Metal-On-Metal Hip Replacement Systems Cause Concern,

But Many Options Are Available For Patients

By Nancy K. Crevier

One year ago, on August 26, Depuy Orthopaedics, Inc, a part of the Johnson & Johnson Family Companies, issued a voluntary recall of the ASR XL Acetablular System and DePuy ASR Hip Resurfacing System, following reports of new information indicating a greater number of required second hip replacements than had been expected.

The ASR Hip System provides a metal-on-metal option for surgeons and patients, and was “designed and developed in conjunction with experienced orthopaedic surgeons and leaders in the biomedical field,” according to the DePuy website.

The hip systems had been approved and in use by US surgeons for approximately six to eight years. A 2010 Australian Orthopaedic Association’s National Joint Registry report, according to the US Federal Drug Administration (FDA), indicated that observational clinical studies suggested a device survival estimate of between 10 and 12 years for metal-on-metal devices.

However, the number of patients complaining about pain and a need for surgical remediation after a far less period of time, or who experience symptoms of allergic response to metals in the bloodstream, continues to grow. A recent New York Times article cited the FDA as having received more than 5,000 adverse reports about a variety of metal-on-metal hip systems, since January 2011.

Dr Sanjay Gupta of Orthopaedic Specialists of Connecticut, at 60 Old New Milford Road in Brookfield, was pleased to begin offering the metal-on-metal hip resurfacing system to his younger, more active patients in 2007.

The hip joint is designed to swing, sway, and swivel, allowing the lower part of the body to move freely. Connecting the thigh bone to the pelvis, the hip — a complex construction of ligaments, muscles, bone, and cartilage — is set up in a ball and joint fashion that provides mobility and stability, and functions as a shock absorber for the body’s upper half. Hip strength is critical for weight-bearing activities, and prior to 2007, Dr Gupta’s patients were fitted with artificial ceramic or ceramic and plastic implants. Because ceramic can chip or break, very active patients of a younger age often expected to undergo a second hip replacement in his or her lifetime. The metal-on-metal hip resurfacing system adds a longer life to the prosthetic device.

He maintains a positive attitude about the metal-on-metal hip resurfacing system for certain patients today, noting that his practice has never used the recalled DePuy systems.

“Most of the failures reported are in how the cup [one half of the metal device] does not bond to the bone properly, so that is a manufacturing problem. Our patients who have undergone hip resurfacing have not had a problem with that bonding,” said Dr Gupta, who added that he uses the Smith & Nephew metal-on-metal system. “This is an implant with a long track record,” he said. “My failure rate [with this implant] is less than two percent.” Because there are so many other options, and because metal-on-metal systems are not necessary or desirable for many patients, only one to two percent of his patients actually opt for a metal-on-metal hip replacement, said Dr Gupta.

He has fielded concerns from patients in recent weeks who are worried about news reports of the dangers of metal allergies and high failure rate of the metal-on-metal hip replacements. “My answer to them is that we have not used the recalled implants, we don’t plan to use them, and we are not concerned.”

Dr Gupta does not dismiss the seriousness of reports of the danger of metal ions in the blood stream, caused by wear of metal against metal. “There is a small inherent danger in using any new technology that is not tested by time,” he said. “Most testing is done first in laboratories, and then FDA approved. The real test, though, is in patients,” he said. “We do know that once people have metal-on-metal implants their ions go up. Healthy kidneys filter that out of the blood. There is,” said Dr Gupta, “a small subset of people who tend to have an allergic reaction, about one to two percent of those with a metal-on-metal implant. Unfortunately, there is no test yet that can be given prior to surgery. The metal allergy is generally a delayed phenomenon, meaning that the reaction occurs a while after the surgery.”

That is why Dr Gupta encourages his patients to consider all of the hip replacement options available.

“Every patient should ask for the different choices and go through the risks and benefits of each with his or her doctor. We can do ceramic on plastic, ceramic on ceramic, metal on plastic, or oxinium on plastic, in addition to metal on metal,” he said.

What an individual hopes to gain from hip replacement surgery, beyond pain relief, is the pertinent question, said Dr Gupta.

“What is the patient’s lifestyle, hobbies? Metal on metal does have the advantage of providing a greater range of motion, postsurgery,” he pointed out. If a patient opts for metal-on-metal hip replacement, it is important to ask about the product that will be used, and to understand the risk of metal ions that will circulate in the bloodstream.

“Hip replacement surgery is the most successful type of surgery we do,” said Dr Gupta. “With the many systems available, I do not believe there is a need for great concern,” he said.

The USFDA noted that “Patients who have MoM hip implants should be aware of potential symptoms which may occur after surgery and indicate that their device is not functioning properly. Common symptoms may include: pain in the groin, hip or leg; swelling at or near the hip joint; and/or a limp or change in walking ability.

“There are many reasons why any of these symptoms may arise or worsen after surgery and it does not necessarily mean that a reaction to the metal particles from the device is taking place. A thorough evaluation by an orthopaedic surgeon is needed to determine the actual cause.”