OBJECTIVE: We describe the CT and sonographic appearance of 15 costal cartilage fractures observed in eight patients. CONCLUSION: On CT, fracture was seen as a low-density area through the costal cartilage, with surrounding calcifications present near old fractures, and gas density within the cleft in some cases. On sonography, cartilage fracture appeared as an interruption of the smooth anterior aspect of the cartilage.
Malghem, J., Vande Berg, B. C., Lecouvet, F., & Maldague, B. (2001). Costal cartilage fractures as revealed on CT and sonography. American Journal of Roentgenology, 176(2), 429-432. https://doi.org/10.2214/ajr.176.2.1760429 (Original work published 2001)