DOC » #435 What can cause aching pain a year after a metatarsal stress fracture?

#435 What can cause aching pain a year after a metatarsal stress fracture?

Today on the Doc On The Run Podcast, we’re talking about what can cause aching pain in the top of the foot a year after a metatarsal stress fracture?




Today’s episode actually comes from a recent live Q and A I did with recovering injured runners and during these calls you can come on and you can ask me anything that you want about your specific situation. And this was a really great question that came from one of the runners on the call and he was concerned about this discomfort he was getting in his foot a full year after he had a metatarsal stress fracture. So let’s listen in and you can join our session now.

Chris:
Good morning, how are you?

Dr. Segler:
Hey, good.

Chris:
Good, my name’s Chris. I’ve had several stress fractures in my left foot that I’ve battled with over the years due to over training, basically running too fast on my workouts.

Dr. Segler:
Okay.

Chris:
And so I’ve learned from my mistakes, and as I’ve recovered from this last one, I’m feeling much better now, but I do get aching in the foot from time to time. And this fracture was that over a year ago.

Dr. Segler:
Okay.

Chris:
And I’ll get this aching from time to time, and then it kind of goes away for a week, and may come back for a day, and then go away. Is that scar tissue? What exactly is this reoccurring pain? It’s on the top of the foot. I mean, I can almost press it and it will hurt, but then it will go away after 24 or 48 hours. I’m just kind of curious about that.

Dr. Segler:
So it sounds like your stress fracture, I’m assuming it’s a metatarsal stress fracture, is that right?

Chris:
Yes. I believe it was either the third or the fourth metatarsal.

Dr. Segler:
Okay. All right. So statistically, according to all the stuff we’re taught in medical school, fourth metatarsal stress fractures are actually the most common. So whether or not that’s what you had doesn’t really matter. It could be the second, third, fourth, whatever, but a metatarsal stress fracture, when you get the stress fracture and it sounds like yours, like you said, you seem to think that it was really your speed work more than anything else, doing some really fast runs that really kind of pushed you over the edge. And with metatarsal stress fractures, all it is is too much stress applied to the bone, whether it’s the muscle pulling on the bone or the pounding from running, ground reactive forces and all that, it doesn’t really matter.

Once you cross over that threshold for injury where it’s not rebuilding as fast as it’s getting broken down due to your workouts, that’s where you get a stress fracture and there’s basically three different sort of phases of injury to the bone that go from normal to abnormal.

Let’s say, if we look at your other foot, the one that’s not been injured, and you were to start training and you’re doing a lot of stuff and then you maybe do a long run or a really hard speed session. If you were to go get an MRI of that foot, the non-injured foot, the next day, you would almost certainly have inflammation in at least one of your metatarsals and if your foot is built in a way that actually the way that you run just happens with your biomechanics and your unique running form, if you happen to pound the fourth metatarsal a bit more, it just gets worked more, than you would be likely to actually have inflammation showing up on your MRI within the fourth metatarsal bone.

Dr. Segler:
Unfortunately when you go get an MRI and you have a complaint of foot pain and you have what we call a signal change on the MRI, where it goes kind of from being dark within the bones on this one set of images to where it looks white within one of those bones, that indicates that you have increased fluid or increased inflammation within that particular bone. And the radiologist reads it as a stress fracture.

If you do that MRI right like the day after one of those hard workouts or after a race or something like that, but you don’t actually have pain, even though according to this one classification scheme called a KD Miller scale, it’s on that scale when you have no pain but you have any kind of imaging abnormality like inflammation on MRI, but you also have no crack in the bone, it’s called a grade one stress fracture.

Dr. Segler:
The problem is it’s not pathologic. It’s not actually a problem and it’s not actually a fracture. So it gets very confusing for us as runners, and frankly for physicians, because the radiologist calls it a KD Miller grade one stress fracture, you hear the term, big, fancy name and grade something stress fracture, and you assume it’s broken and it’s not. It’s a normal physiologic process and there’s a lot of research that’s been done on professional runners and ultra distance runners where they show that this is a normal thing.

In fact, one study of the Trans Europe Race actually showed that as the course of the race goes on, it goes all the way across Europe, so it’s a 2000 mile race. They had an MRI in an 18 wheeler following the athletes and they did serial MRIs on athletes during the event and even during that event, the stage race, the inflammation within the bones would sort of wax and wane throughout the course of the race and none of it’s wrong. None of it is pathologic, none of it’s actually a problem and you don’t have to stop doing the race just because you get it.

Dr. Segler:
That’s true in training as well and so another study of professional athletes actually showed that that inflammation within the bone is completely normal and you shouldn’t as a physician, modify the runners training program if you see that on an MRI. But when you get a pathologic problem, it’s when you have that signal change on an MRI and you have pain in that specific bone in that spot, when we push on it, or when you stand on it, or run or whatever, well, that’s when it becomes a stress reaction. So it’s no longer a stress response, a normal physiological response. It’s now a pathologic or problematic response called a stress reaction.

Dr. Segler:
When you get that stress reaction, if you don’t decrease your activity and you continue to apply stresses to it in the same way, it will predictably turn into a stress fracture where you have an actual crack. And so once you get that, you obviously have to let it heal.

Now, the healing process from a stress fracture, if you get a crack within the bone, it starts to sort of deposit material around it, sort of like spot welding in a sense and wrapping a bunch of duct tape around it or something, and all of that takes up space, and you get what we call a bone callus. And if you look on it on an x-ray months later, a lot of times you’ll see a big lump in the bone where that stress fracture was and that lump of bone is reinforcing and forming kind of a stability, like a buttress around the crack, but it takes up space.

Dr. Segler:
So your foot kind of has no free space in there to take up. There’s tendons, ligaments, bones, even on the bottom of your foot, you have four different layers of muscles, not four muscles, four layers of muscles. And anywhere that you have that additional bulk, it can do two things. One of them is that it can sort of push against the interossei muscles or little muscles that are on the inside of the foot basically sandwiched between those metatarsal bones. And then when you exercise those muscles are actually sort of contracting and bunching up against that bump of bone. And it can cause the sort of aching discomfort that you mentioned.

Dr. Segler:
Now that the big concern, of course, like if your doctor’s looking at you and hears that you have this recurring discomfort, the first thing, of course, they’re going to wonder whether or not you’re getting another stress fracture, or if it’s starting to crack again. If it’s very, very short lived, then it probably is not. If you get the discomfort the day after you run and then it’s gone the next day, it’s probably just intrinsic muscle soreness from that basically intrusive lump of bone. That very, very slowly remodels over time. And it could be though, it is possible, that you can have a recurring stress fracture, but if that’s true I would expect it would bother you some while you’re doing some of those activities as well. You could get an MRI, but again, the problem with the MRI is that if you go get an MRI and you have remodeling happening within the bone, you have to have inflammation for the remodeling process to take place.

Dr. Segler:
In medical school we’re taught that that process of remodeling the bone, the sort of third phase of healing of the stress fracture actually takes a year to a year and a half. So at that point, if you’ve been a year, year and a half in, and you are still having inflammation within the bone that’s normal because the bone is remodeling and it’s actually reshaping that bone callus and it’s making it stronger and better organized, the radiologists will still read it as a stress reaction or a stress fracture. And then your doctor tells you to quit running. So that’s the thing that you have to really kind of sort out.

So more than anything else it’s trying to pay attention to how much it really bothers you in those days after you do your activities. And that can be really helpful to help you figure out, on your own even, whether or not it’s actually a serious issue or not. So does that answer your question?

Chris:
Yes, it does. Thank you.