How can I really tell how severe my navicular stress fracture is? Well, that is what we’re talking about today on the Doc On The Run Podcast.
Stress fractures are common in runners, but one of the worst possible stress fractures is a stress fracture in the navicular bone. It is right at the top of your arch. It is right on the top of your foot, on the inside of your foot, and it is right in front of your ankle.
If you are having ache and pain in this area and you get diagnosed with a navicular stress fracture, it is super important to understand how severe it is and the real way to tell is with a CT scan. I am going to talk about the classification scheme that we use with CT scans to determine the severity of the injury. This is not a thing you can really tell reliably on x-rays.
The first thing is there’s three types of navicular stress fractures and then there are three different modifiers which sort of specify some things that happen that we can see on a CT scan.
The first thing is type one. This is where you have a crack in what we call the dorsal cortex. Now the cortex is the rim of the bone. So, if you look at this bone here, the tibia, you can see there’s sort of like a pipe, right? There’s medullary canal in the middle. The cortex is the bone rim around the outside and so when you have a crack on the dorsal side, meaning top of your foot, just like dorsal fin on a shark, when you have a crack on this side and only in the cortex, that is a type one. According to this study that looked at 22 different athletes that had navicular stress fractures, people with a type one with a crack on the top took them three months to return to activity.
Type two is worse. This is where you have a crack that starts on the dorsal cortex but then continues down into the body of the navicular itself. So, if this is your navicular shape like this, you get a crack on the top, but that crack continues down into the navicular, takes 6.0 months to return to activity with that one. And if it goes all the way through the navicular and goes to the plantar cortex on the bottom, it is cracked all the way through, that one is 6.8 months for you to return to activity.
So, basically the crack generally starts on the top and continues downward and the further down it goes, the longer it should take for you to get back to activity. The more likely it is you are going to wind up in the operating room. In this particular study, the authors of this study, if somebody had a type two or type three, they basically would recommend surgery. The other thing is they would recommend surgery when you have any of these three additional modifiers that we use in classifying how bad they are.
The modifiers are A, C, and S. And they stand for certain things. A stands for avascular necrosis of a portion of the navicular. The navicular bone has a bunch of blood vessels that come into it and if you cut off the blood supply by fracturing the bone and breaking those vessels, and it cuts off the blood supply to a portion of the bone, it might die off. So, avascular means no blood flow.
Necrosis means it is dying and that obviously is bad. In that case, the doctor might have to put some bone graft in or do something creative to get it to heal. If you have the modifier A, meaning avascular necrosis of a portion of the navicular, it is a bad thing and you are more likely to get surgery.
The other thing is cystic changes. When you look at an x-ray and you see a little sort of dark colored circle, and it is not bright white like the rest of the bone, that means there’s a cyst or a sort of hollow spot in the bone. If you have a cyst in the navicular and then you crack the navicular, you don’t have the same amount of surface area to heal across the bone because there’s a hollow spot in the middle.
If you have cystic changes, you are more likely to wind up in surgery and the surgeon would probably curet that out or clean it out with a tiny little ice cream scoop basically. And we clean it out and then we fill it with bone graft or something else to try to get it to heal.
The third modifier is S, sclerosis. When you look at an x-ray and you have, or a CT scan in this case, and you have a crack where the bone is broken, when it gets sclerotic, it means that it is hard, and it is rigid, and it is not easy for it to heal across that hard sclerotic bone. So, when the edges or margins of the fracture become sclerotic or bright white or thicker, then it is a bad thing and what’s interesting is that in this study of 22 athletes. They found that sclerosis was the most common in their series and it was also particularly common in runners who had continually symptomatic navicular stress fractures.
When that continued to hurt for a long time often had this sclerosis, the hard bone right at the edges of the fracture that makes it harder to heal. So, in short, in this study, the surgeons that did the study recommended that if you have a type two, where there’s a crack on the top and it goes down into the body of navicular, you should have surgery. If you had a type three where it starts on the top and goes all the way through the plantar cortex or the bone on the bottom, then you should have surgery.
If you have any of those modifiers, meaning avascular necrosis or where the blood supply has been cut off and it is starting to die off in one spot or you have a cyst or a hole in the bone, or if you have any sclerosis where the edges of the fractures are hard, well, then you should probably have surgery as well.
The authors of this study was Amol Saxena, this guy that I know roughly, he’s not a buddy of mine or anything, but he actually came up with this classification scheme. We’re going to put a reference in the show notes if you want to see it so that you can look up the study and look at it yourself. It is interesting. Maybe scary if you happen to have one of these injuries, but that is the short story on how you tell how severe it is. You look for those three things, a type one, type two, type three, does have any avascular necrosis, any cystic changes or any sclerosis at the edge of the fracture.
If you want to understand the strategies I use with runners who get all kinds of stress fractures in the foot, it is the same strategies I teach to physicians at conferences when I lecture on stress fractures. I lay out all those strategies in a step-by-step process that I follow in the Stress Fracture Masterclass and you can get that for free at www.docontherun.com/stressfracturemasterclass. So, come check it out and I’ll see you in the training.
Reference:
Saxena A, Fullem B, Hannaford D. Results of treatment of 22 navicular stress fractures and a new proposed radiographic classification system. J Foot Ankle Surg. 2000 Mar-Apr;39(2):96-103. doi: 10.1016/s1067-2516(00)80033-2. PMID: 10789100.
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