Internal Rotation Lag Sign | Subscapularis Full-Thickness Tear Assessment

The Internal Rotation Lag Sign or medial rotation lag sign is an orthopedic test to assess full-thickness tears of the subscapularis muscle.

According to a study done by Miller et al. (2008) the internal rotation lag sign has a sensitivity of 100% and a specificity of 84% in the diagnosis of full-thickness tears of the subscapularis. However, the study population was small and the confidence intervals were wide.
Therefore, the internal rotation lag sign has a moderate clinical value in our opinion!

To perform this test, have your patient seated with the hand of the painful shoulder placed at the lumbar region. Then lift your patient’s hand off his back passively with one hand at the wrist and the other at the elbow until full almost full internal rotation is reached. Now ask your patient to maintain this position actively and remove your hand at the wrist.

A positive test or a subscapularis tear is indicated by a lag that occurs with the inability of your patient to maintain the hand off his back.

Other orthopedic tests to assess for full-thickness tears of the rotator cuff muscles of the shoulder are:

• Drop Arm Sign
• Lateral Rotation Lag Sign
• Infraspinatus Test
• Transdeltoid Palpation / Rent Test

Miller CA, Forrester GA, Lewis JS. The validity of the lag signs in diagnosing full-thickness tears of the rotator cuff: a preliminary investigation. Archives of physical medicine and rehabilitation. 2008 Jun 1;89(6):1162-8.