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Pes Cavus

Pes cavus is characterized by a high arched foot. In the most severe case, the patient walks into the examining room to see you, he is walking on the outer edge of his foot. In a severe case, he or she is almost like bow-legged, sort of like a cowboy, they have a lot of genu varum at the knee and they are walking on the lateral border.

When you look underneath their foot, the have these thick, thick callouses on the lateral aspect of the heel, under the fifth metatarsal head, and under the base of the fifth metatarsal. You can also see, because one of primary players in pes cavus is too much plantar flexion of the first ray, they may also be complaining bitterly of a thick, hard, callous under their first metatarsal head. They may tell you when you ask them, yes, I used to get a lot of ankle sprains as a kid and my ankles have always been weak, and I hate to walk on uneven ground, as you can imagine if you are always walking on the outer edge of your foot, a small walk or a pebble on an uneven surface, it doesn’t take much for them to just turn their ankle and sprain their ankle.

I have seen a lot of people who have had ankle surgery with tendon transfers or reconstructions of the ligaments, and still keeps coming back. Why? Because we still haven’t fixed the primary problem. There is a malalignment going on in the foot that is stressing the ankle, and they are manifesting as a chronic ankle sprain when you really have to get to the root of the problem which is arising in their foot. So again, this can be caused by muscle imbalance or even spasticity of the muscles.

It is also supinating the foot a bit, again throwing them on the lateral border of the foot, so the inside arch is raising up, and the lateral border of the foot is getting overloaded. They can also have what we consider is a relatively tight Achilles tendon as well or more powerful Achilles tendon and weak dorsiflexors of the ankle. So what do these people manifest with; well they have the joint contractures, malalignment of their foot, I just mentioned about how they may present with ankle symptoms and that may be the reason they come to see you, but it’s the malalignment in the foot that is causing the problem.

How do we treat this? Well, here is a guy who had his foot corrected, we straightened out his hammertoes, we decreased his arch, but as you can see, he has orthotics that are made to fit his foot. There is a large arch pad here so we load the arch, so instead of the weight being on the heel and out here across the metatarsal head, predominantly the first one and the fifth one out here, we are trying to get weight bearing in his arch. He also has had physical therapy, trying to strengthen his ankle dorsiflexors.

When I look at someone who presents to me with a foot complaint, I try to break it up into what the primary pathology is, and what are the secondary manifestations that they are coming to me to complain about? The foot is a complex weight bearing surface. There re 28 bones and nearly 60 articulating surfaces, so there are a lot of inter-relationships going on between the different segments of the foot, the hind foot, mid foot and forefoot, and problems in one region can have manifestations elsewhere. So it is very important to recognize what the root cause of the problem is, as well as identifying all the secondary manifestations. So when I think of the problems, I start to look at the structural malalignments that might be present in the patient’s foot, is the arch too high, is it too low? Is there some imbalance of the muscle forces that is causing that problem; or imbalance of those muscle balance forces driving the secondary manifestations. Also, as I talked about before, compensatory deformities. There could be a problem in the hindfoot, but the patient comes in to see you because there is a forefoot problem. That is where it hurts them, that is where it’s difficult for them to wear their shoes.