Like other orthopedic surgeons, Dr. Timothy Brox has seen many female patients interested in a gender-specific knee implant made by Warsaw-based Zimmer Inc.

Brox’s experience tells him Zimmer’s aggressive marketing efforts – advertising on TV, in local newspapers, through online banner ads and other media – have been particularly effective. The direct-to-consumer advertising has driven “a flurry of patient requests” for Zimmer’s Gender Solutions knee implant, he said.

Still, the Kaiser Permanente surgeon who has analyzed the results of more than 20,000 knee implant operations involving men and women doesn’t think there’s a proven need for a gender-specific knee. Patients of both sexes receiving traditional unisex knees had similar outcomes, he said, based on his analysis of cases between April 2001 and March 2006. He used a national total joint replacement registry managed by Oakland, Calif.-based Kaiser Permanente, a not-for-profit, group practice program.

More than two years after Zimmer’s Gender Solutions received FDA approval, the debate about the need for a gender-specific implant continues. Some think the knee implant is little more than a marketing ploy that does nothing less expensive, unisex knee implants can’t. Other surgeons believe in its ability to fit a woman’s anatomy and aggressively use it in their practices. And still others remain somewhere in the middle, using it on a limited basis and waiting for more evidence to determine its effectiveness.