Magnetic Resonance Imaging Findings of the Asymptomatic Elbow Predict Injuries and Surgery in Major League Baseball Pitchers

Background: Repetitive pitching produces significant stress on the elbow that may result in structural abnormalities discernable on magnetic resonance imaging (MRI) without causing symptoms. Purpose: To determine whether there exists an association between subclinical MRI findings in asymptomatic elbows of Major League Baseball (MLB) players and future placement on the disabled list (DL) or future operative procedure. Study Design: Cohort study; Level of evidence, 3. Methods: MRI scans of the elbows of professional-level baseball pitchers, taken during routine presigning imaging at a single organization from 2005 to 2017, were retrospectively reviewed. Publicly available databases were queried to exclude pitchers with an injury before the earliest session of elbow MRI. Three blinded reviewers reviewed all MRI scans independently to evaluate for the presence of chondral damage to the joint, loose bodies, ulnar collateral ligament (UCL) heterogeneity or tears, flexor pronator mass defects, and signs of posteromedial (PM) impingement. Binary imaging findings were related to future placement on the DL for elbow complaints and future elbow surgery. Results: A total of 41 pitchers had asymptomatic MRI findings with no prior DL placement. For players who eventually went on the DL, there were a statistically greater number of players with UCL heterogeneity (P = .021), humeral-sided partial UCL tears (P = .031), and PM impingement (P = .004) on preinjury MRI compared with players who remained healthy. PM impingement was related to future elbow-related surgery (P = .003). Pitchers with UCL heterogeneity were associated with reduced career strike zone percentage, innings pitched, and fastball percentage (P < .05 for all). Conclusion: UCL heterogeneity, PM impingement, and humeral-sided partial tears were correlated with future DL placement for elbow-related reasons in MLB pitchers. Asymptomatic PM impingement may be a precursor to future surgery.