Spine: Mehta rib-vertebra angle difference: 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: Mehta rib-vertebra angle difference

Sample item

A 9-month-old infant has a left thoracic curve of 25 degrees. Which measurement helps predict whether this infantile idiopathic scoliosis will progress?

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

The answer and the reasoning

D. Rib-vertebra angle difference (Mehta)

The Mehta rib-vertebra angle difference compares the angle between the rib and the apical vertebra on the two sides. A difference above about 20 degrees predicts progression of infantile idiopathic scoliosis. Risser sign relates to skeletal maturity in adolescents and is of no use at this age.

Option by option

  • A. Cobb angle of the contralateral side

    The contralateral Cobb angle does not predict progression in this setting.

  • B. Risser sign

    Risser sign assesses iliac apophyseal ossification, which is absent in infancy.

  • C. Hilgenreiner epiphyseal angle

    The Hilgenreiner epiphyseal angle is used in coxa vara.

  • D. Rib-vertebra angle difference (Mehta) (correct)

    Correct. A large rib-vertebra angle difference predicts progression in infants.

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, Rib-vertebra angle difference (Mehta). The Mehta rib-vertebra angle difference compares the angle between the rib and the apical vertebra on the two sides.

Why is "Cobb angle of the contralateral side" not the answer?

The contralateral Cobb angle does not predict progression in this setting.

Why is "Risser sign" not the answer?

Risser sign assesses iliac apophyseal ossification, which is absent in infancy.

Why is "Hilgenreiner epiphyseal angle" not the answer?

The Hilgenreiner epiphyseal angle is used in coxa vara.

What concept does this question test?

It tests Spine: Mehta rib-vertebra angle difference in Orthopaedics. A difference above about 20 degrees predicts progression of infantile idiopathic scoliosis. Risser sign relates to skeletal maturity in adolescents and is of no use at this age.

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: Mehta rib-vertebra angle difference?

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.