The lateral radiograph above shows the "double-arc" sign (arrow), characteristic of a fracture of coronal fracture. One arc represents the subchondral bone of the capitellum and the other the lateral ridge of the trochlea.
Reproduced with permission from: McKee MD, Jupiter JB, Bamberger HB. Coronal shear fractures of the distal end of the humerus. J Bone Joint Surg Am 1996; 78:49. Copyright © 1996 The Journal of Bone and Joint Surgery, Inc.
https://journals.lww.com/jbjsjournal/pages/default.aspx.