Why do we Need Menisci and How Can They Help the knee joint?

The knee joint is the biggest and the most important joint in the human body. This is because it does two main functions:

  1-Transmits the weight from the upper part to the lower part of the body.

  2-Moves in many different directions and in many different angles.

These two functions require the knee joint to be flexible and stable at the same time. The medial meniscus is mainly responsible for the stability of the knee because it is fixed, while the lateral meniscus is mainly responsible for the flexibility because it is not as fixed.

Why does the medial meniscus need to be more fixed?

The medial meniscus is closer to the center of the body than the lateral one. That means it receives higher pressure thanthe lateral meniscus because of the gravity. In the figure below, the line shows the direction through which the body weight transmit to the ground. The line is closer to the medial meniscus than the lateral meniscus, which means that the medial meniscus deals with much higher pressure. This is why the medial meniscus is more fixed.

Transition of the body weight 

What makes the medial meniscus more fixed than the lateral meniscus?

The medial meniscus is closely attached to two fixed structures called fibrous capsule and medial collateral ligament. These attachments contribute to the stability of the medial meniscus. on the other hand, the lateral meniscus is not closely attached to stable structures which makes it more flexible.

The attachments of the medial meniscus to the medial collateral ligament 

This great cooperation between the medial meniscus and the lateral meniscus results in a very fixed and flexible knee.