Correlation of Joint Space Widening on Valgus Stress Magnetic Resonance Imaging With Level of Play and Innings Pitched in Professional Pitchers

BACKGROUND: Previous studies have described various techniques and confirmed the clinical utility of valgus stress radiography and stress ultrasound in overhead athletes. The addition of valgus stress and a high-resolution anatomic assessment of the elbow with magnetic resonance imaging (MRI) in the active throwing position (flexed elbow valgus external rotation [FEVER] view) can add valuable diagnostic or prognostic information in throwing athletes. PURPOSE/HYPOTHESIS: The purpose of this study was to evaluate findings on MRI and subsequent performance in professional throwing athletes. It was hypothesized that joint space widening in the FEVER view would be predictive of performance and the risk of subsequent injuries. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: All pitchers on 2 Major League Baseball teams who consented to participate during their preseason screening in 2019 and 2020 underwent standard and FEVER MRI, and performance data from the following season were recorded, including injuries, mean throwing velocity, number of innings pitched, strikeout percentage, walk percentage, weighted on-base average, and level of play reached (not signed, minor league, or major league). Categorical variables were compared using the Fisher exact test or chi-square test, and continuous variables were compared using the Kruskal-Wallis test, as appropriate. Ordered logistic regression was used to determine the independent factors predicting performance. RESULTS: A total of 91 players underwent preseason imaging, and all players had subsequent performance data available. Multivariate analysis revealed that when controlling for age, mean velocity, history of injuries, presence of symptoms, and history of ulnar collateral ligament reconstruction, increased absolute joint space widening was predictive of a lower level of play (β = −0.63; P = .042). Univariate analysis demonstrated a significant correlation between relative joint space widening and level of play reached (β = −0.54; P = .034). Relative joint space widening remained a significant predictor of level of play (β = −0.87; P = .012) on multivariate analysis. Multivariate analysis also showed that both absolute joint space widening (β = −13.50; P = .012) and relative joint space widening (β = −13.60; P = .026) were predictive of the number of innings pitched in the subsequent season. CONCLUSION: The present study demonstrates that findings on MRI with valgus stress correlated with the level of play reached and number of innings pitched in professional throwing athletes.