Not long after health care giant Johnson & Johnson and its subsidiary DePuy Orthopaedics issued a worldwide recall of the ASR hip replacement system and ASR hip resurfacing system due to a higher rate of premature failures than competitive devices, the company launched an internal analysis of its recalled metal-on-metal devices. What the company discovered is that the devices were far more defective than first thought. The analysis showed that the hip implants could be expected to fail within five years in an estimated 40 percent of patients who received the all-metal hip.
It was data from the National Joint Registry of England and Wales that led to the 2010 recall of the ASR hip replacement systems. A year later, the British registry updated its projected failure rates for the device, saying that the ASR hip implants were failing in one-third of patients who had the devices long-term. Yet, Johnson & Johnson and DePuy chose to keep their analysis under wraps, even dismissing the claims made by the registry.
Traditional hip implants are made with plastic or ceramic parts and can last as long as 20 years before needing to be replaced. But the ASR device was designed to be more durable with a metal ball that rotated within a metal socket. The design has turned out to be the problem with the devices. Not only are they more prone than other hip implants to loosen, dislocate or fracture, requiring revision surgery to remove and replace the device, the metal can also corrode over time, dropping bits of metal debris into the joint space causing tissue damage resulting in inflammation and pain.
Metal ions can also leech into the bloodstream causing a type of blood poisoning known as metallosis. The condition has been tied to health complications including headaches and heart problems. The long-term effects are unknown but some researchers say metallosis can cause DNA damage which can cause other serious health problems including cancer.
Johnson & Johnson and DePuy can no longer skirt the issue. The internal analysis on the ASR hip implant is one of numerous documents expected to be made public as the first of more than 10,000 lawsuits by people who received the defective artificial hips prepares for trial this week.
An estimated 93,000 people worldwide are affected by the DePuy ASR hip replacement system recall. About 30,000 of Americans received the recalled hips.
Source: NY Times