Spine: odontoid fracture classification: practice question

A Orthopaedics question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Orthopaedics · Spine: odontoid fracture classification

Sample item

In the Anderson and D'Alonzo classification, which type of odontoid fracture has the highest risk of nonunion?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Type II, through the base of the dens

Type I is an avulsion of the tip, type II lies at the junction of the dens and body and is the commonest, and type III extends into the body of C2. Type II has a watershed blood supply and a high nonunion rate, so fixation is often needed in older adults.

Option by option

  • A. Type I, through the tip of the dens

    Type I is stable and heals well.

  • B. Type III, extending into the body of C2

    Type III has a large cancellous surface and unites well in a halo or collar.

  • C. All have the same risk

    The risk varies by type.

  • D. Type II, through the base of the dens (correct)

    Correct. The type II fracture is prone to nonunion.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Orthopaedics question

What is the answer to this Orthopaedics question?

The best answer is D, Type II, through the base of the dens. Type I is an avulsion of the tip, type II lies at the junction of the dens and body and is the commonest, and type III extends into the body of C2.

Why is "Type I, through the tip of the dens" not the answer?

Type I is stable and heals well.

Why is "Type III, extending into the body of C2" not the answer?

Type III has a large cancellous surface and unites well in a halo or collar.

Why is "All have the same risk" not the answer?

The risk varies by type.

What concept does this question test?

It tests Spine: odontoid fracture classification in Orthopaedics. Type II has a watershed blood supply and a high nonunion rate, so fixation is often needed in older adults.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Spine: odontoid fracture classification?

Pair each fracture with its classic complication and nerve injured. Then use the flashcards and the other Orthopaedics questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.