What do 4-time Superbowl winner Tom Brady, USA women’s World Cup winner Alex Morgan, and Rob Gronkowski have in common? They’ve all suffered from ACL injury and returned to play after rehab.

The knee is an interesting joint – unlike the hip, it’s not built for stability but rather movement, and relies on 4 major ligaments to help support it.

knee health 101 knee ligaments - ae wellness

Did you know the knee can rotate? The tibiofemoral joint can move in 4 directions: flexion (140˚), extension (5˚), lateral rotation (30˚) and medial rotation (15˚).

The ligaments of the knee, along with the meniscus and joint capsule, help to provide stability for this modified hinge joint during movement and stillness.

The four ligaments in the knee are:

  • MCL aka medial collateral ligament
    Found on the medial side (or inner side) of the knee. It’s fascial connection to the medial meniscus means they are commonly injured together.
  • LCL aka lateral collateral ligament
    Found on the outside of the knee. Prevents movement of the tibia inward (adduction) in relation to the femur.
  • ACL aka anterior cruciate ligament
    Found deep within the knee joint capsule, the ACL limits anterior translation of tibia to the femur.
  • PCL aka posterior cruciate ligament
    Also within the joint capsule, the PCL crosses over the ACL and limits posterior translation of tibia to femur when the leg is fixed.

Both the ACL and PCL are strongest at end range of knee extension, but since most athletic endeavors don’t have you hanging out with your knees locked, they are commonly put in vulnerable positions.

Watch my latest episode of Anatomy with Alex (below) to learn:

  • What the 4 ligaments of the knee are
  • How to know when you’ve injured the ACL
  • Why women are more likely than men to tear an ACL
  • If surgery is the best option for all ACL or MCL injuries

Tune in every Wednesday at 3:15 pm PST on the AE Wellness Facebook Page for Anatomy with Alex, my weekly show where I teach you anatomy and physiology in ways that are relevant to you in your life so you can maximize your mobility and live pain-free in your body.

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