Lesions of the central pivot of the knee are responsible for chronic disabling instabilities which, in the long term, lead to irreversible arthrotic destruction of the articular surfaces. Since 1980, we have been using synthetic ligaments and, more recently, since 1986, preserved human ligaments. The principle of ligamentoplasty is quite simply to replace torn ligaments with a prosthesis, aiming to reproduce the anatomical course of the ligament and its functional properties as faithfully as possible.