At the Belgian University Hospitals Leuven, two knee surgeons have for the first time given a full anatomical description of a new ligament that they term the anterolateral ligament (ALL).
The new ligament is thought to play an important role in anterior cruciate ligament (ACL) tears.
Orthopedic surgeons Dr. Steven Claes and Prof. Johan Bellemans and colleagues, write about some of their findings in a recent issue of the Journal of Anatomy.
For the last 4 years, the two surgeons have been researching ACL tears to find out why, despite undergoing successful ACL repair surgery and rehabilitation, some patients still experience "pivot shift," where the knee sometimes gives way.
'Pearly band' first described in 1879
Their enquiries began with an 1879 article by the French surgeon Segond who suggested the front of the human knee had an additional "pearly, resistant, fibrous band."
Until now the mysterious "pearly band" has been given various confusing names, but "no clear anatomical description has yet been provided," write the authors.
So, using macroscopic dissection techniques, they carried out in-depth examinations of 41 cadaver knees and found the new ligament in all but one of them. They write:
"The ALL was found to be a distinct ligamentous structure at the anterolateral aspect of the human knee with consistent origin and insertion site features."
Researchers propose that the ALL controls the rotation of the tibia
They propose, given its structure and location in the knee, that the ALL controls the rotation of the tibia, one of the two bones in the lower leg, and that pivot shift may be caused by an injury to the ALL.
They have since carried out some research that appears to confirm this.
The findings question current views about serious ACL injuries and could signify a breakthrough in the treatment of patients with such injuries.
Dr. Claes and Prof. Bellemans are already working on a technique to correct ALL injuries and hope it will be ready in a few years time.
ACL tears are common among athletes who practice pivot-heavy sports, such as basketball, skiing and football.
A recent study from the US published in the Journal of Athletic Training, found that because they are more prone to landing in a knock-kneed position, women are more likely to tear the ACL than men.