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Kinematically, does the STJ effect distal joints as much / the same / more than the MTJ effect proximal joints?

 

When?


In static stance, equilibrium has been achieved at all the joints, so there would be little kinematic effect from one joint to another. This does point out one of the problems of neutral position theory. In neutral position theory there is an implied assumption that you start in neutral and then compensate for a deformity that is present. However, we should be looking at the position and forces acting on the foot when the pathology occurs and not some ideal position.

Eric

 

thanks Eric, both statically and dynamically, weightbearing, does the relative position of the joints, effect the others. Wasn't thinking pathology wise, just functional anatomically.
If we intervene with external forces at one which results in a change in position of the other (realising a change in net moments does not necessarily result in a change in position / motion) is that going to effect one 'way' more than the other?, mark

 

When the whole foot is on the ground a change in force will most likely affect all joints. You are asking a question with too many variables. As you try to increase force in one location it will reduce in another location (Total force has to equal body weight +/- vertical accelerations that occur with gait.) For some force changes the consequences would be easier to figure out and other locations it would be harder. Shifting the load more medially under the calcaneus is a pretty straight forward center of pressure calculation. What happens at other joints may still have too many variables to figure out what happens at other joints. Increasing the load on one metatarsal would be much more difficult to assess, because it would be harder to figure out where the load decreases.

Too hard. Just make your changes and assess the results.

Eric

 

Agreed. At each instant in time you'd need to take moments about the instantaneous centres of rotation and know the load/ deformation in each of the tissues. Like Eric said- too hard.