Fractures and dislocations: cross-linked polyethylene: 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 and dislocations: cross-linked polyethylene

Sample item

Highly cross-linked ultra-high molecular weight polyethylene is used in hip liners. How does cross-linking change its behaviour?

AIt prevents oxidation completely, so no antioxidant is neededBIt increases wear and increases toughnessCIt lowers wear but reduces fatigue strength and toughnessDIt raises both wear resistance and mechanical strength

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

The answer and the reasoning

C. It lowers wear but reduces fatigue strength and toughness

Radiation cross-linking improves resistance to adhesive and abrasive wear, which reduces particle-induced osteolysis. The cost is reduced ductility, fatigue crack resistance and toughness, so thin liners may fracture. Residual free radicals are quenched by remelting or adding vitamin E.

Option by option

A. It prevents oxidation completely, so no antioxidant is needed
Oxidation is a risk unless free radicals are removed by melting or antioxidant stabilisation.
B. It increases wear and increases toughness
Cross-linking reduces wear, not increases it, and toughness falls.
C. It lowers wear but reduces fatigue strength and toughness (correct)
Correct. Better wear performance is traded for lower fatigue strength.
D. It raises both wear resistance and mechanical strength
Wear resistance improves but mechanical strength is reduced.

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 C, It lowers wear but reduces fatigue strength and toughness. Radiation cross-linking improves resistance to adhesive and abrasive wear, which reduces particle-induced osteolysis.

Why is "It prevents oxidation completely, so no antioxidant is needed" not the answer?

Oxidation is a risk unless free radicals are removed by melting or antioxidant stabilisation.

Why is "It increases wear and increases toughness" not the answer?

Cross-linking reduces wear, not increases it, and toughness falls.

Why is "It raises both wear resistance and mechanical strength" not the answer?

Wear resistance improves but mechanical strength is reduced.

What concept does this question test?

It tests Fractures and dislocations: cross-linked polyethylene in Orthopaedics. The cost is reduced ductility, fatigue crack resistance and toughness, so thin liners may fracture. Residual free radicals are quenched by remelting or adding vitamin E.

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 and dislocations: cross-linked polyethylene?

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.