An improved posterior acetabular wall fracture buttress plate has a buttress plate having a pair of arms extending from a main plate. The main plate is pre-contoured with a concavity contoured to mimic a hip socket contour posteriorly along an undersurface, the arms being 1.0 cm or less wide and bent lengthwise off horizontal about 38 degrees plus or minus 8 degrees to mimic a curvature of the hip to yield an angle on the undersurface of 142 degrees plus or minus 8 degrees. This is a stand-alone buttress plate intended to accomplish a buttress effect similar to previous art of 2-3 pelvic plates.