Should I get an MRI or an X-ray when I have a large bone callus after a stress fracture, and I want to assess the callus remodeling? Well, great question and that is what we’re talking about today on the Doc On The Run Podcast.
When you get a metatarsal stress fracture from running, let us say it is the second metatarsal, if you get a crack in the bone, it will eventually start to heal. One of the first things that you will see on an x-ray is what we call a bone callus, and that is where you get this bulge right around the fracture that is making it stronger.
If you keep exercising, walking, running, doing elliptical training or whatever, and you are aggravating it at all, the callus will get larger. It can get really big. So, if you go to the show notes, I will have a couple of examples there, some images of people I’ve seen that have really big bone calluses after they’ve had a stress fracture, and the problem is that that lump can push on other things.
Over time, the bone callus will remodel, and that lump will get thinner. It will get smaller. But if you are having pain because you have a huge lump of bone in there, at some point you might want to figure out, is it the muscles are getting pushed on or do I have a bursitis issue going on or is it pushing on a nerve or something? Or you may just be curious and want to know, is that lump getting smaller?
If you want to know that, then you need to think about how you are going to look at it and there are a couple of ways to do that. The first way you might want to look at it would be an MRI. Now, we all know about MRIs. You go and you use a very expensive magnet, you sit in a scanner, it makes a bunch of noise, it takes a long time, but it can give you a lot of anatomic detail.
The MRI is something that you can use to assess it. So, you can measure on the MRI and see if the bone is smaller. But the truth is, I wouldn’t pick that as my first choice if I was just going to be measuring the bone. I would be probably more likely to get a CT scan because it looks at bone better. But there’s a big advantage with an MRI.
One of the advantages with an MRI is that it doesn’t just look at the bone itself, it actually looks at the amount of inflammation within the bone. So, if you had an MRI before and you get a second MRI and you are trying to see, is the cortex of the bone getting thinner, you could do that. But more importantly, you could actually look to see if you’d had a decrease in the amount of intracortical inflammation. That means that when you look at the bone in cross section, like if we cut off the toes and looked into the bone this way, it would be round ayou are looking at the rim of that bone.
If on the MRI, you don’t have any intracortical inflammation, that is a very good sign because I always get worried when I see that starting to show up, it usually means to me that it’s about to crack. So, if the inflammation is subsiding in the cortex or wall of the bone, that is a good thing. It’s a good sign.
If you had a prior MRI, the first thing is, is that it’s good to do that for comparison, particularly getting it at the exact same imaging facility using the same machine. The second thing is, is that when you get an MRI, it can show something that is not great and it’s not helpful and I’ll try to explain why.
Within the bone, on the inside of it, in the medullary canal, not in the cortex or the thick shell of the bone, but in that little sort of soft spot in the middle, that channel that we call the medullary canal, well, if you have inflammation showing up in the medullary canal, the radiologist is definitely going to call it a stress reaction. And if you don’t have a prior MRI, then this will often lead to what we call a false positive.
You get the MRI, it shows inflammation on the inside of the bone. The radiologist gets all freaked out and says, oh, there’s inflammation in there. Well, the problem is that you are going to have inflammation in there potentially for a year, maybe even a year and a half as the bone remodels. So, you have to take that with a grain of salt and if you can measure it and compare it to the previous MRI, then you can sort of dismiss that as much of a problem.
However, if you don’t have a prior MRI, and the only positive finding you get is that you have this inflammation within the medullary canal in the center of the bone, it might make you decrease your activities unnecessarily because it’s a false positive. It makes it look like there’s a new problem going on when it’s an old problem working its way out.
The third thing is an x-ray. Okay, so the x-rays, if you had x-rays before and you go back to the same imaging facility and you get x-rays where your foot is positioned the same way, then the shadow of the bone, we can actually measure the cortex on the sides and we can measure the thickness of that bulge or bone callus, and we can see is it improving or not.
If you see that there is a decrease in the thickness, then this is good news for you because you can confirm that you have had some improvement. However, that does happen very slowly and so if you go just a couple of weeks after you got your first x-rays and you get x-rays of the foot again, there’s almost no chance it’s going to be different. It may not be that helpful. It might not give you any answer at all.
The better way to go about this instead of trying to rely on imaging that can maybe be good, maybe be bad, depending upon whether or not you had prior films, whether or not you had a prior MRI, all that stuff, is to try to really monitor the severity of the injury the way that I discuss through the strategies I talk about in the stress fracture secrets presentation. The reason I call them secrets is most people don’t seem to pay attention to them, including doctors when I lecture at medical conferences.
So really, this presentation came out of the things that I present at medical conferences that doctors seem to be confused about or ask me about when I’m lecturing to them on runners with stress fractures. So, if you want to check that out, it’s free. You can go to www.stressfracturesecrets.com and you can check it out there. Thanks for watching and thanks for listening and I’ll see you in the next episode.
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