There are two menisci in your knee. They sit between the thigh bone femur and shin bone tibia. While the ends of the thigh bone and shin bone have a thin covering of soft hyaline cartilage, the menisci are made of fibrocartilage tough cartilage and conform to the surfaces of the bones upon which they rest. One meniscus rests on the medial tibial plateau; this is the medial meniscus. The other meniscus rests on the lateral tibial plateau; this is the lateral meniscus.[4]

These menisci act to distribute body weight across the knee joint. Without the menisci, the weight of the body would be unevenly applied to the bones in the legs (the femur and tibia). This uneven weight distribution would cause the development of abnormal excessive forces leading to early damage of the knee joint. The menisci also contribute to the stability of the joint.

The menisci are nourished by small blood vessels, but the menisci also have a large area in the center of that has no direct blood supply (avascular). This presents a problem when there is an injury to the meniscus as the avascular areas tend not to heal. Without the essential nutrients supplied by blood vessels, healing cannot take place.[4]

A Meniscus tear can be classified in various ways: by anatomic location, by proximity to blood supply, etc. Various tear patterns and configurations have been described.[3] These include:

• Radial tears
• Flap or parrot-beak tears
• Peripheral, longitudinal tears
• Bucket-handle tears
• Horizontal cleavage tears
• Complex, degenerative tears

An injury to the medial meniscus can result from an impact on the outside of the knee. It will often be injured along with the medial ligament. Cartilage injuries can also occur as a result of deep knee bends.

The two most common causes of a meniscus tear are traumatic Injury (often seen in athletes) and degenerative processes (seen in elderly patients who have more brittle cartilage).[4] Meniscus tears can occur in all age groups. Traumatic tears are most common in active people from age 10-45[4]. Traumatic meniscal tears are usually radial or vertical in the meniscus and are more likely to produce a moveable fragment that can catch in the knee and therefore require surgical treatment.

The most common mechanism of a traumatic meniscus tear occurs when the knee joint is bent and the knee is then twisted. It is not uncommon for the meniscus tear to occur along with injuries to the anterior cruciate ligament ACL and the medial collateral ligament MCL — these three problems occurring together are known as the "unhappy triad," which is seen in sports such as football when the player is hit on the outside of the knee. Individuals who experience a meniscus tear usually experience pain and swelling as their primary symptoms. Another common complaint is joint locking, or the inability to completely straighten the joint. This is due to a piece of the torn cartilage preventing the normal functioning of the knee joint.

A torn meniscus can prevent normal pain-free motion of the knee and therefore can interfere with the patient's ability to climb stairs or get in and out of chairs and cars.

Regular neuromuscular training that is designed to enhance proprioception, balance, proper movement patterns and muscle strength.

1. ^ μηνίσκος, "small moon", is diminutive of μήνη, "moon", from the root ma-, "measure", which reflects the fact the time was measured according to the phases of the moon. The word was also used for curved things in general, such as a necklace or a line of battle. (Lexicon of Orthopaedic Etymology, p 199)
2. ^ Platzer (2004), p 208
3. ^ Meniscus, Stedman's (27th ed.)
4. ^ Gray's (1918), 7b
5. ^ Cluett, Meniscus Tear — Torn Cartilage