Conference Focus on Materials
BY EDITOR, NOVEMBER 24, 2003
At the 78th annual reunion of the Société Française de Chirurgie Orthopédique et Traumatologique (SO.F.C.O.T.) held last week in Paris, the focus was clearly on new materials - ceramics, plastics and biologics. And among the most successful new materials companies in the world today has to be, we think, Ceramtec, the German based supplier of medical grade ceramic hip and knee components.
As we stood in the booth talking to Ceramtec's representative, we were literally surrounded by booths featuring the company's high-purity aluminum oxide ceramic, Biolox®. Directly across was Stryker and katy-corner was Wright Medical's booth, both of which highlighted the Ceramtec Biolox® hip. Throughout the rest of the exposition, Biolox® or other ceramic components were in nearly all large joint booths. European suppliers have made ceramic hip components a near universal offering. We've heard from U.S. manufacturers that ceramic hips account for about 35% of all European hip implants. In the U.S., ceramic components drove a 68% increase in U.S. hip sales for Wright Medical last quarter. (Stryker and Wright are the only companies with FDA approved ceramic hip system - both source their material from Ceramtec.)
Ceramtec's message at the conference was quality control and among the featured products was an interesting new knee component (pictured below).
Ball heads and sockets or cup inserts made of Biolox® have been used in artificial hip joints in clinical since 1974. More than 3 million Biolox® components have been implanted worldwide.
Pyrolytic carbon
One of the best understood medical grade materials, had a small, but intriguing presence at SO.F.C.O.T. Pyrolytic carbon, the premier material for artificial heart valves was discovered in 1966 at General Atomics corporation by Dr. Jack Bokros and Dr. Vincent Gott, then at the University of Wisconsin. Before Pyrolitic Carbon, artificial heart valves were made from plastic and metal and typically wore out or triggered blood clotting prematurely. Gott was searching for a material to use in artificial heart valves that did not provoke blood clots and had the mechanical durability to endure a lifetime. Pyrolytic carbon met both of his needs; although its principal use at the time was to coat nuclear fuel particles.
After 30 years, pyrolytic carbon remains the most widely used material for mechanical heart valves. It has been used in more than 4 million cardiovascular implants in more than 25 different valve designs for a clinical experience on the order of 18 million patient-years. But, it has only recently found a couple of champions in orthopedics, which strikes us as unfortunate. Pyrolytic carbon is extremely durable; potentially more so than the aluminum oxide ceramics like Biolox®. It's biocompatibility is well established. So, we were more than a little intrigued to find a very tiny start-up firm creating pyrolitic carbon orthopedic implants at SO.F.C.O.T. Of course, Ascension Orthopedics in Austin, Texas has been developing small joint implants using Pyrolitic Carbon since the early 1990s and their wear rates are excellent, less than one-tenth that of metal on UHMWPe. Interesting!
PEEK plastic and allograft
Among the other materials that were featured in a fair number of booths were two increasingly popular alternatives to metal implants in the spine: PEEK and allograft. Polyetheretherketone (PEEK) materials are semi-crystalline, high purity polymers. They have been used historically as a replacement for machined metals in a wide variety of non-implantable, sterilizable medical instruments like catheters, disposable surgical instruments, and sterilization trays. Because of PEEK's structure, products made from the material can be subjected to autoclave heat, EtOgas, or high-energy radiation.
While we saw a few PEEK spinal implant products at NASS, we saw more at SO.F.C.O.T. In the spine, PEEK's load bearing and wear resistant capabilities appear to make them reasonable, though not necessarily better, alternatives to metal implants. And while the European allograft market is assumed to be about a decade behind the U.S. market, we saw four companies with allograft implants at SO.F.C.O.T; a number that would have been consistent with NASS five years ago.
