Functionally intact rotator cuffs can be distinguished from those with significant tears by a simple perioperative test called the derotation sign.
According to a sensitivity and specificity study by David E. Attarian of Duke University Medical Center, Durham, North Carolina, United States, the derotation sign can specifically diagnose small (<1 cm) full-thickness rotator cuff tears as well as those of grade 3 partial-thickness. This is useful in differentiating such significant tears from insignificant (grades 1 and 2) partial-thickness rotator cuff tears and intact rotator cuffs.
Derotation tests were carried out under general anaesthesia in 123 patients who underwent shoulder arthroscopy for chronic symptomatic rotator cuff disease. Just before arthroscopy, the subject's glenohumeral joint was rapidly distended with fluid.