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Hello,

I am an R.N. who attended the Pedorthic program at Temple Univ. in Phily so I have newly learned knowledge of concepts and vocabulary but will need an explanation that I can follow. As I understand it, there appears to be mostly 2 ways to cast people. The first is non weight bearing with the foot positioned in the neutral position and the great toe dorsiflexed to improve contact with the first metatarsal and the ground. The other is partially weight bearing into a foam box where the foot can also be positioned in a type of neutral position that captures the heel and forefoot positioning in the cast itself.

Now a non weight bearing foot does not stay compact when one weight bears so pressure spots from the orthotic can appear as hot spots or tightness as the foot wants to spread or do other motion in mid stance leading to discomfort wearing the orthosis since a non weight bearing casting has captured a position where the foot is not in motion. A orthotic casted from a foam box impression can suffer from a lowered arch which can lead to more pronation but I understand that one can carve the arch back to be higher if you know the client has a significant collapsing arch.

So, why is the non weight bearing casting seem to be the preferred method when midstance is where most people start to have their biomechanical problem and a partial weight bearing cast would seem to be the way to capture and correct that?

Related threads:
Where Should the First Ray be When Casting for Orthoses?
Improving casting
Cast Modifications
Foot casting with vertical calcaneum
Casting techniques
Laser foot scanner or plaster cast?

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I use both, but mostly use non-weightbearing. Its the only way I know to get the osseous segments into the relationship I want them to be in ...

We are working on a trial with the semi weightbearing foam box, and doing some drastic 'manipulation' of foot position that could not be further away from STJ neutral method .... the orthotics do seem to work well at helping people who do not respond to the traditional orthoses ..... only challenge now is to make them more tolerable....watch this space...

At the end of the day, there is NO evidence for better outcomes with either method...

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Craig Payne
Department of Podiatry
La Trobe University
Melbourne, Australia
http://www.latrobe.edu.au/podiatry
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The main issue with fabicating a foot orthoses from a weight bearing cast is that the dimensions of the foot may be bigger than the footwear they are going in to - tissue spread etc. Compliance issues are then created due to it not fitting properly. However the solution to this is to (ideally) include the shoes that the orthoses are going to be worn in or at least a template of the shoes. The lab should do the rest.
The important thing to remember is that what ever method is used you must evaluate the foot impression for accuracy and remember that it is going to fit shoes. Give the lab as much info as possible about both and in my experince both methods work very well.

Phil

Good point about the difficulty of fitting the orthotic into shoes. I reviewed the threads the Adminstrator highlighted and optimal casting does appear to be an ongoing challenge. Thanks for your input.

I tend to think that its not how you capture the image so much as the shape of orthoses you end up with that really counts....and you'll get better at whatever you do as long as you consistently do the same method long enough to get good at it, and pay attention to detail, and diagnose your pt's problems correctly and change the things that you can change that will help them. I have done loads of weight bearing direct molding imprints, a heap of vacuum casting on the foot, some impression boxes and mostly Langer type casting....they all work if you end up with the right shape device for the problem and foot. Ar the moment I tend to think I have better control over what the foot is doing when taking a non wb cast...and this gives better control over the shape I end up with....does not make that method better for any one else though.
regards Phill Carter

I personally use the foot alignment system ( Neil Smith ) which I think Craig Payne did a study on so I'm very interested to see he doesn't use this method.This is a standing cast where you correct the r/foot and then align the forefoot. I find these orthoses cause less heel irritation and I can see and manipulate the foot into the exact position. I don't know if I just find it easier to get the patients neutral position, but I do find that I don't have to end up making extra additions to the orthoses.

I searched FAS and Neil Smith and read about his technique. Thank you for posting about it. Very interesting and seems abit closer to the filling the question I constantly ask, How can one solve a problem that occurs during motion while a person is standing, sitting, or lying still?

Because you are tied to use the lab that makes the FAS.

__________________
Craig Payne
Department of Podiatry
La Trobe University
Melbourne, Australia
http://www.latrobe.edu.au/podiatry
__________________________________________________ ___________________________________
God put me on this earth to accomplish a certain number of things - right now I am so far behind, I will never die.
The views expressed above are those of the author and not that of La Trobe University
This is where I am, where are you?

Hello to everyone on the mail base.

I'm thrilled that the Foot Alignment System (FAS) has been mentioned on the mail base. The question that jerseynurse asked,"why to cast Non-Weight bearing?", is exactly the question I asked myself 23 yrs ago.

When I was first taught how to make orthotics nearly 25 yrs ago, it was a weird concept to grasp. The negative casts weren't balanced, there were no modifications done to the positive cast and the materials we used were subortholene, EVA,s (called something else),cork, vinyls and I can't remember if Poron was in there, but there was some materials used to pad the jobs.

After a couple of years making the Orthotics this way, my employer went to the USA to visit the labs, PAL and Langer. On his return he showed me about balancing and modifying the casts, showing me pictures, which was a totally different paradigm to grasp. Being confused about what shape I had to achieve, I figured the only way to get it right was to have my feet cast, make the orthotic and practice on myself.

The one thing that stood out when trying all the jobs made from the different modifications was, the amount of variables there were. eg:Where to balance to, How much lateral and heel plaster expansion, arch height and shape, width, length etc..., with all of these changes having an effect on how the job felt and how my foot moved when walking.

At the time the neutral position was the norm, so it dawned on me,"why not align and cast the foot WB". The first cast I took was with Oasis, which is used in flower arranging. It had a firmer density than the impression boxes used today, so I wet it to make it softer to take a mould. The orthotic I made was very comfortable, but didn't move my foot very much or change the way it moved when I walked, basically it just kept my foot in an uncorrected WB position . I experimented with wedges, foams, plasticine and even plaster soaked in sponge, which I got myself stuck on one day whilst trying to take a mould of my body. But that's another story!

Anyway... After years of making orthotics and trying invent something to take a corrective WB cast, I decided to study and do Podiatry as a mature age student. I had a lot of questions to ask about orthotics and found everyone had different opinions as to which way worked and was best, so I left before finishing, which I still regret. Would've been best to learn what was there and try to improve on it. Just like Craig Payne, Kevin Kirby, Richard Blake, the list is endless, but you get what I mean. Nothing beats a good education.

In about 1995 I had an idea to put a length of vinyl under my heel and pull up on it to tilt the calcaneus. Without my muscles working to tilt my heel, I could hold it at whatever angle I wanted. (inversion or eversion)
To take a cast, I made a foam template, put the vinyl under the foam wraped plaster bandage around my foot, stood on the foam and held my heel in a neutral position. The orthotic felt very comfortable, but this time it changed the position of my foot, not as much as it was being held in when I took the cast, but enough to further investigate.

To cut a long story short. I had the mechanisms designed and made, had the FAS petty patented and researched by Craig Payne at the La Trobe uni, with very positive results published in the AJPM vol.35 No3 2001. There was also another research study done on control and comfort with FAS orthotics compaired to Non-WB, with another great outcome but the results weren't published.

The FAS has changed a lot from the first model but the principal is the same. Bacically, the person stands onto foam foot plates that have been pre-set to capture the natural angle and base of gait and the angle and height of the heel. This is done because the shape, height, and angle of the shoe will have an effect on what forces are needed on the foot to align it.

Plaster is placed onto the feet and the Rearfoot is corrected using the Rearfoot Alignment Curves. (You can place the heel into whatever position you want) The forefoot is then maximally pronated or supinated. I also have a new mechanism to raise the MLA, if no heel correction is needed you can move the foot by raising the arch.

There are many different things that can be done using the FAS, as the feet are corrected WB. A lot more research needs to be done though.

I would be very happy for any type of research to be done with orthotics made from the FAS. Would be interesting results because of the good repeatability of the moulds.

http://www.apodc.com.au/AJPM/informa...ewed_paper.pdf

I would also be interested for the FAS to be used, without being tied to the lab.

Cheers,

Neil Smith