The effects of medial ulnar collateral ligament reconstruction on Major League pitching performance

Keller RA, Steffes MJ, Zhuo D, Bey MJ, Moutzouros V. Journal of Shoulder and Elbow Surgery. 2014 November.

Take-Home Message

Pitchers who undergo ulnar collateral ligament (UCL) reconstruction perform worse after surgery compared to earlier seasons. However, they perform comparably to age-matched controls after surgery.


The public tends to think that pitchers perform better after a UCL reconstruction. However, a handful of investigators evaluated the impact of UCL reconstruction on post-operative pitching performance and found mixed results. Hence, the authors sought to clarify if a UCL reconstruction related to a change in pitching performance by studying a large cohort of Major League Baseball pitchers. The authors searched team websites, press releases, and baseball statistics websites. They found 168 Major League Baseball pitchers who underwent UCL reconstruction from 1982 to 2010. The authors also identified 178 age-matched controls. They then collected pitching statistics – such as earned run average, walks plus hits per inning pitched, wins, losses, and the number of innings pitched – from the 3 seasons before surgery and the 3 seasons after surgery.

The authors found that the pitchers with a UCL reconstruction had a higher body weight and body mass index than controls. While both groups of pitchers had similar ages, the pitchers with a UCL reconstruction had more than two years of extra MLB experience and were more frequently starting pitchers. Furthermore, the pitchers with a UCL reconstruction performed better than controls during the seasons two and three years before surgery. After UCL reconstruction, pitchers often performed worse than before surgery: 1) worse earned run average (4.15 vs. 4.74), 2) more walks plus hits per inning pitched (1.40 vs. 1.48), and 3) decreased innings pitched (59.81 vs. 50.28). The pitchers also pitched worse during the season before surgery than during the 2 seasons before that. Surprisingly, control pitchers had a worse earned run average than the pitchers with a reconstruction during the first season after surgery. However, the control pitchers pitched more innings and had a higher winning percentage. By the second and third year after surgery, pitchers with and without surgery pitched comparably.


The authors showed that a pitcher might start to perform worse the season before a UCL reconstruction. While many factors relate to poor performance, coaches and clinicians should consider the potential of a UCL injury when a pitcher’s performance declines. Pitchers may believe that elbow discomfort is common and try to pitch through pain, leading to decreased performance and further UCL damage. Clinicians can educate their players about the harm of pitching through elbow pain and create a more interactive environment where players feel comfortable talking about their health.

Interestingly, pitchers with a UCL reconstruction gave up fewer earned runs per inning than controls during the season after surgery but then performed comparably two and three seasons after surgery. However, we need to keep in mind that the pitchers who underwent surgery started before surgery with more Major League Baseball experience and better performance than controls. Furthermore, pitching performance differences during this first year may be related to how pitchers are managed after UCL reconstruction. For example, the decreased workload of starting pitchers who underwent a reconstruction may ensure pitchers do not go through the opposing team’s lineup more than twice (18 plate appearances). Starting pitching performance drops every time through the lineup, with on-base plus slugging percentage jumping from .731 to .771 from the second and third time through the lineup. Relief pitchers who underwent UCL reconstruction may also be put into less stressful/difficult situations the season after surgery, improving their ERA the season after UCL reconstruction. Clinicians should be aware that performance improvements after surgery may be deceiving. When you take a closer look, you may find that other factors may explain the perceived improvement (e.g., prior pitching performance, management factors).

Questions for Discussion

Why do pitchers who undergo UCL reconstruction perform better the season after surgery than controls? What can we do to make UCL reconstruction less prevalent in starting pitchers?

Written by: Ryan Paul
Reviewed by: Steve Thomas

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