New Ligament in the Human Knee Discovered

Researchers have identified a new ligament hiding out in the knee that appears to play an important role in anterior cruciate ligament (ACL) tears.

For years, physicians have been mystified by certain patients whose knees suddenly give way even after seemingly successful ACL repair surgery and rehabilitation.

To find out why this is, Dr. Steven Claes and Dr. Johan Bellemans, two orthopedic surgeons at University Hospitals Leuven, turned to a 19th century article by a French surgeon that hypothesized about a ligament on the anterior of the knee.

After four years of research, the Belgian doctors have proven the surgeon right. Their study, published in the Journal of Anatomy, represents the first full anatomical description of the ligament, which they found while studying a wide range of cadavers via acroscopic dissection techniques.

Dubbed the anterolateral ligament (ALL), all but one of the 41 cadavers the researchers studied had it, with further research showing that pivot shift, or the giving way of the knee in those with an ACL tear, occurs when the ALL is damaged.

The study, which the Anatomical Society called "very refreshing," is a reminder that there is still much about the human body that remains a mystery despite millennia of research.

Already Claes and Bellemans are working on a surgical technique to correct ALL injuries, with results expected in the next several years.

According to the American Academy of Orthopedic Surgeons, the ACL is one of the most commonly injured ligaments in the knee with some 200,000 tears occurring annually throughout the United States. An estimated 100,000 ACL reconstructions are performed every year, the AAOS reports. Individuals who engage in high risk sports, including basketball, football, skiing and soccer, face the highest risk of incurring damage to their ACL.

To see a picture of the ligament, click here.