In one of the largest studies of its kind, researchers have determined that women have a slightly elevated chance of needing a hip revision before a man.

Researchers from Kaiser Permanente looked at 35,000 hip surgeries in 46 hospitals within their healthcare system. While men had an average of 1.9 % revision surgeries in an average of three years, women experienced a 2.3% revision rate or a 29% increased risk of failure when compared to men within the first three years.

The research is published in this week’s Journal of the American Medical Association (JAMA) Internal Medicine. The research was funded by the U.S. Food and Drug Administration (FDA).

A revision or removal and replacement surgery is usually undertaken when there is a problem with the hip prosthesis loosening, becoming infected or any instability.

The reasons for an increased risk for failure in women are largely unknown but the authors speculate it may be because women may need a small femoral head which is more likely to dislocate. Younger men receiving a larger femoral head component to the hip replacement have the greatest degree of success with hip implant surgery.

Women also tend to have decreased bone density as they age which may be a contributing factor to an earlier revision rate.

Diana Zuckerman of the National Research Center for Women & Families, a nonprofit group in Washington, D.C., says the bottom line may be that women should not be easily sold on the latest and greatest new hip replacement product. Only after years on the market is any product actually tested in real-life conditions, so older medical devices might actually be the best choice.

It was once thought that the new metal-on-metal (MoM) hips would be an improvement over the standard ceramic or plastic models. For women, MoM hip products have failed about twice as often as for men and both Stryker and DePuy (Johnson & Johnson) have recently had to recall some of their best selling MoM hips.

Neither the U.S. nor the European Union study the safety and efficacy of hip implants before the medical devices are sold. The FDA has failed to require clinical data for hip and many other implants which could be invaluable to determine which implants work best for men, women, younger, older, physically active or inactive patients.

Understanding why hip implants fail more often and which hip prosthesis perform best in each population segment, including women, could save billions of dollars and the pain and injuries that occur in some of the more than 400,000 Americans who undergo hip replacements each year.