Posterior meniscal root injuries

Moatshe G, Chahla J, Slette E, Engebretsen L & Laprade RF. Acta Orthopaedica 2016 Oct 87(5):452–458. [Link to free full text article]

This is the editor's interpretation of a paper published in the orthopaedic literature in 2016 - our attempt to make relevant medical articles accessible to lay readers. If you wish to read the original it is easy to ask your librarian to obtain a reprint for you from any medical library.

This article is a literature review where tha authors attempt to summarise the key issues relating to meniscal root tears.

The authors start by defining meniscal root tears as "radial tears within 1 cm of the meniscal root insertion, or an avulsion of the insertion of the meniscus."

[Ed: A radial tear is one that cuts across the wedge of the meniscus, rather than running longitudinally along its length. The meniscal root is the area at the front or back of the meniscus where it is strongly attached to the underlying tibial bone. An 'avulsion' is a 'pulling away' of such a root, where there is not actually any tear of the meniscus itself.]

These types of injury prevent the normal dissipation of forces through the joint, and may result in accelerated degenerative changes in the bones of the joint comparable to those changes seen after the meniscus has been totally removed. The meniscus with a root tear or avulsion may also extrude over the edge of the bone, and extrusion of >3mm may also lead to accelerated degenerative changes.

The authors discuss the two current classification systems for root tears, and you can see illustrations of LaPrade's classification in the full-text version of this article. The different types of tears may cause different degrees of instability of the meniscus.

They discuss the anatomical relationships, and the landmarks that can help the surgeon in exploring the integrity of the meniscal attachments at the back of the knee. In particular, they note the close relationship of the posterior meniscal roots to the attachment of the posterior cruciate ligament, and point out that  badly-positioned tunnel can actually cause damage to the posterior meniscal roots during a posterior cruciate ligament reconstruction.

When talking about the evaluation, the authors highlight that root tears are not always evident on examination or even on MRI scan. Medial meniscal extrusion is an MRI finding highly correlated to the presence of a root tear. Another important sign is the 'ghost' sign, which is the absence of an identifiable meniscus in the sagittal plane (side view). You can see examples of these in their paper. They emphasise that MRI interpretation of root lesions is "highly dependent on the quality of the image and the skill of the radiologist".

The surgeon needs to take factors such as bow-leggedness and body mass into account, as these increase the risk. Patients may complain of pain the back of the knee, and may describe "a popping sound during light activities such as doing housework, going upstairs/downstairs, rising from a chair, and squatting." Exaggerated responses to positive tests for anterior cruciate ligament (ACL) injury should alert the surgeon to the possibility of an associated root tear.

But it is during arthroscopic evaluation that the surgeon has the best chance of confirming the suspicion of a root tear during diligent probing of the roots.


Management of damaged meniscal roots

Conservative (non-surgical)

In the older patient who may have other problems that might make surgery and rehab challenging, it may be possible for them to cope with painkiller and the use of an unloader brace.


Patients with knee arthritis and pain and/or locking of the joint, and who do not respond to non-surgical interventions, may find relief of their symptoms after a meniscectomy. If the tear is partial, and there is still some 'footprint' intact, a partial meniscectomy may relieve symptoms.

Meniscal root repair

The main indications for meniscal repair are:

  • acute (sudden) traumatic root tears in patients with nearly normal or normal cartilage
  • chronic (developing over time) symptomatic root tears in young or middle-aged patients without significant pre-existing osteoarthritis

The authors describe two kinds of repair...

Trans-osseous (through the bone)

Their preferred technique for fixation of posterior horn meniscal root tear involves two simple sutures in the meniscal root passed through two tunnels in the tibia and tied over a button (see their paper for illustration). 

Suture anchors

This is a simpler all-inside technique using one suture anchor with two sutures which are  secured in the bone at the attachment site of the root to be repaired, and apparently it is facilitated by a high posteromedial portal.


Post-operative Rehabilitation

The authors offer a detailed rehabilitation protocol for patients who might have had the transosseous root repair. They are expected to be non-weight-bearing for 6 weeks to protect the repair and, when not working on physiotherapy, they should wear a brace in full extension for 6 weeks. Physiotherapy after the surgery should be started early, to begin working on passive range-of-motion exercises four times a day, with flexion limited to 0–90 degrees for the first 2 weeks, progressing to full knee motion as tolerated. Progressive advancement to full weight bearing begins at 6 weeks. Deep leg presses and squats greater than 70 degrees of knee flexion should be avoided for at least 4 months after surgery to protect the root repair. After 6 months full flexion, squatting, and return to full activities or sports is allowed.



This is still a little bit of an 'open book' because meniscal root repairs are technically challenging, and anatomic repair is paramount to the success of the surgery. So the published literature is a bit variable in terms of success. The authors conclude that -

"this procedure might be better left to experienced surgeons with enough volume. There is a still a need for more studies of better design to address some of the pending questions."


partial meniscal root tear

Partial medial meniscus posterior root tear

Medial meniscal extrusion

Medial meniscus extrusion