A Comprehensive Biomechanical and Clinical Analysis of a Youth Ambidextrous Baseball Pitcher: A Case Report.

Background: Ambidextrous baseball pitchers are a rare phenomenon and present unique challenges in performance optimization and injury mitigation. Biomechanical and clinical analyses are fundamental to understanding performance adaptations and injury risks in developing athletes. Purpose: The purpose of this case report is to describe key biomechanical and clinical differences between the dominant and nondominant throwing arms of a youth ambidextrous baseball pitcher across three timepoints using a multidisciplinary approach. The authors hypothesized that both age-related changes and arm-to-arm differences would be observed in the athlete's anthropometric and biomechanical measurements. Study Design: Case Report. Methods: The athlete was a youth ambidextrous baseball pitcher who underwent voluntary pitching evaluations at ages 11, 12, and 14, while actively competing in organized youth baseball. The athlete first completed a clinical analysis, consisting of a passive range of motion assessment of shoulder internal and external rotation, hip internal rotation, and hamstring flexibility. Then the athlete completed a biomechanical analysis consisting of 3D motion capture to acquire kinematic and kinetic data of both throwing arms. Results: The athlete demonstrated a progressive decline in total shoulder arc of motion bilaterally, with the greatest reduction observed on the nondominant side by age 14. Biomechanical data showed improvement in trunk rotation (>30°) and shoulder abduction angles, aligning with recommended values. However, shoulder distraction force and elbow varus torque increased over time, especially by the third evaluation, potentially reflecting increased pitch velocity and musculoskeletal loading. Conclusion: Few studies have examined side-to-side biomechanical and clinical differences in ambidextrous pitchers. This case highlights changes over time that may reflect developmental adaptations, emphasizing the value of regular monitoring to identify asymmetries and manage injury risk. Level of Evidence: 4.