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The classic metaphyseal lesion (CML) is a highly specific radiographic finding of non-accidental injury (child abuse) in infants. It represents a fracture through the primary spongiosa of the metaphysis, adjacent to the growth plate.

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It is also called:

Metaphyseal corner fracture
Bucket-handle fracture

Etiopathology

Cause: Repetitive traction, torsion, or shearing forces applied to the metaphysis (e.g., from forceful shaking, yanking, or twisting of extremities).
Occurs because infant bones are soft and the metaphyseal region is mechanically weak.
Unlike accidental injuries (usually diaphyseal fractures), CMLs are strongly associated with child abuse.

Pathophysiology

The injury splits off a fragment of primary spongiosa from the metaphysis.
It extends in a transverse, planar fashion along the metaphyseal margin.
Histologically: subphyseal fracture with extension through calcified cartilage columns.

Radiology

Normal appearance:

![Anatomy of the distal immature long bone (a), demonstrating the normal metaphyseal bone collar as a rim of bone encompassing the growth plate and in contiguity with the metaphyseal cortex with the appearance of a step-off contour and/or a small spur. b Corresponding, labeled longitudinal US image of distal immature long bone

Marine, M.B., Hibbard, R.A., Jennings, S.G. et al. Ultrasound findings in classic metaphyseal lesions: emphasis on the metaphyseal bone collar and zone of provisional calcification. Pediatr Radiol 49, 913–921 (2019). https://doi.org/10.1007/s00247-019-04373-w](attachment:c2f34f38-b0f4-4bda-bbee-57acd8b80102:image.png)

Anatomy of the distal immature long bone (a), demonstrating the normal metaphyseal bone collar as a rim of bone encompassing the growth plate and in contiguity with the metaphyseal cortex with the appearance of a step-off contour and/or a small spur. b Corresponding, labeled longitudinal US image of distal immature long bone

CML imaging appearance:

Imaging factor	Description
Technique	Best seen on frontal and oblique views of long bones (especially knee, distal tibia, proximal humerus, distal radius).
Appearance	• Corner fracture: small, triangular fragment at the edge of metaphysis.
• Bucket-handle fracture: curvilinear density paralleling the metaphysis, giving the appearance of a fragment lifted from bone.
• No associated periosteal reaction initially (develops later).
Involvement	Symmetric, bilateral involvement is common.
• Distal femur
• Proximal tibia
• Distal tibia
• Proximal humerus