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I am confused, I can follow most of the podiatry literature but when it comes to the use of certain biomechanical terms, such as "ankle inversion moments" I find it very confusing. To me it would seem to define those moments that apply an inversion force on the ankle but obviously it doesn't. For example, in the Huerta, Kirby et al article in JAPMA on effects of heel wedging on kinetics and also in the Boot Camp notes it reads that varus wedging decreases ankle inversion moments! I am stopped from comprehending the flow of the articles etc when such a, to me, completely opposite term, is used. Obviously the answer is simple, but by G**, it's hard for a novice to get around, yours truly, mark

 

And Kerryn, I'm working hard boss, it's just I'm so good I have a little spare time between pts!

 

Mark:

You are getting confused about internal vs external moments, which is easy to do. We had a discussion a few months ago on this but I can't recall at this time which thread it was. Maybe someone else can find it for you.

 

Thanks Kevin, don't you sleep mate?, yep I'll go looking, it's just I thought using a say rearfoot medial varus wedge would INCREASE external inversion moments, mark

 

Ahh I get it, as i entered that last post, we want to DECREASE internal inversion moments, give the Tib. Post. mm some assistance, got it, thanks Kevin
.. not friggin' bad, a novice like me puts up a question and in no time at all I get a response from, none other thank the Kevin Kirby, or the Simon Spooner, Eric Fuller etc, not friggin' bad!

 

Would it be, in biomechanical discussions, that it is assumed to be INTERNAL moments, or otherwise 'external' or 'net' are stated?

 

Internal inversion moments = external eversion moments (and vice versa).

Newton's third law: for every action there is an equal and opposite reaction

 

Mark:

In biomechanical studies using inverse dynamics analysis of the foot/leg, it is standard to report moments as internal moments, not external moments. Unfortunately this does create confusion for many since this distinction isn't made clear in all studies or by many lecturers.

Here are our few recent discussions on the subject on Podiatry Arena, including one in which you commented on in my thought experiment on the same subject.

http://www.podiatry-arena.com/podia...&highlight=internal moments, external moments

http://www.podiatry-arena.com/podia...&highlight=internal moments, external moments

 

Yep ok with this concept, thanks Craig, excellent weekend and why I was sitting up front was a hearing impairment and not because I think you're cute!

Yep that was my problem, thanks Prof. Kirby

 

Mark and anyone else looking in,

Just to clarify here's a simplified example



dave