Effects of Tommy John surgery on pitch movement in MLB pitchers.

1. Effects of Ulnar Collateral Ligament Reconstruction
on Pitch Movement in Major League Baseball Pitchers
Brooks Platt, B.S. University of Missouri, Columbia
John Worley, M.D. University of Missouri, Columbia
Emily Leary, Ph.D. University of Missouri, Columbia
Aaron D. Gray, M.D. University of Missouri, Columbia

2. UCLR aka Tommy John Surgery
• Studies have investigated the relationship between pitch metrics and
UCLR3,4,5,6
• This is the first study to investigate the effects of UCLR on the
movement of pitches
• We hypothesized that pitches would experience a decrease in velocity
and movement 12-24 months after surgery followed by a return to
form 24-36 months after surgery

3. UCLR had no effect on
average yearly WAR in a
career, and a decrease in
career WAR explained by
a loss in pitching time,
not performance
Fastball velocity decreases
relatively consistently
throughout careers, whereas
movement stays relatively
consistent

6. MLB players
undergoing UCLR
from 2008-2016
n=200
n=185
n=157
MLB pitchers
included in the study
n=57
Non-pitchers n=15
Pitchers with previous
UCLR n=28
Pitchers with
insufficient data in the
12-24 month pre-op,
12-24 month post-op,
or 24-36 month post-op
windows n=100

8. Fourseam Age-Group Analysis: Velocity
Pre-op Post-op
Measure Age
Group
12-24
Months
12-24
Months
P-value 24-36
Months
P-value
Velocity <26,
n=16
93.62 +/-
4.25
93.86 +/-
4.18
0.638 93.79 +/-
4.28
0.687
26-31,
n=25
93.45 +/-
4.83
92.71 +/-
5.40
0.023 92.77 +/-
4.24
0.020
>31, n=9 92.11 +/-
9.76
91.86 +/-
6.70
0.615 92.31 +/-
9.20
0.695

9. Fourseam Age-Group Analysis: Hmov
Pre-op Post-op
Measure Age
Group
12-24
Months
12-24
Months
P-value 24-36
Months
P-value
Hmov <26,
n=16
-5.93 +/-
2.64
-4.86 +/-
3.85
0.010 -4.99 +/-
2.59
0.008
26-31,
n=25
-4.69 +/-
2.05
-4.50 +/-
4.59
0.507 -4.38 +/-
3.39
0.189
>31, n=9 -5.02 +/-
2.86
-5.28 +/-
9.17
0.760 -5.20 +/-
4.86
0.715

10. Fourseam Age-Group Analysis: Vmov
Pre-op Post-op
Measure Age
Group
12-24
Months
12-24
Months
P-value 24-36
Months
P-value
Vmov <26,
n=16
9.45 +/-
1.53
9.41 +/-
1.59
0.890 9.56 +/-
1.07
0.659
26-31,
n=25
9.24 +/-
2.73
8.91 +/-
2.63
0.116 8.77 +/-
2.10
0.033
>31, n=9 9.56 +/-
2.25
8.80 +/-
2.31
0.077 8.90 +/-
1.87
<0.001

11. Take Home Points and Future Discussions
• No metric of breaking pitches changed
• Fourseam fastball movement experienced a small but significant
change
• Movement decrease in the fourseam fastball is likely due to a
decrease in flexion/pronation power

12. References
1. Conte SA, Fleisig GS, Dines JS, et al. Prevalence of Ulnar Collateral Ligament Surgery in
Professional Baseball Players. Am J Sports Med. 2015;43(7):1764-11769.
Doi:10.1177/0363546515580792.
2. Mahure SA, Mollon B, Shamah SD, Kwon YW, Rokito AS. Disproportionate trends in ulnar
collateral ligament reconstruction: Projections through 2025 and a literature review. J Shoulder
Elb Surg. 2016;25(6):1005-1012. doi:10.1016/j.jse.2016.02.036
3. Jiang JJ, Leland JM. Analysis of pitching velocity in major league baseball players before and
after ulnar collateral ligament reconstruction. Am J Sports Med. 2014;42(4):880–885.
4. Keller RA, Marshall NE, Guest JM, Okoroha KR, Jung EK, Moutzouros V. Major League Baseball
pitch velocity and pitch type associated with risk of ulnar collateral ligament injury. J Shoulder
Elbow Surg. 2016;25(4):671–675.
5. Lansdown DA, BT Feeley. The effect of ulnar collateral ligament reconstruction on pitch velocity
in Major League Baseball pitchers. Orthop J Sports Med. 2014. 2(2):2325967114522592.
6. Makhni EC, Lee RW, Morrow ZS, Gualtieri AP, Gorroochum P, Ahmad CS. Performance, return to
competition, and reinjury after Tommy John Surgery in Major League Baseball pitchers: A
Review of 147 Cases. Am J Sports Med. 2014. 42(6):1323–1332.

13. Variable Effect Estimate SE t value p-value
Four-seam Fastball Velocity Intercept
100.82 2.29 43.99 <.0001
(UN) Age
-0.27 0.08 -3.48 0.0009
Post-op 1
-0.42 0.21 -2.01 0.049
Post-op 2
-0.3 0.19 -1.57 0.1219
Four-seam Fastball Hmov Intercept
-7.14 1.48 -4.84 <.0001
(UN) Age
0.06 0.05 1.27 0.208
Post-op 1
0.38 0.21 1.77 0.0822
Post-op 2
0.43 0.17 2.59 0.0121
Four-seam Fastball Vmov Intercept
10.69 1.29 8.27 <.0001
(UN) Age
-0.05 0.04 -1.07 0.2884
Post-op 1
-0.38 0.14 -2.66 0.01
Post-op 2
-0.36 0.13 -2.64 0.0109
Curveball Velocity Intercept
86.88 2.86 30.42 <.0001
(UN) Age
-0.3 0.1 -2.98 0.005
Post-op 1
0.02 0.26 0.09 0.9251
Post-op 2
-0.04 0.33 -0.13 0.8996
Curveball Hmov Intercept
3.24 2.16 1.5 0.1417
(UN) Age
0.06 0.08 0.74 0.461
Post-op 1
-0.01 0.22 -0.05 0.9565
Post-op 2
0.16 0.27 0.6 0.5521
Curveball Vmov Intercept
-5.08 2.22 -2.29 0.0274
(UN) Age
-0.01 0.08 -0.18 0.8583
Post-op 1
-0.12 0.24 -0.52 0.605
Post-op 2
-0.27 0.31 -0.86 0.3941
Slider Velocity Intercept
84.38 2.94 28.65 <.0001
(AR(1)) Age
0.01 0.1 0.06 0.951
Post-op 1
-0.57 0.33 -1.76 0.0826
Post-op 2
-0.49 0.25 -1.94 0.0567
Slider Hmov Intercept
3.69 2.77 1.33 0.1909
(UN) Age
-0.06 0.09 -0.6 0.5533
Post-op 1
0.09 0.25 0.34 0.7347
Post-op 2
0.01 0.27 0.02 0.9826
Slider Vmov Intercept
-1.78 2.44 -0.73 0.4704
(UN) Age
0.1 0.08 1.19 0.2421
Post-op 1
0.17 0.3 0.58 0.5666
Post-op 2
-0.24 0.29 -0.82 0.4151
Repeated Measures Analysis

14. Profile Plots
for each
player