External rotation lag sign revisited: accuracy for diagnosis of full thickness supraspinatus tear.

HYPOTHESIS: This study reassessed the sensitivity and the specificity of the external rotator lag sign (ERLS) for diagnosis of supraspinatus tears in a large cohort of patients.

MATERIALS AND METHODS: The ERLS was used to assess 401 consecutive patients with 406 painful shoulder conditions. The clinical diagnosis was controlled either arthroscopically or by open surgery.

RESULTS: For isolated full-thickness supraspinatus tears, the ERLS had a sensitivity of 56% and a specificity of 98%. When the lesion involved the infraspinatus and the teres minor the sensitivity improved substantially. There was a strong correlation between the extension of the tear and the amount of the lag. The lag increased from 7 degrees for an isolated rupture of the supraspinatus tendon to 26 degrees in case of extension to the teres minor.

CONCLUSION: The ERLS is highly specific and acceptably sensitive for diagnosis of full-thickness tears, even in case of an isolated lesion of the supraspinatus tendon.

LEVEL OF EVIDENCE: Level 2; Prospective cohort treatment study.