Today I wanted to talk about one of the most overlooked and common orthoses in the world – the shoe!
How is a shoe an orthosis? Let’s look at the definition and see if shoe fits;
- An orthosis is a device that is placed upon the body
- Modifies external forces
- Supports, aligns or treats musculoskeletal deformities and assists a person with achieving their activities of daily living
Even if most people don’t realise it, the shoe fits all the orthotic criteria.
A good supportive shoe should:
– Have a thick sole to absorb shock and adequately protect your foot from the elements.
– Have enough room in the toe box to allow your toes to wiggle freely.
-Be deep enough that the section around your heel holds the shoe onto your foot well.
– Made from a material that is stiff enough to provide ankle stability.
– It should also have a sensible pitch that allows the shank to rest in a comfortable position.
– It should be the right size (this is one of the most commonly overlooked features of a shoe.)
Too often I see children wearing the wrong sized footwear. Adults do it too, but because their shoe size is no longer changing it’s less common. Children are constantly growing and to be more economical parents tend to purchase school shoes that are little bit bigger to allow the child to “grow into it”. To an extent this is a good idea; there should not be more than an adult’s thumb width between the child’s foot and the tip of the shoe. When I was nine or so I went shopping for school shoes with my mother. I remember complaining how I only got new shoes four months previously and that this time I wanted to get shoes two sizes bigger. Luckily my mother knew better, and she knew that however annoying it was that she had to keep returning to buy new shoes for me, it was more important that I had adequate support. What she didn’t know is that she was also avoiding a scenario where I was wearing a shoe that had an excessive toe lever and pitch, which would then influence my gait (walking pattern).
The diagram below demonstrates what a toe lever is.
Anatomically it starts at bone called the navicular and finishes at the end of your toes if you are barefoot, or to the end of your shoe, and therefore runs parallel to the sole. The length of this lever will influence how the knee flexes (bends) or extends (straightens). A good way to visualise this is to imagine wearing a big pair of clown shoes. How would you walk around in these? If they were really really big, you would probably have a high-step gait (walking pattern), where you would use a lot of energy to lift each foot up and place it on the ground. Now imagine a slightly smaller clown shoe than the previous scenario, and that you are about to take your first step with your right foot, leaving your left one behind you – you would find you would:
- Have to take a smaller step because the there would be so much shoe material getting in the way of your left leg, preventing you from taking a large/regular step.
- After taking that step with your right leg, your left knee would be extended (straightened) for a really long time, then very suddenly, when you had barely any weight going through your left foot, your knee would flex (bend) dramatically.
Now this scenario is exaggerated and no one is going to send their child to school in clown shoes (I hope not anyway!), but this would still occur on a smaller scale if your child was wearing a shoe that was too big. It is also worth noting other factors would influence this too, including the thickness and density of the shoe’s sole, flexibility of the shoe, among other factors.
Higher and higher
Pitch (also known as heel sole differential (HSD)) is really important for patients who wear AFOs (ankle foot orthoses), patients who have a condition where particular muscles or muscle groups are weakened, or anyone who requires specific parameters to control their shank (lower leg). An able bodied person can wear thongs or ballet flats without too much of an issue (although as an orthotist I wouldn’t recommend wearing them day in day out), however for a person who has limited range of motion at their ankle, or muscle weakness, particular attention must be paid to the pitch (heel sole differential) of the shoe.
When there is a larger pitch (heel sole differential) the shank (lower leg) is more likely to be inclined (lean forward). Studies have shown that the ideal tibial inclination (amount the shank is leaning forward) is around 9 – 11 degrees. Most runners and school shoes provide this naturally.
Running with ideas
There are other factors that influence your heel contact (at the very beginning of a step), your loading response (the shock absorption mechanism your body undergoes when it takes a step) and other events in the gait cycle. These include thickness of the sole, density of the sole, shape of the heel, and flexibility of the shoe, just to name a few. If your orthotist has requested for you to purchase a specific type of shoe it is because they have assessed your biomechanics, range of motion and muscle strength, and have taken into consideration all of the shoe specifications and details that will contribute to your orthotic prescription. Able bodied children and adults don’t need to pay close attention to shoe properties beyond size. Most runners, sports shoes and school shoes compliment natural gait biomechanics.