Paediatric: stable and unstable slipped epiphysis: 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: stable and unstable slipped epiphysis

Sample item

A 12-year-old obese boy with a slipped capital femoral epiphysis cannot bear weight even with crutches because of severe pain. How is this slip classified, and what is the main risk?

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

The answer and the reasoning

C. Unstable slip; avascular necrosis of the femoral head

The Loder classification defines a stable slip as one in which the child can walk, with or without crutches, and an unstable slip as one in which walking is impossible. Unstable slips carry a high risk of avascular necrosis, which can reach about half of cases in some series. They require urgent fixation with gentle handling and no forceful reduction.

Option by option

  • A. Unstable slip; non-union

    Non-union is not the principal risk of an unstable SCFE.

  • B. Stable slip; chondrolysis only

    A stable slip allows weight bearing, which this child cannot do.

  • C. Unstable slip; avascular necrosis of the femoral head (correct)

    Correct. Inability to bear weight makes the slip unstable, with a high risk of avascular necrosis.

  • D. Stable slip; no risk of avascular necrosis

    A stable slip also has a low but real avascular necrosis risk, and this slip is not stable.

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, Unstable slip; avascular necrosis of the femoral head. The Loder classification defines a stable slip as one in which the child can walk, with or without crutches, and an unstable slip as one in which walking is impossible.

Why is "Unstable slip; non-union" not the answer?

Non-union is not the principal risk of an unstable SCFE.

Why is "Stable slip; chondrolysis only" not the answer?

A stable slip allows weight bearing, which this child cannot do.

Why is "Stable slip; no risk of avascular necrosis" not the answer?

A stable slip also has a low but real avascular necrosis risk, and this slip is not stable.

What concept does this question test?

It tests Paediatric: stable and unstable slipped epiphysis in Orthopaedics. Unstable slips carry a high risk of avascular necrosis, which can reach about half of cases in some series. They require urgent fixation with gentle handling and no forceful reduction.

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: stable and unstable slipped epiphysis?

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.