EXAMINING THE RELATIONSHIPS BETWEEN SHOULDER AND ELBOW SOFT-TISSUE PROPERTIES, THROWING MECHANICS, AND RANGE OF MOTION IN ADULT BASEBALL PITCHERS

ECU Author/Contributor (non-ECU co-authors, if there are any, appear on document)

Christopher J Curran (Creator)

Institution

East Carolina University (ECU )

Web Site: http://www.ecu.edu/lib/

Abstract: Overhead throwing places extremely high loads on soft-tissue structures of the shoulder and elbow, causing pitchers to be injured at an alarming rate. Most researchers believe soft-tissue injuries in pitchers are acute manifestations of chronic microtrauma as a result of repetitive near-maximal loading. While specific mechanical factors and range of motion deficits have been reported as predictors of future injury risk in pitchers, it is unknown how the properties of the tissues themselves are changing in relation to these factors. The primary purposes of this research were to examine the structural and material properties of critical soft-tissue structures in the arms of adult baseball pitchers and to evaluate relationships between those properties and previously identified mechanical and range of motion injury risk factors. The reliability of a novel shearwave ultrasound elastography imaging protocol was developed and tested for inter- and intra-rater reliability and found to be reliable for 10/11 tissue properties. After the completion of protocol design, 26 healthy and currently competitive baseball pitchers participated in bilateral imaging, bilateral range of motion evaluations, and full-body 3D motion capture of the pitching motion. Significant bilateral differences were found in 7 out of the 11 tissue properties examined, displaying the effect pitching on the throwing arm. Pitchers with elevated shoulder kinetics during the pitching motion displayed decreased material stiffness of shoulder tendons, specifically the supraspinatus, infraspinatus, and biceps brachii long head. There were not any relationships between elevated elbow kinetic variables and the properties of the medial elbow or UCL. Pitchers with GIRD and TRM were found to have significantly stiffer supraspinatus muscle than pitchers without GIRD or TRM deficits and a significant interaction was found between Arm and GIRD for supraspinatus tendon stiffness. Additionally, interactions between Arm and TRM and Arm and shoulder flexion deficit were found for UCL stiffness. This research expands the field's understanding of the specific tissue changes occurring in pitchers with previously described injury risk factors. This research provides biological evidence strengthening the argument that soft-tissue shoulder injuries in baseball pitchers result from chronic microtrauma produced by repetitive exposure to extreme loads during the baseball pitching motion.

Additional Information

Publication

Dissertation

Language: English

Date: 2020

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