The overhand baseball pitch is among the fastest and highest-stress athletic motions. Consequently, pitching-related shoulder and elbow pain occur in up to 30% to 74% of baseball pitchers. Injuries are also common, occurring in 23% to 31% of youth baseball players. During the overhand pitch, the valgus stress experienced by the elbow routinely exceeds the load to failure of the ulnar collateral ligament (UCL). UCL tears are thus among the most commonly encountered injuries and ulnar collateral ligament reconstruction (UCLR) is among the most frequently performed procedures among baseball pitchers, both youth and professional players in Major League Baseball (MLB). The prevalence of this procedure has increased to the point that many surgeons consider it an ‘‘epidemic.’’
Risk factors of pitching-related injury remain incompletely understood. Fatigue is thought to be a risk factor. Various studies have defined fatigue as pitching for multiple teams, for more than 9 months a year, pitching more than 100 innings per year, and throwing more pitches per game, week, season, and year. To prevent pitchers from throwing through fatigue, USA Baseball, Little League America, and MLB have put forth guidelines restricting pitch counts, yet compliance remains an issue.
However, other studies have suggested that the torque placed through the arm during the pitch may be a primary risk factor for injury. In a prospective study of MLB players, elbow valgus torque correlated with subsequent elbow injury. However, elbow valgus torque also correlates with pitch velocity. In the same cohort, peak pitch velocity was found to be an even better predictor of subsequent injury. These findings have been called into question because only 23 pitchers were included. A subsequent large-scale community study in youth pitchers demonstrated velocity to correlate with shoulder and elbow pain and a history of pitching-related injury. These findings have been called into question because a history of injury was used as a primary correlate. As a result, it remains unknown whether velocity correlates with subsequent injury, specifically an injury to the UCL.
The purpose of this study was to determine UCLR- specific predictors among MLB pitchers. We hypothesized that pitch velocity would be a strong predictor of injury and subsequent need for UCLR.