Fractures in children: supracondylar: 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 · Fractures in children: supracondylar

Sample item

A 6-year-old falls on an outstretched hand and has a displaced supracondylar fracture of the humerus. After the injury he cannot form an 'OK' sign with the thumb and index finger, which stay extended. Which nerve is injured?

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

The answer and the reasoning

A. Anterior interosseous nerve

The anterior interosseous nerve, a branch of the median nerve, is the nerve most often injured in extension-type supracondylar fractures. It supplies flexor pollicis longus, the lateral half of flexor digitorum profundus and pronator quadratus, so the child cannot flex the interphalangeal joint of the thumb and the distal joint of the index finger, and the 'OK' sign fails. The brachial artery must also be checked.

Option by option

  • A. Anterior interosseous nerve (correct)

    Correct. Loss of flexion at the thumb interphalangeal and index distal joints shows anterior interosseous palsy.

  • B. Radial nerve

    Radial nerve injury causes wrist and finger drop, not failure of the pinch.

  • C. Musculocutaneous nerve

    The musculocutaneous nerve supplies the elbow flexors and is not related to hand function.

  • D. Ulnar nerve

    Ulnar nerve injury causes clawing and weak finger abduction, and is more typical of flexion-type injuries.

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 A, Anterior interosseous nerve. The anterior interosseous nerve, a branch of the median nerve, is the nerve most often injured in extension-type supracondylar fractures.

Why is "Radial nerve" not the answer?

Radial nerve injury causes wrist and finger drop, not failure of the pinch.

Why is "Musculocutaneous nerve" not the answer?

The musculocutaneous nerve supplies the elbow flexors and is not related to hand function.

Why is "Ulnar nerve" not the answer?

Ulnar nerve injury causes clawing and weak finger abduction, and is more typical of flexion-type injuries.

What concept does this question test?

It tests Fractures in children: supracondylar in Orthopaedics. It supplies flexor pollicis longus, the lateral half of flexor digitorum profundus and pronator quadratus, so the child cannot flex the interphalangeal joint of the thumb and the distal joint of the index finger, and the 'OK' sign fails. The brachial artery must also be checked.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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 Fractures in children: supracondylar?

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.