Meniscal Root Tears

For Medical Students

What It Tests

A meniscal root tear is a detachment of the meniscus at its tibial attachment rather than a tear through its body.

That matters mechanically rather than just anatomically: the root anchors the circumferential fibres, so detaching it releases hoop tension and the meniscus stops distributing load. 3.6.9 covers root biomechanics.

Examining for it is difficult, because the standard provocative tests trap a mobile fragment and a detached root has no fragment to trap.

So this page is largely about why the examination underperforms and what to rely on instead.

How It Is Performed

Palpate the posterior joint line specifically, with the knee flexed, which is where the root sits and where the standard examination stops short.

Ask about pain in deep flexion and on rising from a squat, which is when the posterior horn is loaded. 4.9.6 covers the squat test.

Look for an early loss of joint space or a new varus alignment, because a root tear can produce rapid degenerative change and extrusion. 4.5.2 covers varus alignment.

Assess for an effusion and for a loss of extension, which are both less common than with a body tear.

Take the mechanism history carefully: a deep squat, a forced flexion, or in older patients no injury at all. 4.2.18 covers twisting injuries.

What a Positive Means

Posterior joint line tenderness with pain in deep flexion, in a patient with a squatting or forced flexion mechanism, is the clinical picture.

An absence of mechanical symptoms does not argue against a root tear, which is the opposite of the body tear pattern.

A new or progressing varus deformity in a patient with recent medial pain raises a medial root tear with extrusion and is an important and time-sensitive picture.

A normal examination is common and does not exclude the diagnosis, which is why this page exists.

The diagnosis is usually made on imaging, and the examination's job is to raise the question.

MRCS Level

What a Positive Means

The reasoning is that hoop tension is what makes the meniscus work, so losing the root is mechanically closer to losing the meniscus than to tearing it. 3.6.2 covers hoop stress.

That is why a root tear produces extrusion, load concentration and rapid degenerative change, and why it is treated more aggressively than a comparable body tear.

It is also why the examination findings are those of a functionally meniscus-deficient knee rather than those of a torn meniscus. 4.9.10 covers deficiency.

In an older patient a root tear frequently presents with new medial pain and a rapidly progressing varus, and the differential includes a subchondral insufficiency fracture, which presents similarly and needs separating.

In a younger patient it usually accompanies a cruciate injury, because the mechanism produces both. 4.10.2 covers acute cruciate injury.

How Good It Is

The clinical examination performs poorly for root tears, worse than for any other lesion in this chapter, and stating that plainly is more useful than listing tests.

The reasons are mechanical: no mobile fragment to trap, frequently no mechanical symptoms, and tenderness in a posterior location the routine examination palpates least well.

Posterior joint line tenderness and deep flexion pain are the most useful findings available, and neither is specific.

The history and the imaging carry the diagnosis, and the examination's contribution is to raise the question in a patient whose presentation would otherwise be called degenerative.

No figures appear, under decision 023.

FRCS Level

How Good It Is

At decision level a root tear changes the operation, so recognising it matters more than the examination's weakness would suggest.

A repairable root in a knee with preserved cartilage and acceptable alignment is a repair rather than a resection, and resecting it accelerates the degeneration it causes. 4.20.3 covers root repair assessment.

A root tear in a varus knee with established degeneration raises the question of realignment alongside or instead of any meniscal procedure. 4.18.3 covers varus disease.

The examination's contribution is the alignment assessment and the progression history rather than any provocative test, which is an unusual conclusion for a chapter of tests.

A new varus with recent medial pain should prompt urgent imaging rather than a course of physiotherapy.

Where It Misleads

The commonest error is labelling a root tear presentation as degenerative disease, because the patient is older and the radiographs show change.

The second is resecting a repairable root, which converts a reparable mechanical problem into a permanent one.

The third is relying on the provocative tests, which perform badly here, and recording a negative examination as reassuring.

And missing the alignment. A root tear with extrusion and progressive varus is a different problem from a root tear in a neutral knee, and only the alignment assessment separates them. 4.5.1 covers mechanical axis assessment.

Fellowship Level

Where It Misleads

In referred practice the root tear appears as a rapidly deteriorating knee in a patient who was told they had arthritis, or as a failed repair.

The first is the more common and the more costly, because a window for repair existed and was missed, and the history of how quickly the knee changed is what identifies it.

A failed root repair presents with the same mechanical picture as the original tear, and distinguishing failure from progression of the cartilage damage is difficult clinically and usually requires imaging. 4.20.3 covers the assessment.

A root repair in a malaligned knee that was not realigned is a recognised reason for failure, and the alignment is the part of the assessment that answers it.

The honest conclusion of this page is that the examination raises the question and almost never answers it, which is unusual in this chapter and should be taught as such.

No figure here supports these claims, under decision 023.