Scientists say the human knee has one more ligament than previously thought.

Two Belgian knee surgeons have identified another ligament buried in the muscles and tendons of the knee. They're calling it the anterolateral ligament (ALL), and say it's present in 97% of human knees.

The researchers found this ligament after studying why sdme patients had issues with their knees after undergoing ACL surgery. researchers say their findings are significant and the ligament may play a role in how patients recover from ACL surgery.