How can pronation cause hallux rigidus in a runner? Well, that’s what we’re talking about today on the Doc On The Run podcast.
At one time in a medical conference, I heard an expert on biomechanics say when a runner develops hallux rigidus he becomes a swimmer instead of a runner. Most of the people in the audience laughed. I really didn’t think that was very funny because I actually have hallux rigidus myself and it doesn’t really disrupt my running, I still run, I run a lot and I see runners who have hallux rigidus. My goal is always to help them figure out how to keep running, but all of the little things that you understand about this condition when you have it can help you keep running a whole lot longer.
Now, hallux rigidus can cause pain and swelling in the big toe joint because the joint gets destroyed. The cartilage gets compressed because of excess pressure in the joint, it gets damaged, it gets eroded and then you have bone-on-bone grinding in there.
You’ve got to make sure you don’t do that. If you understand a little bit more about the mechanics of the joint itself, it may help you understand how to avoid the arthritis that happens from that compression within the joint that can hamper your ability to run in the future.
First of all, what’s hallux rigidus? Well, hallux means big toe. So when you look at your foot and you look at the big toe joint, and you think about the mechanics of the joint, it’ll make a lot of sense. You have the metatarsal bones, the first metatarsal, which goes down to the big toe joint. Then you have the proximal phalanx bone, which is smaller and then you have the distal phalanx bone, that’s not really that important in this equation, but it’s part of it.
What is hallux rigidus?
It just means the hallux is the big toe, rigid means it does not move, limitus which is sort of the precursor to hallux rigidus means it is limited. It doesn’t move as much, limitus. So it doesn’t move up as much. Well, why does it not move up as much? Well, a couple of reasons. One of the most common causes of hallux rigidus is that the first metatarsal is too long and that makes it a lever that makes it stiff. But if you have a normal length metatarsal and you pronate, then that can cause this elongation of the first metatarsal that actually causes a real problem.
How does that happen? Well, your talus bone sits on top of your heel bone. That’s the one that sits underneath your tibia or your shin bone. So you have the heel bone down here and the talus pushes forward when you pronate. So when you pronate and your arch collapses, so your arch comes down and if you think about it, if the base of the bone is here and then it’s flat, instead of upright, that angulation, the difference actually pushes it forward. So as your arch collapses, it actually pushes your toes outward.
Every time you pronate, if you’re an overpronator and your foot looks pretty normal and you don’t really have a long metatarsal, but every time your foot comes down to the ground and your arch height decreases it pushes the big toe out, away from your heel and when it does that, the structures on the bottom of the foot, they connect to the big toe, actually become tethered so tight that when your heel comes up off the ground and you try to move the big toe up, it can’t move.
It actually jams the big toe joint into the metatarsal instead of it gliding up because it has too much pressure on it to glide up and so that forcible elongation of the first metatarsal or what we doctors refer to as the first ray, meaning all these bones, that forcible elongation of the metatarsal tightens everything up and makes it impossible for your big toe to move up.
What does that mean? Well, that means that if you do something to stabilize your foot, you do something to correct the overpronation that’s happening it can decrease the jamming in the joint, because too much tension on the bottom of the foot, big toe can’t move up, the joint locks up it jams and the big toe joint is getting damaged in the cartilage in here because it’s all getting compressed. It just gets eroded over time. Then you wind up with bone-on-bone, you get a bunch of bone spurs, arthritis develops, and then you have a more serious issue.
But if you think you have this issue, early intervention is the key. It’s very difficult to replace all that cartilage, but you can prevent it from getting damaged. You can prevent it from getting eroded, but you got to make sure that you understand that’s happening. So if you know that you’re really pronating a lot and you know that you have some issues in the big toe joint, you might want to think about this.
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