2020). Review of Anatomy of the Medial Ulnar Collateral Ligament Complex of the Elbow. Current reviews in musculoskeletal medicine, 13(1), 96–102. https://doi.org/10.1007/s12178-020-09609-z
Frangiamore, S. J., Moatshe, G., Kruckeberg, B. M., Civitarese, D. M., Muckenhirn, K. J., Chahla, J., Brady, A. W., Cinque, M. E., Oleson, M. L., Provencher, M. T., Hackett, T. R., & LaPrade, R. F. (2018). Qualitative and Quantitative Analyses of the Dynamic and Static Stabilizers of the Medial Elbow: An Anatomic Study. The American journal of sports medicine, 46(3), 687–694. https://doi.org/10.1177/0363546517743749
