Invited Clinical Commentary

Glenohumeral Motion Deficits: Friend or foe?

Authors: Manske R, Wilk KE, Davies G, Ellenbecker T, Reinold M

In most shoulder conditions a loss of glenohumeral motion results in shoulder performance impairments. However, in the overhead athlete loss of glenohumeral internal rotation, termed glenohumeral internal rotation deficiency (GIRD), is a normal phenomenon. Without a loss of glenohumeral internal rotation the overhead athlete will not have the requisite glenohumeral external rotation needed to throw a baseball at nearly 100 miles per hour, or serve a tennis ball at velocities of 120 miles per hour or greater. Not all GIRD is pathologic. The authors of this manuscript have defined two types of GIRD; one that is normal and one that is pathologic. Anatomical GIRD (aGIRD) is defined as a normal adaptation in overhead athletes and is characterized by a loss of internal rotation of less than 18°-20° with symmetrical total rotation motion (TROM) bilaterally.   Pathologic GIRD (pGIRD) is defined as a loss of glenohumeral internal rotation greater than 18°-20° with a corresponding loss of TROM greater than 5° when compared bilaterally.  A more problematic motion restriction may be that of a loss of TROM in the glenohumeral joint. Recent evidence supports that a loss of TROM is predictive of future injury to the shoulder in professional athletes. Additionally, external rotation deficiency (ERD), the difference between ER of the throwing shoulder and the non-throwing shoulder of less than 5°, may be another predictor of future shoulder injury and disability.  

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