Trident Cup: Early Results and Experiences Based on 100 Cases

The Authors report their experience with the new Trident cup in THR. They chose this particular cup because of its anatomical and hemispherical design that allows an almost anatomical load transfer to the pelvis, the material (rough large-grained surface titanium with HA coating), the great initial stability (peripheral fit of 1.8 mm), and intra-operative multiple options (polyethylene or ceramic bearings). From January 2002 to January 2004, 170 Trident cups have been implanted both in degenerative hips and in fractures. Clinical and radiological follow-up was obtained in the first 100 implants with at least one year follow-up in order to assess: 1) bone stock saving; 2) initial stability; 3) flexibility of the system. The results of the revision have underlined: 1) good bone-stock saving: the average diameter of the cup implanted was only 6 mm. greater than the removed femoral head; 2) good initial stability; no evidence of loosening; immediate postoperative weight-bearing in all patients; a further fixation with screws has been necessary only in 3 cases out of 100; good bone ingrowth also in cases of coxa protrusa in which bony grafts were incorporated in the bottom of the acetabulum. 3) the couplings were: CoCr-polyethylene in 82/100, ceramic-polyethylene in 9/100 and ceramic-ceramic in 9/100. Only one patient needed revision surgery, 8 months after the first implant, for recurrent dislocations and was treated with the implant of a constrained bi-articular liner.