What’s the difference between flexor hallucis longus tenosynovitis and sesamoiditis? Well, that’s what we’re talking about today on the Doc On The Run Podcast.
If you have pain under the big toe joint, it could be a thing called sesamoiditis. You have two little bones sitting right under the big toe joint. They’re like tiny little kneecaps about the size of kidney beans, and they can cause stress fractures. They can cause fractures. They can cause inflammation of those things called sesamoiditis. But you could also have inflammation of the sheath that goes around the flexor tendon, the tube around the tendon that actually lets the tendon glide as your big toe moves up and down. There’s a big difference between these two conditions and a big difference between the way that you would treat them. I recently spoke with a physician that actually had what I thought was really the problem with the flexor tendon sheath and not necessarily the sesamoids, but as soon as you have pain under the big toe joint because the sesamoid problem can be so big and can turn into such a catastrophic injury, many times you just get treated with that.
Our thinking is that, well, the other things will calm down anyway, even if we treat you for this maybe more serious condition called sesamoiditis, but they’re in the same neighborhood. But if you’re trying to figure out which one of those you might have, there’s a couple ways you could do that. You can get an MRI. That doesn’t always help. In fact, this person that I saw that had this injury got an MRI, seemed like there was a lot of stuff going on. The sesamoids weren’t that inflamed, could have been lots of things because you do have lots of things in that area. But the two main culprits are really the flexor hallucis longus tendon sheath and the sesamoid bones, totally different things. So if you stand on the foot and you put pressure on it, it squishes the bones between the ground and the bottom of your foot. That will definitely cause pain if you have sesamoiditis.
The harder the surface, the more it hurts. So if you’re standing on tile or hardwood, it generally feels worse. The other thing is that if you do something to stretch the sesamoid bones, that usually hurts a lot. So if you pull your big toe up, if you put your big toe up against the wall and you basically push your foot against the wall with your toes up and it’s flexing the big toe and sort of stretching the sesamoid bones, that’ll hurt a lot. But if you have inflammation within the tendon sheath, that tube where it glides, what happens is the tissue on the inside of the tube actually swells, and it starts to take up space. So when the tendon moves through there, it changes the internal diameter, and that’s what causes the pain.
So if you put your big toe on the ground, you lift your heel off the ground, and then you pull the big toe down against the ground, you’re basically squishing that synovial tissue, but you’re not really pulling on the sesamoids very much. And so if you do that maneuver and it hurts a lot, then often start thinking that maybe you’ve got inflammation in the tendon sheath that we call flexor hallucis longus tenosynovitis. And all those words, I know it sounds real fancy and everything, but flex means to pull down, hallucis, hallux is the big toe, so flex pull down, hallux big toe. So flexor hallucis longus, and there’s a long one and a short one. The long one goes out to the end of the toe. That’s the one that typically gets inflamed. And tenosynovitis just means inflammation of that stuff that lines the tube that the tendon glides through. I know it’s really kind of ridiculous all these terms in medicine. They really are descriptive. They’re just descriptions that you don’t really understand because they’re meant for doctors. That’s why we get to charge the big bucks.
Anyway, hopefully you found this useful and helps you understand a little bit more about how to tell the difference between those two things. But if you have an injury at the ball of the foot under the big toe joint, it’s not getting better, get a second opinion. That’s the thing is that I see people all the time that have had months or years of these kind of injuries where it’s not getting better, and with some simple things it might get better, but not if you’re treating the wrong problem. So hopefully this will help you make a little bit better decision about what’s actually going on with you if yours hasn’t been improving.
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