What is intermetatarsal bursitis in the runner’s foot? Well, that is a great question and that is what we’re talking about today on the Doc On The Run Podcast.
If you start getting pain somewhere in the ball of the foot, you know, these are your toes. These are not toes. These are metatarsal bones. Maybe you are getting pain between those metatarsal bones and something in between the metatarsals is referred to as intermetatarsal. And there is a thing called a bursa, a little fluid-sealed sac that sits between the metatarsals.
Sometimes you get swelling or inflammation of that little bursa, and it causes pain in the forefoot, which is frankly most often misdiagnosed or thought to be caused by a neuroma, an inflamed nerve that runs in that same area.
I was going to talk a little bit about the anatomy, why this is so easy to confuse those things and so, if we look at it from the side and this was your foot, and you have the metatarsal sitting here like this and then the bones that go out into the toes. Well, the bursa is sitting basically right in between the metatarsals here. So, that is basically the side view like this, right? That is this view.
If we were to look into your foot, if we basically chopped off your toes and so we could look in there at the end of the bones from that direction and we draw a picture that simulates that, well, this is what you would get. You have the metatarsal bones and then you have the first metatarsal bone is much bigger and it’s got a couple of little bones sitting under it. The sesamoid bones, but we’re talking about these.
So, what you have when you are looking at this is you have the bone itself, you have a joint capsule holding all the fluid and stuff in there. You have the plantar plate ligament. You may have heard me talk about that before. The plantar plate ligament is under here. So, you’ve got the plantar plate underneath there.
Then you also have in that area, you’ve got the nerve, right? So, you have the common plantar digital nerve, which is the one that often forms a Morton’s neuroma. So, that is down on the bottom and then it kind of curves and goes up into the toes. But in cross-section looking into the foot from the front to the back, that is what you would see.
The bursa though is not that far away from there. So, you’ve got the bursa sitting in between right up here like that. The bursa is in between the metatarsals and because it’s really close to where the nerve is, a lot of times it seems like it is the bursa is what’s really inflamed and irritated.
How can you tell the difference? Well, a couple of ways. One of them is because it’s between the metatarsals, if you squeeze it, it often hurts. I saw a guy one time that was a runner that this was killing him and he actually wrote a skateboard to work. He is in San Francisco, people are more likely to do that here, I suppose, it’s pretty easy to get around. And it was the foot that he was using, pushing off on the pavement over and over and over.
I think that motion of the way that he had to push and his foot twisted, basically moved the metatarsal heads around and squished the bursa and caused it to become inflamed. He was told he had a neuroma over and over. And in fact, he even had a corticosteroid injection that was supposed to fix the neuroma. But when you do a corticosteroid injection, we basically go in from the top, we go down here, and we dump the fluid around the nerve.
I’m sure the doctor put the fluid in the right place all around the nerve, but the fluid filled sac, that bursa is a contained compartment. And if you do not put the fluid inside that compartment, it does not help at all. It went right past the bursa, dumped it in the soft tissue around the nerve, and he didn’t have any improvement at all.
This of course is very frustrating for him. He didn’t run for a long time because of this and then finally, I actually looked at it. There was nothing on the MRI. It didn’t really show up, but we got an ultrasound, and you could see it and then we knew that he had this. In his case, when you would just squeeze the foot alone, it would hurt. There are a couple of different tests we do for neuromas.
One of them is we try to feel the neuroma, that lump under your foot. That is called a Mulder’s click and there’s another thing called Gauthier’s sign where we actually squeeze the foot and we move the toes up and down. And because it can compress the nerve when it’s swollen between the metatarsal heads, when you move it up and down, squeezing the foot and compressing the metatarsals, it causes a positive reproduction of symptoms. And then we say that you have a neuroma.
But if you have bursitis and we squeeze the foot alone, that alone will cause the bursa to hurt. So, this doctor is squeezing the foot and moving the toes saying, oh, he has pain now. It must be a neuroma. Well, it wasn’t and if you are treating the wrong condition, you are not going to get back to running. You are just going to get frustrated. So, if you think it’s something else, it probably is. Talk to your doctor more.
If you want to come check it out, if you think you have a plantar plate injury or one of these things that is in the ball of the foot, you can come check out the plantar plate masterclass. I kind of talk about these other conditions in there a little bit. You can get that for free at www.docontherun.com/plantarplatemasterclass. If you enjoyed this, please like it, please subscribe and I’ll see you in the next training.
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