Foot: Jack test in flatfoot: 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 · Foot: Jack test in flatfoot

Sample item

A 9-year-old has a flat arch when standing. When the examiner passively dorsiflexes the great toe, a medial arch appears and the heel inverts. What does this indicate?

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

The answer and the reasoning

C. A flexible flatfoot with a functioning windlass mechanism

The Jack toe-raise test elevates the arch through the windlass mechanism, which tightens the plantar fascia as the great toe is dorsiflexed. Reappearance of the arch indicates a flexible flatfoot, which is usually physiological and needs no treatment. A rigid flatfoot does not correct and needs further assessment for coalition or vertical talus.

Option by option

  • A. A congenital vertical talus

    Congenital vertical talus is rigid and does not form an arch.

  • B. A rigid flatfoot from tarsal coalition

    A rigid flatfoot from coalition does not reconstitute an arch.

  • C. A flexible flatfoot with a functioning windlass mechanism (correct)

    Correct. Arch formation on toe raising indicates a flexible flatfoot.

  • D. An accessory navicular fracture

    The test does not relate to a navicular fracture.

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 C, A flexible flatfoot with a functioning windlass mechanism. The Jack toe-raise test elevates the arch through the windlass mechanism, which tightens the plantar fascia as the great toe is dorsiflexed.

Why is "A congenital vertical talus" not the answer?

Congenital vertical talus is rigid and does not form an arch.

Why is "A rigid flatfoot from tarsal coalition" not the answer?

A rigid flatfoot from coalition does not reconstitute an arch.

Why is "An accessory navicular fracture" not the answer?

The test does not relate to a navicular fracture.

What concept does this question test?

It tests Foot: Jack test in flatfoot in Orthopaedics. Reappearance of the arch indicates a flexible flatfoot, which is usually physiological and needs no treatment. A rigid flatfoot does not correct and needs further assessment for coalition or vertical talus.

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 Foot: Jack test in flatfoot?

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.