Following on from the popularity of the first 2 parts in this toe-related trilogy (‘toelogy’?!), podiatrist Nick Knight is back with the final instalment! Having covered what orthoses are and what they do it’s on the tricky question of how they are prescribed…
So how do we prescribe orthoses?..
There are many theories, however there are no definitive guidelines, life would be so much easier if people could come into clinic and I say you need this set of orthoses at this dosage, unfortunately life isn’t that simple. There are certain prescription types that we can use to off load certain structures, for example if we want to off load Tibiais posterior (muscle that runs along the medial (inside) aspect of the ankle) we can use a varus (medial) posting, however it is important to make sure the muscles on the lateral aspect of the ankle can tolerate the increased force going through them now, as the force going through the body is a constant so we can off load one area but will increase load elsewhere.
In my opinion there are a few crucial items we need to consider when prescribing orthoses:-
- Material – Need to make sure the material is suitable for the task.
- Weight – This is often over looked as it determines, how the orthoses function, ie are the orthoses flexible or stiff for your weight.
- Cover – Again often over looked, if you are aiming for control with orthoses, using a slippery cover, then the foot can slide around on the orthoses, compared to orthoses with a cover offering increased friction.
- Sport – It’s important to consider what the foot is actually doing during the sport.
- Footwear – Orthoses and footwear have to be like a married couple and work together. An example of this is Solomon running shoes, they tend to be narrow in the heel compared to other brands. Therefore trying to get the same orthoses in Solomon trainers and other trainers may not be possible and may result the orthoses not sitting correct in the shoe. This can lead to changes in the function of the orthoses.
The prescription of Orthoses via the use of just a pressure mat is a personal bugbear for me. The pressure mat requires the patient to walk over it with barefeet and it records and plots pressure data on a screen. I have a couple of issues with using this solely to prescribe orthotics: –
Firstly, this is a two-dimensional image and the foot is a three-dimensional item, you cannot determine arch height from this data, This is a concern as arch height is an important consideration.
Secondly, people often say we have the barefoot data now I’m going to issue a set of custom orthoses. However, it could be that your foot function is much better when in a shoe.
Custom or off-the-shelf orthoses, which are best?
Short answer, it depends on the person and what you need your orthoses to do. Some people need custom orthoses, others can be treated using shoe lining modifications. Let me elaborate. It is about finding the right tool for the right job. Custom orthoses can be very helpful, however they do cost more than off the shelf orthoses. Off the shelf orthoses are still useful and if you find off the self orthoses work for you, then there is no need to change.
When looking at the research on this question we have an issue, research often shows no benefit between custom and off-the-shelf orthoses, however the majority of studies define custom orthoses as a set of orthoses that are just moulded to your feet, not true custom orthoses. They tend not to consider shell material and thickness. So it could be argued that they are not testing true custom orthoses. Another issue is that in the research people often say there was no difference between sham orthoses (control group) and the test orthoses, the issue here is that, I believe sham orthoses do not exist, as the sham device itself will have an effect on foot function as will putting flat piece of foam in the shoe, so the study is flawed from day one, also every person will react differently to the sham device.
If you have a foot that is maximally pronated they are less likely to tolerate off-the-shelf orthoses as there may be an increased risk for them being uncomfortable within the arch the foot, however I do have many patients who have a maximally pronated foot and use off the shelf orthoses very well. So answering the question which type are best is very difficult to answer and is a very case-by-case basis and also depends on the experience of the person prescribing the orthoses and making sure they get the prescription correct for you.
Orthoses and Strength work
I personally always give strengthening exercises when issuing orthoses, the reason for this that the majority of running injuries I see in clinic are due to a load management issue, my goal with orthoses is to reduce the load going through the injured structure, however, we can also give exercises to help strengthen the structure. This increases how much load it can tolerate, effectively giving a bigger window to play with before you get injured again. It is also important to look at proximal (hip) control, if there is hip weakness, it may reduce the effectiveness of the orthoses and may reduce the tolerance of the orthoses. It is important when prescribing orthoses to not just look at the foot however to look at the lower limb as one. If there is weakness noted it is important to get this addressed and this highlights the importance of team working between healthcare professionals.
We know that orthoses do work and for a lot of people they are extremely successful, however I feel we need to change the way we view them. We need to be looking more at using orthoses as part of a treatment plan, working towards a treatment goal where orthoses may be short term or even changed and modified at a later date. Different orthoses are needed for different footwear and for different sporting activities. Hopefully we can start to change views that orthoses are fit and forget, and start to view them as a tool that can be very helpful part of the rehabilitation process.o we prescribe orthoses?..