Barbs 14a, 14b are thus implanted into the superior and posterior portions of theacetabulum of the right- and left-hand coaxal bones, respectively.Barbs 14a, 14b will enable cup 12 to be rigidly affixed to the hip bone, prevent rotation of cup 12 about its axis of rotation A (FIG. 1) and prevent tilting or pull-out of cup 12 after implantation.It is an important feature of the present invention