Medial meniscus

Structure

The meniscus attaches to the tibia via coronary ligaments.

Its anterior end, thin and pointed, is attached to the anterior intercondyloid fossa of the tibia, in front of the anterior cruciate ligament;

Its posterior end is fixed to the posterior intercondyloid fossa of the tibia, between the attachments of the lateral meniscus and the posterior cruciate ligament.

It is fused with the tibial collateral ligament which makes it far less mobile than the lateral meniscus. The points of attachment are relatively widely separated and, because the meniscus is wider posteriorly than anteriorly, the anterior crus is considerably thinner than the posterior crus. The greatest displacement of the meniscus is caused by external rotation, while internal rotation relaxes it.

During rotational movements of the tibia (with the knee flexed 90 degrees), the medial meniscus remains relatively fixed while the lateral part of the lateral meniscus is displaced across the tibial condyle below.

Function

The medial meniscus separates the tibia and femur to decrease the contact area between the bones, and serves as a shock absorber reducing the peak contact force experienced. It also reduces friction between the two bones to allow smooth movement in the knee and distribute load during movement.

Clinical significance

Injury

Acute injury to the medial meniscus frequently accompanies an injury to the ACL (anterior cruciate ligament) or MCL (medial collateral ligament). A person occasionally injures the medial meniscus without harming the ligaments. Healing of the medial meniscus is generally not possible unless the patient is very young, usually

If the meniscus has to be removed (menisectomy) because of injury (either because it cannot heal or because the damage is too severe), the patient has an increased risk of developing osteoarthritis in the knee later in life. If the meniscus is removed and there is no arthritis, there are now meniscus transplant options if the patient is young and has normal alignment.

More chronic injury occurs with osteoarthritis, made worse by obesity and high-impact activity. The medial meniscus and the medial compartment are more commonly affected than the lateral compartment.

Often, moderate to severe injury or injury past early middle age to the meniscus will indicate a total knee replacement.

Additional images

Books

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References

1. Platzer (2004), p 208
2. ''Thieme Atlas of Anatomy'' (2006), p 399
3. Platzer (2010), p 208
4. [http://www.arthroscopy.com/sp05005.htm Torn Cartilage (Meniscus)] {{webarchive. link. (2006-06-24 {{full citation needed). (February 2018)
5. [http://www.orthoassociates.com/meniscus.htm The Meniscus] {{webarchive. link. (2006-07-03 {{full citation needed). (February 2018)
6. [http://orthopedics.about.com/cs/meniscusinjuries1/a/meniscus.htm Meniscus Tear – Torn Cartilage] {{webarchive. link. (2008-03-02 {{full citation needed). (February 2018)
7. http://drpetre.com/injuries/common-knee-injuries/meniscal-tear-meniscus-injury/{{full citation needed. (February 2018)