casting

[paulm]

Hi all

had question from prescriber......my opinion of crush boxes
to set the ball rolling....again just a couple of my views.....
crush box = loss of forefoot to rearfoot alignment..there again i suppose you could always attempt to re-create a forefoot/rearfoot alignment by not applying to much pressure when placeing foot into crush box
crush box = loss of true foot arch definition both medial and lateral, oh you can manually plantarflex the hallux to create a high medial arch...or attempt to re-create a valgus forefoot alignment or plantarflexed 1st ray..but then arn't crush boxes supposed to make cast taking easier ?.....
we did a test sometime ago nothing major as we could not afford it just a few pairs of devices, slipper/3d scan vs crush box....same device/materials made both ways...patient compliance/wearability = slipper/3d scan better.....the crush box devices worked but according to my little test the patients prefered the orthotics from the non-weightbearing sub neut position slipper/3d scan.....
I will stop here as there are other points but then we may not get a debate

regards
Paul

[Admin]

Hi Paul,

Crush-boxes - don't like em!

Using a crush-box it is impossible to position the foot in the same way that you can with a cast.

Lets hear it for casting! ;D ;D ;D

[paulm]

hi David
it is impossible to position the foot in the same way that you can with a cast.

i couldn't agree more but when someone tells you its quicker less messy and produces the goods you can understand why some people prefer them. I believe orthotists use them within the NHS, my understanding they rarely cast, thats maybe why a lot of orthotics sit in the cupboard which have been supplied on the NHS
Just my thoughts

regards
Paul

[Admin]

Hi Paul,
This stems from a lack of skills in casting - nothing else. Its why the crush-boxes came into being I think.

Casting (as those who have attended any practical biomech Courses where I have lectured, need not be slow or messy.

A clinician lacking skill in casting will certainly be slow and messy ;D.

Paul, I know you can cast - for others I put together a tutorial which anyone can access. Linda, who is doing the casting on the tutorial, was actually doing her first ever casts when the pics were taken.
You can find the tutorial on www.chilternmodial.co.uk.
Its totally free and you don't need to register.

Anyone want to defend crush-boxes, or say why they use them?

Regards,

[TimVS]

Casting - piece of cake ;D

[robertisaacs]

Anyone want to defend crush-boxes, or say why they use them?

Happy to help.

Just to be different and to stimulate debate i'd like to fly the flag for impression boxes.

1. Casting, Piece of cake. Agreed. Foam casting, QuickER, easyER and cleanER. Also much easier to do intrinsic modifications, FFO's, Neuros etc.

2. There have been some studies which showed Foam box casting to be more repeatable (which i know is not the same as reliable) than POP. McLay et al was one, the others escape me for now. But they are out there.

3.The study by VL Houston et al on Changes in Male Foot Shape and Size with Weightbearing showed a significant degree of variation in foot shape in WB. It also showed that 75% of this change takes place with only 25% loading. Therefore a semi WB cast with approx 25% weight gives a far more accurate impression of the WB shape of the foot than a non WB. A similar effect can be acheived by cast correction but why guess at it when you can get the actual shape?

For an EG take an egg cup , an egg and a lego brick.
The heel in NWB (before cast correction) is basically round. Therefore the heel cup is also round. You can put an egg in an egg cup ant any angle.
The heel in WB is much flatter with the Calc tubercles providing the actual rotational moments. Put the lego brick in the egg cup, its still able to adopt a number of positions.
Now stick some blue tak in the egg cup in the bottom and flatten it so you have a square base. Now put the lego brick in it and try to rotate it. Much harder.

There are other issues but thats enough to talk about for now.

I know many people who use both POP and Foam casting to great effect. I use both, depending on what i am trying to acheive. But there ARE significant benifits to foam box other than conveniance. A lot of it is down to technique for both modalities.

Regards
Robert Isaacs

[robertisaacs]

[glow=red,2,300]I believe orthotists use them within the NHS, my understanding they rarely cast, thats maybe why a lot of orthotics sit in the cupboard which have been supplied on the NHS[/glow]

You really should'nt make a generalisation like this without any data backing it up. I work for the NHS. I take between 30 and 50 pairs of casted insoles per month (approx the same simples). I am one of 2.5 WTE in biomechanics for our department.

The amount which come back after a year or so worn to death is testement to the fact that most of them don't just" sit in a cupboard".

Respectfully
Robert Isaacs

[dtt]

Hi Robert

You really should'nt make a generalisation like this without any data backing it up.

Yep bloody irritating when that happens isn't it ??

Can I say it is a genuine pleasure to see you posting on this site.

I have followed several of your posts in other places and was impressed not only by your biomx knowledge but your past stance in the fight for the patient /profession within the NHS.

I look forward to learning from your posts ( along with others) in due course

Again just my thoughts

Be Lucky
Cheers
Derek

[TimVS]

Then there's the study at laTrobe which showed OTC orthoses to be just as effective as casted, so then does it really matter which way we cast.......

I used foam boxes when I was first starting out as I was too much of a girl's blouse to use plaster, but then David put me straight.
I prefer NWB casting personally as I get a better view of the foot, and can compare the finished cast with the foot before me, etc. I thought that WB casting in a box has the risk of introducing a supination moment as the foam pushes the forefoot up, but I can't produce any research to back that up.
Clinically I'm not convinced it makes a huge difference, unless anyone can positively prove it either way by research, etc.

So long as it works.

[paulm]

Hi Robert

like Derek, good to see you posting on here, point taken about the generalisation.....

I see patients who have been supplied 1/2/3/4 + pairs or single orthotics which they do not wear, most say they are uncomfortable but there may well be shoe related issues....
I always ask what technique was used ie cast, crush box, drawing around foot.....and was it done by the orthotist or like yourself a podiatrist (they usually know).....in my area its usually the orthotist, usually from a crush box or the drawing technique.....

could i pick up this thread when i get back from my busmans holliday

regards
Paul

[robertisaacs]

Thanks for the kind words guys. I'm looking forward to having another group with which to chew the fat.

Don't sweat it with the generalisation thing. We've all done it. I sometimes look back on other posts i've done when in a foul mood and shudder at the dross i've written!

Then there's the study at laTrobe which showed OTC orthoses to be just as effective as casted, so then does it really matter which way we cast.......

Thats another thread. A good one too if you fancy starting it! In brief my view on that study is that it was severely limited by its design. It appeared to be based on a single orthotic prescription (a STJN semi rigid shell) for a condition (planter fascitis).

There are several problems with drawing a definate conclusion from that study. One is that for me PF is a symptom not a pathology. With many different causes. As such treating them all the same way is not a fair comparison to truly bespoke orthotics.

It would be akin to assessing 100 patients who attend a gp with the diagnosis of "headache" and treating half with propanalol (a beta blocker effective at lowering bp and preventing some types of migraine) and the other half with a regime of diet and exercise. One might find a similar level of effectiveness. However a good assessment will show which patients would benifit more from propanalol so the true figures might be different.

[robertisaacs]

I prefer NWB casting personally as I get a better view of the foot, and can compare the finished cast with the foot before me, etc. I thought that WB casting in a box has the risk of introducing a supination moment as the foam pushes the forefoot up, but I can't produce any research to back that up.
Clinically I'm not convinced it makes a huge difference, unless anyone can positively prove it either way by research, etc.

There are certainly enough people who still consider POP to be the "gold standard".

You are quite correct about the supination moment occasioned by pushing the foot into the foam. One of the common mistakes i see from people useing foam for the first few times is a massive lateral arch and i have seen many of these come back with problems. You have to incorperate this into your technique.

It comes back to technique. Its possible to screw up Foam just as it is possible to screw up POP. POP has the advantage that you have time to position the foot however you want it and that it is easier to manipulate the foot into the desired position. Foam has the advantage that you have a reference point (a fixed plane, ie the ground) and its easier to modify once the imprint / cast has been made.

One of the reasons i favour Foam is that i do a LOT of modifications after casting. This is easier and faster with foam.

I think they are significantly different, but i would'nt wish to call either "better". Some people like 15 blades, others prefer size 11. Are they the same? No. Is one better? Depends.

I defy anyone to prefer pop to foam on a screaming and fighting mad 2 year old or a high functioning autistic who has decided he's not impressed. I've also never figured out a way to do a smafo or a UCBL with foam!

And i am afraid there are good, indifferent and bad orthotists just as with pods and FHPs. I tend to blame it on the wrong prescription rather than the wrong technique.

Regards
Robert Isaacs

[TimVS]

Thats another thread. A good one too if you fancy starting it! In brief my view on that study is that it was severely limited by its design. It appeared to be based on a single orthotic prescription (a STJN semi rigid shell) for a condition (planter fascitis).

There are several problems with drawing a definate conclusion from that study. One is that for me PF is a symptom not a pathology. With many different causes. As such treating them all the same way is not a fair comparison to truly bespoke orthotics.

It would be akin to assessing 100 patients who attend a gp with the diagnosis of "headache" and treating half with propanalol (a beta blocker effective at lowering bp and preventing some types of migraine) and the other half with a regime of diet and exercise. One might find a similar level of effectiveness. However a good assessment will show which patients would benifit more from propanalol so the true figures might be different.



[/quote]

Hmm. That'll teach me to read the whole thing in future, not just the abstract

Good point about foam boxes over POP for 'difficult' patients. Never thought of that. I've not casted below age 5 yet, but I've often wondered how that would work with the younger child.

Can't say I've ever modified a cast, except for popping the 4th and 5th back out afterwards. Do you make your own orthoses ? What modifications do you most commonly do ?

Cheers,

Tim

[dtt]

Hi Robert

comes back to technique. Its possible to screw up Foam just as it is possible to screw up POP. POP has the advantage that you have time to position the foot however you want it and that it is easier to manipulate the foot into the desired position

Can you describe your technique in taking a foam impression ??

I have always found a problem getting a difficult patient ( not as difficult as you see in the NHS) into the foam in the correct position. Any attempts to rectify usually resulted destroying any accurate mould and in a new box and further attempt.

Probably me being ham fisted??

Cheers
Derek

[robertisaacs]

Can't say I've ever modified a cast, except for popping the 4th and 5th back out afterwards. Do you make your own orthoses ? What modifications do you most commonly do ?

Yep i'm lucky enough to have my own lab.

I'd say i modify better than half of my casts at the foam stage and a few at the plaster stage. Mods include (but not limited to)

Flattening the distil end at medial / lateral extremities. Saves thos little pinched in bits at the front of the insole. Usually done by the lab as part of cast "correction" (hate that phrase)

Intrinsic FF posting / balancing

FFO mods

PF 1st ray / j type

Increase medial arch (rarely use)

Increase Lateral arch (even rarer)

FF Varus extension

FF valgus extention

Neuro mods

STDC (soft tissue deviation compensations) / cavities / buttons

mortons extensions / reverse mortons extentions. I know you can do these on the shell it'self but i prefer to do them on the cast. More accurate.

Kirby Skive

Blake inverted

Planter fascial groove

Medial / lateral flare if i'm using a rigid shell (which i don't do very often)

A lot of these will be done at a lab as a part of the prescription and there are more than a few mods available after moulding which don't come under the catagory of cast modifications. However thats most of them i think.

Regards
Robert