If our only clinical aim when issuing foot orthoses was to redistribute plantar pressure more effectively (however that is defined) in asymptomatic patients whilst they are at work then I suppose it may be time to get excited about dynamic casting...but as it isn't... I'm not.
I often wonder the same thing. Why do so many studies try to measure the function of foot orthotics with plantar pressures when none of us are trying to change plantar pressures with functional foot orthotics clinically?
I can't get the paper, what do they mean by dynamic casting? Its not what I think it might be is it?
Not sure exactly what they mean, as I can't get the full text either.
I guess whether this sort of negative model production gets ones pecker up will come back to the value one places on kinematics/visual alignment.
The concept of kinetically quantifiable casting is more exciting in my opinion.
Outcome of coefficient of variation???
We don't even know if that is a good thing to reduce.
A plantar pressure could be very high in a particular location.
Patient symptoms could get worse if that high pressure didn't change.
12 is not an unusual sample size in the biomechanics literature. If you are doing a between groups comparison you need a bigger sample size. If you are doing a within groups/subject comparison (ie each subject acts as their own control)(which is what this study did), you can get away with a smaller sample size, but 12 would be close to the lower end of what is acceptable. Need to look closer at the subject subject responses - if the response was systematic, then I have no problem with 12.
The "healthy" bit could be problematic, as there is no indication that the subjects even needed foot orthoses..... ie I hope they report something like the FPI, so we can make a judgement on the foot types.
I have not had a chance to look at the full paper yet.
There is a system capable of obtaining dynamic digital scans of the foot. I can't remember the name and I'm about to board a plane. Phil wells will tell you what it's called.
Speaking generally, if you are going to use 'healthy' or 'asymptomatic' subjects then you need to know that if they had symptoms then in a typical clinical situation they would have been given foot orthoses if they had symptoms. One way to do that would be to a certain FPI as part of the inclusion criteria. For eg if the FPI was above, say, 7, then you could assume that if they had symptoms then they probably would get foot orthoses in a typical clinical situation.
There is a 3D volumetric scanner from Lion Systems in Luxembourg- uses scattered light at (I believe) 30fps.
So the question would be- what would you actually use it for?
Do you choose a particular frame to base your orthosis on? Would you combine information from multiple images? What information would you use?
Depends on what you do at work, but if these healthy volunteers had desk based jobs then it would occur to me that a static, semi weight bearing plantar capture of the foot may well be preferable if they are looking at plantar pressure redistribution
In Denmark we learn to take the functional feetprint by using a thin evazote-sole for 14 days and then examine the pressure-marks in that sole, and use it as a guide for the final product.
I don't know if this is even considered a "dynamic" way of doing it?
Like I said, probably very comfortable because it's only going to attempt to arrest motion at the end of range of the motion envelope; its not attempting to change anything in terms of kinematics.
My experience from seeing quite a few approaches from around the world is that the aim of practitioners 'prescribing' orthoses is incredibly variable. Having said that, there must be some apparent benefit or they wouldn't keep making them (or so I would hope).
Pressure redistribution is certainly one aim that is recurrent...
The only reason that you would choose coefficient of variation over peak plantar pressure or even mean plantar pressure was that those other measures were not significant.
I don't see how this variable proves that pressure "redistribution" is better.
I would hope the casting method would reduce peak plantar pressure.
Was that even reported?
If it didn't reduce peak pressure better than a foam box then it is worse than a foam box because of the degree of dificulty
Eric
Agreed on what they aim. I'm not convinced that's what they will get though.
I wonder. If you had someone whose COP is medial of the midline, would that mean the medial area on the heel and forefoot would be more squashed and give you a lateral wedge?