Lever Sign Test

For Medical Students

What It Tests

The lever sign uses a fist placed under the proximal calf as a fulcrum, and tests whether the tibia can be levered into reduction by downward pressure on the thigh.

It is testing anterior translation, like the Lachman and the anterior drawer, by a different mechanical route. 4.10.4 covers the Lachman.

Its attraction is that it requires less patient relaxation than the other tests, because the examiner is using a lever rather than overcoming muscle.

How It Is Performed

With the patient supine and the leg extended, place a closed fist under the proximal third of the calf.

Apply a firm downward force on the thigh just above the patella with the other hand.

In an intact knee the heel lifts off the couch as the lever acts. In a deficient knee the tibia translates forwards instead and the heel stays down.

Compare with the other side, which matters here as much as in every other test in this chapter. 4.1.2 covers the principle.

Record what happened to the heel, which is the observation the test rests on.

What a Positive Means

The heel failing to lift, with the tibia translating forwards instead, is a positive and indicates a ruptured anterior cruciate.

The heel lifting is a negative and suggests the ligament is intact.

A partial lift is difficult to interpret and should be recorded as such rather than forced into a binary result.

A positive lever sign should agree with a positive Lachman. Disagreement between them is a reason to repeat both rather than to prefer one.

The test gives no information about rotation, which is the limitation it shares with the other translation tests. 4.10.9 covers rotation.

MRCS Level

How It Is Performed

In a viva the expected points are the fist position, the downward force, the heel observation and the comparison.

The candidate should say what the test is supposed to overcome, which is the patient relaxation requirement that limits the Lachman acutely.

Say that fist position matters: too distal and the lever is inefficient, too proximal and the knee flexes rather than levering.

Say honestly that the test is newer and that its position in the examination is not settled, which is a better answer than presenting it as established.

What a Positive Means

The reasoning is mechanical. The fist creates a fulcrum so that downward force on the thigh produces an extension moment at the knee and lifts the heel, provided the tibia cannot translate forwards.

If the anterior cruciate is absent, the tibia translates anteriorly and absorbs the moment, so the heel stays down.

That means a positive result depends on the tibia being free to translate, which is the same thing the Lachman measures through a different route.

It follows that the test should not add information about structures other than the anterior cruciate, and claims that it does should be treated sceptically.

How Good It Is

The lever sign was introduced with strong reported accuracy, including in acute knees, and subsequent independent reports have been less uniformly favourable.

The honest position is that it appears to perform comparably to the Lachman test and may retain more of its performance in a guarding patient, and that this is not settled.

That pattern, strong initial reports followed by less favourable independent ones, is the same one the Thessaly test showed, and recognising the pattern is more useful than memorising either test's figures. 4.9.4 covers the Thessaly test.

Its practical advantage is that it needs less relaxation, which if confirmed makes it most useful exactly where the Lachman is weakest. 4.10.2 covers the acute knee.

No figures appear, under decision 023, and the uncertainty is part of the claim.

FRCS Level

How Good It Is

At decision level the lever sign is a useful additional test and not yet a replacement for anything.

Its place is as a cross-check on the Lachman in a knee where relaxation is the limiting factor, which is the acute knee and the apprehensive patient.

Agreement between the lever sign and the Lachman strengthens the finding. Disagreement identifies a knee that needs re-examining or examining under anaesthetic. 4.10.10 covers it.

It contributes nothing to the rotational assessment, so it does not address this chapter's central gap.

Adopting a test on its original reports and discovering later that it performs like the test it was meant to replace is a recurring pattern in examination literature, and holding new tests provisionally is the appropriate response. 3.17.5 covers a larger example.

Where It Misleads

The commonest error is treating a new test as more accurate because its reported figures are higher, when early reports are systematically more favourable than later ones.

The second is substituting it for the Lachman rather than adding it, which loses a well established test for an uncertain one.

The third is performing it with poor fist position and recording the result, where the finding is about the technique.

And interpreting a negative lever sign as excluding rotational instability, which it never assessed.

Fellowship Level

Where It Misleads

At this level the lever sign's interest is less clinical than methodological, and saying so is more honest than overstating its place.

It is a well designed test addressing a real limitation, introduced with results that have not been uniformly reproduced, in a field where that sequence is common. 3.17.5 covers the clearest example.

After reconstruction its interpretation is unestablished, because the reports concern native ligaments and a graft's behaviour under this lever has not been characterised in the same way.

So this page does not claim a post-operative use, and recording that a test has no established post-operative interpretation is better than inventing one.

The practical position for a fellowship clinic is to perform it, record it, and weight it alongside rather than above the Lachman.

No figure here supports any of this, under decision 023.