The Anterolateral Ligament: A New Discovery in Knee Anatomy

In 2013, Belgian orthopedic surgeons published a paper confirming what earlier anatomists had suspected: the knee contains a previously underappreciated ligament on its outer (lateral) side, now named the anterolateral ligament (ALL). This discovery has significant implications for understanding knee instability, ACL injury, and why some patients continue to experience rotational instability after technically successful ACL reconstruction.

What Is the Anterolateral Ligament?

The ALL runs from the outer part of the femur (thigh bone) to the anterolateral portion of the tibia (shin bone). Its primary function appears to be controlling internal rotation of the tibia — the rotational movement at the knee that is destabilized in many ACL injuries. The ALL works in concert with the ACL to provide full rotational stability of the knee.

Why This Discovery Matters

A significant proportion of patients who undergo ACL reconstruction continue to report a feeling of rotational instability after surgery. In many cases, this is because the ALL was also injured at the time of the ACL tear — but because its existence was not recognized, it was not repaired. Some patients underwent multiple failed ACL reconstructions before this understanding emerged.

Implications for Conservative Care

From a chiropractic and rehabilitation perspective, the ALL's role in rotational stability underscores the importance of addressing rotational control in knee rehabilitation programs. Hip external rotator strengthening, single-leg stability training, and proprioceptive retraining all contribute to controlling the rotational forces that stress the ALL and ACL.

If you've had knee surgery and continue to experience instability, or if you've been diagnosed with an ACL tear and are exploring conservative options, our doctors at Total Health Family Clinic can provide a comprehensive knee assessment and rehabilitation program.