Metabolic bone disease: bisphosphonate mechanism: 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 · Metabolic bone disease: bisphosphonate mechanism

Sample item

Alendronate lowers fracture risk in postmenopausal osteoporosis. What is its action in osteoclasts?

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

The answer and the reasoning

D. Blocks farnesyl pyrophosphate synthase and triggers osteoclast apoptosis

Nitrogen-containing bisphosphonates bind hydroxyapatite and are taken up by osteoclasts during resorption. They inhibit farnesyl pyrophosphate synthase in the mevalonate pathway, which stops prenylation of small GTPases and causes osteoclast apoptosis.

Option by option

  • A. Binds RANKL and stops precursors from maturing into osteoclasts

    Binding RANKL is the action of denosumab.

  • B. Neutralises sclerostin and so releases Wnt signalling

    Neutralising sclerostin is the action of romosozumab.

  • C. Stimulates osteoblasts through the parathyroid hormone receptor

    Stimulation through the PTH receptor is the anabolic action of teriparatide.

  • D. Blocks farnesyl pyrophosphate synthase and triggers osteoclast apoptosis (correct)

    Correct. Inhibition of farnesyl pyrophosphate synthase leads to osteoclast apoptosis.

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 D, Blocks farnesyl pyrophosphate synthase and triggers osteoclast apoptosis. Nitrogen-containing bisphosphonates bind hydroxyapatite and are taken up by osteoclasts during resorption.

Why is "Binds RANKL and stops precursors from maturing into osteoclasts" not the answer?

Binding RANKL is the action of denosumab.

Why is "Neutralises sclerostin and so releases Wnt signalling" not the answer?

Neutralising sclerostin is the action of romosozumab.

Why is "Stimulates osteoblasts through the parathyroid hormone receptor" not the answer?

Stimulation through the PTH receptor is the anabolic action of teriparatide.

What concept does this question test?

It tests Metabolic bone disease: bisphosphonate mechanism in Orthopaedics. They inhibit farnesyl pyrophosphate synthase in the mevalonate pathway, which stops prenylation of small GTPases and causes osteoclast apoptosis.

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 Metabolic bone disease: bisphosphonate mechanism?

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.