Why do stress fractures or bone stress injuries happen?

I'm going to help you understand whether it's happening to you, happening to a colleague, whether you're a coach, whether you're a clinician, managing someone who, who has this injury.

I want to help you, you better understand the process and and why they happen so we can then better manage when they do or if they if they currently asked.

And my name is Blake.

I work in, in Newcastle, Australia in, in private practice.

I get to work with lots of runners and I also get to work with lots of runners in in the online space.

I'm studying my PhD on running related injuries.

And between that and working with runners, I get to learn and see a lot of stress fractures.

And a question I get asked all the time is, is what are they and why do they happen?

And it is important because in the case of recurrent stress fractures or when they do happen, we know we're going to need some, some time off.

And the, the timelines can vary depending on the injury.

And there's a lot of thinking time, a lot of waiting time.

Why do I need to have this time off?

I don't have any pain.

Why do I need to take so long to, to get back to, to my writing?

And I want to use this video to, to shed some light on that and also as a, as a resource people set that I work with when we, we think of, of stress fractures, I want you to, to imagine a, a bone.

Now we look at where they're going to occur.

They're most likely going to occur, the tibia and the metatarsal.

And it's just easy.

And I, I like to visualize the bone when I think of it.

So metatarsal is this long bone in the foot.

And I'm a, a muscular squid of pediatrist.

Of course, I, I work for the foot, but I, but I see bone trace injuries all over the body.

So they roughly make up around 20% of all running plated injuries.

But the two processes you need to understand is for the bone, you're going to have a a process where you have some damage and then you have some rebuilding.

So anytime you go and do something, whether you, if I just get out of this chair, go for a walk around the park, if I go and do some jogging, if I go doing some sprinting, I'm increasing the load of the stress to the tissue.

Now it is a normal process which we want to happen for the bone to become damaged.

Now the body being the great thing that it is, will come in and take some of that damaged bone away and it will lay down new bone.

So you constantly have this cycle go through where you have some damage and you have some rebuilding, you have some damage and you have some rebuilding and you can have a little bit more damage than rebuilding.

That doesn't mean you're going to end up with a bone stress injury.

Once we know those two processes, we can start to figure out and see well what's going to affect this process over here, which is the damaging and what's going to affect this process over here, which is the red building.

So if I get up out of my chair, it's stress to my muscles, stress to my tissue, and it is damage to the bone, but it's not that much because the low is not that high.

I go for a walk around the park.

That's going to be a little bit more let's I go for a 20 minute walk.

If I go for a 40 minute walk, that's going to be more if I go for a 20 minute jog to a 40 minute jog.

If I go for a 20 minute hard 5K effort or maybe a 10K at the at the 40 minute mark, I'm increasing the stress to the tissue.

I'm going to accumulate more more damage.

And the more that we do, the more damage that we're going to see.

And that just means there's more remodeling that that needs to happen.

Understanding that gives us the answer as to why.

So if I go out and do something where I damage my bone and then I have maybe a eriod of rest, maybe a short eriod and I go out and do it again and I continue to damage that bone, there's only so fast that it can remodel.

O if I do a lot of damage and I don't give it time to remodel, I'm very likely going to end up with a bone trace injury.

And we don't really know why some bones fail compared to others.

There's lots of other factors.

The research probably can't give us that answer.

There's a bio mechanical variances, maybe the way that we're loading, maybe the terrain that we're running on, the intensity, you know, running around a track might load the fibula a little bit more, running uphill might load the tibia a little bit more.

Somewhere with a flutter foot posture, it might load the navicular a little bit more or a second metatarsal compared to the 5th metatarsal.

So the damaging part can happen quite quickly.

So if I go out and run a marathon right now, I'm probably not going to get a bone stress injury tonight.

But if I continue to run a marathon every day for the next week, I might end up with with some severe injury.

It might be my tender that goes, but I might as well also end up with a with a bone stress.

But we don't know exactly how long the remodeling takes, maybe anywhere from 120 to 200 days, depending on if it's a cortical bone versus a trabecular bone.

But the, the essence of understanding is damage can happen really quickly.

We know that it's going to be an overload to the system.

So that's level 1.

Let's go to level 2.

If we're looking at those two factors, we're going to build upon them.

So let's look at a really common risk factor for running.

Running related bone injury is if you're not fueling enough and you might think to yourself, well, how does fueling and eating affect my bones?

What's going to happen there?

When you eat and you consume energy, that energy will be diverted around the body.

Some goes to your brain.

Well, what goes to your brain?

Some go to your organs, your reproductive systems, hair growth, that type of thing.

So if you're not eating and feeling enough, what's going to happen is the energy that your bones need to be able to remodel.

It's not going to get it.

They're going to go to things more important.

I really love bones, but your body prioritizes your brain and your organs, things like your heart to to keep you alive.

So what can happen there is the damaging parts not affected too much, but the remodeling is the body doesn't have the the energy to make the bone remodel.

So then we're not going to see that remodeling take place.

So the damage still happens, but the remodeling doesn't.

And that's how we can see recurrent bone trash injuries happen.

There's genetic factors that can affect some people just have bigger bones.

There's factors are what you did when you were younger and you're growing going through puberty and pre before that and your bones are getting stronger.

If you specialize in sport, let's say you were a long distance runner and all you did was some pretty we're not just running around the track, running in a straight line.

Your bones didn't get the stimulus that they benefit from, which is multi directional and high and make it a little bit different and and variable.

Then your bones may be a little bit smaller.

They're a little bit smaller, they're less less tolerable to to stress.

So there's some other theory factors that we know could be related to their their training distribution.

If someone's newer to running and they're going out and running hard every session, their body's just not going to be ready for that.

And as we spoke about before, the higher their intensity, the more damage is going to be to the bone and their body's not ready.

So they're going to accumulate that damage really quickly and they're remodel is not going to be able to keep up compared to someone had all the same variables to go out and do some slower running, maybe less volume and maybe space 2 days apart.

So you can have the damage occur, have the remodeling help out and have that relationship build over time until we develop that strength within the tissue.

So you can see there's lots of variables and there are plenty more.

So the most frustrating part of course is if you have a diagnosed stress fracture, you are going to have to have some period off where you're doing a significant amount less loading.

Some people may need to wear a moon boot that goes below the knee and some purple may needs mean crutches.

And there's a reason for this.

If we get to the point of a of a diagnosis and we have a stress fracture, we know that that bone needs to remodel, the damage is too much.

We need to have the remodeling occurring.

The bone is at the point that it is so compromised that if we're just walking around doing our day-to-day things, the damage is still too much for the remodeling to occur.

So we have to be really aggressive with the offloading.

And the unfortunate reality is, is the bone is not able to do that without the adequate offloading.

And although it might not be that painful for some, for some people it is there is real significant risk associated say compared to a tendon injury.

A tendon injury can be very sore and very painful, but a lot of the time people can get through day-to-day and the worse it's going to get is really painful.

It's incredibly unlikely for it to rupture if you just do one thing day-to-day.

Whereas with the bone, if we continue to load and walk or even run, just walking around, it can lead to that bone having a really hard time and then sometimes not being able to remodel.

And that can end up with a vascular necrosis, the bone not coming together.

And sometimes surgery where an orthopedic surgeon has to put a pin through the bone for the bone to remodel around there.

And that's quite a serious surgery.

And we see this at higher rate in the higher risk stress fractures like the navicular and the femoral neck.

One of the challenges is that when you damage the bone and you have the remodeling occur, the new bone that gets laid down, it isn't as as strong as the older bone that's been there for a while.

The bone needs to mature.

So although you might not have pain and you're feeling really good, the bone isn't going to be as tolerable as what it was, you know, months before bone syndrome and everything was going OK.

So you need to give it that time.

And the challenge in Healthcare is we don't have the exact days or or weeks on how long that's going to take with a soft tinge injury.

We're pretty safe and using pain as a guide.

The things are feeling OK.

We can continue to to push through and we get some soreness.

We can pull back with a bone threat injury.

We don't have that luxury in most cases where we go through the offloading, which is kind of anywhere from 4 to 12 weeks depending on the severity and what risk factors are associated.

And when we come out of that, we feel pretty good.

We generally have a weak pain free and we start to do it up from there.

Although it is feeling good, it still means the bone is compromised and we need to be very slow with the loading because thinking back to our level 1, we need to have that remodelling occur and that's taking time.

And as we said before, if someone has three or four risk factors present, it's gonna take even longer.

So our loading and our return to running and performance needs to be longer as well.

And it's important because if it's not, then we end up with recurrence.

It can happen, some pain can happen.

We may need to get back in the boot and it's just more time off and it's usually a longer time off than what people are happy with.

There's pretty significant mental stress that goes along with this anxiety.

We I've run myself.

I want to be active and it's hard to find other things to do when you've got crutches and a boot on.

So these are the reasons why people need to have that time off.

And that's why it's so important to understand the bone needs to remodel and it's not going to remodel if the load is too high.

And generally speaking, walking is too high for that.

So that's why we need boot and crutches.

And when we are pain free, that doesn't mean that the bone is ready to tolerate all the loading that we once did.

We need to slowly build up.

If those risk factors are present, then the build up should take longer.

And we are making an educated guess because we don't know the exact timeline and we don't have symptoms to gauge how we're going.

So when that is the case, we always want to make the educated guess less than what we originally think.

So it's safer.

And when I say with my patients is we only want to go through this once.

So we let's take it slower.

It is always difficult when races are coming up and we have a marathon.

But the bone doesn't care what we have coming up.

It knows what it knows.

It's only going to remodel a certain pace.

So we we need to be very safe with that and risk of having again is higher.

So once you've had one bone injury, the risk you're having again is higher.

So we want to try and do everything that we can, good loading, good rehab, a slower return, addressing any risk factors like under fueling so we can get things under control and get back to sustainable running.