Patent ID: 8753405

Claim:
A method of accurately and correctly fitting and axially positioning an implantable ball to the neck trunnion of a hip replacement device, as during surgery, the ball adapted to be received in a socket, the ball having a bore, that method including the steps: a) said neck trunnion provided with deformable metallic surface ribs, defining ridges, extending with screw thread configuration about the neck trunnion, b) providing a deformable adapter and fitting the adapter over said ribs, c) providing a trial ball having a non-metallic bore, and axially forcibly fitting that bore over the deformable adapter to deform the adapter into spaces formed between the ribs, without deforming said ribs, as the trial ball adjustingly arrives at selected axial position on the neck corresponding to correct position of the trial ball in the socket, and correspondingly correct axial position of the implantable ball on the neck, the adapter being rotated to unscrew from the ribs and from said spaces between the ribs, d) removing the trial ball and the adapter from the neck trunnion, the adapter being rotated to unscrew from the ribs and from said spaces between the ribs, e) and axially fitting said bore of the implantable ball over and along said neck trunnion to squeeze and deform said ribs as the implantable ball forcibly arrives at said selected axial position on the neck trunnion, thereby to lock the implantable ball to the neck, for correctly positioning reception in the socket.