The bubble sign: an arthroscopic indicator of an intratendinous rotator cuff tear.

Intratendinous tears of the rotator cuff are, by definition, difficult to diagnose due to the absence of overt tendon disruption on both the bursal and articular surface of the rotator cuff. The authors describe the bubble sign, a bulging expansion of the rotator cuff tendon following injection of saline into the suspected lesion, as a useful indicator of an intratendinous tear of the rotator cuff.