This is one of the most common questions an saw endurance athlete will ask themselves when dealing with any kind of pain or discomfort. The term stress fracture fits in the broader category of bone stress injuries. A bone stress injury is when the micro damage that occurs when we’re running and doing other activities is greater than our body’s ability to remove that damage, and that can be things from a stress reaction, all the way to a full fracture. This is highlighted really well in this article by Warden and colleagues in 2012, this small graphic highlights exactly what that progression can look like when we’re dealing with bone stress injuries.
Bone stress injuries can occur in any bone in the body. When we’re looking specifically at runners, we tend to see these happen the most in their legs because those are the bones and the areas of the body that are having to deal with the biggest increase in stress when we go from walking around our daily lives to being able to run. And when we talk about bone stress injuries, we really have to go back to basic biology and understand how bone behaves and how that impacts both the development of these injuries, as well as how we treat them, and we reduce the risk of them occurring.
One key principle to remember is that our bones are always changing. From the moment that you wake up in the morning to the last minute before you go to bed at night, your bones are constantly getting stronger or weaker based off of the decisions that we make during the day, what we do, what we eat when we rest, all of these things change how our skeleton is adapting to our day to day lives.
We see changes happen on a minute to minute basis, but we also see drastic changes in people’s skeleton when we look at weeks months, and even years of time. When we look specifically at running, our bones have to deal with two different stresses. The first thing that we have to deal with is the actual impact between our foot and the ground. This is called a ground reaction force. The second stress that we have to deal with is the contraction of our muscles.
So every time our foot hits the ground, the muscles of our lower leg have to tighten to make sure that we can absorb that impact and not fall on our face and continue to progress forward. So when that happens, our muscles, they attach to tendons and those tendons attach to bone. Every time a muscle contracts that tendon creates a little bit of a tugging sensation on its attachment site, to whatever bone that it’s attaching to, and that creates a little bit of stress.
Now, in good circumstances when we’re healthy and training well, that can actually prove to make those bones a little bit stronger, but when we’re running into an injury, that can be a little bit of a problem. When we’re dealing with runners we have to remember that idea that our bones are dealing with those two separate forces, the impact between our foot and the ground and the muscle contractions that happen throughout our body.
So how do we figure out if we’re dealing with one of these one? Well unfortunately, a lot of the tests that people do to try to either rule in or rule out a stress fracture are not very good. Back in physical therapy school, we learn things like putting a tuning fork over an area, palpating or pressing on the affected bone, running ultrasound over the area. We learned that these tests might help us figure out if someone is dealing with a bone stress injury and unfortunately, when we look at the research on them, they’re just not very good at ruling in a ruling out a stress fracture. So we can have lots of runners that either have pain when we press on someone’s bone and they don’t have a stress fracture, and we also have a lot of people that have a stress fracture and when you press on the effected bone, they don’t have pain. So these aren’t great tests.
The other thing that people will often do is get an X-ray or a radiograph. Radiographs are easy to get. They’re cheaper than a lot of other imaging and so normally they’re a first line thing that people will go through. While they can help in diagnosing bone stress injuries at some points in time, they’re about 10% accurate. So we can’t put too much stock in someone saying I got an X-ray of the area and it didn’t come back that I had a stress fracture. In order to figure that out, we really have to have an MRI or a CT scan.
Now, when most runners enter the healthcare system and we’re determining if they have a bone stress injury or not, it’s often assumed that they simply ran too much, too fast. They’re runners, they’re crazy, they were just doing too much. And while training plays a key role in injury development, especially with bone stress injuries, our bones are very complex and there’s a lot more stuff that goes into that. While looking at training plans are important, making sure that someone has good hormone function, that they have a good relationship with food, that they don’t have a lot of extra stress going on in life and that they have other interests that they’re a little bit more well rounded, those things tend to help us because it puts our bones in a good position to deal with the specific demands of running.
While topics like menstrual function and sex drive are not things that a lot of healthcare providers want to have conversations about with their patients, these are important topics to check off because they play a key role in our bone health and our risk for developing bone stress injuries. So how do we determine if this is a bone stress injury? Runners tend to sustain two types of injuries. They tend to get bone stress injuries and tendinopathy.
Tendinopathy is a broader term that encompasses tendonitis. While runners can still sustain things like ankle sprains or meniscus tears, those two types of injuries are the things that we see the most in runners and endurance athletes in general. And so being able to differentiate between those two can be challenging because the places where we develop bone stress injuries and the places where we developed tendinopathies tend to be pretty similar and they tend to present in a similar manner. So we really need to be able to dive in and figure out which category this fits into.
This stuff is really important because if someone has a tendinopathy, we can often have them work through that a little bit by modifying training, shoe selection, exercises, different things like that, and they can generally keep training, but when someone develops a bone stress injury, we really have to shut them down for a period of time. And so being able to figure out which bucket that athlete is in is important because we don’t want to do them any longterm damage by having them continue to run on a bone that is not quite ready for that specific stress.
So how do we differentiate between the two? If we go back to physical therapy school one-on-one, when we’re dealing with tendinopathies we learned that if a tendon is causing someone pain, that tendon doesn’t like to be stretched, it also doesn’t like to contract. This table can be helpful in figuring that out if that’s what we’re dealing with. These sites are the most common sites that runners develop tendinopathies. I wanted to further highlight these by seeing where these tendons occur in the body. If runners are experiencing pain not localized to these key regions, we again have to think, is this a bone stress injury?
When a runner has a very aggravated Achilles tendinopathy, they tend to not like that tendon to be stretched so typical calf stretching. They also don’t like to have that calf contract or exercises that put them up on their toes. Those two types of activities put a little bit more strain on the tendon so if someone comes in and they have pain that’s localized to a tendon, it hurts when they stretch the tendon, it hurts when they contract the tendon and they don’t have any other things going on, we can probably start to think this is more of a tendinopathy that we’re dealing with. But when we start to have people that have pain that don’t fit that classic presentation of pain with stretching and pain with contracting, we start to consider, is this a bone stress injury? And what do we need to be doing with that?
When we take people through a standard orthopedic examination, that’s often done on the table in sitting and in standing. When I think someone has a bone stress injury, I’m very interested in what happens to their symptoms when we have them stand up in a weight bearing position specifically on one leg. The reason for this is because they now have to deal with the forces of gravity. They also have to deal with the muscle recruitment to make sure they don’t fall over. And when we go to stand, simply standing on one foot doesn’t place these common running related tendinopathies into the positions that should produce much pain. The one caveat to that would be plantar fasciopathy. So if someone’s plantar fascia is painful, they might not like standing on one foot. But when we look at the common tendinopathies around the hip, the knee and the foot and ankle, we shouldn’t expect simply standing on one foot to reproduce their symptoms.
If someone has a significant amount of pain as they simply go into a single leg position, we have to start to think, is this a bone stress injury?
Now that we’ve dealt with gravity, can you deal with impact? Having someone jump up and down on two feet and one foot puts them in very similar positions to standing. We’re going to place a little bit more load on their calf, but we’re not going to make drastic changes in the position of their hips or their knees. So when we go to initiate that, if someone is having that pain, that reproduction of symptoms that’s not localized to a specific tendon as they jump on two feet or jump on one foot, again, we have to think, is this a potential bone stress injury?
Bone stress injuries are tough. They’re tough to diagnose, they can be challenging to manage, and they’re frustrating for endurance athletes. So I wanted to highlight a few of the key points when we’re going to evaluate a runner. We have to make sure that we’re investigating someone’s past medical history. We have to delve into things like have they had a previous bone stress injury, have they had other issues with fractures? Do they have a good relationship with food? What’s their menstrual function like? Do they have normal hormone function?
We need to investigate when we start to load their body with different assessments and exercises, do they fit that classic presentation of localized pain in a tendon that’s reproduced with stretching the area or contracting the area. And finally, we have to make sure that they can tolerate standing or weight bearing in a single leg fashion, both with basic assessments, as well as with plyometrics, to make sure that we can rule out that they’re having to deal with a bone stress injury, so we can put them in the best position to get back to a hundred percent. Thanks so much for watching, make sure to subscribe to my channel and leave any questions in the comment section below, have a great rest of your day.
Thanks for watching!
Nathan Carlson PT, DPT