Quantity Time: Identifying The Benefit Of Ulnar Collateral Ligament Reconstruction In Major League Baseball

Abstract

Reconstruction of the ulnar collateral ligament (UCL), known colloquially as Tommy John surgery, was first performed in 1974. Today, approximately 30 Major League Baseball (MLB) players undergo this procedure annually; however, 57% of recipients are youth, age 15-19. Despite the abundance of subjects and accessibility of statistics, few investigations have studied its long-term effects on performance. PURPOSE: To evaluate changes in pitching performance following UCL reconstruction. METHODS: We compared 3 samples of MLB pitchers: 1) Underwent UCL reconstruction (REC), 2) Sustained an injury without surgical care (INJ), and 3) Never injured (NON). The REC sample was selected at random from a list of players who had pitched at least 2 seasons prior to the operation and at least 2 seasons post-surgery. Matched samples of INJ and NON were created; there were 50 subjects in each group. Mixed ANOVA with repeated measures compared first season statistics to final season statistics, and means of the first 2 seasons to the last 2. Linear regressions tested the effect of UCL reconstruction on changes in performance across those periods, holding all potential confounders constant. RESULTS: Among all 150 pitchers, during the first 2 seasons, they won 53.6% of games, struck out 0.88 ± 0.23 batters per inning, and had an earned run average (ERA) of 4.01 ± 1.14. Between the first 2 and last 2 seasons, REC subjects experienced a 5.7% decrease in win percentage (p=0.063) but struck out 4.7% more batters per inning (p=0.015). Linear regression, evaluating the change from first to last season, found UCL reconstruction to improve winning percentage by 14.4 percentage points (p=0.026); there was no effect on strikeouts per inning (p=0.339) or ERA (p=0.892). UCL reconstruction failed to elicit significance on the change in performance between the first 2 and last 2 seasons in any variable. The ANOVA models found no group effect between first and last season with win percentage (p=0.190), strikeouts per inning (p=0.428), or ERA (p=0.600). Similarly, there was no group effect between the first 2 and last 2 seasons in win percentage (p=0.454), strikeouts per inning (p=0.961), or ERA (p=0.496). CONCLUSION: UCL reconstruction does not appear to compromise the quality of pitching performance, but does prolong the quantity of pitches in a player's career.