Bone anchor implants, assemblies, systems, instruments, and methods thereof. The bone anchors may be threaded or non-threaded, adjustable or expandable, stackable, or otherwise configured to promote fixation of the sacroiliac joint. The bone anchors may be used independently or may be configured to integrate with long rod constructs, for example, with a tulip or other suitable attachment interface, to fuse the sacroiliac joint.

A bone plate system may include a bone plate having a bone-facing side, an obverse side displaced from the bone-facing side by a thickness of the bone plate, a first end, and second end displaced from the first end along a longitudinal length of the bone plate. The bone plate may have a first fastener hole extending through the bone plate between the bone-facing side and the obverse side, a second fastener hole extending through the bone plate between the bone-facing side and the obverse side, and a plug extending outwardly from the bone-facing side. The plug may have a cross-sectional shape, perpendicular to the thickness, that is elongated along the longitudinal length.