Metal Hip Implants Fail Faster Over Time: UK Report

Metal-on-metal hip devices, including the “resurfacing” variants, are by far the implants that have the highest rates of revision, or eventual surgical removal or replacement, according to NJR. After five years, metal-on-metal devices have a revision rate as high as 13.6 percent and resurfacing devices have revision rates of 11.8 percent, while other hip implants typically have revision rates between 3.3 percent and 4.9 percent, according to the report.

Making matters worse, metal-on-metal implants didn’t age as well as other devices, experiencing “dramatic” increases in revision rates as the years passed, NJR said. While most hip prostheses reported a less than 1% increase in revision rates, resurfacing devices increased by about 2 percent, and the metal-on-metal devices climbed more than 4 percent over time.

The results were worse for women than men, NJR found. After five years, women aged 60 to 69 had revision rates of 12 percent for resurfacing hip implants and 7.34 percent for metal-on-metal devices overall. For men the same age, the rate was 7 percent for resurfacing implants and 5.5 percent overall.

Johnson & Johnson unit DePuy Orthopaedics Inc. announced last August that it would recall two hip replacement devices — ASR XL Acetabular and ASR Hip Resurfacing — two devices that NJR said performed particularly poorly.

The recall helped accelerate a decline in sales of metal-on-metal implants, NJR said. While metal-on-metal devices accounted for 15 percent of hip replacements tracked by NJR in 2006 and 2007, that number fell to 10 percent in 2009 and again to 5 percent in 2010.

In the latest report, the five-year revision rate for the recalled ASR XL Acetabular System was 17%, up from the 13% rate reported in 2010. While the NJR reported an alarming six-year revision rate of 29%, a DePuy spokeswoman said that that number shouldn’t necessarily be taken as gospel.

“The six-year revision rate should be interpreted with caution because it is based on a small number of cases,” spokeswoman Lorie Gawreluk said. “The five-year data is more statistically robust given the much larger patient population from which it is drawn.”

The NJR data is one factor that led to the recall, Gawreluk said. When DePuy voluntarily recalled the ASR device in August 2010, the latest NJR report showed higher revision rates around 12%, which differed from data previously reported to DePuy, according to Gawreluk.

DePuy said it continued to support ASR patients and their surgeons, reimbursing patients for recall expenses and conducting educational outreach for surgeons.

In May, the U.S. Food and Drug Administration ordered 21 manufacturers of metal-on-metal hip replacement systems, including DePuy, to conduct post-market surveillance studies to determine whether their devices were associated with a dangerous increase in levels of metals in patients’ bloodstreams.

The FDA instituted the monitoring program to find out more about safety issues associated with the devices, including concerns that the implant’s metal ball and socket bearings that make up the hip joint generate chromium and cobalt debris that spread to a patient’s surrounding bone and tissue.

A number of medical device giants — including DePuy and Stryker Corp. — have faced thousands of suits arising from problems with the artificial hips, including allegations that metal debris from the implants had damaged bone and tissue surrounding the implant and joint, damaging the implant and causing pain.

The NJR report also found that patients with knee and hip replacements tended to gain weight and have poorer health, while mortality rates within 90 days of hip replacements remained at historic lows, at 0.6 percent overall.

Source: Law 360
– By Dietrich Knauth
– Additional reporting by Roxanne Palmer. Editing by Kat Laskowski.