ACL Reconstruction

For Medical Students

What It Tests

After a cruciate reconstruction the examination is checking the graft's restraint, the range, the quadriceps and the donor site, and each of those has its own expected course. 4.10.11 covers the post reconstruction assessment.

The examination's baseline is the operated knee rather than the normal one, so the comparison with the other side has to be read with that in mind. 4.2.30 covers previous surgery.

It is a staged examination, because what is normal at six weeks is abnormal at six months. 4.7.10 covers the post operative range assessment.

How It Is Performed

Establish what was done: the graft, the date, the rehabilitation stage and any additional procedure. 4.2.30 covers previous surgery.

Look at the scars, which tell you the graft and the approach when the records do not. 4.3.7 covers surgical scars.

Assess the effusion, since a persistent or a recurrent effusion after the early weeks is a finding rather than a stage. 4.8.3 covers the bulge sign.

Measure the range, recording the extension first, because an extension deficit after a reconstruction is the deficit that matters. 4.7.10 covers the post operative range assessment.

Assess the quadriceps bulk and the ability to hold the leg straight, since quadriceps recovery governs the function. 4.3.9 covers muscle wasting.

Perform the Lachman test, accepting that a reconstructed knee has a firm end point with a small excursion rather than no excursion. 4.10.4 covers the Lachman test.

Assess the rotational control, since a graft can restrain the anterior translation and leave the rotation. 4.10.6 covers the pivot shift test.

Palpate the donor site, because the harvest causes its own symptoms. 4.6.6 covers tendon tenderness.

What a Positive Means

A firm end point on the Lachman with a small excursion, a full range and recovering quadriceps is the expected post reconstruction examination.

An increasing excursion with a soft end point indicates graft failure, and it is read against the previous examinations rather than against normal. 4.10.12 covers the revision assessment.

An extension deficit after the early weeks indicates a mechanical block or a contracture, both of which need attention. 4.5.4 covers the flexion deformity.

A persistent effusion suggests graft or meniscal pathology, or synovitis, rather than a normal stage. 4.8.9 covers synovitis.

Residual rotational instability with a controlled anterior translation is a recognised pattern and it is specifically tested for. 4.10.6 covers the pivot shift test.

MRCS Level

How It Is Performed

In a viva this is the post operative knee station and the expected answer establishes what was done before examining.

The expected points are the operation and its date, the scars, the effusion, the range with extension first, the quadriceps, the Lachman, the rotational assessment, the donor site and the function.

Say that you would establish the graft and the date, since the expected findings depend on both. 4.2.30 covers previous surgery.

Say that you would read the examination against the rehabilitation stage. 4.2.34 covers previous rehabilitation.

Say that you would assess function rather than only laxity, because the function is what the patient has come about. 4.21.7 covers return to sport testing.

What a Positive Means

The reasoning expected is that a graft restores the restraint without restoring the original ligament, so a small excursion with a firm end point is a successful result rather than a failure. 3.7.20 covers reconstruction biomechanics.

The graft remodels over months, which is why the examination's expected findings move with time. 3.7.16 covers graft biomechanics.

Quadriceps inhibition after the operation reduces the dynamic restraint, so a knee can feel unstable with an intact graft. 3.7.3 covers the secondary restraints.

Rotational control depends on structures beyond the graft, which is why a restrained drawer can coexist with a positive rotational test. 3.11.1 covers the iliotibial band's function.

How Good It Is

The examination detects graft failure reliably when it is compared against the earlier examinations of the same knee.

Its best contribution is the serial record, because the trend is more informative than any single result here. 4.1.8 covers examination documentation.

It is poor at judging the graft in isolation, since a single examination without a baseline cannot say whether a small excursion is new.

Magnetic resonance imaging assesses graft integrity, so the examination establishes the function and the imaging the structure. 4.1.6 covers that relationship.

No figures appear for any accuracy comparison on this page, under decision 023, and the comparison is the claim being made.

FRCS Level

How Good It Is

At decision level the examination separates graft failure, a new injury, stiffness and a functional problem, and each leads somewhere different.

Increasing laxity across serial examinations with a soft end point indicates graft failure, and the serial comparison is the clinical evidence. 4.10.12 covers the revision assessment.

Stiffness with a controlled graft is a rehabilitation and sometimes an operative problem, and the end feel distinguishes a contracture from a block. 4.7.5 covers the end feel.

Giving way with a controlled graft raises quadriceps weakness, rotational instability or a meniscal problem, and all three are examined for. 4.2.6 covers giving way.

Persistent anterior pain after a patellar tendon graft is a donor site problem until examined otherwise. 4.6.6 covers tendon tenderness.

Where It Misleads

The commonest error is comparing a reconstructed knee against the opposite side and calling the difference failure. 4.1.4 covers the structured approach.

A single examination without a baseline cannot judge graft laxity, and an estimate is made anyway. 4.1.8 covers examination documentation.

Quadriceps weakness produces a subjective instability that is read as graft failure. 4.3.9 covers muscle wasting.

A meniscal injury after reconstruction is attributed to the graft, since both produce giving way. 4.9.3 covers the McMurray test.

Donor site pain is attributed to the joint, because the patient reports anterior knee pain either way. 4.15.9 covers patellofemoral pain.

Fellowship Level

Where It Misleads

At fellowship level the examination's job is deciding whether a symptomatic reconstruction has failed, and the answer rests on findings that are all relative.

Graft laxity is judged against the same knee's previous examinations, so an examination performed elsewhere without a record leaves the question open. 4.1.8 covers examination documentation.

A graft can be intact and malpositioned, which produces stiffness rather than laxity, and the examination finds the stiffness without naming the cause. 4.7.5 covers the end feel.

Residual rotational instability after a reconstruction can come from the graft, from the anterolateral structures or from the alignment, and the examination cannot apportion them. 4.10.9 covers rotational instability.

Alignment contributes to graft load, so a reconstructed knee in a varus limb is examined for both. 4.5.1 covers the mechanical axis.

Return to sport is a functional judgement the laxity examination does not make, and the two are often conflated. 4.21.8 covers return to play decision making.