Figure 1. Salter-Harris epiphyseal-metaphyseal fracture. (A) Note widening of the distal tibial epiphyseal line (arrows). (B) Normal side for comparison. (C) Older child with a Salter-Harris type I fracture manifesting in a very thin-appearing epiphyseal line (arrows) through the distal radius. Note that the ulnar epiphysis is closed; this can provide a clue to the fact that the radial epiphyseal line is abnormal. (D) Normal side for comparison. Note that the epiphysis is closed.

Figure 2. Buckle fractures. (A) Subtle buckle fracture (arrow) in the distal radius. (B) The fracture (arrow) is more clearly visualized on the lateral view. (C) Typical angled buckle fracture (arrow) in the proximal radius.

Figure 3. Angled buckle fractures in the proximal and distal radius. (A) Note the angled buckle fracture in the proximal radius (arrows). (B) Normal side for comparison; the cortex is smooth. (C) A similar angled buckle fracture (arrows) in the distal radius. (D) Normal side for comparison; the cortex is smooth.

Figure 4. Humeral supracondylar buckle fractures. (A) Posterior buckle fracture. Note the buckled posterior cortex (arrows) secondary to a hyperextensioninduced injury. This fracture represents the low end of the spectrum of supercondylar fractures. Also note that the anterior humeral line intersects the capitellum (dot) through its mid-interior portion. (B) Normal side for comparison. Note that there is no buckle fracture and that the anterior humeral line intersects the capitellum (dot) more posteriorly. (C) Medial buckle fracture. Note the angulated cortex (arrows) resulting from a combination of hyperextension and varus forces. (D) Normal side for comparison. Note how smooth the cortex appears.

Figure 5. Buckle fracture of the anterior tibia. (A) Note the buckle fracture (Fx) and increased concavity (arrows) of the notch for the unossified tibial tubercle. (B) Normal side for comparison. Note how smooth the cortex appears. This fracture is often associated with a subtle, transverse hairline fracture through the upper tibia (see Figure 9).

Figure 6. Bunkbed fracture. (A) Note soft tissue edema and a buckle fracture (arrow) through the base of the first metatarsal. (B) Normal side for comparison; note the smooth cortex.

Figure 7. Classic toddler's fracture. (A) Note the subtle spiral fracture through the distal tibia (arrows). (B) Later, with healing, the fracture is visible more clearly as sclerosis (arrows) occurs along the fracture line.

Figure 8. Other hairline fractures. (A) Typical transverse ulnar hairline fracture (arrows) resulting from a direct blow. (B) Linear, spiral fracture (arrows) through the proximal ulna, resulting from twisting forces. (C) Two very subtle ulnar linear fractures (arrows), resulting from hyperextension and twisting. (D) These fractures (arrows) are easier to detect if the film is held vertically, as in this illustration.

Figure 9. Hairline fracture of the upper tibia. (A) Note the clearly visible transverse fracture (arrows) through the upper tibia. A subtle buckle fracture also is present (large arrow). (B) In this patient, the transverse tibial fracture (arrows) is very subtle, and indeed, hairline. Also note the associated buckle fracture (large arrow).

Figure 10. Plastic bending and greenstick fractures. Note the bent radius and the greenstick fracture (large arrow). Also note the bending fracture of the ulna (arrows).

Figure 11. Radius bending fracture. (A) Note the bent radius (arrows). (B) Normal side for comparison. The radius is straight.

Figure 12. Bending fracture of clavicle. (A) Note the downwardly bending, albeit subtle, fracture (arrows) of the right clavicle. Compare with the normal left clavicle. (B) In this case the right clavicle is upwardly bent (arrows). Compare with the normal left side.

Figure 13. Avulsion fractures. (A) Small avulsion fracture of the coronoid process of the ulna (arrow). (B) Subtle, medial epicondylar avulsion fracture (arrow). The space between the epicondyle and the humerus is too wide. (C) Lateral condylar avulsion fracture (arrow). (D) Another lateral condylar avulsion fracture where only a thin sliver of avulsed bone (arrows) is seen.