This one has been floating around in the back of my head for a few weeks. I can't make it jump any higher, perhaps someone better at physics than me can help. Eric's thread gave me a prod.
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Lets consider the 1st MPJ as a simple hinge joint, leaving aside (for starters) any irregularities in joint surface.
Internal PF moments from the PF (loads) and the flexor hallucis muscles (less).
External DF moments from the GRF in the digit. In spades again.
What is the relationship / equation for compressive force in the joint itself (X-)
I will stress that I take to physics like a duck to archery, thats why I'm struggling. I just don't have the physics.
This would appear to be one of those where we have to convert rotational force into translational
I started with, If there is equilibrium then IPF / lever arm + EDF / lever arm yields the total translational force X-. But that did'nt seem right because (in this model) without any IPF, EDF will exert no X- force that I could see. But then of course the system would not be in Rotational equilibrium.
Also to make this model anything approximating to clinically useful (or even mildly interesting) I guess we would need to know the lever arm information (where grf is exerted and where tendons insert). Got myself well confused there as well.
Any chance anyone can give me a nudge? I've got a nasty case of mathematicians block.
Thanks
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