Medical Device Link.

Originally Published MX January/February 2005

COVER STORY

In the world of orthopedic joint replacement research, the big buzz is all about advanced bearing materials. Over the past decade, major players in the orthopedic sector have invested heavily in R&D to develop materials that can withstand the significant stresses exerted on a hip or knee under a normal range of motion. In a joint replacement implant, the bearing material must be tough, with high fatigue strength and the ability to withstand considerable sliding and rotating.

For Smith & Nephew Orthopedics (Memphis), the need for such advanced bearing materials is being amply filled by a form of oxidized zirconium that the company has trademarked as Oxinium. The company's unique manufacturing process enables zirconium to absorb oxygen, turning the surface of the alloy from a metal to a ceramic. The resulting material incorporates the best features of ceramic and cobalt chrome, and is 4900 times more resistant to scratches than cobalt chrome.

Angie Craig

Smith & Nephew researchers invented Oxinium in the mid-1990s, but it took five years of additional research and manufacturing know-how before the first product using the material could be brought to market. "In this market, innovations in materials do not occur every day or even every year," says Angie Craig, Smith & Nephew's vice president for public and investor relations.

Oxinium has proven to be a superior metal in implants due to its hardness, smoothness, and resistance to scratching and abrasion. The ceramic-like surface reduces friction between the implant device and the cartilage, potentially resulting in less wear and tear and a longer-lasting device. With reduced damage and increased longevity, Oxinium may reduce the average age of patients who are candidates for implant surgery.

Advanced materials in Smith & Nephew implants: Synergy hip assembled with an Oxinium femoral head (left); Genesis II knee using Oxinium (right). (click to enlarge)

Smith & Nephew first introduced Oxinium in a knee implant launched in 2001. Today, the company offers Oxinium total and partial (uni) knee replacements, and has plans to introduce an Oxinium revision knee in 2005. Smith & Nephew launched its total hip replacement with an Oxinium femoral head in February 2003, with great success. "Within two quarters, the new hip had reached a market penetration of 45%," says Craig.

Having worked so hard to bring its advanced material to market, Smith & Nephew is making sure to protect its property. "The manufacturing process for Oxinium is very difficult," says Craig. "We have process patents running out quite far. We think Smith & Nephew will enjoy a proprietary position on Oxinium for a long time to come."

Copyright ©2005 MX