With Charité on the Rocks, Can ProDisc Succeed?

When Charité gained FDA approval in October 2004 as the first artificial disk available in the United States, the market forecasts for the device were quite robust. Sales were projected to reach $100 million in 2005 and $1 billion by 2010. Yet, shortly after market entry, Charité ran into reimbursement resistance from the Centers for Medicare and Medicaid Services ( CMS; Baltimore) and private insurers. Additionally, spine surgeons were slow to embrace the device. The disk's manufacturer, DePuy Spine Inc. (Raynham, MA), a Johnson & Johnson company, has acknowledged that adoption of Charité has fallen far short of initial expectations, with only about 6000 of the devices implanted in the United States since market entry.

With last month's FDA approval of the ProDisc from Synthes Inc. (Solothurn, Switzerland), many industry analysts are wondering whether the product will fare any better in the marketplace than Charité.

One believer in the future of ProDisc is Anthony G. Viscogliosi, principal of Viscogliosi Bros. LLC (New York City), a merchant banking firm specializing in the musculoskeletal-orthopedic sector. Viscogliosi predicts that ProDisc will perform substantially better than Charité as a result of its “superior design, minimal invasiveness, extensive surgeon training, and elegant tools, which ease implantation and consistently yield repeatable results.” Viscogliosi's confidence isn't surprising: Synthes acquired ProDisc in 2003 as part of its $350 million purchase of Spine Solutions Inc., a Viscogliosi Bros. portfolio company.

But Viscogliosi isn't alone. Robin R. Young, publisher of Orthopedics This Week, also thinks that ProDisc is a stronger candidate for market success than Charité. “The key to ProDisc is, we think, its design. ProDisc is a three-part implant: two metal endplates with a polymer disk in the middle. The disk has a convex bump on it, and that allows the metal endplates to rotate. That, in turn, matches the range of motion in flexion, extension, axial rotation, and lateral bending of a normal spine.”

ProDisc was developed in France and has undergone more than 15 years of study in Europe. Clinical trials in the United States were launched in 2001 at 19 centers. The lead facility was the Texas Back Institute (TBI; Plano, TX), which also served as a clinical study center for Charité. Ralph F. Rashbaum, MD, cofounder of TBI and a principal ProDisc investigator said, “After being implanted, the ProDisc device is designed to perform and move like the body's own spinal disk, helping to maintain the position of the disk space while allowing for the flexibility to bend and twist.”

David E. Janssen, MD, an orthopedic surgeon at the Center for Spinal Disorders (Thornton, CO), a ProDisc study center, described the device as a “revolutionary and unique total disk replacement system that holds promise in significantly reducing spinal disorders and back pain, while restoring mobility to the lumbar spine after surgery that cannot be achieved through fusion.”

Unlike the Charité studies, which compared the device to an older, largely discontinued form of fusion surgery, ProDisc was evaluated against the most modern spine surgery procedures. DuPuy's use of what many consider a flawed study is often cited as a significant factor in the device's failure to win over spinal surgeons.

In February 2006, citing a growing number of problems with Charité, CMS proposed a national noncoverage determination for the device. Following pressure from medtech's spinal device sector, however, the agency's decision was subsequently modified. Last May, CMS issued its final determination, which excluded coverage only for patients age 60 and over, and permitted “local decisions” for others.

In addition to its problems on the reimbursement and market-acceptance fronts, Charité is now the focus of a growing number of medical malpractice and product liability suits. As of this past July, FDA has received reports of more than 130 serious adverse events associated with the device.

But are the issues confounding Charité unique to that particular device, or is there a potential problem with first-generation spinal arthroplasty—whether using Charité or ProDisc?

Charles Rosen, MD, founding director of the spine center at the University of California, Irvine, was reportedly “stunned” when he heard the news regarding FDA's approval of ProDisc. An early and persistent critic of Charité, Rosen said he was shocked to learn that the agency's approval was granted without the deliberation and evaluation of an FDA advisory panel. “Such a meeting is important given the questionable results—and even dangerous consequences—of the Charité artificial disk.”

Rosen said he got nowhere when he attempted to bring his concerns to the attention of FDA, so he took his case to Congress. In a letter to Senator Charles Grassley (R–IA), chair of the Senate Finance Committee, Rosen wrote, “The process of approval and monitoring of both of these disk replacements by the FDA has occurred under suspicious and secretive circumstances that suggest that this is the work of undue influence by industry. I believe this presents a real danger to the American people in a circumstance of money triumphing over patient care.”

Rosen insists that there is no conflict of interest or financial gain in his concerns about the safety and efficacy of both Charité and ProDisc, and says he is dismayed to find his comments often prominently displayed on lawyer-run Web sites that are trolling for new product-liability clients.

Rosen has gotten a good deal of attention in both the general interest and financial press. While the issues he has raised regarding Charité are thought to be well founded, many in the medtech industry think he may be overreaching in his concerns regarding ProDisc. John Engelhardt, CEO of Knowledge Enterprises Inc. (Chagrin Falls, OH), publisher of the OrthoKnow and BareBones newsletters, says that it was “not at all unusual” that FDA did not assemble an advisory panel for ProDisc. “Such a panel was convened for Charité, and ProDisc is in the same class of devices. That's a fairly common practice at the agency.”

Synthes plans to proceed very cautiously in rolling out ProDisc. In addition, the company is instituting a comprehensive training program for physicians and facilities that are interested in adding ProDisc to their therapeutic procedures for patients suffering from chronic back pain.

Three more artificial replacement disks are currently in clinical trials and are expected to find their way to the U.S. market eventually: Maverick from Medtronic Inc. (Minneapolis), FlexiCore from Stryker Corp. (Kalamazoo, MI), and KineFlex from SpinalMotion Inc. (Mountain View, CA).

Whatever the troubles of current-generation products may be, some still have faith that the market for artificial disk products has only begun to show its potential. Anthony Viscogliosi believes that new product entries and steadily advancing technology are setting the stage for artificial disk replacement to seriously challenge spinal fusion surgery. He sees a $3.8 billion market for spinal arthroplasty by 2008.

Synthes Inc. reported 2005 revenues of $ 2.08 billion, a 16.8% increase over year-earlier revenues of $1.78 billion.

© 2006 Canon Communications LLC

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