Glenohumeral motion deficits: friend or foe?
A GIRD has long been pointed to as a common cause of throwing injuries – in recent literature however, this concept has been challenged and further refined. Other additional measures may help provide a more accurate representation of alterations in ROM that may occur.
Although the rotational arc can differ between the dominant and non-dominant shoulder, a side to side difference in TROM of >5 degrees in either direction contributes to a greater risk for sustaining a throwing injury. Moreover, a Glenohumeral External Rotation Gain of more than 5 degrees is normal – a gain of < 5 degrees in the dominant shoulder is pointed to as an External Rotation Deficit (ERD).
If a GIRD is present, and there is an accessory loss in TROM or an increase in ERD, the condition is pathologic. There is no definitive consensus yet on the threshold value: relative (>20% loss of internal rotation or >10% loss of TROM) and absolute measures (>18 degrees loss of internal rotation), as well as ratios (the side to side difference in internal rotation divided by external rotation) are used. > From: Manske et al., Int J Sports Phys Ther 8 (2013) 537-553. All rights reserved to The Author(s).