Glenohumeral internal rotation deficit in throwing athletes: current perspectives

Abstract

Glenohumeral internal rotation deficit (GIRD) is an adaptive process in which the throwing shoulder experiences a loss of internal rotation (IR). GIRD has most commonly been defined by a loss of >20° of IR compared to the contralateral shoulder. Total rotational motion of the shoulder is the sum of internal and external rotation and may be more important than the absolute value of IR loss. Pathologic GIRD has been defined as a loss of IR combined with a loss of total rotational motion. The leading pathologic process in GIRD is posterior capsular and rotator-cuff tightness, due to the repetitive cocking that occurs with the overhead throwing motion. GIRD has been associated with numerous pathologic conditions, including posterior superior labral tears, partial articular-sided rotator-cuff tears, and superior labral anterior-to-posterior tears. The mainstay of treatment for patients with GIRD is posterior capsular stretching and strengthening to improve scapular mechanics. In patients who fail nonoperative therapy, shoulder arthroscopy can be performed. Arthroscopic surgery in the high-level throwing athlete should be to restore them to their functional baseline with the minimum amount of intervention possible.

Keywords: GIRD; internal impingement; shoulder; throwing athlete.

Figure 1

The six phases of the throwing motion: windup, early cocking, late cocking, acceleration, ball release and deceleration, and follow-through. Note: Reproduced with permission from Braun S, Kokmeyer D, Millett PJ. Shoulder injuries in the throwing athlete. J Bone Joint Surg Am. 2009;91(4):966–978. Available from: https://journals.lww.com/jbjsjournal/Abstract/2009/04000/Shoulder_Injuries_in_the_Throwing_Athlete.29.aspx.

Figure 2

Total rotation motion of the shoulder is the summation of passive ER and IR. Notes: In overhead throwers, the arc of motion is shifted more posteriorly (external), which can lead to GIRD. Copyright ©2011. SAGE journals. Reproduced from Wilk KE, Macrina LC, Fleisig GS, et al. Correlation of glenohumeral internal rotation deficit and total rotational motion to shoulder injuries in professional baseball pitchers. Am J Sports Med. 2011;39(2):329–335. Abbreviations: GIRD, glenohumeral internal rotation deficit; ER, external rotation ; IR, internal rotation.

Figure 3

Magnetic resonance imaging of the throwing shoulder. Notes: (A) Axial MRI of the shoulder (T₁), with small black arrows showing thickening of the posterior capsule; (B) MR arthrography (T₂) performed in the ABER position, with small white arrow showing an articular-sided tear in the supraspinatus tendon. Copyright ©2015. John Wiley and Sons. Reproduced with permission from Fessa CK, Peduto A, Linklater J, Tirman P. Posterosuperior glenoid internal impingement of the shoulder in the overhead athlete: pathogenesis, clinical features and MR imaging findings. J Med Imaging Radiat Oncol. 2015;59(2):182–187.³⁶ Abbreviations: ABER, abduction and external rotation.