Our knees could be made of more parts than we originally thought! Two knee surgeons from Belgium have discovered an unknown ligament in the human knee! The surgeons say the newly found anterolateral ligament or ALL is located in the muscles and tendons of the human knee.

According to Dr. Steven Claes and Dr. Johan Bellemans from the University Hospitals Leuven, after undergoing successful anterior cruciate ligament or ACL surgeries, many patients will experience a condition known as pivot shift, which means the knee could give away during an activity. In order to understand the strange condition, Dr. Claes and Dr. Bellemans have spent the past four years conducting research on ACL tears.

During the study, they looked into a previous theory made by a French surgeon in 1879, in which he claimed that the human knee contained an unknown ligament. By using macroscopic dissection techniques in a large cadaver study, they were able to find that the surgeon’s theory was correct. They found that the anterolateral ligament can be found in 97 percent of all human knees and may also play a major role in how a patient recovers from ACL tears. These results could lead to new treatments for patients who suffer ACL tears.