Reviewing the Gender Knee Debate

Amidst the clatter of gender-based knees coming to market, some have hit the advertising trail while others are calling shenanigans. Yet many questions still remain unanswered for these implants. And without answers, the camp calling shenanigans may be sitting on the bench while the game continues.

The largest advocate for gender-specific knees, Zimmer Inc., continues to heavily market its Gender Solutions Knee Replacement. With Gender Solutions® being the primary contributor, Zimmer posted an 11.5% revenue increase for first quarter 2007 over previous year’s revenues in total knee sales. In the second quarter Zimmer reported revenue growth of 10.6% versus the numbers for the second quarter of 2006. Because nearly 42% of Zimmer’s revenue is based on knee sales, the revenue potential and the stakes of such a game are clear.

Other large joint manufacturers are also offering gender-specific knees. Stryker, for example, has released the Triathlon® Knee System, Smith & Nephew has brought to market the Genesis II® Total Knee System, and DePuy now has the PFC® Sigma Knee System. As of the second quarter 2007, both Stryker and Smith & Nephew had posted year-over-year knee implant revenue increases of 14.7% and 15.4%, respectively. Only Depuy lagged behind with a year-over-year increase of 5%.

On the other side of the field are those who argue that there is too little evidence in support of different knee designs for each gender. The highest profile orthopedic company in this position is Biomet. While Biomet’s revenues are not as reliant on knee implants as are Zimmer’s (just over 28%), it too has a considerable amount at stake.

Consider the facts. Women represent two-thirds of the population receiving knee transplants.  Also, it is widely claimed that various regions of the female knee are different in size than their male counterparts. As recently as September 2007, a study led by Shinro Takai, M.D., from the Teikyo University School of Medicine in Tokyo was presented providing further evidence (using the Kellgren & Lawrence scale) that various points of the knee joint are a different size in women and men. 

But whether you believe these recent findings or not, they may be becoming less and less relevant. Long before 2006 when we began to see the rise of gender-designed knees, implants were already being constructed in various sizes to accommodate patients of all different builds. During the time period prior to 2006 we did not see a disproportionate number of women requiring revisions to their knee replacements. In fact, looking specifically at data within the PearlDiver database for 2004 and 2005, two-thirds of patients receiving knee replacements were women, but of the patients requiring revisions to their knee replacement only 56% were women. So is it possible women were doing okay without the gender-specific knees after all?

If this were true, why are we seeing growth in sales spurred by the gender-specific knees? The answer is the consumer. We can’t forget who is ultimately purchasing the product. At the end of the day the person with the implant in her r knee is the one who made the decision. Most of these consumers aren’t scientists, and few will have heard of Kellgren & Lawrence. But consumer behavior dictates that a product tailored towards them will be more attractive.

Moving out of orthopedics for a moment, let’s say, for example, that it is your first day on a new job. You walk into the office and after introductions the boss tells you to go ahead and set up your office. As you look around you see three empty offices, all with a nice window view and the same accessories (desk, chair, etc.). In a moment of uncertainty—you are after all the newbie so it is a little expected—you turn back to your boss with a look of doubt, wondering if it makes a difference which office you set up in. Smiling, your boss informs you that all three offices are free game, but the office on the left was specially designed for men, the office in the middle was designed for women, and the office on the right did not receive any design specialty.  It may seem silly, but which office are you now heading to? 

The average consumer would head to the office designed for his or her respective gender, feeling relieved someone was nice enough to tell them about the special designs rather than letting them go in the wrong office. 

Why would the average consumer behave this way? While the chosen office doesn’t look any different from the others, there is the possibility it will provide a more comfortable space. And in those moments when the consumer finds a pleasing element, he or she will attribute it to the specially tailored office and feel pleased that he or she was a well-informed consumer. Those customer perceptions create customer satisfaction and customer loyalty. 

We must also consider that the success of gender-specific knee implants is a signal customers are looking for products that are specifically tailored to meet their individual needs. It’s a sign these products are not like the McDonald’s Arch Deluxe of the mid-‘90s, simply pushed on a market that wasn’t interested.