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 .