The truth about how orthoses work is we are not 100% sure, we have different models and theories. To answer this question we need to understand patient and treatment goals, is it pain relief, running quicker for longer, or, in a diabetic patient, reducing the risk of ulceration?
Do orthoses work all the time? No.
Do need to wear orthoses all of the time? No.
Orthoses are just like any other type of treatment, it is about getting the correct treatment for that patient. In a way orthoses can be related to physiotherapy (in the context of the patient can attend my clinic and they have not brought the orthoses to the appointment with them) I can have a patient come see to see me who has had physiotherapy, however I do not know what treatment. Is it stretching, a loading program, taping or massage? This information is important and necessary to know before treatment. This is similar to Orthoses, in that the healthcare professional needs to know the material type, prescription, stiffness etc in order to get a complete idea of their treatment.
I hear in my clinic on a weekly basis that patients have been prescribed orthoses in the past in order to correct their alignment which shall reduce pain, the idea that Orthoses can help with this is a myth and not true.
A bit of science now, when we talk about ‘straightening’ people up this is referring to what is known as kinematics. Kinematics is the study of movement and angles, and in simple terms, the visual changes we can see. To have a successful treatment outcome we do not have to change kinematics, however this does not mean that they’re not important.
A second, important consideration is the effect of the orthoses on kinetics. Kinetics is the study of forces acting on an object. Forces (kinetics) can change despite no visible change in movement (kinematics). There are a couple of ways of visualising this; one is to lean against the wall with one hand, now push slightly harder and you’ll see no visual change in the movements within the arm and the wrist, however the force applied to the wall is greater. The other way is to stand on a flat surface, now stand on the edge of a step making sure your heel remains horizontal, your heel position is visually in the same position regardless of if you’re standing on the edge of a step or a flat surface however the forces going through the calf muscle are completely different;
Picture source Ian Griffiths blog on mechanics
The point being that we can have a kinetic effect without changing the kinematics and this can often lead to a positive treatment outcome, the issue we have is how do we measure the kinetics in clinic? If we can’t actually see kinetic changes they can be hard to assess and quantify and challenging to study scientifically. One of the biggest issues we have with the research regards to orthoses is that every person reacts differently to them and there is no way of predicting how one person will react compared to another, to put this into context if you are trying to compare orthoses to drugs and you to put them into a trial you would have to give every different participant in the trial a different dosage of the drug, making the trial flawed from day one.
It is also important to remember the psychological effect orthoses can have and how can we quantify this in research, runners can sometimes feel vulnerable without using the orthoses. It could be argued that we know orthoses are not causing any harm or weakening muscles so if the patient feels they are offering some benefits why remove them?
I still hear from time to time that orthoses weaken the foot and surrounding leg muscles, this is not true. I am yet to find any studies that back this claim up, yet there are many studies showing muscle activity remains the same.
Then there’s also the neuromotor effects orthoses have on the body and this area of research is growing. There was a good paper in the British Journal of medicine showing that orthoses reduced the frequency of falls within an elderly population, but again and how can we measure the neuromotor effects in most standard clinics?
Looking at all this information, you can appreciate that whilst we know orthoses work, the reason why they work we are not sure of and moreover the reason may be different for different people.
In one of my clinics we can use in-shoe pressure analysis and 3D gait analysis to help with orthoses prescription, however not many clinics in the country have access to this type of technology. It is important to know what to do with the data, i.e. treat the patient not the scan, as there is no definition of normal function. It is important to look at the big picture and look at function with and without orthoses, whilst trying to problem solve differences and consider if orthoses are the answer or not.
Coming up in part 3 – which are best custom orthoses or ‘off the shelf’ and how are orthoses prescribed?…