Women who have received DePuy Orthopaedics’ recalled ASR Hip Resurfacing System and ASR XL Acetabular System may be at highest risk for premature failure of their implant. That’s because ASR hip implants with femoral head sizes below 50 mm have the highest failure rate, according to data from the National Joint Registry of England and Wales. The DePuy hip implants with smaller femoral heads are more likely to have been implanted in female patients.

In August, the DePuy recall of the ASR XL Acetabular System was issued worldwide (a hip socket used in traditional hip replacement), and the ASR Hip Resurfacing System, a partial hip replacement that involves placing a metal cap on the ball of the femur. The recall was issued after data from the National Joint Registry of England and Wales showed that 1 out of every 8 patients (12%-13%) who had received the recalled devices had to undergo revision surgery within five years of receiving it. A hip implant should last for 15 years or so.

The J&J hip recall followed a warning DePuy issued in March 2010 regarding the same implant. In a letter, DePuy warned doctors that recently analyzed data from Australia suggested that the ASR had a higher-than-expected failure rate when used in traditional hip replacement on certain types of patient. According to the letter, patients of small stature, a group that typically includes women and patients with weak bones, faced the highest risk.

Incidentally, DePuy stopped selling the ASR system in Australia in 2009. The company also indicated a plan to phase out the system worldwide in 2010, but claimed it was taking the action because of slow sales, not health problems.

The DePuy Acetabular Hip Replacement System is a metal-on-metal hip implant made of chromium and cobalt, the device consists of a cup that’s implanted into the hip with a ball joint that connects to the leg. It is believed that many of the complications linked to the DePuy ASR XL Acetabular hip implant are caused by wearing of the metal components, which can allow metal shavings to make their way into patients’ bloodstreams. The resulting cobalt poisoning could increase the risk of a number of health problems, including dementia and heart failure. DePuy now recommends that implant patients have a blood test to check for high levels of chromium and cobalt.

Since the August recall, around 150 lawsuits have been filed against DePuy by victims of the ASR hip implant, and many more such suits are expected. Recently, all federal lawsuits involving the DePuy ASR XL Acetabular Hip Replacement System were consolidated in a multidistrict litigation in the US District Court for the Eastern District of Ohio.