Many already know about the four ligaments in the knee- medial collateral, anterior cruciate, posterior cruciate, and lateral collateral. However, according to a New York Times article, doctors in Belgium have identified a fifth ligament in the knee called the anterolateral ligament (A.L.L.). This ligament was originally speculated about in the 19th century by a French surgeon named Paul Segond. While Segond did note evidence of its presence and function, he failed to name it, and its presence was forgotten.
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However, it has been discovered again and given a proper name. The A.L.L. on the outside, front portion of the thighbone and continues down to the beginning of the shinbone. This placement allows it to stabilize the knee and prevent it from collapsing inward. Previously, doctors thought that the A.L.L. was just a continuation of the illiotibial band, but it is clear now that it is a completely different entity.
A few years ago, Dr. Claes and his colleagues noticed that some patients that had underwent and recovered from A.C.L. surgery had problems with their knees collapsing. He guessed at the existence of a new ligament and searched for the ligament in donated knees; he easily found it. Now doctors are beginning to practice procedures for torn and sprained A.L.L.s. Thanks to Dr. Claes’ rediscovery of Segond’s original hypothesis, doctors will now be able to fully treat all ligaments in the knee.