Prosthesis with surfaces having different textures and method of making the prosthesis
A joint prosthesis system is suitable for cementless 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 a solid metal portion and a porous metal portion. The porous metal portion has surfaces with different characteristics, such as roughness, to improve bone fixation, ease removal of the implant component in a revision surgery, reduce soft tissue irritation, improve the strength of a sintered bond between the solid and porous metal portions, or reduce or eliminate the possibility of blood traveling through the porous metal portion into the joint space. A method of making the joint prosthesis is also disclosed. The invention may also be applied to discrete porous metal implant components, such as augment.
1. A method of making a tibial implant component comprising a bearing and a tibial tray, the tibial tray having a solid metal portion and a porous metal portion that is coupled to the solid metal portion and having a void space, the solid metal portion including a proximal surface to receive the bearing and a distal surface positioned opposite the proximal surface, and the porous metal portion including a proximal portion along the distal surface of the solid metal portion, an exposed distal bone-engaging surface, and an exposed peripheral surface extending around at least a portion of the periphery of the tibial tray,
wherein:
the exposed peripheral surface is generally perpendicular to and extends from the level of the exposed distal bone-engaging surface of the porous metal portion toward the solid metal portion;
the exposed peripheral surface has a static coefficient of friction; and
the exposed distal bone-engaging surface has a higher static coefficient of friction than the exposed peripheral surface;
the method includes treating the exposed peripheral surface to reduce its static coefficient of friction.
2. The method of claim 1 wherein the step of treating the exposed peripheral surface comprises one of the following: machining, milling, polishing and smoothing the exposed peripheral surface.
3. The method of claim 2 wherein the exposed distal bone-engaging surface of the porous portion has a higher static coefficient of friction than the exposed peripheral surface after the treatment step.
4. The method of claim 1 wherein the porous metal portion has a void space of at least 60% by volume.
5. The method of claim 1 wherein the exposed peripheral surface extends around the entire periphery of the tibial tray.
6. The method of claim 5 wherein the metal foam includes titanium.
7. The method of claim 1 wherein the porous metal portion comprises metal foam.
8. A method of making a tibial implant component comprising a bearing and a tibial tray, the tibial tray having a solid metal portion and a porous metal portion that is coupled to the solid metal portion and having a void space, the solid metal portion including a proximal surface to receive the bearing and a distal surface positioned opposite the proximal surface, and the porous metal portion having a void space and including a proximal portion along the distal surface of the solid metal portion, an exposed distal bone-engaging surface, and an exposed peripheral surface extending around at least a portion of the periphery of the tibial tray,
wherein:
the exposed peripheral surface is generally perpendicular to and extends from the level of the exposed distal bone-engaging surface of the porous metal portion toward the solid metal portion;
the exposed peripheral surface has a porosity; and
the exposed distal bone-engaging surface has a higher static coefficient of friction than the exposed peripheral surface;
the method includes treating the exposed peripheral surface to reduce its porosity.
9. The method of claim 8 wherein the step of treating the exposed peripheral surface comprises one of the following: machining, milling, polishing and smoothing the exposed peripheral surface.
10. The method of claim 9 wherein the exposed distal bone-engaging surface of the porous portion has a higher static coefficient of friction than the exposed peripheral surface after the treatment step.
11. The method of claim 8 wherein the porous metal portion has a void space of at least 60% by volume.
12. The method of claim 8 wherein the exposed peripheral surface extends around the entire periphery of the tibial tray.
13. The method of claim 8 wherein the porous metal portion comprises metal foam.
14. The method of claim 13 wherein the metal foam includes titanium.