A previously unknown, un-described ligament has been found in the human knee. This ligament reportedly plays an important role in patients with anterior cruciate ligament (ACL) tears.

The discovery was made by two researchers from the University Hospitals Leuven. Up until now, researchers have not been able to figure out why some patients with ACL tears continue to experience so-called 'pivot shift', or episodes where the knee 'gives way' during activity even after successful ACL repair surgeries.

Therefore, for the last four years, surgeons Dr. Steven Claes and Professor Dr. Johan Bellemans have been conducting studies regarding serious ACL injuries in an effort to find out why such a pivot shift occurs. During one such study, the new ligament was discovered.

The doctors became the first to provide a full anatomical description of the ligament after a broad cadaver study using macroscopic dissection techniques. Their research shows that the ligament, called the anterolateral ligament (ALL), was present in all but one of the 41 cadaveric knees studied. Subsequent research shows that pivot shift, the giving way of the knee in patients with an ACL tear, is caused by an injury in the ALL ligament.

The new discovery led researchers to questions information regarding serious ACL injuries and it may also provide a breakthrough in developing new treatments for patients with such injuries.

These knee injuries are very different from those caused by arthritis. A previous study claimed that such knee injuries can be avoided by losing 10 percent of a person's current weight. This also helps reduce the knee pain of people suffering from knee osteo-arthritis.