Triplane Fracture (Ankle)

Description

A triplane fracture is a more complex ankle fracture that occurs in older adolescents as the ankle growth plate is in the middle of closing. The break travels through the bone in three different planes, hence the name, and a CT scan is often used to map it.

How it happens (the mechanism)

This usually happens from a twisting injury, such as rolling the ankle in sports. The growth plate at the bottom of the shinbone does not close all at once. Over about a year and a half in the early teen years, it closes in a set order: it starts near the middle, then the inner side closes, and the outer side closes last. While part of the plate is closed and part is still open, a twisting force takes the weakest path, through the open parts. That sends the break through the bone in three directions: up and down through the end of the bone, sideways along the growth plate, and front to back through the bone above it. A CT scan shows exactly where the pieces are. A well-lined-up fracture can then be treated in a cast, and a shifted one can be fixed precisely, usually with screws.

What matters

Because these happen near the end of growth, growth problems are usually not the concern: there is little growth left to disturb. The focus shifts to restoring the smooth joint surface of the ankle, which is why the fracture is mapped with a CT and the joint is aligned precisely.

Symptoms

A painful, swollen ankle after a twisting injury, with difficulty bearing weight.

Doctor examination and imaging

The doctor examines the ankle and its circulation and feeling; X-rays show the fracture and a CT scan maps the three-plane pattern to guide treatment.

Nonsurgical treatment

A well-aligned fracture is treated in a cast, with X-rays to confirm it stays in position.

Surgical treatment

A displaced fracture, especially through the joint surface, is realigned, often through a small operation with screws, to restore a smooth ankle.

Recovery and long-term outlook

Outcomes are generally reassuring, since growth is nearly complete; restoring the joint surface is what protects long-term ankle health.

When to call the doctor

Call the office right away if your child’s toes become numb, pale, blue, or cold; pain keeps worsening even after raising the leg and giving medicine; swelling does not improve with elevation; the cast feels too tight, cracked, or wet, or smells bad; or your child develops a fever.

Learn more

OrthoInfo (AAOS), Growth Plate Fractures: orthoinfo.aaos.org (opens in a new tab)

This information is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. For specific concerns about your child, consult a board-certified, fellowship-trained pediatric orthopaedic surgeon.

More for families

OrthoKids · POSNA

POSNA's OrthoKids: illustrated, family-friendly information on this condition.

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