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I would like to open discussion up on the simple insole...what are your thoughts?
Insoles to reduce painfuls corns typically have a metatarsal pad with or without a cut out or divot on a flat base.
The overall effect of this insole will position the foot 'up-hill', block the 1st ray from plantarflexing; the long term effects of cuts outs can cause clawing of the toes and the skin to herniate through.
Orthotics would never be prescribed to throw the weight back, nor would the 1st ray be intentionally blocked...why does the rule change for corns/ treatment associated with 'generic podiatry'?
Should they be banned? Where is the research to support them? Should we just use a flat base memory Poron? Should the 'arch support' with forefoot cushioing be rekindled?
Goodaye Nina, hopefully you'll get a reply from someone who knows what they're talking about. My query is why would a met. pad necessarily "block" 1st ray plantarflexion (assuming you're talking about a 2-4 met pad)?
Definitely (but only recently saw the 'light') with you on cut-outs being contra-indicated.
All the best, Mark C
Nina, I agree with your concerns on forefot padding, as it isn't high on the agenda of research. I only use a simple template from p/lite with full poron cushioning if depth is available, or a simple leather cover in its place, and cut out the deflection using a 15 scalpel blade (on the insert, not the foot). This removes the problem of weight distributin backwards. Alternatively you can burr a dint into the insert. P/ite just as a template without deflection will also mould naturally to the foots pressure in time. Sometimes it is the simple things in life that are best.
I make a few insoles, and I have found often less is more. A simple insole really only needs minimal modification to deflect pressure. Ever grabbed a piece of 6mm PPT poron and whacked it under your foot? It feel HUGE. I'm having some great success offloading forefoot using 3-4 mm PPT poron plantar covers with a wing/apeature/cutout (whatever you want to call it). However I always make it part of a whole insole, usually involving some sort of arch padding/countour/cookie which helps to redistribute pressure nicely and help maintain 'normal' foot mechanics.
The overall effect of this insole will position the foot 'up-hill', block the 1st ray from plantarflexing; the long term effects of cuts outs can cause clawing of the toes and the skin to herniate through.
I was thinking along similar lines when we did this simple insole study. Hence we did not use a pad under the forefoot. rather, we just used flat 4mm EVA and cut a hole under the lesion.
The results of our study suggest that additional forefoot padding may not be necessary. I agree about the herniation, you also get increased pressure around the edge of the cut-out. This is reduced if you back fill with lower density material and/ or bevel the perimeter of the cut-out.
Quote:
Originally Posted by Nina Davies
Orthotics would never be prescribed to throw the weight back, nor would the 1st ray be intentionally blocked...why does the rule change for corns/ treatment associated with 'generic podiatry'?
Nina, this is not true; intentionally blocking first ray motion is very useful in the treatment of painful halllux limitus. As for throwing weight backward, forefoot padding will increase the pressure beneath the metatarsal heads and increase dorsiflexion moment acting on the metatarsals, except under the metatarsal(s) with the cut-out. Is this the same as "throwing the weight backward"? What about the external environment? Think about the heel height differential of footwear and also inclinations of the ground that we walk upon. How will this influence the net effect?
A simple insole is a blank canvas. You can put almost anything on there. Forefoot cavity pads are just one possibility.
Personally if i have a forefoot lesion to offload i usually use a heel to pre toes pad with a softer button under the lesion and a dome or similar to elevate the metatarsal somewhat. But like any orthotic you have to match it to the foot. If the patient has a vast amount of inter metatarsal flexability / movement a forefoot cavity won't work, the met head will just drop into the hole. In that patient you need to load the shaft of the metatarsal to reduce pressure under the head. If the patient has a very stiff forefoot with little intermetatarsal movement the shaft raise will be painful and a cavity pad will work much better.
You can also do things with different grades of materials which you can't do with a cast.
I consider simples to occupy a niche somewhere between chairsides / freelans with SCF modifications and perminant casted devices. Far less control than a casted device but more options / better finish / longer lasting than freelans with some felt stuck on!
I think like most things, it's horses for courses in some cases, a simple insole is all that a patient can tolerate & from my experience where I have used them, I get pretty good results & I agree less is definately more when it comes to forefoot padding. Also find ensuring the footwear is suitable for a simple insole increases the chances of success....but you would be surprised the numbers that don't check before issuing
Its not especially evidence based, its rather simple and its written for folks who don't do a lot of / any biomechanics (you won't find any moments or vectors here). But for what its worth i've written quite a bit on simple insoles here http://www.davidmhol.proboards29.com...2 4670&page=1
Might be of use / interest to some. If not then just ignore it.
The first bit is an introduction and some ideas for different mods.
The second section is a method for accuratly templating.
The third section is a discussion of the "forefoot pad" thing which most people think of as a simple insole.
Thank-you very much for posting! You've introduced food for thought. Interesting thoughts on met flexibilty. Thank-you also for the links.
I've been looking into the research on this area, most of it supports moulded insoles to reduce forefoot pressure - the arch takes away the pressure from the forefoot and heel - but perhaps not what the arch was designed for (Journal of Biomechanics: Goske et al 2006; Chen et al 2003). Insoles with softer buttons are also in favour (JAPMA: Caselli et al 1997). No mention of the pesky met pads!
I have to say, I was quite surprised when I had the opportunity to work with an F-scan, that despite using 'fancy biomechanics' nothing had quite the same effect at reducing planar pressures as a piece of cushioned material. An expensive way of finding out - it left me thinking are we trying too hard!?
My belief is simple is better. I am in a position where I have to influence training needs for a large group of podiatrists and also be mindful of resources - time and money. On a large scale this is difficult to control.
In light of research and with the advent of better cushioning materials e.g. memory Poron, If I had to say 'try this first', I would like to say - for mild/ moderate callous use flat bed Poron insole with a medial flare (to avoid the insole putting a line in the arch) and slight reduction of the material underneath (if needed). For the heavy callous use moulded insoles.
I do find it interesting how a biomechanics camp will look more closely at moments of force and the other camp will just get on with it!
In the end it is horses for courses and footwear is key.
The second section is a method for accuratly templating.
YES, you've got to mark these landmarks (lesions especially) with the foot IN the shoe! There are still so many pod's, from 20 yrs of noting, that use those ink pads, where they trace the foot onto a piece of paper, and they wonder why the pt doesn't think much of their insoles. Nice post (with those pictures)
A simple insole was an extension of chairside padding and the introduction of better (user friendly glues) and foam (cellular) materials saw a popular uptake of foot appliances, post World War II. The key centre was Manchester , UK and Franklin Charlesworth became the leading luminary who eventually moved the US and introduced appliance therapy there. If I am right FC may have been an orthotist and chiropodist but the local orthopaedic surgeon Sayle Creer was a prime mover in encouraging orthopaedics in chiropody. Adaptation of appliance therapy came thick and fast from all regions as the 'technology' began to take hold. Needless to say developement was sereptitious. Apart from Charlesworth's book (there were several editions) the only "serious works" to cover manufacture of foot appliances came from Coates. As far as the simple insole (with metatarsal prescriptions etc) the claims for deflection etc had been taken from what was thought to happen with adhesive padding but had no scientific basis whatsoever. As a simple understanding of scientific priniciples will clearly illustrate. By the early eighties pedobaragraphic studies (small) were begining to show chiropodists really knew little about the actual events of their insoles. About the same time podiatric biomechanics with emphasis on balanced shells almost immedicately comdemned the simple insole to the back benches. All of which was rather a pity since there had been a revolurtion in material technology due to the space race. The new materials were 'intellegent' with good elastic memory etc., offering far superior properties to their cellular forebares. Sadly pods ignored this in preference for orthotics defined by anatomical position and a preoccupation with the arch support. Had they concentrated on material science like the footwear industry subsequently did then things might be a little different today.
I wrote this up in 1988 in the Chiropodist.
If you chose the material by its properties, flat laminate layers with double edge tape (non inflammable and can allow separation without destroying original surfaces) and use a serial management approach, simple insoles are ideal for dealing with most simple foot ailments that would benefit from insulation, isobaric and isotactic managment.
The simple insole
Linear Mode
