A buckle useful for cortical fixation has a graft retention loop slidably affixed thereto for movement from a first position adjacent a first end of the buckle to a second position at about the midpoint of the buckle. The buckle, with a graft over the loop, is drawn up lengthwise through a bone tunnel through a tibia and then flipped sideways to rest against the surface of the bone with the loop and graft depending back into the tunnel. The sliding attachment of the loop permits flipping of the buckle minimizes the flipping distance, which is the excess amount of the loop which must be pulled free of the tunnel to allow the buckle to be flipped sideways.