Women seem to fare less favorably than men following total hip-replacement surgery, according to a large medical analysis that comes in the wake of continuing federal scrutiny into certain types of implants.
Researchers in California who studied more than 35,000 cases of artificial hip implants found women have a slightly higher risk of implant failure compared with men regardless of the type of device that was implanted.
"One of the main reasons for failure [in women] is dislocation and this can lead to a revision surgery," said Maria Inacio, an epidemiologist with Southern California Permanente Medical Group in San Diego, who studied patients' outcomes for three years after their initial surgeries.
The research, she added, is ongoing and will continue. Statistics were culled from her HMO's registry of hip-implant patients nationwide.
Although the failure rate for women during the three years of study was 2.3 percent compared with 1.9 percent for men, Inacio said it is unknown whether problems will continue at an elevated rate for women compared with men. About 57 percent of patients in the investigation were women.
Hip implants are medical devices, made from a range of materials designed to restore mobility and relieve pain associated with arthritis or injuries.
"This is a very successful operation that provides a lot of relief to the patients who receive it," said Inacio, underscoring that her research should not dissuade patients from hip-replacement surgery.
The analysis involved patients who had received implants made from a range of materials, including metal-on-polyethylene, a device in which the ball is made of metal and the socket of plastic; ceramic-on-polyethylene; ceramic-on-ceramic; ceramic-on-metal; and metal-on-metal.
The latter type of device was implanted least frequently in women but tended to cause the most problems, Inacio said.
All-metal devices, known as the ASR XL, were developed by DePuy, a division of Johnson & Johnson, and can leach chromium and cobalt particles into patients' blood, studies have found.
The ASR XL was recalled in 2010, but possibly as many as 500,000 patients -- men and women -- may still have them, federal experts say.
Last month, the U.S. Food and Drug Administration updated its alert to physicians about the implants, saying problems with them include pain, loosening, malpositioning, allergic reactions and dislocation. The problems occur regardless of gender.
Dr. Geoffrey Westrich, director of research at the Hospital for Special Surgery in Manhattan, said while the California analysis is intriguing, it is far from the be-all and end-all of gender differences in hip-implant surgeries.
"We have tens of thousands of cases [in a database] and when I looked at our registry, we did not see that women fared worse than men in the short run," Westrich said, referring to a three-year period similar to the California research.
However, in a 2011 study, he and his collaborators found in a project including Long Island patients, that women tended to wait longer before hip- or knee-joint replacement surgery and that they report greater pain than men. His investigation involved 6,000 people.