An undercutting sacroiliac fusion system for preparing a region between an ilium and a sacrum for sacroiliac fusion, wherein the undercutting system comprises: an insertion apparatus having an elongated shaft and a handle, wherein the insertion apparatus comprises a guide channel extending between a proximal end and a distal end of the insertion apparatus, wherein proximate the proximal end, the guide channel is aligned substantially parallel to a central axis of the insertion apparatus, wherein proximate the distal end, the guide channel is substantially transverse to the central axis and wherein intermediate the proximal end and the distal end the guide channel comprises a transition region; and a cutting assembly (32, 132, 232, 332, 432, 532, 632, 732, 1432, 1932, 2032, 2132, 2232, 2532, 2832) comprising a distal end, wherein the cutting assembly is operably attached to the insertion apparatus, wherein the cutting assembly is movable with respect to the shaft between a retracted configuration and an extended configuration, wherein the distal end of the insertion apparatus has an aperture formed therein, wherein the cutting assembly is substantially within the aperture when the cutting assembly is in the retracted configuration and wherein in the extended configuration, the distal end of the cutting assembly extends laterally from the shaft; wherein the cutting assembly is rotatably mounted to the insertion apparatus, and wherein the distal end of the insertion apparatus has a width and wherein the cutting assembly is substantially within the width when the cutting assembly is in the retracted configuration characterized in that: the handle is rotatable; and the cutting assembly is rotatable about an axis that is parallel to, and offset from, the central axis of the insertion apparatus. an insertion apparatus having an elongated shaft and a handle, wherein the insertion apparatus comprises a guide channel extending between a proximal end and a distal end of the insertion apparatus, wherein proximate the proximal end, the guide channel is aligned substantially parallel to a central axis of the insertion apparatus, wherein proximate the distal end, the guide channel is substantially transverse to the central axis and wherein intermediate the proximal end and the distal end the guide channel comprises a transition region; and a cutting assembly (32, 132, 232, 332, 432, 532, 632, 732, 1432, 1932, 2032, 2132, 2232, 2532, 2832) comprising a distal end, wherein the cutting assembly is operably attached to the insertion apparatus, wherein the cutting assembly is movable with respect to the shaft between a retracted configuration and an extended configuration, wherein the distal end of the insertion apparatus has an aperture formed therein, wherein the cutting assembly is substantially within the aperture when the cutting assembly is in the retracted configuration and wherein in the extended configuration, the distal end of the cutting assembly extends laterally from the shaft; wherein the cutting assembly is rotatably mounted to the insertion apparatus, and wherein the distal end of the insertion apparatus has a width and wherein the cutting assembly is substantially within the width when the cutting assembly is in the retracted configuration characterized in that: the handle is rotatable; and the cutting assembly is rotatable about an axis that is parallel to, and offset from, the central axis of the insertion apparatus. the handle is rotatable; and the cutting assembly is rotatable about an axis that is parallel to, and offset from, the central axis of the insertion apparatus.