A method of assessing the volume of a lesion in a bone comprises inserting a steerable catheter comprising an expandable structure, a suction member, and a steerable element into the bone along a longitudinal axis. The method further comprises steering the steerable element away from the longitudinal axis toward the lesion, removing cellular matter from the lesion using the suction member, and inflating the expandable structure with inflation medium to create a cavity defining the boundary of the lesion. The method also comprises measuring the volume of inflation medium in the expandable structure, thereby determining the volume of the cavity.
