Systems for and methods of fusing a sacroiliac joint are provided which may include an implant adapted to be inserted into the joint space defined by the bones of a sacrum and an ilium and a delivery tool for inserting the implant into the sacroiliac joint. The method may include delivering the implant into the SI joint in a first position and transitioning the implant from the first position to a second position in situ. The implant may be configured such that in the second position the implant generally mimics a shape of the joint space of the sacroiliac joint. The implant may further include an actuation mechanism configured to cause the implant to transition from the first position to the second position. The actuation mechanism may include a hydraulic, pneumatic, geared or screwed mechanical arrangement.
