Black line sign
The black line sign refers to a linear finding of the articular cartilage on magnetic resonance imaging initially seen the trochlear groove 1-3.
These lesions have been found also in all other regions of articular cartilage in the knee and not only on T2 weighted images but also in other sequences e.g. fat-suppressed proton density-weighted images 4.
Correlation of those findings with arthroscopy showed that a significant number of dark articular lesions linear or non-linear in nature correspond to areas of cartilage degeneration 4.
Therefore it has been suggested that the black line sign or focal areas of low signal intensity within healthy cartilage indicate areas of ‘fissuring’ or ’cartilage degeneration’ 1-4.
- 1. Stephens T, Diduch DR, Balin JI, Gaskin CM. The cartilage black line sign: an unexpected MRI appearance of deep cartilage fissuring in three patients. (2011) Skeletal radiology. 40 (1): 113-6. doi:10.1007/s00256-010-0994-1 - Pubmed
- 2. Wissman RD, Ingalls J, Nepute J, Von Fischer N, Radhakrishnan R, Hendry D, Kenter K. The trochlear cleft: the “black line” of the trochlear trough. (2012) Skeletal radiology. 41 (9): 1121-6. doi:10.1007/s00256-011-1356-3 - Pubmed
- 3. Markhardt BK, Chang EY. Hypointense signal lesions of the articular cartilage: a review of current concepts. (2014) Clinical imaging. 38 (6): 785-91. doi:10.1016/j.clinimag.2014.05.002 - Pubmed
- 4. Markhardt BK, Kijowski R. The Clinical Significance of Dark Cartilage Lesions Identified on MRI. (2015) AJR. American journal of roentgenology. 205 (6): 1251-9. doi:10.2214/AJR.15.14409 - Pubmed