A method to guide in preparation of a bone relies on an instrument having a shaft with a working end and a stop member. The shaft is free to translate along an axis. Surgical planning data is registered to the bone to determine intra-operative coordinates of the desired axis and depth. The instrument holder is positioned by the bone so the stop member contacts the instrument holder to prevent translating beyond the desired depth. Alternatively, an arm is manipulated to align the instrument with the desired axis. The working end rests on the bone to define a linear separation to the desired depth. By proximally translating the instrument holder to contact the stop member and distally translating the instrument holder along the shaft, the stop member physically stops translating beyond the desired depth. A surgical system for performing the methods is provided； a reamer or impactor are also disclosed.
