Orthopedic Firms put Positive Spin on Negative Implant Reports

There’s been a steady stream of negative news this year about metal-on-metal implants.

The Journal of Arthroplasty initiated the barrage in January by publishing an article titled, “Metal on Metal: Is It Worth the Risk?” In it, the authors question whether metal-on-metal joint replacements are superior to those containing polyethylene or ceramics. “The consequence of wear with metal-on-metal bearings appears to be different to that with more conventional bearings,” the article states. “There are many early reports of osteolysis in metal-on-metal total hip arthroplasties. These are often postulated to be due to hypersensitivity; but the mechanism is not important, whereas the presence of osteolysis is important.”

The authors also discussed the disadvantages of metal implants, noting that the Australian Orthopaedic Association’s 2008 National Joint Replacement Registry identified metal-on-metal bearing surfaces as having the highest risk of revision.

The New York Times followed suit in early March with an article that detailed the growing number of concerns orthopedic surgeons have with metal implants. “What we see is soft-tissue destruction and destruction of bone,” Young-Min Kwon, an orthopedic surgeon at Massachusetts General Hospital in Boston, told the newspaper. Some doctors said they planned to scale back their use of all-metal implants until scientific evidence uncovered better proof of their safety.

The Times followed up that story several days later with a piece about Warsaw, Ind.-based DePuy Orthopaedics Inc. warning its doctors about the high failure rate of its ASR XL metal-on-metal hip system.

None of those stories, however, were potentially as damaging as the edict that recently was handed down by the Medicines and Healthcare Products Regulatory Agency (MHRA) in the United Kingdom. On April 22, the MHRA issued a medical device alert on all metal-on-metal hip replacements due to soft tissue reactions in patients. Metal shards from wear debris have caused adverse reactions in a small number of patients, including necrosis (cell death).

As a result, the MHRA is requiring orthopedic surgeons in the United Kingdom to monitor patients with the implants. The monitoring system must be in place by May 17; patients must be tested annually for five years after their surgeries to measure cobalt and chromium ion levels in their blood. In addition, they also must undergo cross sectional imaging to check for soft tissue reactions.

That edict turned out to be the last straw. On May 3, Smith & Nephew officials countered the bombardment of negative publicity about metal implants by issuing a news release touting the safety record of its Birmingham Hip Resurfacing System. Executives hosted a press conference and webcast several days later. Smith & Nephew’s Orthopaedic division is located in Memphis, Tenn.

In the news release, Smith & Nephew officials reviewed data they presented earlier this year at the American Academy of Orthopaedic Surgeons annual meeting in New Orleans, La. That data featured a new study that tracked results from patients at nine Canadian academic hospitals. The data also included recent medical journal articles that assessed outcomes based on national joint registries in both Australia and Great Britian.

Results from the nine Canadian hospitals showed that 99.91 percent of the 3,400 hip resurfacing patients who participated in the study experienced no implant failure from metal wear debris. Smith & Nephew’s Birmingham Hip was the most used resurfacing device in the study.

The journal articles and registry data reinforce the study’s conclusion. The Australian Orthopaedic Association’s 2008 National Joint Replacement Registry tracked 6,773 Birmingham hips and found that less than one-third of 1 percent may have been revised due to an adverse patient reaction.

The Birmingham Hip’s inventor, Derek McMinn, M.D., collected his own data between 1997 and 2009. Of the 3,095 patients that underwent hip resurfacing procedures during those 12 years, the Birmingham Hip remained successful in 99 percent of men aged 60 and older, and 97 percent of men under age 60, McMinn’s data indicated.

Wright medical Group Inc. executives also addressed concerns about metal implants in a conference call with analysts after the Arlington, Tenn.-based firm released its first-quarter earnings report on May 4.

“Products with metal-on-metal articulating surfaces represent a significant portion of our hip sales,” said Lance A. Berry, Wright’s chief financial officer. “That logically raises questions about the risk that recent publicity has to our business. We believe a lot of the issues being reported are design and technique related. We believe that specific design features of our metal-on-metal devices and our instrumentation systems make them less susceptible to the type of negative outcomes that have been reported.”