Spine: bilateral facet dislocation: 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: bilateral facet dislocation

Sample item

A 30-year-old falls from a height and lands on his head with the neck forced forward. He has quadriparesis. A lateral cervical radiograph shows C5 displaced anteriorly on C6 by more than half the anteroposterior diameter of the vertebral body. What is the injury?

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

The answer and the reasoning

C. Bilateral facet dislocation of C5 on C6

Forward translation of more than 50 percent of the vertebral body width implies that both facet joints have been disrupted. The injury is grossly unstable and the cord is commonly damaged. Unilateral dislocation gives about 25 percent translation and often only a root lesion.

Option by option

  • A. Jefferson fracture of the atlas

    A Jefferson fracture is a ring fracture of C1 from axial load and does not cause forward slip at C5-C6.

  • B. Anterior wedge compression fracture of C5

    A simple wedge fracture keeps the posterior elements and the alignment of the vertebrae intact.

  • C. Bilateral facet dislocation of C5 on C6 (correct)

    Correct. Over 50 percent anterior translation means both posterior facet joints are dislocated, with a high risk of cord injury.

  • D. Unilateral facet dislocation of C5 on C6

    A unilateral dislocation produces translation of about a quarter of the body width and usually spares the cord.

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.

More Orthopaedics questions

Questions about this Orthopaedics question

What is the answer to this Orthopaedics question?

The best answer is C, Bilateral facet dislocation of C5 on C6. Forward translation of more than 50 percent of the vertebral body width implies that both facet joints have been disrupted.

Why is "Jefferson fracture of the atlas" not the answer?

A Jefferson fracture is a ring fracture of C1 from axial load and does not cause forward slip at C5-C6.

Why is "Anterior wedge compression fracture of C5" not the answer?

A simple wedge fracture keeps the posterior elements and the alignment of the vertebrae intact.

Why is "Unilateral facet dislocation of C5 on C6" not the answer?

A unilateral dislocation produces translation of about a quarter of the body width and usually spares the cord.

What concept does this question test?

It tests Spine: bilateral facet dislocation in Orthopaedics. The injury is grossly unstable and the cord is commonly damaged. Unilateral dislocation gives about 25 percent translation and often only a root lesion.

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: bilateral facet dislocation?

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.