Orthopedic device industry loses UHMWPE supplier
(from "OrthopedicsToday")
January 1996
WILMINGTON, Del.--One of the only two U.S. producers of ultra-high-molecular-weight polyethylene (UHMWPE) will no longer supply the raw material used to manufacture joint replacement components. The decision leaves the domestic orthopedic device industry dependent upon a single supplier of UHMWPE, the most common material used as a bearing surface in joint replacement systems.
Montell Polyolefins, formerly Himont, decided to eliminate its business in the medical device industry due to product liability concerns, according to spokesperson Nick Nagurney at Montell's North American headquarters located here.
Leaving the medical device market "is strictly a business decision," Nagurney said. "We never marketed our material to the medical device industry. UHMWPE is a very small part of our global business and the opportunities within that business that relate to the medical applications industry is even a smaller part of a small part of our business. For business reasons it's not worth our while to go through the testing and the regulatory processes that might qualify that material to be used in such applications. The potential exposure that is out there unless there is tort reform is disproportionate with what that business means to us."
Montell Polyolefins produces Hifax 1900 CM UHMWPE in the form of powder and supplied it to Biomet and Zimmer. The companies used the resin in a process called compression molding to manufacture acetabular components used in hip replacement systems and tibial inserts for knee replacement systems.
Biomet uses a proprietary process to convert the UHMWPE resin into ArCom, which is their tradename for argon-processed compressed-molded UHMWPE. The company claims that ArCom has improved wearing capability over parts machined from extruded rod.
Biomet's president and CEO, Dane Miller, PhD, has stated that Biomet has enough polyethylene to continue manufacturing hip and knee implants for approximately nine months. Meanwhile, they are looking for another supplier.
While Zimmer purchased polyethylene from Montell Polyolefins, it is not their primary supplier, and the action has no immediate effect on Zimmer, according to Ted Wendt, Zimmer's vice president for regulatory and clinical affairs.
Montell's pullout will not directly impact most other orthopedic device manufacturers who obtain their polyethylene in the form of extruded rod from companies known as converters. The two converters are Westlake Plastics of Lenni, Pa., and Poly Hi Solidur of Fort Wayne, Ind. Both purchase UHMWPE exclusively from New Jersey-based plastics manufacturer Hoechst Celanese and are unaffected by the loss of the polyethylene supplier.
Risk assessment
While Hoechst Celanese intends to continue supplying the polymer for use in medical devices, that aspect of their business is subject to periodic review. The next corporate risk assessment review is scheduled to take place during the first half of the year, according to Jorge E. Ramirez, PhD, of Hoechst Celanese. "We have intentions to behave as a reasonable supplier of these polymer materials into these applications as a supplier to the implant industry," Ramirez said.
Hoechst Celanese's parent company, Hoechst AG of Germany, has supplied UHMWPE to implant makers in Europe for more than 30 years. In 1983, the company opened its Houston plant and began supplying UHMWPE for industrial applications. Before Hoechst Celanese entered the U.S. plastics market, Westlake and Poly Hi Solidur obtained UHMWPE from Himont, which later merged with a number of other companies forming Montell Polyolefins.
Because the Himont polymer was not made specifically for surgical implants, there were often problems with lot-to-lot consistency and contaminants in the polymer. The converters hand selected resin intended for use in orthopedic implants and it was up to them to ensure that the material complied with ASTM's UHMWPE standard for surgical implantation.
By the late 1980s, both Westlake Plastics and Poly Hi Solidur had switched from Himont to Hoechst Celanese due to supply problems. In addition, the new supplier provided technical and customer service support, previously unavailable, to both the converters and the orthopedic device manufacturers.
In January 1994, Hoechst Celanese began marketing a specific grade of the polymer, Holstalen GUR 4150 HP, which is used for orthopedic implants. The converters pay more for it, approximately $4 per lb compared to $1.20 per lb, but it conforms to the ASTM standard.
If Hoechst Celanese decides to stop supplying UHMWPE to the medical device market "it could potentially cause short term supply problems," said John Ploskonka of Westlake Plastics. "That would be very, very tough." Although there are other sources of UHMWPE outside of the United States, they are much smaller than Hoechst Celanese, he said. These other companies have "never been in the medical implant market, and there would be a large learning curve to go through."
"Montell's departure doesn't affect our ability to supply our customers," Mark Evans, of Poly Hi Solidur, said. The converter is able to obtain resin from Hoechst Celanese or Hoechst AG through a a joint venture with its German sister company, Poly Hi Solidur/MediTech, according to Evans.
Extruding UHMWPE for the medical device industry is only a small part of the converters' business, about 5% of Westlake Plastics' business and only 10% of Poly High Solidur's business.
Compression molding
Any company currently developing or planning to develop compression-molded implants would be affected by the Montell decision, Stephen Li, PhD, an associate scientist at the Hospital for Special Surgery in New York, pointed out.
Research at HSS showed that compression-molded parts used in Zimmer's Miller-Galante I and Insall-Burstein I knee replacement systems may have an advantage over implants machined from extruded rod when it comes to oxidation degradation following gamma radiation sterilization. "Recent studies on a limited number of components indicate that 1900 resin seems to resist this oxidative process much more than the other grades of resin. It seems to have a longer shelf life if you are going to use oxidation degradation as a benchmark." Li said. "We don't know what role this plays in the actual performance of these devices, but it is surprising data." Li has submitted abstracts from this research to the Orthopaedic Research Society and the Society for Biomaterials.
Biomet has been using Montell's 1900 CM UHMWPE to manufacture joint replacement components for nearly 18 years. "In our opinion and for our process, we feel rather sure that the Montell material is a better material. That may be specific to the ArCom process and the molding that we do," Miller said.
Biomet evaluates and tests samples of 1900 CM before ordering the complete lot, which consists of 10 to 20 tons of UHMWPE, from Montell. "Typically only one or two lots will process properly and will give us the end result that we are looking for. We worked very closely with Montell to obtain the optimum material for our particular process," Miller said.
"We now have some pretty clear evidence that careful control of the time/temperature/pressure profile and the atmosphere in which the molding process takes place are extremely critical in ensuring a non-oxidized surface layer on the polymer. We think that the oxidation that takes place at the elevated temperatures used in the extrusion process can lead to lower long-term durability of the material for both the wear and mechanical properties standpoint," Miller said. "ArCom is a very predictable, reliable and durable material, which thus far we have not been able to achieve with the Hoechst material."
Biomet is currently looking at ways to qualify UHMWPE from Hoechst AG for its ArCom process. In addition to compression molding, Biomet machines some components and recently began producing its own supply of bar stock using an isostatic pressing technique. "It gives us total control from start to finish of the endpoint material," Miller said. "Because of the tolerances required we have to machine some of our components. The molding process, due to shrinkage, doesn't provide the very tight tolerances we often need, for example, when we are assembling shells to liners."
Despite these alternatives, Montell's exit is likely to have a major impact on Biomet's operations. "We feel rather strongly, not that we won't be able adapt the Hoechst materials to our process, but at least at this point in time, it may be a step backwards," Miller said.
Biomaterials crisis
Montell's decision to no longer supply UHMWPE to the device manufacturer coincides with the $14 million dollar judgement against Dow Chemical Co. Dow Chemical supplied silicone for use in breast implants manufactured by Dow Corning.
Montell charged Biomet approximately $2 per pound for UHMWPE, according to Miller. "That pound of material can be processed into maybe a dozen or so total joint components each of which could carry a multimillion dollar liability. In a practical sense, those aren't real good numbers. It's just a matter of dollars and sense."
Concerns about liability related to biomaterials supply are affecting and could potentially affect many other products in the orthopedic device industry. "We're anticipating that if the litigation environment doesn't change, many more raw material suppliers will go the route of Dow Chemical, Dow Corning, Dupont and now Montell. This biomaterials crisis that some have predicted for now a year or two is in fact a reality," Miller said. "Anybody, whether they're supplying forgings or castings or bar stock or metal alloys that ultimately find their way into implant applications, with the unlimited risk at the back end of the process, many material suppliers are currently asking themselves questions about whether they really want to be in this market."
EBI, a Biomet company, lost its supplier of silicone adhesive for its implantable bone healing products when Dow Chemical decided to no longer supply silicone to the medical device industry. EBI now purchases silicone adhesive from NuSil Silicone Technology, a much smaller company than Dow Chemical that agreed to supply the medical device industry with silicone.
Legislative efforts
Miller and others believe the biomaterials crisis facing the medical device industry can only be solved through legislation. Two bills, approved by both the House and Senate and now being worked through a conference committee, would provide some protection to suppliers of raw materials to the medical device industry.
Ramirez described legislators' efforts as well-intentioned, but weak. "The legislation is not strong enough at this point in time and not clear enough to really invoke the kind of relationship that is necessary for other polymer suppliers to participate in these kinds of advanced applications."
"I think the legislation goes a long way, but it doesn't go as far as it should," Miller said. "Nowhere in any of the tort reform legislation is the issue of contingency fees addressed. But certainly it goes a long way. There have to be caps and limits on punitive damages and pain and suffering."
"We would support legislation that would be reasonable for both companies and patients," Evans said. "Patients have to be protected from shoddy materials, but if businesses assume unlimited risk to develop all new products, development will come to a halt. If all risks are incumbent on the manufacturers and there are no types of caps then you are going to look at a dwindling amount of resources." |
