Orthopedic Specialists

ALC, PCL, MCL, LCL - What are they and where are they located?

December 29, 2020

Most of us probably know someone who has had an ACL reconstruction/tear. Many people have also watched as athletes are carted out of the arena with what announcers presume is an ACL injury.

The content below will cover what an ACL is and where is it located. It also shares information about your PCL, MCL, and LCL as well as the location of these ligaments in the knee. These are the four main ligaments or tough bands of tissue in the knee.

ACL is the anterior cruciate ligament, which connects the thigh bone to the shin bone. The ACL stabilizes the tibia (shin bone) from sliding too far forward.  It is the most commonly injured knee ligament among athletes. 70% of ACL tears are the result of non-contact injuries, 30% are the result of direct contact.  

Women are 4-6 times more likely than men to experience an ACL tear.  Most people who sustain an ACL tear will undergo surgery to repair the tear. However, some people avoid surgery by modifying their activity and limiting joint stress.

The PCL is the posterior cruciate ligament which also links the thigh bone to the shin bone. It is the ligament that prevents the tibia (shin bone) from sliding too far backward. The PCL helps maintain the tibia in position below the femur (thigh bone). Posterior cruciate ligament injuries account for about 20% of knee injuries; these are usually related to car accidents.  

MCL is another of the four ligaments of the knee, the medial collateral ligament. This ligament connects the femur to the tibia on the inside of the knee. The MCL resists widening of the inside of the joint and prevents it from “opening up”.

It is usually injured when the knee is struck, causing the outside to buckle and the inside to widen. The MCL tear may be an isolated injury or it may be part of a complex injury to the knee.

The final ligament is the LCL or lateral collateral ligament. It connects the femur to the fibula, the smaller bone of the lower leg on the outer side of the knee. The LCL helps to prevent excessive side movement of the knee joint.

If the LCL is torn, the knee joint may move too far sideways when stressed. This usually occurs during sports activities. The LCL tears when the knee bends inwards excessively and the LCL is stretched too far. 

Knee ligament injuries are hard to prevent, but you can take some precautions that may make them less likely.  Keep the muscles around your knee strong with regular stretching and strengthening. It is important to warm up with light activities before taking part in tougher ones. Maintaining flexibility and slowly making changes to workout intensity will also aid in knee injury prevention.

Should you sustain an injury or have constant knee pain, you should come in for an evaluation with our orthopedic providers. No referral is necessary. 515-955-6767.

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