Preventing Tommy John Surgery: The Identification of Trends in Pitch Selection, Velocity, and Spin Rate Before Ulnar Collateral Ligament Reconstruction in Major League Baseball Pitchers

Background: Ulnar collateral ligament (UCL) reconstruction is a common surgery among Major League Baseball (MLB) pitchers that results in a significant number of missed games. Little has been reported regarding game-by-game trends that can identify those on the verge of becoming injured. Purpose: To determine if there is a patterned change in MLB pitchers' pitch selection, velocity, or spin rate in games leading up to Tommy John surgery that may predict subsequent UCL surgery. Study Design: Case series; Level of evidence, 4. Methods: A retrospective review of MLB pitchers who underwent primary UCL reconstruction between 2009 and 2019 was performed. Pitch characteristics were evaluated on a game-by-game basis for the 15 games leading up to surgery. A Mann-Kendall trend test was used to identify trends in pitch selection, velocity, and spin rate for multiple pitch types. A Kendall tau(b) correlation coefficient was identified, with values closer to 1 or -1 signifying a stronger monotonic trend. Results: A total of 223 MLB pitchers underwent UCL reconstruction in the time period. In the 15 games leading up to surgery, decreases in pitch velocity for 4-seam fastballs (tau(b) = -0.657; P < .001), 2-seam fastballs (tau(b) = -0.429; P = .029), and sliders (tau(b) = -0.524; P = .008) were significantly associated with game number closer to injury. There was a significant positive association in the spin rate for cutters (tau(b) = 0.410; P = .038) and a significant negative association in spin rate for 4-seam fastballs over the course of these 15 games (tau(b) = -0.581; P = .003). In addition, there was a significant positive association in the percentage of curveballs thrown (tau(b) = 0.486; P = .013). Conclusion: The study results suggest that there is a patterned change in certain pitch statistics in MLB pitchers in the games leading up to Tommy John surgery. Although the absolute change from game to game may be small, it may be possible for these trends to be monitored before a player becomes injured, thus reducing the significant burden Tommy John surgery places on these athletes.