Peter Kriz, MD

Director, Thrower's Clinic
Boston Children's Hospital | Sports Medicine Division

[Peter Kriz, MD @NEBaseballDoc]

Update from our database of 851 pitchers selected in 1st 5 MLB rounds (2011-20), data thru '24 season:
⚾️281 (33%) underwent primary UCL-R
⚾️Median MLB career earnings (adj. for inflation) significantly ⬆️er for middle- & late-career UCL-R vs. early-career UCL-R pitchers... 1/

[Eric Cressey @EricCressey]

New podcast: I welcome Dr. Michael Freehill, team doctor for the #Athletics and @StanfordBSB. As a shoulder/elbow expert, avid researcher, retired player, and baseball father, Dr. Freehill has unique insights about where baseball sports medicine is headed. https://t.co/qP1WF4Zqry

[Peter Kriz, MD @NEBaseballDoc]

@dpopowich1972 @TheAMSSM @TheDrROBO @DrZSportsDoc @gretchendoliver Good question... there was a remote option as well as in-person. I assume it was recorded. AMSSM staff likely has the answer.

[Peter Kriz, MD @NEBaseballDoc]

Had a great time presenting on elbow injuries in throwing athletes with this All-Star panel in front of >2200 sports med docs at @TheAMSSM Annual Meeting in Seattle! @TheDrROBO @DrZSportsDoc @GretchenDOliver ⚾️🥎🔥

[Peter Kriz, MD @NEBaseballDoc]

@rancadore No, you're reading that right. The study referenced in that systematic review was performed by Dr. Glenn Fleisig et al. Study population was 9-14 yos:

[Peter Kriz, MD @NEBaseballDoc]

The concern is early-"career," high-volume workload that predisposes to injury (usually growth plate injuries at that age), which then predisposes to UCL injury:

[Greg @PittsburghFan33]

@NEBaseballDoc What’s the difference between a 9u UCL and a 12U UCL?

[Peter Kriz, MD @NEBaseballDoc]

9U travel ⚾️/showcasing needs 2 be banned.

HS & college pitching staffs R currently decimated w UCL inj's, and most current pitchers @ that level DNP on the 9U circuit.

A tidal wave of injury is coming. More HS & college coaches need to speak out to save their future programs.

[Peter Kriz, MD @NEBaseballDoc]

@GarethHooton @moreau_daryl @devenmorgan Gareth, I'm not sure the car analogy works. The medial elbow is exposed to traction during throwing, not compression. The UCL is not really a spring. Rubber band or resistance band? yes...

[Peter Kriz, MD @NEBaseballDoc]

@GarethHooton @moreau_daryl @devenmorgan https://t.co/NLIr67XPRC

[Peter Kriz, MD @NEBaseballDoc]

@GarethHooton @moreau_daryl @devenmorgan Yes, certainly, but the UCL & dynamic stabilizers work in tandem to prevent failure. If 1 is weakened, the other is jeopardized.
Certain pitches also require ⬆️ activation of FDS & FCU. See attached excellent editorial by Dr. Michael Freehill (Stanford)... link in next comment.

[Peter Kriz, MD @NEBaseballDoc]

Appreciate the interest in this topic from our 🇯🇵 colleagues! Great opportunities to collaborate here!

[理学療法士_海津陽一 Ph.D. @copellist]

■ Ref info: Kriz et al. "Do Pitching Restriction Policies Reduce Shoulder and Elbow Injuries in High School Baseball Players?." Orthopaedic Journal of Sports Medicine 14.2 (2026): 23259671251412404.
■ Ref link: https://t.co/ZrAdFKWSrb
■ note link: https://t.co/sAjJOlUFeU

[Peter Kriz, MD @NEBaseballDoc]

Spot-on. With LL Elbow and LL Shoulder (growth plate injuries), recurrence rates are 20-50%, usually within 8-9 months of original injury. Some institutions recommend no pitching/catching for a full calendar year after LLE/LLS.

[B. P. Thr⚾wer @5280Bsblr]

@NEBaseballDoc I feel like many "overuse" injuries might fall into these categories even if you're otherwise following best practices like pitch count, but it's never discussed. And the growth plates at this age ....

[Antonio García-Hermoso @a_garciahermoso]

💪🌱 La potencia muscular también se cultiva desde la infancia. Prevenir la “powerpenia pediátrica” con juego activo, saltos, carreras y fuerza adaptada ayuda a crear una reserva física que puede proteger la función muscular durante toda la vida 🧒🏃‍♀️🏃‍♂️👟

https://t.co/zpQQkMGrrH

[Peter Kriz, MD @NEBaseballDoc]

2 disturbing trends I'm seeing this spring in New England ⚾️:
1) 8th grade pitchers playing JV
2) 6th graders pitching on their middle school teams (60/90)

The UCL pandemic will continue exponentially unless common sense returns to the equation.

We're robbing Peter to pay Paul.

[Peter Kriz, MD @NEBaseballDoc]

Renewed my @BostonGlobe subscription today, @GlobeKPD .

Doing my part to not only keep journalism alive, but to keep that 2010 (?) Prius on the road 👊🏼

[AOSSM Journals @aossmjournals]

⚾ Baseball is back, and so is the latest research!

Explore OJSM’s baseball sports medicine collection featuring injury, prevention, treatment, and performance insights all in one place.

Explore → https://t.co/UN6DrUEcps

#OJSM #SportsMed #Baseball

[Peter Kriz, MD @NEBaseballDoc]

In the past yr, I've tx'ed a 9 yo with a displaced medial epicondylar avulsion fx & a 12 yo with a proximal UCL avulsion requiring UCL repair w IB. In both instances, those are injuries usually seen 4-5 yrs later in development. It's going to be coach pitch in HS in a few yrs 🤷🏻‍♂️

[Eric Cressey @EricCressey]

It's not uncommon for pre-teen baseball players to play 150+ games per year. Sadly, this is not an April Fool's joke.

[WeRateDogs @dog_rates]

This is Henry. He knows that if he turns right at the stop sign it means a shorter walk. Not today. 13/10

[AOSSM Journals @aossmjournals]

Today on #TheHotCorner, @Anthony_YuMD welcomes @NEBaseballDoc to discuss his study “Do Pitching Restriction Policies Reduce Shoulder and Elbow Injuries in High School Baseball Players?” Have the measures to keep pitchers safe implanted a decade ago worked?
https://t.co/GSZ55YnHZD

[Peter Kriz, MD @NEBaseballDoc]

Appreciate the opportunity to discuss our HS⚾️pitching restriction policy study & shoulder/elbow injuries with @Anthony_YuMD & @aossmjournals
on The OJSM Hot Corner! Our research team will be discussing this study at 2026 AMSSM Annual Meeting in Seattle!
https://t.co/vg2tjeGdRi