Ultrasound-guide Corrected Glenohumeral Internal Rotation Deficit

Background: Glenohumeral internal rotation deficit (GIRD) is believed to be one of the risk factors contributing to shoulder injuries. In addition, athletes with GIRD of greater than 20° appear to be at a greater risk for the shoulder injuries and surgery. Recently, GIRD can be divided in anatomical GIRD and pathological GIRD (pGIRD). The dominant arm of the athletes with pGIRD have not only humeral retrotorsion (HR) but also stiffer posterior capsule. The soft-tissue effect is believed to be the key point in pathological cascade of throwers. Therefore, the previous studies use gross GIRD as a risk factor may be modified by ultrasound-guide corrected GIRD. Objective: There are 4 objectives for the present study: (1) to investigate the Receiver operating characteristic (ROC) curves of the gross GIRD; (2) to investigate the ROC curves of the ultrasound-guide corrected GIRD; (3) to compare the area under curve (AUC) of the two methods; (4) to compare the gross GIRD and the ultrasound-guide corrected GIRD in baseball players. Design: Baseball players who have played baseball for at least 1 year and still active in training or competition will be recruited in this study. Participant characteristics will be collected by the main assessor, including age, gender, height, weight, dominant arm, practice time, years of playing baseball. Performance/function will be assessed via a Kerlan-Jobe Orthopaedic Clinic shoulder and elbow (KJOC) self-report questionnaire. The shoulder rotation ROM, ultrasound examination including ultrasound-corrected GIRD and posterior capsular thickness and posterior shoulder tightness will also be measured. we will follow subjects for a season. Once the injury occurs, deterioration or at the end of the season, we will collect the data again. Main outcome measures: The shoulder rotation ROM, ultrasound examination and posterior shoulder tightness are main outcomes of the study.