A bone milling instrument is disclosed for creating a shaped cavity from an initial cavity in a bone, the bone milling instrument comprising a reference frame having a proximal end and a distal end, the reference frame defining a longitudinal axis between the proximal end and the distal end, a centering member provided at the distal end of the reference frame, the centering member configured for placement within the initial cavity so as to selectively maintain a relative positioning of the longitudinal axis of the reference frame and the bone with one another, a registration surface for engaging a portion of the initial cavity so as to establish a desired vertical position of the reference frame along the longitudinal axis, the registration surface located proximally of the centering member, and an attachment site provided proximally of the registration surface, a guidance support member having a first end and a second end, an attachment mechanism at the first end of the guidance support member for adjustable connection thereof at the attachment site of the reference frame and a constrained pathway extending between the first end and the second end of the guidance support member; a shuttle having a first connection element and a second connection element, the first connection element configured for positionably attaching the shuttle to the guidance support member so as to allow movement of the shuttle within the constrained pathway, and the second connection element configured to provide a rotational coupler within the shuttle; and a cutting device having a proximal end and a distal end, a cutting portion configured at the distal end of the cutting device, and an attachment portion provided at the proximal end, wherein the cutting device is selectively attached to the rotational coupler within the shuttle so as to allow rotational motion of the cutting portion as the shuttle is selectively positioned within the constrained pathway so as to create the shaped cavity from the initial cavity in the bone.