The invention concerns a system for partially cutting a bone, comprising a device for guiding a cutting tool. According to the invention, the device comprises: —an upper face forming a mechanical stop for a first part of the cutting tool, the upper face being non-cutting and thicker than the blade, so as to limit the insertion of the blade into said bone in order to partially cut said bone, the upper stop face having a profile that is a homothety of the edge profile of said hinge, the guide device having a pre-defined range to ensure the steering of the blade of the cutting tool in a pre-defined direction of partial cutting of the bone, —a second part that fastens to the bone and a first fastening means for fastening the guide device to the second part and —a means for adjusting the orientation of the guide device relative to the second part.