Knee ligament injuries: Lachman versus anterior drawer: 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.

Try it

Orthopaedics · Knee ligament injuries: Lachman versus anterior drawer

Sample item

Why is the Lachman test usually more sensitive than the anterior drawer test in an acutely injured knee?

AIt needs the patient to be anaesthetisedBIt is done at 20 to 30 degrees where hamstring guarding and meniscal blocking are lessCIt is done at 90 degrees where the hamstrings relaxDIt tests the posterior cruciate ligament directly

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

The answer and the reasoning

B. It is done at 20 to 30 degrees where hamstring guarding and meniscal blocking are less

At 20 to 30 degrees of flexion the hamstrings are relaxed and the posterior horn of the medial meniscus is less likely to wedge the tibia, so anterior translation is easily appreciated. At 90 degrees guarding and a locked meniscus often hide laxity. The Lachman test is therefore preferred in acute injuries.

Option by option

A. It needs the patient to be anaesthetised
It can be performed in the awake patient.
B. It is done at 20 to 30 degrees where hamstring guarding and meniscal blocking are less (correct)
Correct. Less guarding and less meniscal blocking improve sensitivity.
C. It is done at 90 degrees where the hamstrings relax
At 90 degrees guarding is greater, and that describes the drawer test.
D. It tests the posterior cruciate ligament directly
The Lachman test assesses the ACL, not the PCL.

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, It is done at 20 to 30 degrees where hamstring guarding and meniscal blocking are less. At 20 to 30 degrees of flexion the hamstrings are relaxed and the posterior horn of the medial meniscus is less likely to wedge the tibia, so anterior translation is easily appreciated.

Why is "It needs the patient to be anaesthetised" not the answer?

It can be performed in the awake patient.

Why is "It is done at 90 degrees where the hamstrings relax" not the answer?

At 90 degrees guarding is greater, and that describes the drawer test.

Why is "It tests the posterior cruciate ligament directly" not the answer?

The Lachman test assesses the ACL, not the PCL.

What concept does this question test?

It tests Knee ligament injuries: Lachman versus anterior drawer in Orthopaedics. At 90 degrees guarding and a locked meniscus often hide laxity. The Lachman test is therefore preferred in acute injuries.

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 Knee ligament injuries: Lachman versus anterior drawer?

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.