Paediatric: migration percentage in cerebral palsy: 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: migration percentage in cerebral palsy

Sample item

A child with spastic quadriplegia has regular hip surveillance radiographs. What does the Reimers migration percentage measure?

AThe length discrepancy between the legsBThe proportion of the femoral head lying lateral to the acetabular edgeCThe depth of the acetabulumDThe angle of the femoral neck

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

The answer and the reasoning

B. The proportion of the femoral head lying lateral to the acetabular edge

Reimers migration percentage is the proportion of the femoral head that lies outside the lateral edge of the acetabulum on an anteroposterior pelvic radiograph. A rising value signals progressive subluxation of the spastic hip. Surveillance allows early soft tissue release before dislocation develops.

Option by option

A. The length discrepancy between the legs
Leg length discrepancy is measured clinically or by scanogram.
B. The proportion of the femoral head lying lateral to the acetabular edge (correct)
Correct. It expresses how much of the femoral head is uncovered laterally.
C. The depth of the acetabulum
Acetabular depth is described by other indices such as the acetabular index.
D. The angle of the femoral neck
The neck-shaft angle is a different measurement.

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 B, The proportion of the femoral head lying lateral to the acetabular edge. Reimers migration percentage is the proportion of the femoral head that lies outside the lateral edge of the acetabulum on an anteroposterior pelvic radiograph.

Why is "The length discrepancy between the legs" not the answer?

Leg length discrepancy is measured clinically or by scanogram.

Why is "The depth of the acetabulum" not the answer?

Acetabular depth is described by other indices such as the acetabular index.

Why is "The angle of the femoral neck" not the answer?

The neck-shaft angle is a different measurement.

What concept does this question test?

It tests Paediatric: migration percentage in cerebral palsy in Orthopaedics. A rising value signals progressive subluxation of the spastic hip. Surveillance allows early soft tissue release before dislocation develops.

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 Paediatric: migration percentage in cerebral palsy?

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.