Fractures: mechanism of central fracture dislocation: 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 · Fractures: mechanism of central fracture dislocation

Sample item

A man falls from a height and lands on the side of his hip. Radiographs show a fracture of the medial wall of the acetabulum with the femoral head pushed into the pelvis. Which mechanism is responsible?

AA lateral blow over the greater trochanterBA direct blow to the front of the pelvisCAxial force along the femur with the hip flexedDForced abduction and external rotation

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

The answer and the reasoning

A. A lateral blow over the greater trochanter

A force that strikes the greater trochanter drives the femoral head against the quadrilateral plate and medial wall, producing a central fracture dislocation. Axial loading with a flexed hip produces a posterior wall fracture or posterior dislocation. Central fractures often damage articular cartilage and lead to early arthritis.

Option by option

A. A lateral blow over the greater trochanter (correct)
Correct. A lateral trochanteric blow drives the head medially.
B. A direct blow to the front of the pelvis
An anterior pelvic blow produces pubic ramus or ring injuries.
C. Axial force along the femur with the hip flexed
Axial loading of a flexed hip typically causes a posterior wall fracture.
D. Forced abduction and external rotation
Abduction with external rotation is not the cause of central protrusion.

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 Orthopaedics question

What is the answer to this Orthopaedics question?

The best answer is A, A lateral blow over the greater trochanter. A force that strikes the greater trochanter drives the femoral head against the quadrilateral plate and medial wall, producing a central fracture dislocation.

Why is "A direct blow to the front of the pelvis" not the answer?

An anterior pelvic blow produces pubic ramus or ring injuries.

Why is "Axial force along the femur with the hip flexed" not the answer?

Axial loading of a flexed hip typically causes a posterior wall fracture.

Why is "Forced abduction and external rotation" not the answer?

Abduction with external rotation is not the cause of central protrusion.

What concept does this question test?

It tests Fractures: mechanism of central fracture dislocation in Orthopaedics. Axial loading with a flexed hip produces a posterior wall fracture or posterior dislocation. Central fractures often damage articular cartilage and lead to early arthritis.

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 Fractures: mechanism of central fracture dislocation?

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.