Pharmaceutical

Injuries from all-metal hip implants usually difficult to diagnose and detect

Metal-on-metal hip implants are creating “an expanding public health crisis” that threatens hundreds of thousands of people and leaves physicians throughout the country baffled, the New York Times reported. Studies have found that all-metal hip replacement systems such as DePuy’s ASR XL Acetabular System and ASR Hip Resurfacing System can cast metal particles into the recipient’s blood and tissue. Elevated levels of chromium and cobalt in the blood manifest in a number of ways, from depression and memory loss to chronic pain and deterioration of muscle, tissue, and bone, but these symptoms are often misconstrued and improperly treated because they often don’t show up on tests and unsuspecting doctors have never faced such a massive medical device failure of this nature before.

According to the New York Times, researchers warned more than a decade ago that all-metal hip devices released heavy metal debris into the body that created a potential health threat, “but those warnings were never heeded.” Caution seems to have been trumped by the exciting promise of longer lasting all-metal hip implants, allowing the dangerous devices to flood the market even though clinical testing had been minimal.

Before DePuy recalled its ASR hip devices in August of 2010, metal-on-metal hip implants accounted for nearly one-third of the quarter-million hip replacements performed in the U.S. every year. As a result, some half a million Americans and even more worldwide face the injuries and illness that these implants potentially pose.

“All orthopedic implants, regardless of their composition, shed debris as they wear,” the New York Times article explains. “But researchers say they believe that the particles released by all-metal hips pose a special threat because scavenger cells dispatched by the body to neutralize the debris convert it into biologically active metallic ions. In some patients, a chain reaction begins that can destroy tissue and muscle.”

Dr. Young-Min Kwon, an orthopedic surgeon at Massachusetts General Hospital, is one of the physicians most familiar with the damage the all-metal implants can cause. Dr. Kwon recently operated on a 52-year-old man whose all-metal hip implant created “matted strands of tissue stained gray and black” and “a large strip of muscle near the hip” that no longer contracted. The whole area around the implant was, as the New York Times described, “a biological dead zone.”

Testing before the surgery did not reveal the full scope of the damage done, which Dr. Kwon worries could be permanent. Implant patients who suffer from such damage must undergo revision surgery to remove the faulty devices, but the replacements can be difficult for surgeons to implant when the damage to supportive bone, muscle, and tissue is severe.

The dangers of all-metal hip implants are also exacerbated by the elusive nature of the injuries, which can be as complex and difficult to detect for doctors as they are painfully real for the patient. Patients often “bounce around” from doctor to doctor seeking treatment for their pain while inside the damage deepens. According to the New York Times, one of Dr. Kwon’s patients “saw seven doctors over the course of a year who told him not to worry or who gave him shots for his pain.”

“Diagnostic tests also did not point to a problem. Only recently have researchers determined that such scans need to be run in a specific way to detect the extent of metal-related damage,” the New York Times reported.

Fortunately, many patients who received DePuy hip implants are finding their way to Dr. Kwon. His case load has tripled within the last year, a surge indicative of a larger trend occurring in the U.S. and rest of the world.

The FDA received 5,000 complaints concerning metal-on-metal hip devices since January 2011, more than the agency had received in the previous four years combined. Seventy-five percent of those complaints involved DePuy’s ASR Acetabular system.

Source:

The New York Times