Cartilage interface sign, also referred to as double cortex sign, refers to the sonographic presence of a thin markedly hyperechoic line at the interface between the normally hypoechoic hyaline articular cartilage of the humeral head and an abnormally hypoechoic supraspinatus tendon. This arises due to the marked difference in acoustic impedances of the two tissues at the interface 1. The sign indicates the presence of partial or complete supraspinatus tear with fluid replacing the fibers and has been shown to be 100% specific 2. However, it is not often present and has a low sensitivity for supraspinatus tear, around 30% 2.
- 1. Jacobson JA. Fundamentals of musculoskeletal ultrasound. W B Saunders Co. (2007) ISBN:1416035931. Read it at Google Books - Find it at Amazon
- 2. Jacobson JA, Lancaster S, Prasad A et-al. Full-thickness and partial-thickness supraspinatus tendon tears: value of US signs in diagnosis. Radiology. 2004;230 (1): 234-42. doi:10.1148/radiol.2301020418 - Pubmed citation
- 3. Moosikasuwan JB, Miller TT, Burke BJ. Rotator cuff tears: clinical, radiographic, and US findings. Radiographics. 2005;25 (6): 1591-607. doi:10.1148/rg.256045203 - Pubmed citation