Meniscus Pathology

Discoid external meniscus

What is it ?

1% of the population in Europe (10% in Asia) have a discoid external meniscus, i.e. instead of being crescent-shaped, the external meniscus is solid and has a “wafer” shape, which makes it more fragile because it is subject to compressive stresses during movement; as a general rule, a discoid external meniscus is asymptomatic as long as it is healthy; if it is problematic, it is because it has torn or become unstable. It is often a problem in young patients (adolescents and young adults).

Clinical presentation

A torn external discoid meniscus causes lateral knee pain, sometimes joint effusion, and joint locking or popping during knee flexion-extension movements.

When to consult a specialist?

In case of persistent pain in the lateral part of the knee, joint effusion or joint blockage or protrusion during movement.

Non surgical treatment

If a discordant external meniscus tears in a knee that already has osteoarthritis, conservative treatment (pain relief, physiotherapy, infiltrations) is preferred to avoid decompensating the osteoarthritis present.

Surgical treatment

Often the discoid external meniscus is torn in its centre, it is then advisable to perform a meniscoplasty which corresponds to a “sculpture” of the meniscus to give it back a normal “crescent” shape, without removing too much meniscal tissue either so as not to trigger chondrolysis (see in risk and complication). If the external meniscus is not itself torn but is deinserted at its periphery, this makes it unstable and can cause joint blockages; it should then be put back in place and fixed with mensicocapsular sutures.

Postoperative follow-up

Post-operative re-education must be progressive: in the case of meniscoplasty only, constraints are reintroduced progressively to accustom the cartilage to function with a meniscus that has another shape and to avoid chondrolysis, which corresponds to a rapid disintegration of the cartilage (see risks and complications) In the case of a meniscal or meniscocapsular suture, the treatment is the same as for any other meniscal suture, i.e. 4 to 6 weeks of crutches for partial weight-bearing, and a limitation of joint mobility depending on the suture performed.

Risks and complications

The main risk in meniscoplasty is chondrolysis, which is a rapid disintegration of the cartilage in the external compartment of the knee; chondrolysis is manifested by pain and persistent effusion in the knee; diagnosis and treatment is by arthroscopic joint lavage and unloading of the knee with crutches to let the cartilage regenerate. In the case of meniscal suturing, the risks are the same as for any other meniscal suture.