Re: Tennis anyone? First of all, no knee is better an any other on the market. The rest is all marketing hype! But to get to the tennis, the most I can do is tell you the theory behind it. The principle reason why surgeons specifically advise against singles tennis is because of the short stops, sudden changes of direction and speed and immense torque applied within the joint. It's not the device itself that can't cope with those stresses but the bone/cement interface which by comparison is inherently weak and shear force is the biggest danger to that interface. If you would check out this article (I know it's referring to hips but the principle of cement security described there is still germane) and see how important the bone/cement interface is. In a knee, the cement layer is not as bulky or contained as it is in a hip. The cement is layered onto the femur and the tibia and the implants, also layered with cement, placed on top and the cement pressurized by hammering the implants home. But the amount and depth of embedding in the bone is necessarily going to be fairly superficial. This places the knee at a greater risk of loosening under those stresses than it would in a hip replacement. The more so because the shear forces involved are specifically driven through the knee joint. Something more to consider is that loosening doesn't just happen overnight. It can take months, maybe even years to develop. It can range from micro-movement to actual wobbling in the bone loose; though somewhere in between is the most common. And it can manifest as anything from just a mild ache to pretty bad. It all depends on how much loosening takes place. All of which is, for the most part, theoretical. In actual fact, there is contrary evidence that sports actually enhance the security of knee replacements, a study that is infrequently referred to by surgeons because, in my humble opinion, they are too litigation conscious to actually advocate such a thing! Knee Replacements Not Harmed by Most Sports In the long run, it's your knee, your life and your choice.