Capsulitis versus plantar plate sprain. What’s the difference? That’s what we’re talking about today on the Doc On The Run Podcast.
If you’re a runner and you have pain around your second toe joint where the toe actually attaches to the foot, somewhere in the ball of the foot, it might be a thing called a plantar plate sprain and many, many years ago if you had this kind of pain, it would probably have just been called capsulitis. But a plantar plate injury is something that’s become recognized a lot more widely in the last 10 or 20 years and they’re not ignored as much as they used to be and it can be a real problem. Plantar plate injuries frankly are very difficult to heal in runners because they get stretched and strained anytime you stand on it or you bend the toe. But the joint capsule can also get injured and they are different injuries, they’re not the same.
So how do you tell the difference between these things? Well, first of all, the plantar plate ligament is a ligament on the bottom of the foot at the ball of the foot and it connects the toe, to the metatarsal right where the toe bends up. So when you bend the toe up, you’re stretching the plantar play ligament. Usually, this happens at the second toe, it can’t happen at others, but that’s the most common. Now, the joint capsule is what actually holds all the fluid in and around the joint, so when you have capsulitis you have inflammation of the joint capsule that’s holding the fluid inside the joint. That’s a little bit different, the plantar plates on the bottom, it’s under there. Completely different structures, but they can seem the same.
How can you tell the difference? Well, the first thing is tenderness. So if somebody tells me that most of their tenderness is on the bottom of the foot under the second toe and that’s where they feel most of the pain, well that’s in my mind most likely going to be a plantar plate ligament. If you say that you have pain all around the joint and you’re going to have swelling on the top of the foot at the base of the toe, well that’s more likely to be capsulitis because it swells upward and outward in all directions, and can be a bit more tender all around.
The next thing is the swelling itself, swelling with the plantar plate you get this diffused swelling, but you don’t really see it because the skin on the bottom of the foot’s thicker, so it feels full. Patients describe it has a sense of fullness or just feels tense, or something like that, but you don’t really see much swelling on the top of the foot. On the top of the foot it’s more likely to be capsulitis than it is for that swelling to be caused by the plantar plate because it’s pretty far away from the top of the foot.
Thee next thing is deviation. So when we talk about that, we’re talking about the position of your toe. So if your toe drifts over in one direction or the other, how does that happen? Well, you have the joint capsule that’s holding the toe straight and if the capsule swells in one direction or another, then it can push the toe one direction or another and cause what we describe as deviation or tilting of the toe either toward your big toe or toward one of the little toes in the other direction. And deviation in most cases, if you haven’t had a serious injury or you haven’t had pain for a really long time, it’s probably more likely to be capsulitis and it’s just swelling of the joint capsule pushing the toe in one direction than it is an actual plantar plate spray.
Now, the plantar plate ligament being on the bottom of the foot, if you rip let’s say half of it on one side, then the toe could actually deviate. So you could get deviation of the toe when you have a plantar plate ligament injury or if you’ve injured the plantar plate ligament and you’ve messed up one of the collateral ligaments on the side, that would do that as well. But that can give you a clue, whether or not the toe’s tilting in one direction or another.
The other thing is that if you have, let’s say a comparison between a structural problem, you rip the ligament, okay, you rip a ligament and it tilts over because now it’s not attached on that side anymore. Okay, if you do something, you reduce the swelling, it’s still not going to be attached over there, so it’s going to look the same. But if you have all the swelling in the joint and you do something to reduce all the inflammation in the joint and you really get rid of that swelling in the joint, then the toe’s going to come back straight. So capsulitis might respond to really icing it aggressively or doing contrast bath soaks, or something to reduce the inflammation. And if it reduces the inflammation the toe goes back straight and you know it’s not because of a torn ligament like the plantar plate.
The next thing is manipulation. So by manipulation, I mean we grab your toe, we move it around. It’s really that simple. Now there are a couple of different ways we manipulate your toe. And to help you determine the difference between these two, let’s say if we take the toe and we distract it or we pull it straight out and we stretch the joint capsule. Well if you have capsulitis and the whole joint capsule is inflamed and we stretch your toe, well that is going to hurt because it stretches the joint capsule. When we do it, we kind of plantar flex the toe or pull it down a little bit so that we relax the plantar plate ligament so that we’re not stressing that because the other test is a thing called the modified Lachman maneuver.
It’s where we hold your toe and we actually push it upward to just stress and strain the plantar plate ligament and if you have pain when you do that, if I’m in your living room looking at you and I grab your toe and I do this modified Lachman maneuver and you jump off the couch, well that’s a plantar plate sprain. It doesn’t necessarily mean how bad it is, but we know that that’s the issue and it’s not just capsulitis because that would not really hurt that way. But manipulating the toe can also give you a lot of information about whether or not you’ve got capsulitis or a plantar plate sprain.
The last thing is imaging. X-rays don’t really show you too much with any of these, but things like an MRI, ultrasound, an arthrogram, they’re all things that can actually tell you whether it’s one structure or another. On an MRI you’ll have inflammation all around the joint capsule if it’s capsulitis, you’ll have inflammation around the plantar plate and maybe even see a rip if it’s torn on the MRI. You can see this on ultrasound where the plantar plate ligament, we move the toe, we look at it under ultrasound, and if it’s torn, we might actually see that tear in there at that time.
We can also see some fluid in there around the plantar plate ligament on ultrasound if that’s your issue. And an arthrogram is just where we squirt some die into your joint and then take an x-ray to see if the fluid leaks out. If you’ve ripped the joint capsule, the fluid leaks out. So they’re all different kinds of imaging that can help you tell the difference, but you’ve got to figure out what the difference is because they’re treated differently.
If you have a plantar plate sprain and you’re treating it like capsulitis and you’re not going to get better quickly, the worst thing actually is if you have a plantar plate sprain and you think you have capsulitis and your doctor injects it with corticosteroids, it can actually make everything weaker and then you can get a complete rupture of the plantar plate, which does lead to surgery. So you want to make sure that you know the difference between these things.
Now, if you want to take a deep dive into plantar plate injuries for runners, you can join me in the Plantar Plate Masterclass for runners that I created for you. It’s about half an hour, but it’s a deep dive into all of the things you really need to think about if you’re a runner with a suspected plantar plate sprain and you really want to get back to running as quickly as possible. You can get it, it’s free, you just go to docontherun.com/plantarplatemasterclass. So go sign up and I’ll see you in the training.