Though it’s generally assumed that all parts of the human body have been mapped and accounted for, it turns out that the study of human anatomy isn’t quite complete.

Two Belgian surgeons have recently published a paper in the Journal of Anatomy titled “Anatomy of the anterolateral ligament of the knee.” The paper provides a clear anatomical description of the anterolateral ligament (ALL), a previously unnamed ligament found near the front of the knee.

Though the new paper provides a full description of the newly-found ligament, the existence of the ligament was speculated upon as far back as 1879 by a French surgeon.

Dr. Steven Claes, lead author of the paper, and his colleagues examined 41 human cadaver knees using macroscopid dissection techniques. They found the ALL in 40 of them, meaning that perhaps up to 97% of all humans have the ALL in their knee.

In addition to describing the ALL, the doctors were interested in whether the ligament could play a role in pivot shift – an occurrence in which the knee of athletes with former anterior cruciate ligament (ACL) injuries gives way under stress. In examining the ALL it was found that injuries to the newly-named ligament are, in fact, the cause of pivot shift.

Claes and his fellow researchers are now working on a technique to repair ALL injuries. A new surgery of that type could be ready in the coming years, meaning the treatment of ACL injuries and tears could change significantly.

(Image courtesy University of Leuven)