Musculoskeletal imaging: posterior shoulder dislocation: 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 · Musculoskeletal imaging: posterior shoulder dislocation

Sample item

After a generalised seizure a patient holds the arm internally rotated and cannot externally rotate it. The AP shoulder radiograph looks almost normal but shows a rounded humeral head with a light-bulb outline and loss of joint overlap. What is the injury?

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

The answer and the reasoning

D. Posterior glenohumeral dislocation

Posterior dislocation is easily missed on an AP view because the head sits behind the glenoid, giving a light-bulb outline from internal rotation. It follows seizures and electric shock, and an axillary view or CT confirms it.

Option by option

  • A. Inferior dislocation (luxatio erecta)

    Luxatio erecta fixes the arm in full abduction overhead, with the head inferior to the glenoid.

  • B. Anterior glenohumeral dislocation

    Anterior dislocation holds the arm abducted and externally rotated, with the head below the coracoid.

  • C. Proximal humeral fracture

    A proximal humeral fracture shows cortical breaks that are visible on the radiograph.

  • D. Posterior glenohumeral dislocation (correct)

    Correct. A fixed internally rotated arm with a light-bulb humeral head after a seizure indicates posterior dislocation.

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 Radiology question

What is the answer to this Radiology question?

The best answer is D, Posterior glenohumeral dislocation. Posterior dislocation is easily missed on an AP view because the head sits behind the glenoid, giving a light-bulb outline from internal rotation.

Why is "Inferior dislocation (luxatio erecta)" not the answer?

Luxatio erecta fixes the arm in full abduction overhead, with the head inferior to the glenoid.

Why is "Anterior glenohumeral dislocation" not the answer?

Anterior dislocation holds the arm abducted and externally rotated, with the head below the coracoid.

Why is "Proximal humeral fracture" not the answer?

A proximal humeral fracture shows cortical breaks that are visible on the radiograph.

What concept does this question test?

It tests Musculoskeletal imaging: posterior shoulder dislocation in Radiology. It follows seizures and electric shock, and an axillary view or CT confirms it.

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 Musculoskeletal imaging: posterior shoulder dislocation?

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.