PITCHf/x Forensics: Matt Harvey and Thoracic Outlet Syndrome

A lot was expected from Matt Harvey and the New York Mets starting rotation in 2016, but aside from the Norse God of Thunder, the season was a bit of a let down (to say the least). Having fully recovered from Tommy John Surgery, and a consequent missed season in 2014, Harvey missed the end of the 2016 season when he was diagnosed with Thoracic Outlet Syndrome and opted for season-ending surgery. Unless you’ve been living under a rock, chances are baseball fans know what Tommy John Surgery is, and where the ulnar collateral ligament resides. A lot less is known about Thoracic Outlet Syndrome, so let’s dig in.

Anatomy

To provide the arms with sensation, motor control, and blood flow, the nervous and circulatory systems have to send nerves and blood vessels into the extremities from the spinal cord. These major nerves and blood vessels that supply the arm come through a small space, just under the collar bone and above the first rib, called the thoracic outlet (Figure 1). 

Also contained in this space, are muscles, tendons, and other connective tissue that support the rib cage, and protect the vital organs within the chest. This is not a big space, but there are a lot of very important structures that pass through it. When the tissues in the thoracic outlet become irritated, they can become inflamed. Given the hard structures surrounding the thoracic outlet, these inflamed tissues have nowhere to move, but to compress the nerves. As a result, the person suffering from thoracic outlet syndrome (TOS) will lose sensation in their hands and fingers, and may experience difficulties moving their hands. Numbness and tingling is extremely common.

In industrial cases, TOS can occur when workers spend large periods of their work day with their arms above their heads, and is one of the more common upper extremity repetitive strain injuries (like carpal tunnel syndrome) (Sommerich et al., 1993). In baseball pitchers, TOS is less common, but not unheard of. Aside from Matt Harvey, Mike Foltynewicz, Luke Hochevar, Phil Hughes, Josh Beckett, Jaime Garcia, Kyle Zimmer, Chris Carpenter, Matt Harrison, Tyson Ross, and Clayton Richard are amongst the MLB pitchers who have had TOS. Some have had the surgery and returned, while others have retired.

The most concerning case of TOS related to a pitcher, was in J.R. Richard, over 30 years ago. Richard did not have his TOS diagnosed early on, and as a result of the impingement of his blood vessels, he ended up with a blood clot, and eventually had a stroke. Richard never returned to success at the major league level (Fields et al., 1986). This is without a doubt, a very serious injury with implications far more severe than those associated with other repetitive strain injuries. If you would like to read more about the nitty gritty details of thoracic outlet syndrome, check out this article from Baseball Prospectus (Dawkins & Lindbergh, 2012).

The surgical procedure associated with TOS, and the one most recently undergone by Matt Harvey, involves the surgical removal of the first rib. While this sounds extremely severe, this rib does not provide a lot of structural support, and removing it gives much more space for the blood vessels and nerves to run through, and into the arm. Because of the nature of the surgery, you won’t see a person get a second TOS surgery. Unless, that rib is removed, and used to spawn a new human being, and then that new human being requires TOS surgery. But, I’m lead to believe that might just be a made up story. Anyway.

Performance Implications

A very exciting new study was published in the Journal of Sports Biomechanics last week, which looked at a high speed analysis of the fingers during fastball release (Matsuo et al., 2017). This is an exciting piece of research, because there is very little understanding as to how pitchers can generate spin. The folks at Driveline baseball have found a strong relationship with velocity, but were not able to tie spin rates to any sort of anthropometrical measure.

It me, Mister Fun Stealer.

This episode: Hand size / finger length doesn’t appear to impact FB spin rate. pic.twitter.com/Ax9lOt4gEE

— Kyle Boddy (@drivelinebases) August 11, 2016

 

In this figure from Matsuo et al., (2017), you can see the forces that act on the ball at the instant of release. They are very highly coordinated, and occur at an extremely specific point in time (Figure 2). The authors conclude that this highly coordinated movement pattern, and the specific contractions of the fingers are highly related to the amount of control that a pitcher has over a pitch.

How would the symptoms of TOS manifest in pitchers? Let’s take a closer look and examine (using PITCHf/x and Statcast data), the performance changes associated with those pitchers who have had TOS surgery. My hypothesis is, pitchers who have had thoracic outlet syndrome will have less command in the season leading up to their surgery compared to the season before their surgery, and they will regain their command in the season after they recovered from the surgery.

Methods

Pitchers who have had TOS surgery in the PITCHf/x era (since 2008), and pitched in the season in which they had TOS surgery were: Clayton Richard, Mike Foltynewicz, Phil Hughes, Matt Harvey, and Luke Richard. Command and Control were determined from Baseball Prospectus’ called strikes above average (http://www.baseballprospectus.com/article.php?articleid=31022), and strike probability statistics, respectively.

The hypothesis reduced command was true for Clayton Richard, Mike Foltynewicz, Matt Harvey, but didn’t carry forward for Luke Hochevar or Phil Hughes. The exact opposite was true for the control statistic. There was limited data on spin rates, but only Matt Harvey (and not Luke Hochevar and Phil Hughes) saw declines in their fastball spin rate. If I were one of those guys that picked and chose when to support his hypotheses, I’d tell you that the evidence presented in the Matt Harvey case perfectly support my hypotheses (Figure 4), but the reality is, these same trends are not seen in all pitchers who suffered from TOS.

Now, let’s call a spade a spade – this is hardly a scientific look into TOS. There is just simply not the power you’d require to do a statistical work up of this type of analysis. Even further, there is not a lot of work that looks at the return of pitchers from TOS. Mechanically, I can’t see that the TOS surgery would have a negative impact on pitchers in their return – so, with Matt Harvey, I would expect that he should be able to return to form following his surgery. That being said, there have been enough red flags in his career, that it’s tough to say he isn’t going to have another significant injury.

Conclusions

Based on the research performed in the field of Sports Biomechanics, one would expect a pitcher dealing with TOS to suffer control issues, but not necessarily velocity issues. Matt Harvey’s case directly support this research, but other pitchers who have had the TOS surgery don’t necessarily follow suit. From a performance perspective, the symptoms of TOS should not bother Harvey in 2017, but his significant injury history indicates where there is smoke, there’s fire.

 

References

Sommerich, C. M., McGlothlin, J. D., & Marras, W. S. (1993). Occupational risk factors associated with soft tissue disorders of the shoulder: a review of recent investigations in the literature. Ergonomics, 36(6), 697-717.

Fields, W. S., Lemak, N. A., & Ben-Menachem, Y. (1986). Thoracic outlet syndrome: review and reference to stroke in a major league pitcher. American Journal of Roentgenology, 146(4), 809-814.

Matsuo, T., Jinji, T., Hirayama, D., Nasu, D., Ozaki, H., & Kumagawa, D. (2017). Middle finger and ball movements around ball release during baseball fastball pitching. Sports Biomechanics, 1-12.

Dawkins, C., & Lindbergh, B. (2012). Collateral Damage: Rounding up the Usual Suspects: Thoracic Outlet Syndrome. Baseball Prospectus. Retrieved from http://www.baseballprospectus.com/article.php?articleid=15834, March 8, 2017.