Surgeons in Belgium have found a new ligament in the human knee, which might hold the key to treating particular sports injuries.

The discovery of the anterolateral ligament gives particular hope for people who have torn their anterior cruciate ligament (ACL).

Such tears are particularly common among footballers.

The ligament was uncovered by orthopaedic surgeons Steven Claes and Johan Bellemans of the University of Leuven who were looking to understand why patients with ACL-repaired knees could still suffer from recurrent "pivot shifts" where the knee "gives way" during activity.

The surgeons began their investigation by looking back at an article from 1879 by French surgeon Paul Segond who suggested there might be another ligament located on the anterior of the knee.

After a four-year study using macroscopic dissection techniques on 41 corpses, the scientists found that the anterolateral ligament (ALL) was present in all but one of the knees studied.

The scientists say the research could signal a breakthrough in the treatment of patients with serious ACL injuries.

"This study is the first to provide a detailed anatomical description of the anterolateral ligament (ALL) of the human knee," the authors wrote.

"Given its suggested role in common knee instability patterns such as the pivot shift, the precise anatomical knowledge of this enigmatic structure delivered by this study could be highly relevant for clinical practice.

"However, further research is needed to establish the function of the all and to determine its role in clinical knee injuries", They are currently working on a surgical technique to correct all injuries but say the results will not be ready for several years.

The results of the study, published in the Journal of Anatomy which described the research as "very refreshing".

The journal congratulated the researchers for "reminding the medical world that, despite the emergence of advanced technology, our knowledge of the basic anatomy of the human body is not yet exhaustive".