A method of fusing a sacroiliac joint includes inserting expandable implants into multiple implant-receiving holes in ilium and sacrum； expanding the implants to engage both bones； and permitting bone growth to fuse the bones. Alternatively, implants may be inserted into multiple non-round implant-receiving holes in ilium and sacrum formed using a power impact driver attached to a broach tool to prevent movement of the sacroiliac joint. The expandable implants have an outer shell with bone-engagement ridges in porous outer surface to permit ingrowth of bone； an inner expander screw with forcing cone and threads； the outer shell portion having threads engaged with threads of the inner expander screw and an inner conical mating surface for the forcing cone of the inner expander screw； the outer shell engaging an outer sleeve of an insertion tool； and the inner expansion screw engaging a rotatable bit of an insertion tool.
