Shoulder
External rotation lag sign
ERLS
- What you examine
- Tear of supraspinatus and infraspinatus.
- Procedure
- Arm at the side, elbow at 90 degrees. Passively bring the shoulder into near-maximal external rotation and let go.
- Positive when
- With the arm at the side, the forearm visibly drops back into internal rotation; the difference from the passively achieved position is the lag.
- What the test is worth
- Sensitivity around 0.45 and specificity around 0.94, rising with the size of the tear. A lag of more than ten degrees is clinically relevant.
- Caution
- Measure the lag in degrees and record it: it is one of the few cuff tests yielding a number to track recovery with.
- Body region
- Shoulder