The Charite is marketed by the DePuy Spine division of Johnson & Johnson and is approved for spinal arthroplasty in patients with degenerative disc disease at one level of the spine, defined by the FDA as discogenic back pain with degeneration of the disc confirmed by patient history and radiographic studies.
According to the FDA, patients should have failed at least 6 months of conservative treatment prior to implantation. Non-surgical alternatives listed include: "conservative treatment without intervention, medications, chiropractic care, disc injections, and/or physical therapy."
At the time of Charite's approval, approximately 200,000 spinal fusion surgeries were performed in the US each year. Spinal fusion eliminates mobility on that section of the spine to relieve pain. Because spinal fusion limits motion, the Charite was promoted as a disc replacement that could reduce back pain while preserving motion.
J&J is facing a growing number of lawsuits alleging the Charite is a defective product and malfunctions in a variety of ways. There are complaints that the Charite migrates from its implant location to other locations, and that the plates of the disc grind together, causing the release of disc fragments into the body. Others complaints allege defects at the center of the disc's rotation causing instability in the spine.
Some experts believe the device should be taken off the market. In a May 13, 2005, interview with The Street.com, Dr Charles Rosen, an associate clinical professor of spine surgery at the University of California at Irvine, told Melissa Davis, "These artificial disc replacements should be recalled by the FDA to protect the American public."
"I think there are going to be thousands and thousands of people who suffer failures and wind up in chronic pain with no solution for it," he warned.
"I don't know how anyone, in good conscience," he told Ms Davis, "could put these things in knowing the past history and the potential for so many failures."
"It's just money," Dr Rosen states, "over everything else, and it's just cruel."
In the US, between October 2004, and July 2006, the FDA received over 130 reports of serious adverse events in patients implanted with the Charite. Experts have criticized the FDA for ever approving the artificial disc to begin with. To win approval, all J&J had to do was prove that the Charite worked at least as well as Bagby and Kuslich, or BAK, cages used in spinal fusions.
For the study submitted to the FDA with the application for approval, the Charite was implanted in 205 subjects and compared to 99 patients who received the spinal fusion cage. However, each investigational site was required to enroll their first 5 Charite patients as surgeon training cases and a total of 71 subjects were enrolled.
During a May 26, 2005, interview with John McCormick for Research Daily, Dr Rosen explained that he originally became interested in the Charite to decide whether he wanted to use the device or not. As with all new procedure, he said, he researched the literature.
Dr Rosen looked first at the FDA study and noticed immediately that 71 patients, or 25% of the initial subjects, were excluded. "I have never come across a randomized controlled trial," he stated, "where data is excluded because it is simply the initial data."
"The learning curve aspect to the argument," he states, "only tells me there are mistakes that they don't want revealed."
The limited data that is available on the 71 patients shows that the incidence of adverse events within the first 2 days after surgery was much higher among training subjects at 46.5%, compared to 28.3% of the patients who went on to participate in the study.
Overall, the incidence of device related adverse events was also higher in the training group at 11.3%, verses 7.8% in actual trial patients. Adverse events considered by the investigators to be device related, included back and lower extremities pain, implant displacement, and subsidence.
These adverse events also occurred more often in the Charite patient group in the study when compared to the rate in the spinal fusion patients of 4.0%.
The FDA's Orthopaedic and Rehabilitation Devices Advisory Panel held a hearing on June 2, 2004, and the committee voted to approve the Charite, despite the many warnings expressed by experts while testifying at the hearing.
For instance, Dr John Peloza explained that the Charite would be expected to last a lifetime in young patients and it had only been studied for 2 years in the US. "Revision surgery to remove the implant," he warned, "will be potentially life-threatening in every case."
"And at present," he added "there is no consistently successful strategy to deal with a failed implant."
Danish surgeon, Dr Andre van Ooij, who tracked hundreds of Charite surgeries in Europe, warned the panel about retrograde ejaculation and erectile dysfunction in men, and leg complications in other patients, and said joint degeneration was an especially big problem.
"All of these patients have really terrible leg and back pain," Dr van Ooij stated. He also warned that "revision is dangerous and sometimes impossible."
He explained that spinal fusion surgery that may have been successful if done first, was rarely successful in failed Charite patients.
Critics say, the FDA ignored over 17 years of evidence on Charite use in Europe, including a study that found more than half of the patients had fair or poor results.
According to Dr Rosen, the Charite has regularly failed in Europe, leaving patients with life-threatening complications, and calls it "unbelievable" that the FDA ever approved the device. In the end, the conclusion in the approval letter cited by the FDA as the basis for approval states in part:
"The valid scientific evidence presented in the preceding sections demonstrates that the CHARITE Artificial Disc is safe and effective in the treatment of DDD at one level in the L4-S 1 region of the lumbar spine; and the device is non-inferior when comparing Overall Success rates to the control in treatment of DDD at one level (L4-S 1)."
While this may have been enough for the FDA, it was not good enough for the overseers of public health programs. When deciding whether to pay for a device, the Centers for Medicare and Medicaid Services evaluates all relevant evidence to determine whether it supports a finding that an item is reasonable and necessary to improve the functioning of a malformed body member.
In reviewing the Charite study submitted to the FDA, the CMS noted that 24 months after surgery, 73 of the 114 patients listed as successful were still on narcotics for pain. The CMS also mentioned the limited information on the initial training group of 71 patients.
In reaching its decision, CMS reviewed an analysis of adverse events reported in the Manufacturer and User Facility Device Experience database. A total of 101 Medical Device Reports were analyzed for 96 patients. The most frequent event was device migration out of the implant location, in 54 of the 96 patients.
Seventy-six had a second surgery with 50 of the 76 due to device migration. The second most common surgery was to remove all or part of the disc followed by spinal fusion of the implanted segment. Twelve patients had 2 Charites despite the device labeling for only one implant and most events that required second surgery occurred in the first 2 months. There were 2 deaths attributed to pulmonary emboli.
In the end, the CMS decided not to pay for Charite surgery for patients over the age of 60, after concluding in part: "The results of the Charite Premarket Approval noninferiority trial are unconvincing as a demonstration of net health benefit."