This chapter of anatomy and biomechanics of the knee is guided by my proper experience through precise critical learning by doing knee ligament surgery and studying anatomy of the ligaments from 1970 on in a first phase by doing the operations following the general scientific evolution until 1974. After the unsatisfactory outcomes with these types of operations, published and practiced in the 1960s and 1970s, which did rarely restore a knee to the expected full function, Prof. Arthur von Hochstetter from the Basel University Anatomy Institute showed me the key to understand knee ligament kinematics by the work of Alfred Menschik (Mechanik des Kniegelenkes 112:481–495, 1974; Mechanik des Kniegelenkes 113:388–400, 1975; Biometrie, das Konstruktionsprinzip des Kniegelenks, des Hüftgelenks der Beinlänge und der Körpergrösse. Springer, Berlin/Heidelberg/New York/London/Paris/Tokyo1985). The crossed four-bar link system with the cruciate ligaments is the central pivot gear of knee motion determining the anatomic position of the peripheral ligaments for their cofunction. The menisci are parts of the enlarged central pivot with a longer lever arm from the axis of rotation—the important controllers and stabilizers of the rotation next to the cruciate ligaments towards the periphery. Some of the peripheral ligaments like MCL or LCL are primary stabilizers against varus–valgus rotation as well as IR and ER. Some of the ligaments are connected with tendons to be actively reinforced and tightened in critical positions when the ligaments are at risk and need help by muscular force as actively dynamized ligaments.