Simple Insoles, What are they.Simple insoles, for those who are not familiar with them, are insoles made by attaching components to a flat base (as opposed to casted). They have a long and not always noble history, particularly in the NHS. Like any treatment they are effective if used appropriately and ineffective if used inappropriately.
As Kevin Kirby has often observed, anything that exerts a force on the foot will alter moments around an axis. As such it is, perhaps, erroneous to divide insoles into “functional” and “simple” categories. A simple insole will affect function and, as David keeps pointing out, casted insoles can be simple. However we will stick with the existing terminology for clarity’s sake.
The “classical” simple insole which many people will have come into contact with via the NHS and surgical appliance departments is the ubiquitous “arch support” (shudders). I have seen many of these issued and they are frequently too thin, in the wrong place or made to a standard shape and wrong for the shoes. Some orthotists are also fond of the “pre met raise”. Like the arch support this is not often not constructed correctly.
Let us leave these older specimens in the wardrobe (where most of them end up
) for a second and reconsider simple insoles as they CAN be.
With a simple insole the only limit is the imagination of the prescriber. Unlike a cast where you are limited to the shape you can hold the foot in and the modifications you can make to the positive cast, with a simple you can do well nigh anything. What follows is just a few ideas i have found useful…
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Rearfoot mods
Heels cups.
Can be done up to about 6mm on a simple (material limitations prevent anything much higher.)
Heel cushions
Can be done in any depth (that the shoe will take) and in a variety of materials.
Heel spur cutouts
Support the heel around the margins and leave the centre of the heel with something soft under it. Anyone who has had heel pain will probably tell you that whilst it may have a functional cause you don’t want to be walking on anything hard with it!
Heel postings / wedges
Can be done to any degree and at any angle and extended as far up the foot as desired. A pretty decent analogue of a medial heel / mosi wedge can also be achieved...
Heel Raises
Obviously
Midfoot Mods
Valgus pads.
Should be the same shape and size as the arch of that particular patients foot (i.e. bespoke and analogue, not selected from a series of sizes. They should be the depth specified by the clinician not a standard thickness. The choice of material should also be dictated by the needs of the foot, you could use anything from almost solid to the most compressible latex foam. You can even get clever with laminates for a variety of effects on timing if you are so minded...
If the foot requires a planterflexed 1st ray this can also be incorporated into the valgus pad (so the whole ray is planterflexed rather than just dropping the met head).
Sagital plane rockers
Can be applied to move the sagital pivot point proximally (delays forefoot loading). Can be used with a soft rocker on the top or a hard rocker under the insole. (punk rockers ceased to be available in the 80s although a few specimins are still in circulation ;D.)
Pre met domes / bars
Can be used to delay forefoot loading and can be useful for neuromas. Pre met bars do not serve liquor! Sorry.
Forefoot mods
1st met head cut-outs / reverse mortons extensions
Can be made in any depth with any materials. Good for planterflexing the 1st ray in Functional hallux limitus.
Mortons extensions
If you want to send the 1st met the other way… Also useful if the 1st met has become non weight bearing due to being dorsiflexed.
Cushioning
Never underestimate the effectiveness of putting something squishy under a sore bit. Its simple
Cluffy wedge
Does what it says on the tin. If you are into that sort of thing.
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Keep in mind that all of these modifications can be done with a variety of materials with a variety of compressibility’s / memory / loading speed in any thickness required. The prescription should be defined by what the patient needs not what materials are on the shelf. If the patient needs a valgus pad with a dent for a prominant navicular, with a plasterzote top layer to conform to the arch and a poron base layer to give support, then that is what they should get (rather than "an arch support")
Many of these modifications are not commonly used due to the perceived difficulty of accurate templating. If i had a quid for every time i had heard that simples are made by drawing around the foot
... There is a templating method which does allow for the required degree of accuracy, more on that later if people are interested.
When should simple insoles be used?
Basically the simple insole is useful if you wish to make gross changes to foot range or function. If you need to meet the foot where it is and control its motion more accurately, casted is the way to go. For example a tibialis posterior insertion pain or tendon tear should be treated with a cast because any movement can be destructive. A sub talar joint which is painful at end range due to sinus tarsi compression or deltoid ligament sprain can be treated quite nicely just by holding the joint away from that end range.
Some patients (you know the type) cannot tolerate a casted device, due to bony prominences in the MLA, the volume of force being pushed through the navicular or poor soft tissue viability in the MLA. These might suit a simple insole better because you can make the arch support higher but softer to achieve a similar degree of control or a lower pad to protect the joint end ranges.
Some patients do not NEED a casted device! If all which is wrong is a loss of fibro fatty padding under the forefoot leading to corns / callus, a fibrous corn, or bruising under the heel because they are working long hours on hard floors they don’t need a casted rear foot just to get the cavity pad in the forefoot!
Essentially Simple insoles offer a level of treatment somewhere between a modified freelan and a bespoke cast. Properly made, to specific specifications with a nice leather cover they look a lot more professional than a freelon or piece of regen with some semi compressed pad stuck to it. They will last a good deal longer as well. However they do not challenge the patients budget quite so much as a casted device (if it is not needful).
That’ll do for starters. More to follow if anyone is finding this at all useful or interesting…
Questions / feedback welcome.
Regards
Robert