How shoe construction

Welcome to the first of a series of articles from ShoeMed Limited, your one stop footwear resource for you and your patients.

Through our Business Referral Scheme, we found there was a real need for educating and training podiatrists in footwear and including footwear as part of their patients’ treatment plan. About the author, Lisa Preston is a qualified Australian certified Pedorthist working with ShoeMed to help develop training resources for anybody with an interest in foot and ankle health, who wish to learn more about therapeutic footwear, fitting and modifications to shoes. Following our webinar in November 2022, this article further discusses shoe construction and how this can affect its fit. As Podiatrists, you are all aware of the many varying foot deformities and chronic health conditions which can affect the lower limbs; each condition posing a different challenge to finding the right footwear. How often are you asked for footwear advice? Could you confidently offer the right advice to support your treatment? Hopefully after you have read this short article you will have a little bit more knowledge and confidence to be able to guide your patients correctly. A starting point would always be an inspection of their current footwear.

Check the outsole wear – a useful inspection to help diagnosing biomechanical issues.

Check the inside wear – a top tip is to insert your hands inside your patients’ current shoes and have a good feel around which will give you information on the construction and the fit.

o What is the lining made of? o Are there any wear patterns/holes at the end of the shoes? • If the toes have been touching the ends of the shoes, the shoes are too short.

o Is there any excessive heel wear? o Are there any removable insoles? • What lies beneath these insoles?

Does your patient have diabetes?

o In this case you would be checking for sharp objects that could cause harm and damage to the foot.

Are there any seams?

o These could be sitting over hot spots which could result in corns.

Having checked the shoes, you now have a great deal of information, coupled with your biomechanical assessment you can now start the shoe conversation!

Materials & construction

Materials used in the construction of footwear do affect how a shoe fits. From the outside upper material to the lining used and the insoles fitted, all of this has an instant effect on how a shoe feels when tried on, but also a longer-term effect on how a shoe fits after some time of use.

As an example, an all leather, seam free upper on a shoe will be more inclined to form the shape of the foot, stretching in width as necessary. A synthetic lined upper with lots of decorative seams will not stretch as easily. However, a shoe upper made on a 3D knitting machine, a technique commonly used in running shoes is being used more and more by the comfort/lifestyle footwear sector, or with stretch uppers, either leather or manmade, will ease over the foot instantly giving comfort for bunions and hammer toes.

Many brands now use this upper technology, such as X sensible, Joya, Fidelio, DB Shoes and more. It is also important to note that this can therefore sometimes provide a vegan shoe choice. Outsoles Leather, of course was the traditional choice of soling material, but is not often used now due to advances in man-made materials offering more comfort and durability. Some examples of soling materials used are:

Direct polyurethane (PU) injection moulded soles

o durable with correct care, cushioning, and waterproof.

Ethylene vinyl acetate (EVA)

o shock absorbing o available in different densities and often used in sports shoes. o used in therapeutic footwear also as it is easily adapted, lighter and available in sheet form. o less durable and not as cushioning as PU. o It can be used in cement (glued) construction and commonly used in insole and orthoses manufacturing.

Rubber soles

o very hard wearing, good grip but can be heavier.

Polyvinyl chloride (PVC)

o hard wearing, stronger, cheaper but do not offer as good a grip as other materials. Important to note that they are not biodegradable and more expensive to recycle.

Outsole heel shape

Let us start from the back of a shoe. Look at the width of the outsole at the heel. The wider the heel, the more stability. Many footwear manufacturers ‘roll’ the outsole of the heels and this will only be a problem if your patient requires rearfoot stability. When looking at a shoe, are the edges rounded or the heel flared?

The wider the heel, the more stability. You do not need to change brands – there is no doubt an option in the same brand but with a different outsole heel shape.

An example of this would be if you have a patient with excessive pronation. So, choosing a shoe with a heel such as the one shown above, can increase support for them and help to support your orthotic prescription.

Heel counters and heel fitting

At the heel area, a shoe to help people with foot problems should have a firm heel counter. This is a piece of thermoplastic material which is inserted between the lining and the upper and then lasted to form the shape of the heel.

A good heel counter should be nice and firm when new and should gradually mould to the shape of the wearers’ heel as they warm up. Your orthosis should fit neatly and securely between the heel counters and not bulge them out, as this will encourage heel slippage (every shoe fitter’s nightmare!). To keep the integrity of the heel counters the patient should always loosen the laces and use a shoehorn.

Finally, how wide does the heel look at the back, as if your patient has a wide forefoot but a narrow heel, then this heel fitting will need to be narrow. How deep are the shoes under the lateral malleoli? This is important if your patient has a history, for example, of an ulcer in this area, so the topline needs to sit well clear of the lateral malleoli. Not an impossible problem however, as a good shoe modifier can roll this topline down a little to help.

Most shoes will have a leather lining on the inside of the heel, often this is a suede finish for a better grip. Around the topline of the heel, there should be padding, and some have more than others, for example a sports style shoe will generally have a more padded topline and ‘peaks’.

Shoe linings

Even if the heels are leather lined, the whole shoe may not be leather lined. A good tip is to put your hand inside a shoe and have a good feel around if you are unsure. A full leather lined, all leather upper is perceived to stretch more readily to the shape of the foot. However, with advancing technology, many man-made materials are great for moisture wicking, insulation and conforming to the foot.

A handy tip to remember is that a GoreTex® lined shoe can fit a little snugger, as the lining wraps all around the inside of the shoe. If a shoe states ‘leather lined’ check which kind of leather – pigskin is a commonly used lining in a less expensive shoe.

Shoe fastenings – laces & straps

If the shoe is a full lace up style, then there will be a tongue which is either padded or not padded. Padding is useful to cushion the top of the foot and to assist in preventing the foot sliding forwards. Handy tip – an experienced shoe fitter will have self-adhesive tongue pads to use if necessary during the fitting.

Zips, whilst often included for fashion reasons in recent times alongside laces, are in fact very useful for removing shoes easily

The vamp

The vamp is the front portion of the shoe which covers the forefoot area, which as we know is the source of many problems with shoe fitting. Look closely at the depth of shoes. Shoes with a higher vamp are sometimes known as ‘extra depth’ so they give more room for bunions and retracted toes and also, of course, for a full-length orthosis.

Looking down onto the vamp will clearly show the shape of the forefoot area – if your patient has a square shaped forefoot then they will require a shoe with a similar forefoot shape, so if the toe shape is too narrow the shoe simply will not fit comfortably.

Shoes made with lots of pattern and therefore stitching on the vamps may look attractive, but where there is a seam sitting over a deformed joint there will be no stretch, which will potentially cause harm to the patient’s skin.

Removeable insoles/footbeds

Are there removeable insoles/ footbeds in the shoes? These can assist with fitting the shoe if a slight alteration is required.

The way a shoe fastens has a huge impact on fit and function. A court shoe is always fitted too short so that it stays on the foot, as there is nothing holding the shoe onto the foot apart from this snugness. Smart/casual lace ups are thankfully now more acceptable for fashion, so starting with lace ups, always open the laces up fully, if the shoes are new and not been tried on before. Factory lacing is often very tight. If a patient has a wider and fuller in the foot, long lacing opening is essential.

Strap fastenings are useful to replace laces if a person is having difficult doing up laces, and strap fastenings can always be used in replacement of laces as an additional modification to a shoe. A tip also is that a strap fastening which just touches over, will not provide as much support as a strap which fastens through a metal loop then back on itself. For example, if there is a little too much room in the front of the shoe a forefoot liner can be added to make the fitting a little snugger. Or of course, you can design your orthosis to be slightly thicker at the front.

Some shoe brands in the comfort sector now offer two insoles as standard, so the depth fitting can be adjusted. Removeable insoles or footbeds are essential if you are fitting a foot orthosis.

The toes!

Ending at the toes – better constructed shoes have a ‘toe puff’ which again is heat mouldable, to hold the toe area of the vamp off and away from touching the toes and helping the shoe to keep its shape. When trying shoes on, it is not wise to push firmly with fingernails to feel where toes are, as this toe puff can get dented from this. Knowing the basics of footwear design and construction can help you to not only discuss this with your patients but can also give you more confidence for a conversation with footwear brands and representatives about the features, benefits, and points of difference they offer.