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Articles from 2008 In January


Stent Grafts Safer than Surgery for AAA Patients

Many patients and surgeons prefer endovascular repair to surgery because it is much less invasive and recovery is about four times faster.

FDA Lags on Foreign Inspections

Transforming FDA LogoFDA is so understaffed that it would, at its present pace, take 27 years to inspect each foreign plant manufacturing medical devices for the U.S. market, according to a Government Accountability Office report. This adds fuel to the criticism that FDA is a "fundamentally broken" agency that can no longer be counted on to protect the public health, reports the New York Times. The number of foreign plants making medical devices for the U.S. market has soared in recent years, especially in China. But FDA has not had the resources to keep up. It is time for Congress and the Bush Administration to stop fidding around and give the agency what it needs to accomplish its mission. UPDATE: Some in Congress are calling for a substantial increase in FDA's budget. UPDATE 2: The New York Times agrees.

Eastman Unveils New Web Site

They want to do research on their own before they decide to call someone," said Gary Hawkins, technical platform manager for medical packaging and tubing. "Before, a sales, marketing, or technical person had to navigate them through things.

A Pacemaker for the Eye?

(Drugs can't; they can only prevent further sight loss.) He recruited a team of doctors and engineers who designed a device that uses electrodes to release low-intensity electrical currents into the eyelids. An algorithm tells the device what the amount and frequency of the charges should be. The device has been tested in about 1000 patients in 29 countries since 2002. The company says 95% of them experienced no further sight loss, and 80% of them experienced improved vision. Full-scale trials are now being conducted in the United States and India, and the firm is raising money to fully fund them.

Drug-Eluting Stents Safe, Study Finds

(Drug-eluting stents are only approved for use in short and straight artery segments.) While restenosis (re-narrowing of the artery) occurred more often in off-label uses than on-label ones, it occurred less often with drug-eluting stents than bare-metal ones. There was no difference in death rates. Another study in the same NEJM issue found almost no difference in survival rate between patients who received stents and those who had bypass surgery. However, bypass had better overall results for patients with multiple lesions.

Polymer-Coated Stent Could Be Safer Than DES

Preliminary data from a study presented at the International Symposium on Endovascular Therapy demonstrates that Polyzene-F allows the inside of the blood vessel to heal "almost perfectly" in 30 days. When DES are implanted, blood vessel healing can take several months, if healing even occurs at all, according to the study's principal investigator. This study is the first instance that the coated stent has been used in humans. Made of cobalt chromium, the stent has a modified open-cell design, and its 40-nm thick coating is supposed to prevent thrombosis. Polyzene-F has already been used to coat particles that block arteries to treat liver cancer, uterine fibroids, and malformed arteries. The material could also have use on dental, orthopedic, and breast implants, as well as catheters.

Stainless Steel Takes a Backseat to Newer Biomaterials

A product family of biomaterials includes Zeniva PEEK, which can replace metals in some applications.

Owing to its biocompatibility, proven history, and cost-effectiveness, stainless steel has long been a dominant force in the biomaterials market. And nickel-free grades currently entering the market will likely further secure stainless steel's longevity in the industry. While stainless steel is in no danger of becoming an obsolete biomaterial, it is increasingly being passed over in favor of alternative materials. The rising demand for more-complex applications and nonmetal options has manufacturers turning to younger, more inexperienced biomaterials such as nitinol and PEEK for their applications, leaving the veteran medical metal sidelined.

Nitinol Gives Medical Metals a Makeover

"Since the 1960s, nitinol has been looking for a home," observes Audrey Fasching, senior metallurgist for Memry Corp. (Bethel, CT; www.memry.com), a supplier of nitinol and associated engineered components.

In the 1990s, it finally found one in the medical device industry. Named for its nickel-titanium composition and the Naval Ordnance Laboratory where it was discovered, nitinol has steadily emerged in the past decade as a viable alternative to stainless steel for many biomedical applications.

Prized for its shape-memory effect, the alloy is also superelastic, flexible, kink and corrosion resistant, and, of course, biocompatible. This combination of desirable material characteristics has enabled nitinol to carve out a niche in the minimally invasive market, most notably in cardiovascular and peripheral vascular stents.

"Nitinol, because of its elastic nature, is always applying a constant force against the vessel wall," says Dave Niedermaier, director of sales and marketing for Nitinol Devices and Components (NDC; Fremont, CA; www.nitinol.info), a material fabricator that supplies nitinol wire, strip, sheet, and tubes. "And if that force is disturbed, if you have motion crushing, twisting, or bending, the material gives but springs back, so it's a very well-adapted material for the body," he continues.

Despite success in stents and several other minimally invasive devices, nitinol has experienced slow adoption in the medical market. Dennis Norwich, process engineering manager for Memry, attributes reticence toward replacing stainless steel with nitinol to a lack of awareness about the relatively new material.

"Unlike steel--which has been around for hundreds of years with volumes of information on it--nitinol is new and there are no true textbooks to describe it," Norwich says. "But with more exposure, the customer base is becoming more knowledgeable and sophisticated. Awareness is starting to grow."

Jim Hartle, Memry director of marketing, concurs. He states that, over the past eight years, questions from medical device OEMs have evolved from the basics (What is nitinol?) to more-complex application-specific queries (Can nitinol do this for my device?) Memry feels that as information becomes more accessible and success stories are relayed, OEMs will be more receptive to designing with nitinol in lieu of stainless steel.

OEMs are opting for nitinol over stainless steel for some applications, owing to its shape-memory and superelastic properties.

Cost has also been a deterrent. But Norwich says the bottom line is that OEMs are paying slightly more for functionality with which stainless steel simply can't compare. "If you want to get to the next tier of product capabilities, there's really no other choice," he says.

Although it can replace stainless steel, nitinol is a completely separate material with its own unique properties and processing needs. Niedermaier stresses that OEMs need to understand the effects of heat treatment on the material as well as how to yield a smooth, uniform oxide surface to ensure biocompatibility and corrosion resistance. Nitinol can also be difficult to machine and cut, and can wear out tooling quickly, adds Norwich. Memry, which offers proprietary processes for nitinol, recommends that OEMs let specialty companies handle the material.

As awareness and comfort level continue to grow, so may the potential uses of nitinol as a biomaterial. Niedermaier points to orthopedics as an untapped market; nitinol could be employed in such applications as anchors and fixation devices. Norwich predicts that nitinol will continue to flourish in the minimally invasive sector.

For now, Niedermaier says much of the nitinol R&D is focused on taking baby steps forward in such areas as improving component processing. NDC is preparing to offer the ability to roll nitinol in thin, wide constructions on a continuous coil for laser cutters that want to work with long lengths, and for those who may want to use nitinol for stamping applications. The company's aim is that this offering will enable better tolerance control than is currently available.

"Nitinol is the answer in search of a question," says Hartle. "[It is the answer] any time someone comes up with something that needs a dynamic material that can undergo deformation and return to its original construct."

PEEK-ing into the Future of Biomaterials

Like nitinol, polyetheretherketone (PEEK) is a newer biomaterial that is edging out stainless steel, titanium, and other traditional metals in a number of biomedical applications. Characterized by its stiffness, strength, design flexibility, biocompatibility, strength-to-weight ratio, and chemical resistance, PEEK has become increasingly prominent during the past decade for its use in fusion and stabilization devices, as well as in numerous other implantable devices.

Its future appears promising as well. Studies have planted the seed of doubt regarding the use of metal in implantable devices. As a result, some OEMs are looking for an alternative material that offers the attractive properties of metal without the potential risk. "There are issues with stress shielding," says Shawn Shorrock, global market manager, healthcare, Solvay Advanced Polymers (Alpharetta, GA; www.solvayadvancedpolymers.com). "So they're looking for ways to make implants lighter, specifically speaking to things like orthopedics, but then the [materials] also need to be biocompatible and able to handle the loads that orthopedics [require]."

Moreover, studies have suggested that there could be a correlation between metal-on-metal hip replacements and elevated metal ion concentrations in the body, according to Michael Callahan, president of Invibio (West Conshohocken, PA; www.invibio.com), supplier of PEEK-Optima.

Potential red flags associated with metal, coupled with a swelling market base, have primed the biomaterials industry for an expansion of PEEK. "It's the right time for the market with the aging population and the medical device technology really outpacing the materials that are available," says Shorrock. "It's a good time to come in."

Observing the receptive state of the marketplace, Solvay was attracted to the notion of adding biomaterials to its polymer-based product portfolio. In October, after two years of R&D, the company unveiled its first family of long-term biocompatible materials, Solviva, which includes Zeniva PEEK. It is chemical resistant and features strength, stiffness, toughness, and fatigue resistance comparable with the leading PEEK products, according to the company.

A veteran provider of the polymer, Invibio trumpets the advantages of its PEEK-Optima over metals. "It is less stiff than titanium alloys, which may help prevent stress-related resorption of surrounding bone and the loosening of implants," Callahan says.

The product has also demonstrated good wear resistance almost on par with metal-on-metal orthopedic implants, according to Callahan. As a polymer-based product, the company's PEEK-Optima is not in danger of releasing metallic ions, experiencing corrosion, or generating image artifacts, either. However, Invibio recently introduced PEEK-Optima image-contrast compounds that contain a radiopaque additive enabling visibility of the implant and potentially eliminating the need for tantalum markers. The company also launched carbon-reinforced PEEK for enhanced stiffness.

PEEK and nitinol are still relatively young. However, their influence has the potential to substantially grow as applications require more flexibility or shy away from metal. And, as these biomaterials improve and more applications are determined, stainless steel may just find its grasp on the biomaterials market weakening.

Brain-Stimulation Device Fails in Trial

The device has been investigated for a number of uses, but initial positive data had driven the company toward pursuing an indication for stroke victims. Unfortunately, after 24 weeks there was little difference between patients who used the device along with physical therapy and patients who underwent aggressive physical therapy. If anything, the trial showed that physical therapy is quite beneficial for stroke patients.

Linear Rails Bear the Weight of Revamped X-Ray Table

ENGINEERING SOLUTIONS

Linear Rails Bear the Weight of Revamped X-Ray Table
Redesigned for use with overweight patients, an imaging table required rails with a high load capacity and extended stroke.
A line of rails offered by a linear motion product manufacturer enabled the redesign of an x-ray table to accommodate obese patients.

When Arcoma (Växjö, Sweden; www.arcoma.se), a provider of automatic x-ray equipment, originally designed its mobile imaging table, it aimed to create a flexible system that was easy to operate and kept the ergonomics of the hospital staff in mind. With a minimum table height of only 55.5 cm, the low tabletop enables patients to sit down easily, which increases their feeling of security while hospital staff avoid heavy lifting. Most importantly, the table is configured to allow radiographs on trauma patients without having to reposition them.

However, several pain management and orthopedic studies revealed new applications for the table that would require modifications in order to support obese patients and comply with associated FDA requirements. In light of the new weight-based demands, the company sought to alter the design so that the table could support up to 500 lb.

Facing the challenge of redesigning one of its flagship products, Arcoma delegated the reworking of the system to its California-based tech support and service center. “The increased load capacity would have been too great a strain on our existing tables, so the key was to find a linear motion system that could not only hold weight, but also had a long enough stroke for the applications,” says Brian Gogan, executive vice president of Arcoma North America. “Because the tables move around the imaging equipment, rather than moving the patients themselves, there is a huge extended load on the bearings, and the stress on the parts can be tremendous.” Along with extra load capacity, the system needed a reliable linear bearing system, Gogan adds.

Arcoma investigated several linear motion options and finally partnered with Rollon Corp. (Sparta, NJ; www.rollon.com). The linear motion product supplier brought to the table its telescopic rails, which feature the load capacity and extended stroke desired for the redesign.

“Drawer slides [traditionally] were simple bent-steel products suited for desk drawers, filing cabinets, keyboard trays, and other light-duty applications,” explains Rollon general manager Andrew Cook.
“In fields where high load capacities, reliability, low deflection, and smoothness of movement are important for a drawer-slide-type extension, there was no solution.

“By creating the telescopic rail family, Rollon’s engineers succeeded in creating a telescopic linear bearing––similar in movement to a drawer slide, but closer in function to a linear bearing,” Cook says.

Demonstrating the necessary flexibility for mobile imaging with reach strokes of more than 200 cm, the slides also showed zero deflection despite extremely high loading during testing phases, according to Gogan. “They also have 60 hardness rating raceways to ensure a smooth movement, which is critical for patient safety and comfort,” he notes.

Incorporating Rollon’s telescopic rails into its mobile imaging table enabled Arcoma to achieve the desired flexibility and weight capacity, while maintaining the features that had originally established the system on the market. The modified system was introduced to the marketplace in 2007.

Copyright ©2008 Medical Product Manufacturing News

Critics Decry DTC Device Ads. They're Wrong.

The article goes on to note that CDRH has few resources to devote to scrutinizing DTC device ads, and most are looked at only glancingly by the agency before airing. But there is good reason why drug ads need to be heavily scrutinized before airing, and device ads don't: the role that the doctor plays in the process. If a patient comes in and asks for a specific drug, it doesn't take much effort on the doctor's part to grant the patient's wishes. All the doctor has to do is write a prescription. And there is a risk that he or she will do so even if not fully aware of the drug's risks and benefits. The doctor usually doesn't notice them unless the patient comes back with a problem. But surgery is different. The doctor is intimately involved and must be familiar with all the available products that could be used. The doctor's opinion of the available devices matters greatly; if he or she is not comfortable with using a product in surgery, it won't be used, regardless of the patient's wishes. And if a problem or complication arises, the doctor knows about it, for sure. And certainly remembers it the next time the device is being considered for use. The responsibility and potential liability is too great to leave these decisions to the whims of marketers and those who listen to them. The comments in the article by the National Research Center for Women and Families and the petition sent to FDA by the Consumers Union imply that doctors, or at least some of them, are stupid enough to let commercial messages override medical judgment when it comes to performing risky surgical procedures. It is a rather insulting stance. And it is also insulting for a media outlet to give that stance such prominence.