Adwatch: Knee Replacement

I heard a commercial for a knee replacement implant, which seems odd. It was by Johnny Bench, all about how a new smaller knee replacement is perfect for older women, and to talk to your doctor. I thought knee replacements were based on need. Sounded like a commercial for a new car. "Get rid of that old broken down knee, and get a brand-new 2009 model! Now offering cash back and dealer incentives!" Are we entering a world where people get mechanical replacements for body parts, not because they have to, but because they want to? Seems like cyborg territory.