MSK imaging: unstable osteochondritis dissecans: practice question

A Radiology 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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Radiology · MSK imaging: unstable osteochondritis dissecans

Sample item

A 14-year-old athlete has knee pain, and MRI shows an osteochondritis dissecans lesion of the medial femoral condyle. Which finding suggests an unstable fragment?

AA normal subchondral plateBA high T2 signal line of fluid behind the fragmentCA small area of marrow oedema aloneDIntact overlying cartilage with no fluid line

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

The answer and the reasoning

B. A high T2 signal line of fluid behind the fragment

Fluid tracking between the fragment and its bed indicates loss of attachment and instability, which may need fixation. Intact cartilage and no fluid favour a stable lesion that can be managed conservatively. MRI is the best test for stability.

Option by option

A. A normal subchondral plate
A normal plate suggests no fragment problem.
B. A high T2 signal line of fluid behind the fragment (correct)
Correct. A fluid line beneath the fragment shows instability.
C. A small area of marrow oedema alone
Isolated oedema does not show detachment.
D. Intact overlying cartilage with no fluid line
Intact cartilage without fluid indicates a stable lesion.

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.

Questions about this Radiology question

What is the answer to this Radiology question?

The best answer is B, A high T2 signal line of fluid behind the fragment. Fluid tracking between the fragment and its bed indicates loss of attachment and instability, which may need fixation.

Why is "A normal subchondral plate" not the answer?

A normal plate suggests no fragment problem.

Why is "A small area of marrow oedema alone" not the answer?

Isolated oedema does not show detachment.

Why is "Intact overlying cartilage with no fluid line" not the answer?

Intact cartilage without fluid indicates a stable lesion.

What concept does this question test?

It tests MSK imaging: unstable osteochondritis dissecans in Radiology. Intact cartilage and no fluid favour a stable lesion that can be managed conservatively. MRI is the best test for stability.

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 MSK imaging: unstable osteochondritis dissecans?

Learn signs with the image, and the disease they point to. Then use the flashcards and the other Radiology 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.