Paediatric: hinge abduction in Perthes disease: 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 · Paediatric: hinge abduction in Perthes disease

Sample item

A 9-year-old with Perthes disease and a deformed, enlarged femoral head has pain on abduction. Radiographs on abduction show the lateral margin of the head impinging on the acetabular edge, with the joint opening medially. What is this called?

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

The answer and the reasoning

D. Hinge abduction

In hinge abduction an enlarged, flattened femoral head cannot enter the acetabulum on abduction and hinges on the lateral edge, leaving a medial gap. It is a poor prognostic feature of Perthes disease and may be treated with a valgus or other femoral osteotomy. It is revealed on an abduction arthrogram.

Option by option

  • A. Coxa vara adiposogenital

    Coxa vara adiposogenital is not a standard term for this finding.

  • B. Chondrolysis

    Chondrolysis is cartilage necrosis with joint space narrowing.

  • C. Wandering acetabulum

    Wandering acetabulum occurs in tuberculosis of the hip.

  • D. Hinge abduction (correct)

    Correct. Lateral impingement with a medial gap on abduction is hinge abduction.

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, Hinge abduction. In hinge abduction an enlarged, flattened femoral head cannot enter the acetabulum on abduction and hinges on the lateral edge, leaving a medial gap.

Why is "Coxa vara adiposogenital" not the answer?

Coxa vara adiposogenital is not a standard term for this finding.

Why is "Chondrolysis" not the answer?

Chondrolysis is cartilage necrosis with joint space narrowing.

Why is "Wandering acetabulum" not the answer?

Wandering acetabulum occurs in tuberculosis of the hip.

What concept does this question test?

It tests Paediatric: hinge abduction in Perthes disease in Orthopaedics. It is a poor prognostic feature of Perthes disease and may be treated with a valgus or other femoral osteotomy. It is revealed on an abduction arthrogram.

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 Paediatric: hinge abduction in Perthes disease?

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.