Diagnosis: Forearm radiograph shows a fracture as bulged cortex at the distal end of the radius. This is a classic torus (buckle) fracture.
Key Takeaways and Discussion: Axial loading on extremity with/without other forces (i.e. varus, valgus, hyperextension or hyperflexion). Failure of cortex on the compression side, resulting in fracture. Torus (buckle) fracture of distal radius and ulna is most common fracture in lower forearm of young children. Two appearances are typically seen: 1) classic buckle fracture — cortex bulges outward, 2) angled buckle fracture — cortex angles inward (the second type is more difficult to appreciate)
Jadhav SP, Swischuk LE. Commonly missed subtle skeletal injuries in children: a pictorial review. Emerg Radiol 2008 (November)
Source: RadiologyinThai.com – Dr. Rathachai Kaewlai, M.D.