The invention relates to a system for aligning a first bone (1) with respect to a second bone (2) belonging to a limb and forming a joint (3) together, the first bone having been partially cut into one first segment and a second segment partially interconnected, said system being characterized in that it comprises in particular: a computer-assisted surgery station including a screen (20) and a processing device (19) comprising a memory in which a computer program and a processing unit adapted to execute said program are recorded, - two followers (181, 182) intended to be each set up on one of the two segments of the first bone (1), the position and the orientation of said followers (181, 182) being detectable by said station, said system being further characterized in that said computer program comprises instructions for carrying out the following steps: - whereas e each of said followers (181, 182) has been attached to one of said segments, respectively, and the two bones (1, 2) are rotated about the proximal end (4) of the second bone (2 ), the two bones being held fixed relative to one another, the acquisition of the point representing the proximal end of the second bone (2), in the frame of one of the followers (181, 182).L'invention est relative à système pour l'alignement d'un premier os (1) par rapport à un second os (2) appartenant à un membre et formant ensemble une articulation (3), le premier os ayant été partiellement coupé en un premier segment et un second segment liés partiellement entre eux, ledit système étant caractérisé en ce qu'il comprend notamment : - une station de chirurgie assistée par ordinateur incluant un écran (20) et un dispositif de traitement (19) comprenant une mémoire dans laquelle est enregistré un programme d'ordinateur et une unité de traitement adaptée pour exécuter ledit programme, - deux suiveurs (181, 182) destinés à être chacun mis en place sur l'un des deux segments du premier os (1), la position et l'orientation desdits su
