EFFECT OF SUBSCAPULARIS MANIPULATION ON GLENOHUMERAL INTERNAL ROTATION DEFICIT.

Abstract

Purpose A common entity among overhead throwers, glenohumeral internal rotation deficit (GIRD), is defined as significantly decreased glenohumeral internal rotation of the throwing shoulder when compared with the nonthrowing shoulder. Throwers also demonstrate a significant gain in external rotation of the throwing shoulder compared with the nonthrowing shoulder. The function of the throwing shoulder is unaffected as long as every degree of internal rotation loss is accompanied by a degree of external rotation gain and the total motion arc from maximal internal rotation to maximal external rotation remains approximately 180°. It is when the loss of internal rotation exceeds the gain in external rotation that shoulder problems such as subacromial impingement, superior labral injury, anterior capsular failure, and posterosuperior rotator cuff injury may arise. Explanations that have been offered for this pathologic change in glenohumeral range of motion include posterior capsule tightness, humeral osseous adaptation and posterior muscle tightness, and subtle microtraumatic injury to shoulder joint restraints from repetitive overhead throwing. Posteroinferior capsular stretching and external rotator stretching and strengthening are two therapies that have been recommended for treating GIRD. There are no reports in the literature of subscapularis manipulation as therapy for decreasing GIRD. If such therapy is successful, it may help elucidate the origin of the pathologic cascade leading to shoulder injuries in overhead throwing athletes. Methods A case series of subscapularis manipulation was performed on 20 overhead student athletes with documented asymptomatic GIRD of greater than 20° or GIRD greater than 20% of non-throwing side internal rotation. Range of motion measurements, including internal rotation, external rotation, and cross-shoulder adduction, were obtained pre- and postmanipulation. Subscapularis manipulation was performed by an experienced physiotherapist who was blinded to measurement, and measurement was likewise performed, blinded to manipulation. Paired t-tests were used to compare pre- and postmanipulation glenohumeral internal rotation. Results and Conclusions Data are currently in the process of being collected and analyzed. Clinical Relevance This is a pilot study to set the platform for future investigation on the effect of subscapularis manipulation on glenohumeral range of motion. If this technique is shown to be beneficial to glenohumeral range of motion, it should supplement the current therapies for treating GIRD and preventing disabling shoulder injuries that must be treated with surgical intervention.