NewsInferno; February 19, 2013
Hip implant failure rates are greater in women than men, according to a recent study conducted at the Southern California Permanente Research Group in San Diego, California.
The research revealed that hip implant failure rates were 29 percent higher in women than men based on information from a large United States registry study, said MedPage Today. The team controlled for factors such as device type and adjusted for age, body mass index, diabetes status, degree of presurgical symptom severity, implant fixation method, device category, and femoral head size, MedPage Today said. Study results appear online in JAMA Internal Medicine.
The team, led by Maria C.S. Inacia, MS, followed 35,140 patients who were undergoing primary total hip arthroplasty for a median period of three years. The failure rate in women was 2.3 percent, said MedPage Today, compared to a 1.9 percent failure rate seen in men, said Inacia. The risk was greatest in so-called “aseptic” revision surgeries.
Larger femoral head sizes caused more problems in women. In head sizes of 36 mm or greater, the adjusted failure rate in women, when compared to men, was 1.49; differences in revision rates involving smaller head sizes were not found to be significant after adjustments, MedPage Today explained. Increased risks in women also appeared to be concentrated in metal-on-metal implants. In fact, the risk was doubled for women when these metal devices were involved.
Data for the current study was derived from the Kaiser Permanente system’s registry of total joint replacements from 2001 to 2010; procedures were conducted at 46 hospitals in California, Hawaii, Oregon, Washington, and Colorado by 319 different surgeons, said MedPage Today. The registry is the largest of its type in the U.S., according to the study’s authors, and includes data on surgeons’ and hospitals’ arthroplasty procedure volumes; patients and the type of implants they received (cemented, uncemented, or hybrid); and the implant bearing surface (metal-on-metal, metal or ceramic on highly crosslinked polyethylene, or ceramic-on-ceramic. The researchers put the DePuy metal-on-metal hip resurfacing monoblock device in a category of its own, MedPage Today noted. Patients undergoing unilateral procedures—procedures on one hip—were included and more than half (58 percent) of the 35,140 procedures were conducted on women with a mean age of 65.7; the male mean age was 63.8, MedPage Today added.
We previously wrote that 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.
DePuy Orthopaedics is a unit of Johnson & Johnson and the DePuy ASR is at the center of a lawsuit brought by Loren Kransky against Johnson & Johnson over the device. Kransky’s is the first of some 10,000 similar cases that have been filed.
In August 2010, DePuy issued a worldwide recall of its ASR XL Acetabular System (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 revealed unexpectedly high revision rates within five years of original implantation. Traditionally, hip implants are expected to last 15 years or so.
The recall followed a warning DePuy issued in March 2010 in which the device maker 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 of device failure.
The DePuy ASR metal-on-metal hip implant is made of chromium and cobalt and many of the complaints involve allegations that normal wear causes the device’s metal components to rub against one another and shed into patients’ bodies and bloodstreams, leading to serious injuries.