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“GetAroundKnee” Study Shows No Clinical Difference

A recent study, which was funded by the company that manufactures and sells the “GetAroundKnee” did NOT show enhanced mid-range stability of this “round” knee even though it was compared to a more than 20-year old obsolete “oval” knee implant.

The study authors set out to test the idea that a single radius design would reduce mid-range instability. To test this idea, the authors compared knee kinematics (movement) and stability in three types of knees – a normal knee, a knee implanted with a “single radius” geometry (Stryker Triathlon, the “GetAroundKnee”) and a knee implanted with a much older “distinctly multi-radius geometry” (Stryker Kinemax). The authors stated that “a clear evolution of performance was expected” from the comparison.

Yet, this was not the case, as the authors plainly state:


“We examined the hypothesis that a TKA with a single-radius femoral component would provide a closer match to the kinematics

(knee movement) and limits of laxity (stability) of the natural knee than would a multi-radius design, avoiding mid-range instability.

This hypothesis was not supported; significant differences were not found between the behavior of the two TKAs.”


That’s right.  A study, which seems to be clearly designed and funded to prove the message highlighted by the “GetAroundKnee” campaign, found no significant difference between the movement and stability of the “single radius” and a 20-year old “multi-radius” design. The authors state that the design of the study eliminated variables and “was a powerful way to show up any differences caused by the implants themselves, and significant differences between their stabilities were not found.” In fact, the study actually “suggested that the multi radius design may tense the MCL more than the single radius design in mid-flexion” – which is positive for knee stability and detracted from the authors’ original hypothesis and expectations.