Apley Compression Test

For Medical Students

What It Tests

The Apley test compares rotation under compression with rotation under distraction, and the comparison is the point.

Compression loads the meniscus. Distraction unloads it and loads the collateral ligaments instead.

So pain on compression and not on distraction points to the meniscus, and pain on both or on distraction alone points to the ligament. No other test in this chapter has that control built in.

How It Is Performed

Place the patient prone with the knee flexed to about ninety degrees.

Stabilise the thigh, conventionally with your own knee, and hold the foot.

Apply axial compression down through the heel and rotate the tibia internally and externally, noting any pain and where.

Then apply distraction by pulling up on the leg while stabilising the thigh, and rotate again.

Compare the two, and ask the patient which reproduced their pain.

What a Positive Means

Pain on rotation with compression, relieved or absent on rotation with distraction, is a positive for a meniscal cause.

Pain on rotation with distraction points to the collateral ligaments rather than the meniscus. 4.12.1 covers valgus stress testing.

Pain on both is uninformative and common in an irritable or degenerate joint.

External rotation pain under compression points to the medial meniscus and internal rotation pain to the lateral, by the same logic as the McMurray test. 4.9.3 covers it.

A negative test excludes very little, as with the whole group.

MRCS Level

How It Is Performed

In a viva the expected description is prone, ninety degrees, thigh stabilised, compression and rotation, then distraction and rotation, then the comparison.

The comparison is the mark. A candidate who performs the compression half and omits the distraction half has performed a different and much less useful test.

Say what each half loads and therefore what each half is testing.

Say that the prone position is part of the technique, because it allows axial compression through the heel with the thigh stabilised, which supine does not.

What a Positive Means

The logic of this test is worth holding because it generalises: a test with a control is worth more than a test without one.

Compression plus rotation traps and grinds the meniscus between the condyle and the plateau, which is the meniscal provocation.

Distraction plus rotation tensions the collaterals and relieves meniscal compression, which is the ligamentous provocation.

A discriminating positive therefore requires both halves and a difference between them.

In practice the test is often performed as compression alone, which removes the control and makes it a weaker McMurray.

How Good It Is

The Apley test shares the group's pattern, more specific than sensitive, and it is not clearly better than the McMurray test for detecting a tear.

Where it is better is in attribution. The distraction half gives information about the collateral that no other test in this chapter supplies.

That makes it most useful in the knee with medial pain where the question is meniscus against collateral, which is a common and genuinely difficult distinction. 4.12.7 covers it.

It is uncomfortable, requires the prone position, and is therefore performed less often than it deserves.

No figures appear, under decision 023.

FRCS Level

How Good It Is

At decision level the Apley test earns its place in one specific situation: medial pain where the imaging shows both a degenerate meniscal tear and a thickened or oedematous collateral.

In that knee the question is which is symptomatic, and a compression-positive, distraction-negative result answers it in a way no scan does. 4.12.7 covers the separation.

It is also useful in the knee whose joint line tenderness is ambiguous, because the compression half localises by load rather than by palpation.

It contributes nothing to repairability or urgency, which the history settles. 4.9.8 covers the one urgent finding.

Where It Misleads

The commonest error is performing only the compression half, which discards the test's only advantage.

The second is performing it in an acute knee, where prone positioning and forced rotation are both poorly tolerated and the result is uninterpretable.

The third is interpreting pain on both halves as a positive, when it indicates a generally irritable joint.

And in a degenerate knee with diffuse tenderness the test loses its discrimination along with the others. 4.9.11 covers the pattern.

Fellowship Level

Where It Misleads

After surgery the Apley test has the same limitation as the other passive provocative tests: the structure it was trapping may no longer be there.

Its distraction half retains value, because a collateral that is symptomatic after meniscal surgery is a recognised and under-diagnosed cause of persistent medial pain.

That matters in the knee resected for a medial tear whose medial pain persisted, where the original problem may have been the collateral or the meniscotibial attachment rather than the meniscus.

Establishing that retrospectively is difficult and the history of what the pre-operative examination found is usually the only route. 4.1.8 covers the record.

The test is also poorly tolerated prone in a knee with limited flexion, which is common after surgery, and attempting it then produces a finding about the flexion rather than the meniscus. 4.7.4 covers flexion assessment.

No figure here supports these claims, under decision 023.