Orthopedic implants are often utilized to help their recipients recover from injury or disease. To promote quick recovery, orthopedic implants are designed to cooperate with the body's natural inclination to heal itself. Some orthopedic implants are designed to foster osseointegration. As is known in the art, osseointegration is the integration of living bone within a man-made material, usually a porous structure. Cells in the recipient form new bone within the pores of the porous structure. Thus, the porous structure and the bone tissue become intermingled as the bone grows into the pores. Accordingly, orthopedic implants may include a porous surface to enhance fixation between the orthopedic implant and adjacent tissue. Of course, the faster the surrounding tissue grows into the porous surface, the sooner the patient may begin to resume normal activities. However, the manufacture of the orthopedic implants with porous structures is not without difficulty.
Orthopedic implants are usually made from various metals. One difficulty encountered during manufacturing is bonding separate components, each made of a different metal, together. For example, cobalt is a popular metal used to make orthopedic implants, and other popular metals include alloys of cobalt with other metals, such as chromium. The porous structure may be made from an entirely different metal, such as tantalum. In this case, bonding the porous metal to the orthopedic implant involves bonding tantalum to cobalt or to cobalt-chromium alloys. Bonding these two metals together has proved to be particularly problematic.
Thus, there is a need for an improved method of bonding of porous structures, specifically tantalum, to cobalt and cobalt-alloy implants such that the bond has sufficient strength while the corrosion resistance of the metals in the resulting implant are maintained.