Surgical system for cutting an anatomical structure (F, T) of a patient according to at least one target plane defined in a coordinate system of the anatomical structure, comprising: (i) a robotic device comprising: - an end effector comprising a cutting tool or a cutting block, - an actuation unit comprising from three to five motorized degrees of freedom, attached to the end effector, configured for adjusting a position and orientation of the cutting tool or cutting block relative to each target plane, (ii) a passive articulated lockable holding arm supporting the actuation unit; (iii) a tracking unit configured to determine in real time the pose of the cutting plane with respect to the coordinate system of the anatomical structure, the tracking unit comprising a first tracker configured to be rigidly attached to the actuation unit, a second tracker configured to be rigidly attached to the end effector and a third tracker configured to be rigidly attached to the anatomical structure; (iv) a control unit configured to determine the pose of the cutting plane with respect to the target plane and to control the actuation unit so as to bring the cutting plane into alignment with the target plane, wherein the control unit is configured to implement a control loop comprising the following steps: - determining poses of the actuation unit, the end effector and the anatomical structure using localization information provided by the tracking unit; - computing a deviation between the cutting plane and the target plane; - if the deviation is less than a threshold, allowing operation of the cutting tool and returning to step to determine a new pose of the actuation unit, end effector and anatomical structure; - if the deviation is greater than or equal to the threshold, expressing the cutting plane and the target plane in the coordinate system of the actuation unit, - computing a correction matrix between a plane attached to an output of the actuation unit and the cutting plane; - updating the target plane with the correction matrix computed in step; - computing a new attitude of the actuation unit to align the cutting plane with the updated target plane, and determining the movements to be applied by the motors of the actuation unit; - activating the actuation unit to apply said movements. (i) a robotic device comprising: - an end effector comprising a cutting tool or a cutting block, - an actuation unit comprising from three to five motorized degrees of freedom, attached to the end effector, configured for adjusting a position and orientation of the cutting tool or cutting block relative to each target plane, - an end effector comprising a cutting tool or a cutting block, - an actuation unit comprising from three to five motorized degrees of freedom, attached to the end effector, configured for adjusting a position and orientation of the cutting tool or cutting block relative to each target plane, (ii) a passive articulated lockable holding arm supporting the actuation unit; (iii) a tracking unit configured to determine in real time the pose of the cutting plane with respect to the coordinate system of the anatomical structure, the tracking unit comprising a first tracker configured to be rigidly attached to the actuation unit, a second tracker configured to be rigidly attached to the end effector and a third tracker configured to be rigidly attached to the anatomical structure; (iv) a control unit configured to determine the pose of the cutting plane with respect to the target plane and to control the actuation unit so as to bring the cutting plane into alignment with the target plane, - determining poses of the actuation unit, the end effector and the anatomical structure using localization information provided by the tracking unit; - computing a deviation between the cutting plane and the target plane; - if the deviation is less than a threshold, allowing operation of the cutting tool and returning to step to determine a new pose of the actuation unit, end effector and anatomical structure; - if the deviation is greater than or equal to the threshold, expressing the cutting plane and the target plane in the coordinate system of the actuation unit, - computing a correction matrix between a plane attached to an output of the actuation unit and the cutting plane; - updating the target plane with the correction matrix computed in step; - computing a new attitude of the actuation unit to align the cutting plane with the updated target plane, and determining the movements to be applied by the motors of the actuation unit; - activating the actuation unit to apply said movements.