Dislocations: posterolateral rotatory instability of the elbow: 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 · Dislocations: posterolateral rotatory instability of the elbow

Sample item

Months after an elbow dislocation, a man feels the elbow give way and click when pushing up from a chair with the forearm supinated. Which ligament is deficient?

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

The answer and the reasoning

D. Lateral ulnar collateral ligament

Deficiency of the lateral ulnar collateral ligament allows the radial head and ulna to rotate off the humerus in a posterolateral direction, causing posterolateral rotatory instability. The lateral pivot-shift test reproduces it, with the apprehension greatest near 40 degrees of flexion. Treatment is ligament reconstruction.

Option by option

  • A. Anterior band of the medial collateral ligament

    The medial collateral ligament resists valgus and is not the cause here.

  • B. Annular ligament alone

    The annular ligament holds the radial head and does not alone explain this instability.

  • C. Quadrate ligament

    The quadrate ligament is a minor structure.

  • D. Lateral ulnar collateral ligament (correct)

    Correct. Lateral ulnar collateral ligament insufficiency causes posterolateral rotatory instability.

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, Lateral ulnar collateral ligament. Deficiency of the lateral ulnar collateral ligament allows the radial head and ulna to rotate off the humerus in a posterolateral direction, causing posterolateral rotatory instability.

Why is "Anterior band of the medial collateral ligament" not the answer?

The medial collateral ligament resists valgus and is not the cause here.

Why is "Annular ligament alone" not the answer?

The annular ligament holds the radial head and does not alone explain this instability.

Why is "Quadrate ligament" not the answer?

The quadrate ligament is a minor structure.

What concept does this question test?

It tests Dislocations: posterolateral rotatory instability of the elbow in Orthopaedics. The lateral pivot-shift test reproduces it, with the apprehension greatest near 40 degrees of flexion. Treatment is ligament reconstruction.

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 Dislocations: posterolateral rotatory instability of the elbow?

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.