Abstract: A medical instrument and procedure is adapted to mill bone along a curve and with respect to at least two angles of orientation with respect to an input source of rotary motion. Particularly, the medical instrument is a bone milling apparatus that is configured to mill bone along a predetermined curved path or curve. The bone milling apparatus includes a reamer that is rotatable about a curved shaft which is retained by a frame. The shaft has a predetermined curve that corresponds to a desired milling curve. The reamer is comprised of a plurality of interconnected segments, with each segment having cutting surfaces such that each segment is a cutter. The reamer is thus flexible with respect to the interconnection between the individual segments.