Decreased Upward Vertical Movement for Fastballs After Ulnar Collateral Ligament Reconstruction in Major League Baseball Pitchers

PURPOSE: To analyze the velocity and movement of the 4-seam fastball, curve, and slider thrown before and after ulnar collateral ligament reconstruction (UCLR) in Major League Baseball pitchers using PITCHf/x data. METHODS: Velocity and movement data of the 4-seam fastball, curve, and slider were collected for 3 time frames (12-24 months before the date of UCLR as an uninjured baseline, 12-24 months after the date of UCLR, and 24-36 months after the date of UCLR). Pitchers were separated into 3 age groups (<26, 26 to 31, and >31 years). A paired t-test for means was used to assess mean differences between 2 time periods and a generalized linear model, with time-dependent covariance structure and age group as a covariate, was used to determine differences across time. All analyses were performed using SAS, version 9.4. RESULTS: Vertical movement of the 4-seam fastball decreased in the 24 to 36 months’ postoperative time frame, compared with 12 to 24 months’ preoperatively (9.46 to 9.14 inches, P = .032). Movement decreases in the 4-seam fastball were not age-related. Velocity did not significantly change for any pitch and movement did not change for the slider or curve pitches. CONCLUSIONS: Following UCLR, Major League Baseball pitchers experienced no changes in horizontal or vertical movement or velocity of the curve or slider in either time frame. Decreased upward vertical movement of the fastball occurred after UCLR at final follow-up, but no change was observed in velocity. Similar trends in pitch movement and velocity effects were observed regardless of age. LEVEL OF EVIDENCE: IV, case series.