A sacroiliac joint implant includes an implant structure formed from an elongated base member, an elongated first side member, and an elongated second side member, with an internal support structure extending in an implant plane from the base member to each of the first side member and the second side member. Three or more fusion passages are defined in an area between the base member, first side member, and second side member. Each fusion passage defines a respective open area through the implant to facilitate bone growth across the sacroiliac joint when the implant is properly implanted in the joint.