The cruciate ligaments are the important central 'stays' of the knee joint, contributing significantly to the stability of the joint.

Page updated October 2023 by Dr Sheila Strover (Clinical Editor)

cruciate ligaments

 

The knee joint from the front. The word 'cruciate' means 'crossed', referring to the fact that the two cruciate ligaments cross over one another in the centre of the joint in the area called the 'notch'.

cruciate ligaments - bones distracted

 

Here, just to help you understand, the bones are distracted and you are looking from the side so that you can see the attachments of both anterior and posterior cruciate ligament.

 

What do the cruciate ligaments do?

There are two cruciate ligaments - anterior (ACL) and posterior (PCL) - and they tether the femur and tibia together while still allowing the knee to bend, There are two of them - anterior (ACL) and posterior (PCL), and they tether the femur and tibia together while still allowing the knee to bend, stabilising the joint from frontwards and backwards forces. The posterior cruciate ligament (PCL) attaches to the tibia at the back of the knee and the anterior cruciate ligament (ACL) attaches to the tibia at the front of the knee.

how the anterior cruciate twists

Note in the sketch on the left how the anterior cruciate ligament attaches, and the anatomy when the knee is bent and straightened. This is one of the reasons why ligament replacements do not do as good a job as the original ligament as this cannot be mimicked by the replacement.

 

 

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What kind of injuries damage the cruciates?

The ACL is more commonly damaged than the PCL. Injury to the ligaments may be 'non-contact' or 'contact'. Injury to the ACL may occur while cutting and running to that side during a fast non-contact activity like football, or from landing from a twisting jump on that leg while the body still has momentum and continues to twist.

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What are the symptoms of a torn anterior cruciate ligament?

During the injury event, the person may hear a loud 'pop', immediately followed by swellling of the knee and instability.

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Peer-reviewed papers

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Synonyms: 
Crucial ligament
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