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I read it on the Internet/saw it on TV

What about the "Get-Around Knee" from Stryker?

Stryker recently started a brilliant advertising campaign for one of their total knee implants. The advertisements focus on the "fact" that "round is better". These advertisements feature bicycles with oval tires, oval shaped bowling balls, and other normally round items replaced with ovals. Brilliant marketing! Unfortunately, the advertisements are neither completely true nor honest.

Yes, round is better, if you're a basketball or a tire for an automobile. However, the natural, or God given knee is not round. ("Natural" is also a brand name for a different company's implant, but for the purposes of this discussion I will refer to "natural" as the knee with which we were all born.) It requires only common sense to understand that the knee implant that more closely mimics the natural knee is likely to feel more normal. Early knee replacement designs tended to be more rounded than most available today.

I have to introduce a bit of technical information to continue. If one looks at the end of the femur (thigh bone) from the end, there are two knuckle shaped portions separated by a gap where one finds the cruciate ligaments. The fancy medical term for "knuckle" is "condyle". Looking now from the side, the condyles, at the front of the knee, have to meet up with the mostly flat "top" of the knee. The radius of the curve on a natural knee varies from the start (in front) to the back. Further the center of rotation also varies in position. In the natural knee, the radius decreases, so that as one slides over the condyle from the front to the back, the curve becomes tighter. All knee designs, including the Get-Around knee" have some variation in the radius, if to do nothing else than transition fromn the mostly flat top surface to the mostly rounded end and back of the knee. Stryker's claim that their knee is round has to do with the total arc where the radius and the center of rotation are both constant is large. Unfortunately for Stryker, if  "round" really is better, then the "Get-Around knee" is not the most rounded on the market.

The brand name for the "Get-Around knee" is the Triathelon knee. While the advertising program is new, the knee itself is not. The Triathelon knee has been around for at least 15 years unchanged. This is however, at least the second "new" adversising campaign for this knee implant. A proven track record over 15 or more years is something about which a manufacturer should be proud. However, this is not Stryker's claim in their ads to the public.  

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This page represents the opinion of Dr. Adam I. Harris