Evelyn Pringle August 2006
According to the Institute of Medicine, over a million Americans are severely injured each year by medical devices. In 2002 alone, the FDA received more than 111,000 reports of adverse events involving medical devices.
That number has increased since the Charite artificial spinal disc was approved for use in the US in October 2004. As of July 2006, there have been more than 130 serious adverse events reported to the FDA associated with its use.
Examples of the serious adverse events include: migration of the artificial disc resulting in either removal of the disc or maintaining the disc, both followed by fusion; pedicle fractures; subsidence or a settling of the disc into the bone; and nicking of an vein or artery.
Professor Karin Büttner-Janz and Professor Kurt Schellnack, considered to be leading spine specialists, originally developed the Charite disc at the Charite University Hospital in Berlin, Germany in the mid-1980s. Further refinements to the design were later incorporated at Waldemar Link GmbH, a European based medical device maker.
In 2003, DePuy Spine, a division of Johnson & Johnson, acquired the Link Spine Group, and gained exclusive worldwide rights to the Charite.
According to Spine Health.com, the Charite is approved for patients who have severe lower back pain and have obtained little or no pain relief after at least 6 months of non-surgical treatments, such as pain medications, physical therapy, injections, or manipulation. "The FDA clearance for disc replacement," the site says, "is for one level of the lower spine, and it must be done at one of the two lowest levels of the spine (L4-L5 or L5-S1)."
The device was approved to relieve pain by replacing the damaged disc with the Chirate disc, as an alternative to the surgical procedure known as lumbar spinal fusion surgery
Spinal fusion surgery works to stop motion at the painful level of the spine. In this procedure, implants are used to help provide initial fixation, such as metal screws, rods and cages, and are inserted between the vertebrae. Because the fusion eliminates the motion in the lumbar segment of the spine, if the surgery is successful, the pain is reduced or eliminated.
When done correctly for the right indications, experts say, a fusion has a high success rate in relieving pain. However, because it limits the range of motion, extra stress may transfer to the discs above and below the fusion site.
An artificial disc is supposed to allow continued motion in the spinal segment, and therefore, the Charite was thought to be a viable alternative to spinal fusion surgery for patients with the right indications.
However, in the paper, "Total Disc Replacement for Chronic Low Back Pain: Background and a Systematic Review of the Literature," by M de Kleuver, F Oner, W Jacobs in the European Spine Journal Volume 12, Number 2, April 2003, the authors determined that despite the fact that these devices have been implanted for almost 15 years, on the basis of this literature survey there are currently insufficient data to assess the performance of total disc replacement adequately.
There is no evidence, the paper said, that disc replacement reliably, reproducibly, and over longer periods of time fulfils the three primary aims of clinical efficacy, continued motion, and few adjacent segment degenerative problems.
Total disc replacement, they said, seems to be associated with a high rate of re-operations, and the potential problems that may occur with longer follow-up have not been addressed.
Therefore, the authors advised, total disc replacements should be considered experimental procedures and should only be used in strict clinical trials.
J&J beat out competitors Stryker and Medtronic by securing approval of the Charite, but many surgeons have criticized the FDA for approving the device and ignoring over 17 years of evidence related to its use Europe, including a study showing that more than half of recipients had fair or poor results.
The FDA approved the Chirate based on the results of a single two-year clinical trial, that was designed to merely establish that the Charite disc worked at least as well as the Bagby and Kuslich cages (BAK) used in spinal fusions.
The trial was conducted at the Texas Back Institute in Plano, Texas, on 304 patients, and was led by a team of surgeons that included Dr Scott Blumenthal, Dr Barton Sachs, and Dr Stephen Hochschuler, who are considered to be among the best spine surgeons in the field. Dr Blumenthal presented the results of the trial at a hearing before an FDA advisory panel.
A transcript of the June 2, 2004, hearing, reveals the agency’s own reviewer found the study to be biased in favor of Charite, and that important data about patients had been excluded. A voting member of the panel, Brent Blumenstein, complained about omitted patients during the hearing, but went on to vote for approval anyways.
In a nutshell, the study basically showed no significant differences in complications between the Charite group and the spinal fusion group.
According to Sergio del Castillo, a biochemical engineer, and the FDA's lead reviewer of the Charite approval application, the "purpose of the study was to evaluate the safety and effectiveness of the Charite and compare it to the BAK Interbody Fusion device."
The study was to show that the Charite would be at least as good as the BAK within a non-inferiority margin of 15%, Mr del Castillo explained, and was not designed to demonstrate superiority of one group over the other.
The first five subjects at each investigational site were treated with the Charite as part of the training of the surgeons and they were not included in the final assessment of effectiveness of the devices.
The success rates for the Charite and the BAK groups were 64% and 58 percent, respectively. Considering the overall success rate is within a non-inferiority margin of 10% of the BAK success rate, "it appears the study has demonstrated the non-inferiority of the Charite compared to the BAK," Mr del Castillo told the panel.
Adverse events in the study, he explained, were categorized as typical or unusual, severe or life threatening, device related or not device related, severe and device related occurring within two days of surgery and by date of onset.
The percentage of Charite and BAK subjects experiencing at least one adverse event, he said, was essentially equal. However, Mr del Castillo said some adverse events were reported in a higher percentage of Charite subjects compared to the BAK group, and included infection, abdominal events, device related events and severe life threatening events.
He noted that 7.3% of Charite subjects experienced adverse events compared to 4% of BAK subjects. A greater percentage of Charite patients experienced: (1) back or lower extremity pain; (2) neurological events, such as numbness, motor deficit or nerve root injury; and (3) additional surgery at the index level.
It should be noted, he advised, that the rate of adverse events was higher in the training group compared to the randomized subjects in the study and pointed out that training subjects were not included in the assessment of safety.
Safety and effectiveness in the study were evaluated in terms of the complications that arose during implantation and post-operatively including infection, thrombosis, migration and subsidence, re-operation, the incidence of adverse events, the level of the subject's disability and assessment of the subject's neurological status.
The primary endpoint for effectiveness consisted of four components: (1) pain in function as measured by the ODI; (2) any device failures requiring revision, re-operation or removal; (3) any major complications; and (4) neurological status.
A surgery was determined to be a success if the subjects: (1) ODI score increased by at least 25% at 24 months compared to the subject's baseline score; (2) experienced no device failures requiring revision, re-operation or removal; (3) did not experience any major complications defined as major blood vessel injury, neurological damage or nerve root injury; and (4) the subject's neurological status was maintained or improved at 24 months with no new permanent neurological deficits compared to baseline.
An individual subject was considered a success only if he or she was a success in all four components, Mr del Castillo advised the panel.
The study was defined as a success if the success rate of the Charite group was found to be non-inferior to the overall success rate of the BAK group, and safety was assessed by comparing the rate of incidence of all adverse events observed in the two groups.
The secondary effectiveness endpoints, according to Mr del Castillo, consisted of all the primary endpoint components, listed previously, which are pain in function as measured by ODI, device failures requiring a revision, re-operation or removal, any major complications and neurological status.
A Danish surgeon, Dr Andre van Ooij, also testified at the hearing, and advised the panel about the known complications associated with the Charite, and provided the members with visual slides showing the adverse events that occurred in a number of patients.
Dr van Ooij tracked hundreds of surgeries in Europe and in eight years, he treated 49 Charite patients, 28 women and 28 men, with some their surgeries performed as early as 1989. All of these patients, he noted, suffered terrible leg and back pain after the device was implanted and many were unable to undergo a surgical revision of the disc due to the dangers involved in spinal surgery.
Dr van Ooij also advised that some men implanted with the device suffered retrograde ejaculation and erectile dysfunction, and others patients suffered leg complications and joint degeneration.
"One big issue that was not spoken about today," he pointed out, "is breakage of the metal wire."
"If you look good at the x-rays," he advised the panel while showing a slide, "you can see the breakage and the flattening of the polyethylene core and probably also some wear debris."
Overall, more than half of the patients in Europe ended up with fair or poor results after the disc was implanted.
Orthopedic and spine surgeon, John Peloza, also testified at the hearing and told the panel that first and foremost, the Charite disc had to last the lifetime of the patient and that the average age of a person that would be a candidate for the procedure is about the mid-40s.
"I think it is critical that these implants last for the life of the patients," he said, "because revision surgery to remove the implant particular from an anterior approach will be potentially life threatening in every case."
"And at present," he advised, "there is no consistently successful strategy to deal with a failed implant."
"I don't think the polyethylene as they have in this implant will last anywhere near 40 years or the lifetime of the patient," he advised.
In addition, he said the fixation of the disc to the bone was compromised.
"The metal base is secured with a press fit with little spikes," he explained. "This is not adequate and will predictably fail," he added.
There are published studies, he told the panel, that show significant re-operation rates between 5 and 20 percent with complication rates reported greater than 10 percent.
As for results in regard to pain relief, the clinical studies in Europe and Australia, he said, essentially report results equivalent to fusion in regard to pain relief.
After listening to all the testimony about the dangers of the Charite disc, in the end, the FDA advisory panel's vote for approval of Charite was unanimous.
Seven months later, on May 13, 2005, the Street.com, reported that Dr Charles Rosen, an associate clinical professor of spine surgery at the University of California at Irvine, was calling for an immediate recall of the Charite, pointing out fundamental flaws in J&J’s study design.
He told the Street that J&J compared the Charite to BAK cages in spinal fusions, a failed procedure that had not been performed in years. According to Dr Rosen, the comparison is “the worst possible operation to compare these things to.”
J&J responded by saying the BAK was the standard treatment for degenerative disc disease at the time of the study.
According to the Street, Dr Rosen said J&J ignored the first patients who underwent the surgery, and that exclusion of such a significant portion of the sample size can seriously compromise the quality of statistical data.
Dr Rosen, who is also the founder of the UCI Spine Center, told the Orange County Register on April 12, 2006, that the Charite can cause more pain than it cures.
Forty-five year old, Dane Titsworth, from a hospital bed at UCI Medical Center, recovering from his fourth back surgery, told the Register, that the pain he experienced with the Charite he had implanted in May 2005, was like driving a big rig over your legs.
After the Charite surgery, Mr Titsworth said the pain became unbearable and cost him his job with State Farm Insurance, and nearly his marriage.
Dr Rosen fused the part of his spine where another surgeon had implanted the disc.
The Charite does not absorb shock like a healthy disc or mimic natural motion, Dr Rosen told USA Today on July 25, 2006, and a dislocation or fracture of the disc can also cause problems, he said.
In March 2006, Dr Rosen says, eight more patients like Mr Titsworth contacted him, who have more pain in their back with the Charite than without it.
In May 2006, Medicare decided to stop paying for the device in patients over 60, noting that the $30,000 to $50,000 surgery had not been sufficiently tested for long-term affects.
Blue Cross and Blue Shield also determined that more research was needed over a longer period of time, although insurance plans in each state determine coverage decisions individually, according to USA Today.
On October 20, 2005, the Bagolie Friedman law firm announced the formation of the “International Charite Artificial Disc Practice Group,” based on a belief that numerous people in the US and abroad, "suffer Charite artificial disc failure," and that "Johnson and Johnson is responsible for manufacturing a medical device they knew or should have known was unreasonably dangerous in an attempt to capture some of the lucrative multi billion dollar back surgery market."
"We will be reviewing potential cases from the United States, Australia and Europe," said Mr Bagolie.
On June 5, 2006, the Street.com reported that Chicago-based attorney, Pete Flowers, has more than 200 clients who have complications from the Charite and who are seeking reparations from DePuy Spine.
Twenty-eight lawsuits have been filed, Mr Flowers told the Street, and he expects an additional 40 to 50 more to be filed this month. Dane Titsworth is a client of the firm.
Mr Flowers’ clients claim the Charite is defective and that J&J improperly marketed the device and did not adequately warn of the disc's dangers.
"Most of these people are between 25 and 45 years old," he told the Street.com. "A lot of them have lost their jobs, their spouses, their families, their houses -- everything."
Since the disc was approved in the US, more than 5,000 people have received the implant, says DePuy Spine's Bill Christianson, vice president of regulatory affairs, according to USA Today on July 25, 2006.