In 1982 a student at the University of Athens wrote a paper on a new finding in the ankle. The student's name was Constantinos Nikolopoulos. He reported a new ligament never seen before in the ankle. The paper wasn't published.
In 1990 another group of researchers reported on the same thing. They called the new structure a fascicle. A fascicle is a bundle. In this case, it was a fascicle of the anterior tibiofibular ligament. In this article Nikolopoulos, now a medical doctor, reports on a special study of this structure.
Looking at 24 cadavers, he found a separate ligament in 22 of the ankles. In each case the ligament was just below and parallel to the anterior inferior tibiofibular ligament (AITFL). The AITF ligament and the newly discovered ligament were two separate structures.
The new ligament was named the accessory anteroinferior tibiofibular ligament. In this report Dr. Nikolopoulos proposes that this structure is a separate ligament in the ankle. It's not a fascicle at all. This ligament may be the cause of ankle pain after some injuries if it gets pinched between two ankle bones.
Dr. Nikolopoulos says the accessory AITL isn't abnormal or a disease. It's a change in the normal anatomy found in maybe more than 90 percent of all people. It can become a problem when the ankle gets sprained.