Revision ACL Assessment

For Medical Students

What It Tests

A revision assessment tests why the first operation did not work, which is a different question from whether the knee is lax.

There are four common answers and they lead to four different operations, so the assessment is about attribution rather than detection.

Graft failure, an unaddressed rotational component, malalignment or meniscal deficiency loading the graft, and a rehabilitation or confidence problem.

How It Is Performed

Take the history of the original injury, the original operation and the re-injury separately, and build a timeline. 4.2.30 covers previous surgery.

Ask whether the current symptom resembles the original one, which separates graft failure from a new problem. 4.10.1 covers the history.

Assess standing alignment, because a varus knee loads a graft abnormally and is a correctable cause of failure. 4.5.1 covers mechanical axis assessment.

Assess the menisci and the joint lines, because a deficient meniscus also loads the graft. 4.9.10 covers deficiency.

Then assess laxity and rotation, and plan an examination under anaesthesia, because the awake examination in a previously operated knee is frequently inconclusive. 4.10.10 covers it.

What a Positive Means

A soft endpoint Lachman with a history of a defined re-injury is graft failure.

A satisfactory Lachman with a persisting pivot shift is a rotational component that was never addressed, and this is the commonest of the four. 4.10.9 covers it.

A varus knee or a deficient meniscus indicates a mechanical environment that will fail a second graft as it failed the first.

A stable knee with a quadriceps deficit and poor dynamic performance is a rehabilitation problem, and revising the graft will not help. 4.10.8 covers dynamic assessment.

More than one of these is common, which is why the assessment covers all four rather than stopping at the first.

MRCS Level

What a Positive Means

The reasoning expected is that a graft fails for a reason and the reason determines the revision.

A technical cause, usually tunnel position, is addressed by revising the tunnels, and the imaging rather than the examination settles it.

A biological cause, graft choice or fixation, is addressed by changing them.

A mechanical environment cause, malalignment or meniscal deficiency, is addressed by correcting the environment, and the examination is what identifies it. 4.20.4 covers osteotomy assessment.

A rotational cause is addressed by adding a lateral procedure, and the examination under anaesthesia is what identifies it. 3.17.5 covers why that decision is unsettled.

A patient cause, rehabilitation or an early return, is addressed by not operating and by rehabilitating properly. 4.2.34 covers rehabilitation.

How Good It Is

The examination performs well in revision assessment for the mechanical environment and poorly for the technical causes, which imaging settles.

It performs well for the rehabilitation and confidence group, because that group has a stable knee and a functional deficit, which the examination demonstrates directly.

It performs poorly awake for the rotational component, which is the commonest structural cause, and that is why the examination under anaesthesia matters here more than anywhere. 4.10.10 covers it.

The pre-operative record from the first operation would be the most useful single document and is frequently absent, which is a limitation of the system rather than of the examination. 4.1.8 covers the record.

No figures appear, under decision 023.

FRCS Level

How Good It Is

At decision level the revision assessment determines whether a revision is appropriate, whether it is single or two stage, and what has to be done alongside it.

A patient in the rehabilitation and confidence group should not be revised, and identifying them is the most valuable thing this assessment does.

A patient with malalignment should have it corrected, before or with the revision, because a second graft in the same environment has the same prospects as the first. 4.20.4 covers osteotomy assessment.

A patient with meniscal deficiency may need that addressed, which raises transplantation and its own uncertain evidence. 4.9.10 covers deficiency.

A patient with a rotational component should have a lateral procedure considered, and the examination under anaesthesia is what establishes the grade that decision rests on.

Where It Misleads

The commonest error is revising the graft and nothing else, which repeats the first operation in the same environment.

The second is revising a knee whose problem was never structural, which is the largest single group and the one most likely to be operated on because an operation is available.

The third is accepting a pre-operative record that does not contain a rotational assessment as evidence that rotation was normal. 4.10.9 covers the distinction.

And attributing failure to graft choice when the tunnel position, the alignment or the meniscus explains it better.

Fellowship Level

Where It Misleads

This page closes the chapter and the chapter's argument lands here: most revisions are performed for a rotational component or a mechanical environment that the first assessment did not record, and both were assessable before the first operation.

That makes the revision clinic the place where the cost of an incomplete pre-operative examination is paid, which is 4.1.8's argument that the pre-operative record is part of the operation.

The practical sequence at this level is a timeline, an alignment assessment, a meniscal assessment, a functional assessment, and an examination under anaesthesia with everything recorded. 4.10.10 covers the last.

The hardest judgement is the patient who has had two or three reconstructions, has a knee that is lax and painful, and wants another. The examination's job there is to establish what the joint can still tolerate, and frequently the answer is that no further reconstruction is appropriate. 4.23.5 covers revision patients.

Saying that is the service, and the examination is what makes it defensible rather than an opinion.

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