About the ASR
The DePuy ASR debacle may well represent one of the biggest medical device failures in recent decades; upcoming trials are expected to shed some light on what DePuy officials were aware of regarding potential problems with the ASR prior to its recall. DePuy recalled the ASR (Articular Surface Replacement) in 2010, due to its high rate of failure only a few short years following FDA approval via the 510(k) process. Metal-on-metal hip implant replacements like the ASR—in which both the cup and ball of the device are made from metal—accounted for one in three hip implants used in the United States just a few short years ago, yet now reportedly only account for 10% or less. This is likely due to the many reports of problems associated with these all-metal hips. Johnson and Johnson and DePuy are currently facing well over 10,000 lawsuits related to the ASR.
While it appears that few records were maintained regarding those implanted with the ASR hip device, it is estimated there are over 100,000 of the implants, worldwide. Between 2008 and 2010 when the ASR was recalled, the FDA received over 400 adverse event reports. The ASR gained FDA approval in 2005, claiming it was substantially equivalent to the DePuy Pinnacle implant. By 2006, it appears there were problems with the ASR, particularly among women and those with weak bones. Nearly a year prior to the U.S. recall of the ASR, Australian officials discontinued sales of the implant. When asked about the reason for this discontinuation, DePuy and Johnson & Johnson officials maintained the implant was pulled due to a decline in sales rather than safety issues.
Construction of the ASR
The ASR hip system is a one-piece cup and socket which can be used for a total hip replacement (ASR XL) or hip resurfacing (DePuy ASR). DePuy claims that the ASR hip system was designed with orthopedic surgeons in an attempt to provide a hip implant option with a reduced risk of dislocation. The design was marketed as being especially good for the younger, more active patient. While the DePuy ASR Hip Resurfacing System was approved only for use outside the U.S., the ASR Acetabular Hip System was made available worldwide.
DePuy states that “a clinical need existed for a hip bearing surface like metal that reduced the risk of dislocation and was more durable than polyethylene with reduced wear debris but without the fracture risk of ceramic. That was the goal of the ASR.”11 DePuy execs went on to say that although there had been “theoretical concern over metal ion release from metal-on-metal implants, no definitive data establishes that the level of metal ion release has clinical significance.”11 The ASR Acetabular Hip System is comprised of a metal femoral head (ball) connected to a metal stem and a one-piece metal cup lining the acetabulum. During periods of activity on the part of the implant recipient, these metal components rub against one another, causing microscopic metal ions to shear away and enter the body.