Release Location in a Risk Factor for Ulnar Collateral Ligament Reconstruction in Major League Baseball Pitchers

OBJECTIVES: Medial ulnar collateral ligament reconstruction (UCLR) is a common procedure performed for Major League Baseball (MLB) pitchers. The etiology of UCL injury is complex and not entirely understood. The purpose of this study was to use publically available pitch tracking technology (PITCHf/x) to compare the pre-injury throwing mechanics of MLB pitchers who require UCL reconstructive surgery with those of pitchers who have never undergone UCL reconstruction. METHODS: Pitch tracking and demographic data on MLB pitchers who had undergone UCL reconstruction between the 2010 and 2017 seasons was gathered. Pitchers were excluded if they did not throw 100 total pitches in each of the three years prior to surgery. Furthermore, only pitch types that a given pitcher utilized more than 25 times in each of the three years prior to surgery were included for individual analysis. Pitch type, release location, and velocity were compared between the UCL reconstructive surgery cohort and a matched-control cohort. RESULTS: The average pitch release location for pitchers who required UCL reconstruction was more lateral in the two years immediately preceding surgery than the control cohort (p=0.001 and p=0.023). Furthermore, a time-based comparison between the year immediately preceding surgery and two years prior showed a more lateral release immediately prior to surgery (p=0.036). Pitchers who required UCL reconstruction throw similar rates of fastballs as the control cohort and the average pitch velocity and fastball velocity were similar between the UCL group and the control group. The control pitchers displayed a significant decrease in average pitch velocity (p=0.005) and average fastball velocity (p=0.012) over the period of the study. CONCLUSION: Pitch tracking indicates pitch selection and pitch velocity are similar before that the average release point is more lateral preceding UCL reconstruction as compared to the control cohort suggesting that pitch release location might be an independent risk factor for UCL injury and reconstruction. On the other hand, pitch selection and pitch velocity are similar between these cohorts. Powerful technology including PITCHf/x allows for accurate monitoring of factors such as arm position and could potentially be used to identify pitchers at risk for UCL rupture.