Take a Knee

The big takeaway from this year’s annual meeting of the American Academy of Orthopaedic Surgeons (AAOS) was knees, knees and more knees. Three of the biggest orthopedic players had offerings on the table—Johnson & Johnson had its Attune knee system (marketed by JNJ’s DePuy Synthes Companies); Zimmer introduced its Persona knee; and Smith and Nephew plc showcased its Journey II bi-cruciate stabilized knee replacement.

It was the year of the knee.

Why knees? Leerink Swann industry analyst Richard Newitter told Orthopedic Design & Technology (ODT) that during the past several academy meetings, hips have been a big focus. But, of course, innovation comes in waves. And because orthopedic products take years to make their way to market and direct competition is a healthy market driver, companies tend to shift together when it comes to the technology they focus on.

“We haven’t seen new knees from those companies in several years,” Newitter said. But during those years, the knee technology debuted at AAOS has been incubating in the development stage. “The biggest innovations in knees have largely been around the instrumentation. We saw patient-specific instruments launching in the last several years, but that was the most that we saw in manufacturers’ product launch initiatives in knees. This year we have more full products launches—more complete packages and new designs in implant.”

ODT spoke with a number of executives from firms with new knee offerings. The following reports detail our findings by company.

DePuy Synthes Revamps Approach to New Knee Design
Many of the changes in the medical device industry are incremental, iterative in nature. They happen slowly over time. Small changes are made as knowledge is gained about how devices work in practice, and then companies tweak designs year after year. That’s one of the numerous ways the medical device industry distinguishes itself from its cousins in the pharmaceutical arena—fewer blockbusters but more consistent, ongoing new product development and launches.

That’s all well and good, unless you’re on the team involved in new knee product development in the DePuy Synthes Joint Reconstruction division of Warsaw, Ind.-based DePuy Orthopaedics Inc.

During this year’s March meeting of AAOS in Chicago, Ill., the DePuy Synthes booth was buzzing with news of the company’s latest release, the Attune total knee replacement system (photo on opposite page). Officials were on hand to walk the press, physicians, industry analysts and other invited guests through a special four-room display that included presentations about the effort undertaken to create Attune.

“Given that studies show 10 to 20 percent of knee replacement patients aren’t completely satisfied with their knee replacement, we dedicated a significant amount of resources to designing a knee that would help to address these concerns. The Attune knee is the result of our largest research and development project ever,” said Hannah McEwen, worldwide director for Knee Product Development, DePuy Synthes Joint Reconstruction. “To date, more than 3,500 patients have received an Attune knee as part of a limited launch and we’ve received positive feedback regarding patient recovery, stability and motion.”

It wasn’t hyperbole when McEwen noted that this was one of the company’s largest R&D undertakings. The project took more than six years and carried a price tag of approximately $200 million. The goal, according to McEwen and others, was to address unmet patient and surgeon needs. The new knee is designed to provide better range of motion and address the “unstable” or “wobbly” feeling some patients report during everyday activities, such as bending, going down stairs, or even something as routine as getting out of a car, officials said.

To achieve an improved feeling of stability for patients, the team at DePuy had to throw out convention and come up with a new implant that might at first glance appear to be the same as other knee replacement technology, but upon closer inspection differs from previous generations of devices in shape, form and function. It’s a tall order in a crowded market, with new knee implant offerings released at AAOS by competitors such as Zimmer Holdings Inc. and Smith & Nephew.

Through research collaboration with the University of Denver in Colorado and the University College Dublin (Ireland), researchers evaluated current knee designs to assess how implant geometry aids in maintaining stability through patients’ daily activities. An implant with a new shape employing what the company calls the “Gradius Curve” was the result.

The research—with a team of surgeons and industry experts from around the world working on the project—led to more than 19 patents for Attune as well as its related instrument technology. For example, the research and design teams spent more than 10,000 hours working with surgeons in different settings to get feedback and record data, McEwen said. That included ethnological research with doctors—filming them, studying movements and behaviors, and even looking for operating room efficiencies. Other research activities included X-rays of patient movement, extensive tests with cadaver knees and computer simulations.

Tim Czartoski, director of marketing at DePuy Orthopaedics, told ODT during an interview at AAOS along with McEwen, that the effort to create Attune “mobilized the best talent in the organization and partnered with outstanding outside research organizations” to solve problems highlighted by research teams, patients and doctors.

“The process started with a blank page—no boundaries and no limits on what we knew from the past. It was really a new attitude and culture we had to create,” Czartoski added. “If we really didn’t make a difference, then why bother? Speed to market and quick revenue weren’t our first priorities. It was about creating game-changing technology and, as a result, better outcomes for patients.”

“We brought together a huge group of engineers and scientists and cross-functional teams that partnered with external research groups. Let’s understand the natural knee; let’s understand current total knee devices; let’s understand the science of how we can make the design changes,” McEwen added.

A lot of the process in creating Attune and its related instruments was about “taking the theory and the science and marrying it with the feel, experience and art of the surgeon,” Czartoski said. “And so we’d see if our research assumptions played out, and we assessed the outcome. If they didn’t, we went back and started again. That was a three- to four-year period. There are lot of products out there today that are only designed with the surgeon experience without all the other in-depth research and development. We wanted to get beyond that.”

A number of patented technologies resulted from the research into the Attune knee. Attune’s Gradius Curve is described as a “gradually reducing radius” that is designed for improved conformity throughout the range of motion, providing better anterior/posterior stability. The Sofcam Contact is an S-curve designed to provide smooth engagement for stability through flexion, while reducing stresses placed on the implant. The Logiclock tibial base is a locking design intended to improve kinematics while reducing wear to what the company claims is “the lowest reported levels in the industry.” The Logiclock feature also gives surgeons the options to choose the best size and fit for each patient from a range of sizes, according to DePuy Synthes. The system’s Glideright Articulation is designed to accommodate patient variation and soft tissue interaction, while optimizing patella tracking.

As part of its many hours of Attune research and development, DePuy Synthes also developed a line of instruments branded Intuition. Like the knee itself, the design of the instruments also went back to the drawing board to make them—as the name suggests—more intuitive. The tools include lighter weight composite materials, color-coded technology, and easier-to-see gauges and measurements.
Single-layer instrument cases are lightweight with fewer instruments, reducing weight by 51 percent as compared to previously available instruments. Theinstruments also minimize the number of cases in the operating room while maintaining durability.

When asked to pick some of the key lessons or surprises learned after going though this six-year process, Czartoski and McEwen agreed that “millimeters matter.” Small changes to the geometry of the knee design led to significant changes in outcomes.

In addition, Czartoski noted that the systematic process that was created to tackle the knee redesign was perhaps even more impressive than the knee itself.

“Our industry and our society so want to point to one thing and say it makes all the difference. And, of course, Gradius is a big part of that for us. However, the other discovery that I believe we made is that you have to have a systematic approach that is integrated,” he explained. “So, the Logiclock leads to the matching of the insert to the femur, which leads to kinematics that match the Gradius, which leads to the box size, which leads to the patella femoral kinematics. When you have all these pieces working together, that’s synergy.”

Going forward McEwen and her team will use the lessons learned with Attune and apply them to upcoming projects in other product categories.

“All good organizations are learning organizations and we’ll take the things we’ve learned here and apply it to new projects,” she said. “The tools we’ve developed will help us leverage the science and technology we’ve developed.”

In addition to the U.S. introduction (U.S. Food and Drug Administration approval and clearances were granted for the various parts of the Attune system throughout 2011 and 2012), DePuy Synthes plans to release Attune in select international markets later this year.

Zimmer Gets ‘Personal’ at AAOS
The whispers began well before any formal announcement was made. Something big was brewing at Zimmer Holdings Inc., the newsmongers said, and the company seemed truly excited about it.

The rumors appeared oddly accurate, judging by the grandiose booth Zimmer rented at the AAOS (the exhibit was outfitted with blue strobe lights, a movie theater-sized screen, plush carpeting and sleek counters for product displays) and a hard-to-spot door that opened only to invited guests (the door itself was partially concealed behind a larger-than-life model of a knee joint).

Persona knee joint replacement system. Photo courtesy of Zimmer Holdings Inc.

Then suddenly on March 20, the rumor became a reality. Something big was indeed brewing at Zimmer and that something big was called the Persona (photo on the opposite page), a knee system that company executives called the “most comprehensive, anatomically accurate and highest fidelity” replacement product ever designed.

“Zimmer scientists and engineers and their designing surgeon partners pushed the boundaries of implant design, drawing upon advanced morphology, physiology, kinesiology and material sciences to develop a truly revolutionary system that allows surgeons to provide each patient with a personalized fit,” said Jeff McCaulley, president of Zimmer’s Global Reconstructive unit. “It’s the most anatomically accurate system ever seen and it’s the biggest launch the industry has ever seen.”

It certainly was one of the biggest launches at this year’s AAOS meeting, far surpassing the near non-existent publicity surrounding Smith & Nephew’s Journey II Bi-Cruciate Stabilized knee replacement, and the more understated (but nevertheless showy) debut of DePuy Orthopaedics Inc.’s Attune knee.
Zimmer’s launch of the Persona Knee system included an informal press junket at the company’s booth, where in a similar fashion to DePuy, executives provided a guided tour through a multi-station display of the components that comprise the new knee. The invitation-only tour began with a 15-minute video that detailed the motivation for the Persona (to create a knee with “no compromises”) and the efforts undertaken to create it.

The Persona system combines personalized implants with intelligent instruments to provide surgeons with better intraoperative precision to customize the best fit for patients.

Among the technologies incorporated into the design of the new knee (on display in a hidden back room of Zimmer’s conference-floor booth) were:

• A Bone Resection Atlas, which allowed surgeon designers and engineers to study the morphology of hundreds of bones, representing a diverse global population, to precisely define anatomically accurate implant shapes and sizes.
• The company’s Virtual Biomechanical Knee, a kinematic computational analysis program that allowed rapid testing of hundreds of different design options to virtually assess their impact on soft tissues, motion and overall performance to optimize designs that more closely replicate natural feel and normal function.
• Zimmer’s Robotic Simulator, a six-axis, high-precision robot that replicated the kinematic patterns and biomechanical forces for various daily activities. The simulator was used to validate the design’s fidelity, precision and robustness.

The Persona knee contains trabecular metal and was infused with vitamin E for increased strength, ultra-low wear and oxidative stability for long-term performance. The company also introduced a range of patient-specific instruments with the new system, including the iAssist Knee, the Personalized Guidance System (a surgical guidance technology that provides simple, intuitive and accurate intraoperative feedback and alignment verification at the surgical site without the need for bulky capital equipment) and the eLibra Dynamic Knee Balancing System, which enables precise rotation of the femoral components to facilitate efficient and reliable soft tissue balancing (a top concern among joint replacement specialists).

“Our whole focus was how do we eliminate the 25 percent of patients who are not satisfied with their knee replacement surgeries?” McCaulley noted. “That was the lens we took to every component, every instrument associated with the Persona knee.”

In addition to the instruments, Zimmer also designed modular trays for the Persona system that enable surgeons to select only the instruments and sizes needed to successfully complete the surgery. The tray design minimizes the total number of trays needed for each case; when used in conjunction with intelligent instruments, Persona procedures can be performed using only two to three trays, executives said.

“We designed the Persona system to meet the demands of today’s patients and provide surgical precision for surgeons, all in the context of concerns about the total cost of care,” McCaulley said. “The Persona system was designed to help hospitals deliver high-quality, consistent outcomes while reducing total costs.”

Smith & Nephew’s Continuing Journey
At AAOS this year, Smith & Nephew’s unveiled its Journey II bi-cruciate stabilized (BCS) knee—the second generation of the Journey knee product.

“The Journey II BCS knee takes knee performance beyond the current standards for fit and alignment and gives patients the complex motion, strength and stability of a human knee,” said Gaurav Agarwal, president of Smith & Nephew’s joint reconstruction business. “You don’t have to ask patients if it feels like a normal knee—you can see it in their gait and in their post-op[eration] X-rays. We redefined knee implant function when we launched the original Journey knee in 2005, and with Journey II we have again outpaced traditional knee replacement technology.”

According to officials from Smith & Nephew, this most recent Journey knee is more than an iterative change to an existing product. It is, they claim, the result of “intense research and design,” and the development of what the company calls “Physiological Matching” technology. Using its LifeMOD human simulation software, Smith & Nephew engineers were able to conduct proprietary analysis of the bone, ligament and muscle forces that impact the knee, and then account for those forces within the design of an implant that restores anatomic shapes and normal motion.

“Unlike implants that create unnatural motion with a symmetric, circular design, or with a rotating platform, the Journey II BCS knee accommodates the swing-and-rotate of the knee with the same engineering principles the body naturally uses,” explained Steven Haas, M.D., chief of the Knee Service at Hospital for Special Surgery in New York, N.Y. “As a result, the muscles and ligaments around the new joint don’t have to work harder because the implant’s natural shape and resulting motion allow these soft tissues to move in familiar ways. This leads to higher patient satisfaction scores, more mechanical efficiency of the muscle, and a more natural feeling while walking or bending in the months after their procedure.”

The Journey II is made from Smith & Nephew’s Verilast material, which is the combination of two wear-reducing materials—the firm’s proprietary Oxinium alloy and a highly cross-linked plastic liner. Smith & Nephew claims that Verilast “significantly” reduces implant wear compared to traditional bearing couples on the market. According to the company, Oxinium is 4,900 times more abrasion resistant than cobalt chrome and reduces knee replacement wear on traditional liners by up to 85 percent compared to cobalt chrome components.

And every little bit helps for getting knee replacement patients back to normal activity, particularly for younger patients. According to one study presented during the AAOS meeting, total knee patients are back to work quickly following their procedures.

Adolf V. Lombardi Jr., M.D., from Joint Implant Surgeons Inc. in New Albany, Ohio, and colleagues conducted a multi-center study involving patients of working age (18 to 60 years old) who underwent total knee arthroplasty (TKA). The study results, presented during the meeting, followed patients one to three years from their procedure to examine the return to work. Complete data was collected for 661 patients (average age, 54.2 years) by an independent third-party survey center.

The researchers found that 74.6 percent of participants were employed in the three months before TKA. After surgery, 91.1 percent returned to work, 93.3 percent of whom returned to the same job. Based on the labor category of the patients’ jobs, return to work was 92.3 percent for sedentary jobs, 79.2 percent for light jobs, 89 percent for medium jobs, 87.8 percent for heavy jobs, and 78.2 percent for very heavy jobs. Compared with females, males were significantly more likely to return to work (82.3 versus 73.7 percent).

“In this group of young, active patients, most returned to work at their usual occupation,” study authors wrote. “While those with sedentary occupations had the highest return to work rate, even those with very heavy jobs returned to work almost 80 percent of the time.”

Smith & Nephew is headquartered in London, the United Kingdom. The company’s U.S. base is in Memphis, Tenn.