External Rotation Lag Sign (ERLS)

The External Rotation Lag Sign (ERLS) was first described by Hertel et al. in 1996 as a clinical diagnostic test for identifying full-thickness rotator cuff tears. It is particularly useful for assessing the supraspinatus and infraspinatus tendons, which are key stabilizers of the shoulder and essential for external rotation¹.

Procedure

Patient position

• Patient is seated in a relaxed posture.

Examiner position and movement

1. The examiner flexes the patient’s elbow to 90° and abducts the shoulder to 90°.

2. The shoulder is placed at 5° short of maximum external rotation to prevent capsular recoil.

3. While maintaining elbow support, the examiner releases the patient’s wrist.

4. The patient is asked to actively maintain the position.

Interpretation

• Positive test: The patient cannot maintain the externally rotated position and the arm drifts medially → suggests a full-thickness tear of supraspinatus and/or infraspinatus.

• Small deviations should be compared with the contralateral side, as hyperlaxity or over-rotation by the examiner may affect findings.

Sources of error

• Limited passive mobility of the glenohumeral joint → false results.

• Capsular contracture → possible false negatives.

• Subscapularis tears → may produce false positives.

Diagnostic accuracy

Study	Sensitivity	Specificity	+LR	-LR
Hertel et al. (1996)	91 %	100 %	∞	0.09
Miller et al. (2008)	46 %	94 %	7.2	0.55
Castoldi et al. (2016)	56 %	98 %	28.0	0.45

Interpretation

• Sensitivity: ability to detect tears in those affected.

• Specificity: ability to exclude those without tears.

• Positive LR: very high → strong indication of cuff tear if positive.

• Negative LR: low but not conclusive → a negative test does not fully rule out a tear.

Clinical relevance

• High specificity: A positive ERLS strongly indicates a full-thickness tear of supraspinatus and/or infraspinatus.

• Lower sensitivity: A negative result does not rule out rotator cuff tear; additional tests are recommended.

• Best practice: Use in conjunction with other rotator cuff tests such as:

  • Jobe’s Test (Empty Can)

  • Drop Arm Test

  • Belly-Press Test

• Should be supplemented with MRI or ultrasound for confirmation.

Summary

The External Rotation Lag Sign is a highly specific clinical test for diagnosing full-thickness tears of supraspinatus and infraspinatus.

• Positive test → strongly suggests rotator cuff rupture.

• Negative test → lowers the likelihood, but does not exclude the condition.

• Most valuable when used as part of a test cluster combined with imaging for accurate diagnosis.

References

1. Hertel R, Ballmer FT, Lambert SM, Gerber C. Lag signs in the diagnosis of rotator cuff rupture. J Shoulder Elbow Surg 1996;5:307-13.

2. Miller CA, Forrester GA, Lewis JS. The validity of the lag signs in diagnosing full-thickness tears of the rotator cuff: a preliminary investigation. Arch Phys Med Rehabil 2008;89:1162-8.