Prosthesis for cemented fixation and method for making the prosthesis
View Patent ↗A joint prosthesis system is suitable for cemented fixation. The system has two metal implant components and a bearing. One of the metal implant components has an articulation surface for articulation with the bearing. The other metal implant component has a mounting surface for supporting the bearing. One of the metal implant components includes an extension, such as a stem or pegs, with an exposed outer surface. The metal implant component from which the extension extends comprises titanium and the exposed outer surface of the extension comprises a different form of titanium. A method of making the joint prosthesis is also disclosed.
1. A joint prosthesis comprising:
a first metal component having a solid metal portion with a solid metal articulation surface and a second solid metal surface opposite the solid metal articulation surface, the first metal component further having a porous metal portion along the second solid metal surface, the porous metal portion including a bone-engaging surface opposite from the second solid metal surface;
a bearing having an articulation surface shaped to bear against the articulation surface of the first metal component and an opposite surface;
a second metal component having a solid metal portion with a solid metal mounting surface and a second solid metal surface opposite the solid metal mounting surface, the second metal component further having a porous metal portion along the second solid metal surface, the porous metal portion including a bone-engaging surface opposite from the second solid metal surface; and
an extension extending beyond the bone-engaging surface of one of the porous metal portions of one of the metal components to an exposed end, the extension having an opposite end received in a recess in the second solid metal surface of the solid metal portion of one of the metal components, an exposed outer surface and a length from the opposite end to the exposed end;
wherein:
the extension is configured for stabilizing the metal component when implanted in a bone of a patient;
the length of the extension from the bone-engaging surface to the exposed end consists of titanium foam having a void space of at least 65% by volume;
the solid metal portion of the metal component from which the extension extends comprises a titanium alloy; and
the titanium foam of the extension comprises commercially pure titanium.
2. The joint prosthesis of claim 1 wherein the exposed outer surface of the extension at the exposed end of the extension has a different roughness than at least a part of the exposed outer surface of the extension between the exposed end and the opposite end.
3. The joint prosthesis of claim 1 wherein the extension is selected from the group consisting of a peg and a stem.
4. The joint prosthesis of claim 1 wherein the porous metal portions of the metal components comprise commercially pure titanium.
5. The joint prosthesis of claim 1 wherein:
the prosthesis is an ankle prosthesis;
the first metal component comprises a distal tibial component; and
the extension extends out from the bone-engaging surface of the distal tibial component.
6. The joint prosthesis of claim 1 wherein:
the prosthesis is a knee prosthesis;
the first metal component is a distal femoral component configured to replace the distal end of the femur; and
the second metal component is a tibial tray configured to replace the proximal end of the tibia.
7. The joint prosthesis of claim 6 wherein:
the extension extends outward from and is bonded to the solid titanium alloy of the tibial tray by sintering.
8. The joint prosthesis of claim 7 wherein the bone-engaging surface of the tibial tray comprises commercially pure titanium foam bonded to the solid titanium alloy of the tibial tray by sintering.
9. The joint prosthesis of claim 6 wherein:
the articulating surface of the femoral component comprises solid titanium alloy, the solid titanium alloy extending from the articulating surface toward the bone-engaging surface; and
the extension is bonded to the solid titanium alloy of the femoral component by sintering.
10. The joint prosthesis of claim 9 wherein the bone-engaging surface of the femoral component comprises commercially pure titanium foam bonded to the solid titanium alloy of the femoral component by sintering.