The feet are extremely powerful when it comes to movement being successful or not. This is most likely for a few reasons, firstly, because it is the feet that hit the floor, they are the first link in the chain of a vast majority of our movements. If at this point they go through motions that help the rest of the chain, that’s good. If on the other hand they do not go through the required motions that can cause a big knock on effect further up the chain.
Another reason they are so powerful is because they are extremely stubborn!! They are ‘built’ to withstand large forces and to withstand those forces repeatedly without complaining. So when things aren’t as they should be that stubbornness can play against us.
Today I wanted to go through a few of the anatomical foot deformities that we all see day to day to varying degrees and I think in subsequent posts we will have a look at the effects of those deformities locally and globally before we have a look at how to deal with them when you see them.
Rear Foot Varus
I thought we’d start with the rear foot varus because it is really common and we see them to varying degrees each day in the clinic. A varus is when the foot is in a relatively inverted position, even when in sub talar neutral. It’s normal for the calcaneus to be in about 2 degrees of varus, so there’s no need to worry about that. However, if there is more than that it could be that the body is having to compensate for those differences. This could cause many varying types of compensation in the range of motion, the speed of motion or the timing of motion locally at the foot, with knock on consequences further up the chain.
A rear foot varus is when the calcaneus is excessively inverted relative to the tibia. So to assess a rear foot varus I will have the patient prone with their feet freely dangling off the end of the treatment table. It’s then important to find sub talar neutral for the tab individual and then you can assess the relative position of the calcaneus to the tibia. Personally, I eyeball the result and make my clinical decision based on that. However, there are ways of measuring it, which are to detailed to go into on here. If the calcaneus is excessively inverted relative to the tibia I will consider them positive for a rear foot varus.
I think from memory this is statistically the most common foot deformity. However, whereas the rear foot varus is the relationship between the calcaneus and tibia, a forefoot varus is the relationship between the rear foot and the forefoot. Again, because this is a varus, the deformity will be if the forefoot is excessively inverted relative to the rear foot.
I assess in the same position, prone with feet off the end of the bed. There’s no need for sub talar neutral as you are simply looking at the relationship between the rear foot and the forefoot. Position yourself over the foot so you are looking down on the calcaneus and can see along the sole of the foot. To assess I imagine a plane under the calcaneus that is where the floor would be, which give me the plane of the rear foot. Then I compare that to the imaginary plane under the metatarsal heads, which gives me the plane of the forefoot. If the two planes line up you can begin to think there is no forefoot varus. If the plane of the forefoot is showing a position of an inverted forefoot, then you can begin to think there is a forefoot varus.
Though this is less common you will see them. The assessment is exactly the same as for the forefoot varus, however the plane of the forefoot will show it to be everted relative to the rear foot. If this is the case you can begin to think you are dealing with a forefoot valgus.
Plantarflexed First Ray
This is when the first ray of the foot is lower/plantarflexed relative to the plane of the other metatarsals. I assess again in prone with the patients feet off the end of the table. You need to look at the alignment of the metatarsal heads. If they are all in line, then there maybe no problem, however, if you see the first ray is lower/plantarflexed relative to the others then you may be dealing with a plantarflexed first ray.
These often occur in conjunction with other deformities. You particularly have to be careful with a forefoot varus that also has a plantarflexed first ray as in combination they can look like a normal foot. So keep an eye out for that one!!
An equinus is when the forefoot is plantarflexed relative to the rear foot. So again looking down on the calcaneus along the sole of the foot or looking from the side of an off weight bearing foot you will see that the forefoot is plantarflexed relative to the rear foot. This is a really stubborn one and the patient will have very little functional dorsiflexion as they are using all the range they have to compensate for the deformity…however, we’ll get into that more when I post about that specifically.
These are just some of the more common things you will see when assessing the structure of a foot. I always say that even if you are assessing and see an apparent deformity that you ‘may’ be looking at that type of deformity. This is because I use a battery of tests to assess a foot. The off weight bearing assessment is key, but is only part of it. I always want to know their function on weight bearing too. Only then can I make a clinical decision as to what will best help that patient.
The follow up posts to this will deal with the functional side to the assessment, the kinetic chain compensations you see with the different deformities and how I go about treating them. I think I’ll do 1 post a week on this so not to overload on the foot (again!!!)
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