Abstract: A guide assembly for surgical instruments used for performing surgical procedure on a bone having a longitudinal axis. At least one stand-off member secured to and extending from the bone is coupled to a support member holding the support member laterally from and in parallel relationship with the longitudinal axis of the bone. The support member provides a base for a locating assembly which comprises an arm a positioning member and a guide member. The arm is coupled to the support member and is movable linearly between the extremes thereof, along a path related to the longitudinal axis of the bone. The positioning member which includes a plurality of positioning apertures along its length, is defined by a constant radius equal to the distance the support member is laterally offset from the longitudinal axis of the bone.