Bone infection: Phemister triad: 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 · Bone infection: Phemister triad

Sample item

Early radiographic changes of tuberculosis of a large joint are described by the Phemister triad. Which is part of it?

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

The answer and the reasoning

B. Juxta-articular osteoporosis

The Phemister triad comprises juxta-articular osteoporosis, peripheral osseous erosions and gradual narrowing of the joint space. Sclerosis and osteophytes are features of osteoarthritis, and the joint space narrows slowly in tuberculosis compared with pyogenic arthritis.

Option by option

  • A. Osteophyte formation

    Osteophytes are typical of osteoarthritis.

  • B. Juxta-articular osteoporosis (correct)

    Correct. Periarticular osteoporosis is one component.

  • C. Periosteal onion-skin reaction

    Onion-skin periosteal reaction suggests Ewing sarcoma.

  • D. Subchondral sclerosis

    Sclerosis suggests osteoarthritis.

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 B, Juxta-articular osteoporosis. The Phemister triad comprises juxta-articular osteoporosis, peripheral osseous erosions and gradual narrowing of the joint space.

Why is "Osteophyte formation" not the answer?

Osteophytes are typical of osteoarthritis.

Why is "Periosteal onion-skin reaction" not the answer?

Onion-skin periosteal reaction suggests Ewing sarcoma.

Why is "Subchondral sclerosis" not the answer?

Sclerosis suggests osteoarthritis.

What concept does this question test?

It tests Bone infection: Phemister triad in Orthopaedics. Sclerosis and osteophytes are features of osteoarthritis, and the joint space narrows slowly in tuberculosis compared with pyogenic arthritis.

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 Bone infection: Phemister triad?

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.