05/11/2013    Roy H. Lidtke, DPM

Dr. Lidtke's Remarks (George C. Trachtenberg, MS, DPM)

I am not sure what Dr. Trachtenberg means by "all
the research." All the research is available at
ncbi.nlm.nih.gov/pubmed

I am a clinician and a researcher. As a
researcher, I use the scientific method to
establish a finding at the 95% confidence level
that the finding is true. At Rush University, we
do NIH-sponsored level of research and publish in
journals that have a high impact factor where the
editors and reviewers make sure our methodology
and conclusions are correct.

So, as a researcher, I can tell you that wearing
the Flex OA shoe does decrease the loads on the
medial compartment of the knee around 20%. As a
scientist, I cannot tell you the mechanism of
action as of yet. This is the current area of
research we are working on. As a clinician, I
must decide what treatment is best for each of my
patients individually based on the available
information.

The conservation of energy theorem is probably
not the correct analogy for cell destruction in
osteoarthritis as much of the external energy of
gait is taken up into joint motion and internal
muscular contraction and has not been proven to
be an acceptable biomarker for osteoarthritis.
The external knee adduction moment has been shown
to be a good biomarker for knee OA and is
dependent on the magnitude and orientation of the
ground reaction force vector.

While the magnitude of the ground reaction force
is dependent on the body mass and gravity (not
easily altered), the direction of the vector can
be altered. The observed gait with the Flex OA
shoe demonstrates that the ground reaction force
vector functions closer to the instantaneous
center of rotation of the knee joint thereby
reducing the lever arm that is causing the
greater moment of force to load the medial
compartment of the knee.

Roy H. Lidtke, DPM, Chicago, IL,
Roy.Lidtke@dmu.edu

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