Children's fractures: buckle, greenstick and plastic bowing

Written by the X-Ray Atlas editorial team from the sources listed below · Medical review pending · Updated 24 October 2026 · Level: Beginner

Children's bones are more flexible than adults'. Their cortex is more porous and the periosteum is thick and strong, so a child's bone often bends, buckles or breaks on one side only rather than snapping cleanly. These incomplete fractures are among the most common injuries in childhood, especially of the distal forearm. Recognising the type matters, because a stable buckle fracture can be managed with a removable splint, while a greenstick fracture may need reduction. This page covers the patterns, how to tell them apart, and the injuries they can hide.

1. Why children's bones break differently

• Flexible bone: a child's bone can absorb more bending before it fails, so it may deform without a visible line.
• Thick periosteum: the strong outer sleeve often stays intact on one side, holding fragments together and helping fast healing.
• Weak growth plate: the cartilage physis is weaker than ligament, so injuries near joints may involve the growth plate instead (see Salter-Harris fractures).
• Porous metaphysis: the flared ends of long bones have thin cortex and crumple under compression, which is why buckle fractures cluster there.

2. How to look

• Use two orthogonal views. A buckle can be obvious on one and nearly invisible on the other.
• Include the joints above and below for forearm and lower leg injuries. One bone rarely fails alone in the forearm without something happening to the other bone or a joint.
• Trace the cortex of both bones as a smooth line. Any kink, bump, step or sharp angle where the metaphysis meets the shaft is suspicious. The normal metaphysis flares smoothly.
• Look at the soft tissues: swelling and displaced fat planes (such as the pronator quadratus fat pad at the wrist) support a fracture.
• Check the growth plate and the epiphysis on both views. A "buckle" that reaches the physis is a different injury.

The general description template is in how to describe a fracture.

3. The patterns

Pattern	What happens	X-ray	Typical site
Buckle (torus) fracture	Compression along the bone crumples the cortex.	A bulge, kink or ripple of the cortex on the compression side, with no break in the opposite cortex. Often seen on both sides of a bone as a subtle bump.	Distal radial metaphysis (the most common), distal ulna, distal tibia.
Greenstick fracture	Bending force breaks one side and bends the other, like a young twig.	The cortex is broken on the tension (convex) side, while the compression (concave) side is bent but intact. There is often visible angulation.	Forearm shafts (radius and ulna).
Plastic (bowing) deformation	The bone bends beyond its elastic limit without a fracture line.	Curvature with no visible fracture line. Easy to miss without comparing with the expected straight shape or the other side.	Ulna and fibula, often with a fracture of the partner bone.
Complete fracture	Both cortices break, as in adults.	Transverse, oblique or spiral line through both cortices.	Any long bone.

4. Buckle or greenstick?

The distinction changes management, so state clearly which you think it is:

• A buckle fracture has no cortical break; it is a bump. Both cortices may be bumped, but neither is broken through, and the bone is not significantly angulated.
• A greenstick fracture has a definite break in one cortex, usually with angulation.
• If there is a line through the cortex, or the bone is angulated, it is not a simple buckle.

5. Toddler's fracture

A toddler's fracture is an undisplaced spiral or oblique fracture of the distal tibial shaft in a newly walking child, typically aged about 9 months to 3 years. The child usually limps or refuses to bear weight after a minor twist or fall, which may not have been witnessed.

• The initial X-ray may be normal. The line can be hair-thin and seen on one view only. An oblique view can help, if your protocol allows.
• If the first film is normal but the child cannot bear weight, many centres immobilise and repeat the X-ray at 7–10 days, when periosteal new bone or a sclerotic line may appear.
• A similar fracture in a child who is not yet walking needs a safeguarding assessment (see non-accidental injury).

6. Remodelling: what corrects itself

Children's bones can straighten as they grow, which is why some angulation is accepted without manipulation. Remodelling is generally greater when:

• the child is younger, with more growth remaining;
• the fracture is close to a physis, especially a fast-growing one such as the distal radius;
• the angulation is in the plane of movement of the nearby joint.

Rotational deformity does not remodel well, and nor do displaced intra-articular fractures. Acceptable limits vary with the bone and age, and are decided by the orthopaedic team, not from a single film.

7. Pitfalls and mimics

• Missing the second injury: a greenstick fracture of one forearm bone with plastic bowing of the other, or an ulnar fracture with a radial head dislocation (Monteggia). Check the radiocapitellar line on every forearm film.
• Normal metaphyseal flare mistaken for a buckle: the normal contour is a smooth, gentle curve without a sharp angle or step.
• Nutrient canals mimicking fracture lines: they are thin, smoothly marginated and run obliquely through one cortex.
• Plastic bowing called normal: compare with the other side if genuinely unsure.
• Distal radius fractures in adults behave differently (see distal radius fractures).
• Pathological fractures: a fracture after trivial injury, or through a lucent area, may involve a bone cyst or lesion (see bone tumours).

Red flags: act now

What to focus on, by role

Role	Priorities
Medical student	Define buckle, greenstick and plastic bowing, and explain why children's bones behave differently.
Nurse / ENP	Apply the local buckle fracture pathway (removable splint, written advice), check circulation and sensation, and recognise when an injury needs orthopaedic review.
Junior doctor	Separate buckle from greenstick and Salter-Harris II, image the joints above and below, and look for the second injury.
Radiographer	True AP and lateral views including both joints for forearm and leg shafts, and an oblique for a suspected toddler's fracture where the protocol allows.
Advanced / FRCR	Subtle plastic bowing, Monteggia variants, acceptable angulation by age, and fractures that should prompt safeguarding review.

Practise on paediatric X-rays →

References

1. National Institute for Health and Care Excellence. Fractures (non-complex): assessment and management (NG38). nice.org.uk
2. Radiopaedia. Distal radius fracture. radiopaedia.org
3. Radiopaedia. Monteggia fracture-dislocation. radiopaedia.org
4. Radiology Masterclass. Fracture description. radiologymasterclass.co.uk
5. Don't Forget the Bubbles. Paediatric emergency medicine education. dontforgetthebubbles.com

For education only. Not a substitute for a formal report, senior review or your local policy. Never use this page to make decisions about a real patient.