Design Team
Physician, manufacturer collaborations are key to successful implant design.
Michael Barbella, Managing Editor
The same three questions pop into George Weaver’s head every time he looks at a new product design or idea.
“The phone rings at least twice a day with new ideas, and I can’t work on all of them,” said Weaver, vice president of marketing and co-founder of Precision Medical Products Inc., a contract manufacturer
Physician-industry relationships can help design engineers better understand the needs of surgeons and patients. |
based in Denver, Pa. “So when I look at a new product, I ask myself, ‘what is it going to do for the patient, what is it going to do for the practitioner or the hospital, and what is it going to do for the insurance company?’ If that new product or idea brings something to all three of those areas, I feel very strongly about that product being successful.”
Success, however, is dependent upon various other elements as well, including design, target market, manufacturing costs, quality, device functionality and exclusivity, and marketing. But none of those factors are as important to the design of medical products—orthopedic devices, specifically—as the end user, industry experts told Orthopedic Design & Technology.
Orthopedic devices are designed as much for surgeons as they are for patients. Aging baby boomers have triggered a huge demand for implants that last more than 20 years as they seek to maintain their active lifestyles, while advances in medicine over the last several decades are helping people live longer. A national life expectancy of nearly 80 years is prompting orthopedic OEMs to produce durable devices that are tailored to the needs of patients in their 80s and 90s, according to industry reports.
Aging baby boomers and octogenarians, however, are not the only end-user populations influencing device designers. Surgeons have become just as important to the design process because they use orthopedic instruments and devices on a daily basis. Consequently, they often can provide engineers with invaluable input about a device before it is designed, which can help orthopedic manufacturing firms remain competitive in the market as well as improve product quality and safety.
Many companies have realized the importance of collaborating with surgeons on product design and have brought them on board as paid consultants. Surgeons insist that such partnerships are necessary to improve devices and advance the practice of medicine. Physician-industry relationships also can help engineers better understand the needs of both surgeons and patients, industry experts noted.
“It’s like trying to design a car if you’re not a driver. How can you do that?” asked Steve Maguire, general manager of Orchid Design, a division of Orchid Orthopedic Solutions, a Holt, Mich.-based designer and manufacturer of implants, instruments and technologies for the orthopedic, dental and cardiovascular markets.
“Orthopedic designers are not surgeons. We can’t go in and do surgery and learn on our own. We have to learn through clinicians, and we have to learn to observe; we have to learn to listen; we have to learn to understand their challenges and then adopt that learning into good product design. That can only be done through collaboration.”
Maybe so, but critics contend that financial relationships between the medical industry and doctors occasionally can lead to unethical behavior and felonious activity. Growing scrutiny of these alliances over the last few years has culminated in the filing of criminal charges against companies and admissions of wrongdoing by surgeons.
In 2007, federal prosecutors in New Jersey accused five orthopedic device manufacturers of conspiring to violate an anti-kickback statute by making payments to surgeons in an attempt to keep their business. Four of the companies—Biomet Inc., DePuy Orthopaedics (a division of pharmaceutical giant Johnson & Johnson), Smith & Nephew, and Zimmer Holdings Inc.—paid a total of $310 million but did not admit wrongdoing. The fifth manufacturer, Stryker Corp., cooperated with the federal probe and was not charged.
Investigations such as the one conducted in New Jersey (and dozens of others nationwide since then) have only added credence to detractors’ claims that company payments to doctors create conflicts-of-interest and can unduly influence everything from research findings to prescribing practices. To discourage such desires, a number of states have enacted laws requiring medical companies to disclose the payments they make to doctors. Federal lawmakers have drafted legislation that would require similar disclosure; the legislation—called the Physician Payment Sunshine Act—is part of the healthcare reform bill under consideration in the U.S. Senate.
Industry experts acknowledge that greater transparency of financial relationships between doctors and device companies is needed. However, they contend that alliances between physicians and industry are an important part of patient care and can lead to the development of better drugs and medical devices. The partnerships also can provide the industry with cross-educational opportunities that can benefit patient safety, experts noted.
“Medicine is incomparably better than when I started out practicing about 40 years ago,” Thomas P. Stossel, M.D., a professor of medicine at Harvard Medical School Boston, Mass., and director of translational medicine at Brigham and Women’s Hospital in Boston, recently told an orthopedic trade journal. “It is not because doctors are now somehow more ethical or have been more heavily regulated. Rather, it is because of the products that they have developed and gotten through their collaborations with industry.”
Collaborations with academic institutions can advance medical technology as well.
Such a partnership in the United Kingdom recently led to the invention of a non-intrusive device that can accurately measure patients for hip replacements.
The device—called KingMark—was developed by Richard King, an orthopedic surgeon at University Hospitals Coventry and Warwickshire, and Damian Griffin, a professor at the University of Warwick Medical School. Industry executives said the invention could significantly improve the accuracy of the size of replacement hips. In the United Kingdom, where more than 55,000 hip replacement procedures are performed annually, replacement hip sizes are correct in only about 30 percent of cases, according to industry estimates.
KingMark uses two separate markers—one behind the pelvis and the other in front, as the patient lies on his or her back, according to a news release about the product. The anterior marker is a flexible strap that secures radio-opaque balls at regular intervals. The posterior marker is a radiolucent pad with steel rods embedded in a vertical row.
Marketing literature for the device describes it as a less intrusive system than current methods of hip replacement measurement, and a particularly useful way to measure larger patients. KingMark also possibly can be used for spinal work and trauma implants as well as other joint replacement procedures, the literature states.
“Before KingMark, accurate calibration relied on a single marker being exactly located in the coronal plane of the hips, requiring special expertise and extra time from technicians,” said Adam Ehrenraich, M.D., vice president of clinical solutions at Voyant Health Ltd., a Columbia, Md.-based company that is distributing the product worldwide. “KingMark is quick and easy to position correctly, even on very large patients—eliminating mistakes that affect accurate calibration during pre-operative planning. KingMark also is much less awkward for patients and staff—eliminating intrusive positioning of a device between the patient’s thighs.”
KingMark is not the only product to come from a collaboration between the medical and academic worlds. In nearby Italy, researchers have developed a method for turning rattan wood into a substance that bonds with natural bone. The researchers, based at the Istituto di Scienza e Tecnologia dei Materiali Ceramici in Faenza, Italy, hope the discovery can someday be used to create transplant material for humans.
Researchers created the synthetic bone by cutting long tubes of rattan wood into small pieces and then fusing the pieces with phosphate and calcium. After fusing the wood with both chemicals, researchers heated the pieces twice—once in a furnace and the second time in a machine similar to an oven. The resulting material, according to published reports, was a substance comparable to natural bone; when implanted, small pores in the substance allow blood and nerves to migrate from surrounding bone.
Orthopedic surgeons at Bologna University Hospital are monitoring the effects of this material in sheep. X-rays of the sheeps’ legs have shown that particles from the animals’ own bones are migrating to the rattan-based bone. Testing performed on the sheep showed that the real bone fused with the implant within a few months to form a continuous bone.
Surgeons have not observed any signs of rejection in the sheep. Researchers hope the breakthrough will lead to a natural, cost-effective replacement for bones. Authorities estimate that implants of the rattan wood-based bone are about five years away.
Better Solutions Through Biologics
The Italians’ promising bone-bonding substance brilliantly illustrates the type of medical breakthroughs that can result from collaborations between doctors and the academic world. However, it also represents a growing trend among research and development teams to find more compatible materials for orthopedic implants.
“Matching the properties of a biological tissue to mechanical tissue is a challenge and has been a challenge for our industry from day one,” said Brian R. McLaughlin, business development manager for Orchid Design. “Taking a tendon, for instance, and matching its biological properties to polyethylene is difficult. You may fix one thing right away but end up with a problem somewhere else down the road. The closer you can match the replacement part to the biological makeup of the body, the better off the solution and the chance of recovery will be.”Scientists have been trying to match implants and replacement joints to the biological makeup of the human body for years without much success. But the development of several new materials indicates that researchers are moving closer to overcoming the orthopedic industry’s greatest challenge.Kensey Nash Corp., which produces bovine dermis derived collagen used in spinal disc and cartilage repair and foamed scaffolds used in tissue engineering applications, has designed an implant to repair damaged knee cartilage. The company’s Cartilage Repair Device is described on its Web site as a bioresorbable scaffold that is implanted at the site of damaged cartilage and then slowly broken down by the body.
Articular cartilage injuries are difficult to completely heal because treatment options involve generating a repair tissue that cannot be totally absorbed by the body. The repair tissue also cannot properly distribute loads and is prone to failure.
The Cartilage Repair Device is approved for use in Europe and is expected to undergo testing in clinical trials in the United States shortly.
Absorption by the body is a frequent problem companies have encountered in experimenting with new implant materials. Researchers at North Carolina State University though, may have found a way around that predicament with the development of a metal “foam” that has a similar elasticity to bone.
The metal foam is lighter than solid aluminum and can be made entirely of steel or a combination of steel and aluminum. But it is the foam’s “modulus of elasticity” that makes its application in the medical device industry so promising. Modulus of elasticity is defined as the relationship between a force applied to an object and the amount of deformation the object experiences as a result of that force (elasticity refers to an object’s ability to return to its original state undamaged once a force is removed).
The metal foam created by researchers in North Carolina has a similar modulus of elasticity to that of natural bone in humans, making it an ideal material for implants. The modulus of titanium implants, by contrast, can be anywhere from three to 10 times higher than bone, according to industry estimates. While such strength is ideal for most medical devices, it can cause a problem for implants: Artificial joints made from material that is too strong (i.e., stainless steel and titanium) weakens the bone surrounding an implant, which in turn loosens the device and requires another replacement surgery.
The porosity of the metal foam though, makes it a very light substance, and its rough surface may help natural bone adhere to the implant, further increasing its strength and stability inside the body.
Additional research into natural bone growth is being conducted by RepRegen Ltd., a London, England-based company that has developed a bioactive glass material to mend and regenerate hard tissue. The glasses used in the process are biocompatible material that dissolve over time and help form new bone lost to disease or trauma. An in-vivo study has found that the addition of Strontium metal ions to the glass material helps grow new bone. RepRegen is currently conducting additional in-vivo studies to support the finding.
Made to Fit
As researchers tinker with ways to regrow bone with metal, wood and glass substitutes, orthopedic device companies have begun to modify the implants themselves as well as surgical procedures in order to stay competitive in the market.
Recognizing the growth potential of personalized medicine, device manufacturers have launched implants optimized for different genders or geographies. The traditional mass-manufactured orthopedic implant comes in a limited number of sizes and shapes. Fitting these implants to patients requires extensive bone resection and shaving in many cases to fit the joint to the shape of the implant.
“The ideal implant is one that fits your particular anatomy perfectly and solves your particular problem perfectly,” Orchid’s Maguire said. “That means there’s probably an infinite number of sizes and shapes that would be required on an inventory basis if you just have a standard product line.”
Companies such as ConforMIS Inc. and Zimmer Holdings Inc. are capitalizing on this concept to provide patients with custom-fit implants. ConforMIS, a Burlington, Mass.-based firm, uses a software-enabled design process called iFit to convert CT (computed tomography) and MRI (magnetic resonance imaging) data into implants that are precisely sized and shaped to conform to the 3-D topography of an individual joint.
Last year, ConforMIS launched two new knee resurfacing tools, iUni and iDuo, which help create customized orthopedic implants for patients who do not need their entire joint replaced. The company is waiting on U.S. Food and Drug Administration approval to launch iTotal, a resurfacing implant for patients with tri-compartmental osteoarthritis. ConforMIS executives believe the iTotal device would be an alternative for patients whose only option today is total knee replacement.
Zimmer began offering a knee implant designed specifically for women nearly four years ago after learning that more women than men undergo joint replacement procedures. The company estimates that 65 percent of all total joint replacements are performed on women.
Zimmer’s Gender Solutions knee replacement has a thinner profile, a contoured shape, and accommodates a more natural range of motion. The contoured shape, according to the company, improves the fit and helps prevent the implant from overhanging the bone and potentially pressing on or damaging surrounding tendons and ligaments.
Other companies that offer gender-specific knee implants include Biomet (the Vanguard Knee), DePuy Inc. (PFC Sigma Knee), Stryker Corp. (Triathlon), and Smith & Nephew (Genesis II Knee).
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Surgeons, engineers and scientists have driven innovation in the orthopedic device industry for the last several decades. Their ideas, research and creativity have helped create ground-breaking implants and surgical instruments, while technological breakthroughs have provided doctors with new techniques for performing joint replacement procedures. Much of the success of these implants (and surgical procedures, to a certain extent) can be attributed to the collaboration between physicians and orthopedic device manufacturers. Though lawmakers have criticized these relationships and federal prosecutors, doctors and orthopedic industry executives are quick to note that collaborations foster innovation and advancements in medicine that ultimately benefit patients. Not every idea though, is a marketable one. Precision Medical’s Weaver has some advice for physicians with an idea for a medical product: “Think about all the people that will come into play with the product. Look at the entire picture and think about how that product can help all of those people. If it will help everybody, there’s a good chance you will be successful.”