Everything old is new again.
First there were plastic-on-plastic bearing surfaces for hip implants, yet the concern was that the polyethylene would wear too quickly.
Then there were ceramic-on-ceramic bearing surfaces, and the squeaking let everyone in the house know when Granddad was coming down the hall. Today orthopaedists are dealing with the aftermath of one of the largest recalls ever in the industry, the 2010 voluntary recall of the DePuy ASR XL Acetabular System and the DePuy ASR Hip Resurfacing System. The problems with the ASR systems are caused by the metal-on-metal design, the newest iteration in bearing surfaces.
What’s next? Polyethylene is looking pretty good again, said William B. Kurtz, MD, orthopaedic surgeon and chief of orthopaedics with Baptist Hospital. He practices with Tennessee Orthopaedic Alliance. “We’ve kind of gone full circle back to polyethylene again,” said Kurtz, who added, “There’s not one bearing surface that’s perfect for every single person.”
A subsidiary of Johnson & Johnson, DePuy recalled both ASR hip devices on Aug. 24, 2010. About 93,000 of the implants had been sold worldwide. According to data from an independent national registry in the United Kingdom that tracks implant performance and outcomes, an alarming number of patients had undergone revision surgery, replacing the existing hip implant with a new one.
The UK information revealed that within five years of having the resurfacing device implanted, about 12 percent of patients had revision surgery. For the total hip replacement, the revision rate was about 13 percent within five years. DePuy claimed that these percentages were much larger than had been previously reported.
“The standard of care is that they want failure rates of implant devices to be less than 2 to 3 percent. That’s the acceptable threshold for failure. Yet they were finding failures that were unacceptably high,” explained Joseph D. Chenger, MD, a Centennial Medical Center orthopaedic surgeon who practices with Premier Orthopaedics & Sports Medicine. “The companies in their research and development labs test these things and under their optimal circumstances find that these devices are good for use in human beings. But the reality of life is that when you put something in humans, they will push it to limits that you just normally can’t test in a laboratory environment. That’s just one of the downsides of humans – they do things that you just can’t predict,” he added wryly.
Chenger said he was never “a firm believer” in the ASR implants and only installed 11 of them. Just one of his patients has required revision surgery.
While the revision rate of the implants is high, Kurtz said, “It’s not an absolute that just because you have a recalled hip you need to have another surgery. About 88 percent of them are functioning fine.” Nonetheless, the apprehension of patients, the concern of physicians and the staff time consumed with paperwork and patient contacts has been a strain on many orthopaedic practices.
“It has been a huge level of frustration for us in the office, even though it’s a tiny percentage of my patients,” Chenger said. “Because the attorneys are so aggressive trying to find every patient out there, they scare everybody to death. So every patient who’s had a hip or knee replacement has called in asking if they have a recalled device. It created for a while a tremendous amount of anxiety amongst the patients and a huge burden of work for our staff here.”
At Baptist, Kurtz said the DePuy ASR implants represented less than 1 percent of the hip replacements in the last five years, yet the hospital and TOA fielded a flurry of patient calls. He echoed Chenger’s observation, saying, “I think this recall has been pretty unique, especially in the legal response to it. It seems like the legal community has been especially aggressive with this recall.”
The response to the recall by Nashville orthopaedists appears to be consistent, with letters going out last year to patients who received an ASR implant. While practices relied on their own records, DePuy also notified each physician with a list of their affected patients. “I’m very confident that anybody in Nashville who’s had a recalled hip has been informed. So those who haven’t received any notices can rest assured that there is nothing to worry about,” Kurtz said.
Problems with the ASR system are two-fold. First, some of the joints are loosening with one particular implant size creating the most problems, according to Chenger. Second, the wear may release metal ions into the surrounding fluid and soft tissue.
“A majority of the concern in this recall is the metal-on-metal wear,” Kurtz said. “Sometimes it can result in an abnormal amount of metal ion production and can lead to a lot of soft tissue damage and inflammation in the hip. Those patients universally have pain, and they know something’s not right with their hip. Those patients I’m sure have seen their doctor by now and gotten it fixed.” In a small number of patients, the metal ion release has caused systemic damage.
Kurtz surmised that the metal-on-metal device is the result of orthopaedics’ “quest for the holy grail, which is the perfect bearing surface that never wears out and lasts people a lifetime.” Chenger predicted that metal-on-metal devices “may eventually disappear. The good news is now companies have made the plastics much better. Honestly, the metal-against-plastic or the ceramic-against-plastic bearing surfaces have wear limits that are probably as good as what the companies hoped metal-against-metal bearing surfaces would accomplish.”
Meanwhile, in May, the U.S. Food and Drug Administration asked all makers of the 22 commercially available metal-on-metal hip implants to conduct post-market surveillance to monitor for joint loosening, local inflammation and the dangerous release of metal ions into the bloodstream.
On another front, Kurtz has requested a grant from BlueCross BlueShield of Tennessee to establish a joint implant registry in the state. There isn’t a national registry, and some states already have taken the initiative to start their own. “The goal of any joint registry is to pick up on things like this ASR recall before it becomes a commonly used implant … to catch these patients early so we can identify the bad apples and stop using them,” he explained.
And what has the orthopaedics industry learned from this recall? “If we’ve learned anything,” Kurtz said, “it’s that recalls should be avoided.”