Have you noticed how many people are given a boot to treat stress fractures? If you’ve had to wear one you’ll know they’re pretty uncomfortable (not to mention expensive!!!). Perhaps you didn’t have the fun experience of a boot but were put on a knee scooter or crutches – still not much fun! So, is this approach to stress fracture always necessary? Is this routine backed up by research? I have blogged about stress fractures previously (parts 1 & 2), but some recent patients and a nice social media post by researcher Dr Rich Willy encouraged me to expand a little!

Immobilization and stress fractures:

In many aspects of life there are a continuum of options to reach a solution. Some might be the best, some might be the worst, and some are in-between. This is certainly the case in medical care, and I think that we see this with boot prescription and stress fractures; People do get better using them, but coming out of the boot and getting back to all activities is not straightforward and may not be the most efficient process. People are often given a boot for a standard six weeks (do they really need this long?!) and little guidance/parameters are given on what to do when they come out of the boot. So, I see people who take the boot off early as it is either uncomfortable and they don’t believe they need it (and in the process lose confidence in their provider). I also see many athletes who have stuck with it to the letter of the law (worried that not following the advice will put their season at risk) but then come out of the boot like a bat out of hell! They have kept their endurance up with swimming or cycling so they an easy run at two or three miles is very reasonable. With the tissues having been unloaded for so long they have developed weakness and have lost tolerance meaning they are less capable of dealing with the load and end up flared up (either the original problem or something else!). Sometimes, this is significant enough that the doctor puts them back in the boot (not necessarily with any better logic or guidance) and they end up in a horribly vicious cycle. A great example from research as to why there could be recurrence coming out of the boot is that a 1cm difference in calf girth (circumference) leads to a 400% increase in tibial stress fracture!¹ Of course, this doesn’t always happen! Some people do pretty well coming out of the boot with a gradual return to activity, but could they have done better? How will the majority fair and is this the most optimal approach? Could they have gotten better more quickly, and/or in a way that reduces the odds of future stress fracture?

Low-Risk Stress Fractures

As common as the prescription of a boot and reduced weight bearing is for stress fracture, you would think there would be clear evidence showing stress fractures should be immobilized! You would think the same is true for the common time of six weeks confinement to the boot. Sadly, this is not the case for the majority of stress fractures. These so-called ‘low-risk’ stress fractures occur in areas with good blood flow and experience low-to-moderate stress – they typically heal well without complication². For these stress fractures we should modify activity to reduce pain and allow controlled loading to encourage bone growth. In the majority of these patients, pain is low with normal activity – boots, crutches, or scooters are not needed. If there is notable pain with normal daily activity, some form of device to reduce motion and load can be used, but should be assessed on a weekly basis and stopped as soon as those activities are comfortable. Some providers might question if patients do a good job deciding if pain is too much, and yes we should consider on a case-by-case basis, but if good education is given most adults and a good number of adolescents can do well with this progression. Perhaps this is a glimpse into a driver for the current care – under insurance-based care, with packed schedules and limited time with the patient, is it hard to provide the requisite education to optimize care? 

To help put the above info into real world situations, let’s consider the treatment of two patients with low-risk tibial stress fracture that have slightly different presentations:

• Joey has pain with running and is diagnosed with a low-risk posterior tibial (shin) stress fracture. He is painfree walking so there is no benefit in using a boot. Instead he is told to continue to walk, aiming for 30-min with no pain. He is also told to start weightlifting exercises and are then progressed through appropriate loading exercises to stimulate bone growth (We’ll discuss these more below!)
• Jack has pain with running, walking, and has a visible limp and are diagnosed with the same low-risk posterior tibial stress fracture. He is given a walking boot or crutches and is told to try walking without it after one week. If it is then pain free (or very low grade pain) he is to stop wearing it and to start to build up time walking to 30-minutes. If it was notably painful (or becomes painful again) he is to wear it for another week and assess again. He is also started on weightlifting exercises that are low-to-no pain.

High-Risk Stress Fractures:

Obviously, there is more to their treatment, and we will come onto exercise prescription in a bit as this is highly important. Let’s discuss when immobilization is appropriate, and for how long. First, what makes a stress fracture ‘low risk’ or ‘high risk’? High risk, in this case, refers to the risk that the injury may not heal, or may require surgery to heal. High-risk stress fractures occur in areas that experience high stress and also have poor blood supply; these two features are what makes healing more difficult, and because of this there is more of a case for reducing movement and load.

In fact, these fractures are so challenging that in athletes there is even a suggestion that some should go straight to surgery as it will allow for earlier return to sport and less risk of complications! For example, in the case of a navicular stress fracture in the foot, it is common and advisable practice to immobilize for 6 or more weeks. Even then, for athletes, perhaps they should be surgically fixed in the first place with the average return to sport being 16.4 weeks after surgery compared to 21.7 without³. 

Is it Cookie-Cutter Treatment?

So, with the above distinctions, why does it seem so many people are treated in boots in such a cookie-cutter way? In patients I meet, I look through their charts (notes from other providers, their MRI, etc) and don’t see specificity in the diagnosis. For example, high-risk anterior tibial stress fractures and low-risk posterior ones should be treated differently, but in so many charts I just see the words “tibial stress fracture” and the initial treatment given is walking boot and follow up after 6-weeks…. As we have seen this might be the right treatment for the high risk tibial stress fracture, but for the low-risk one?!!! Also in the case of tibial stress fractures there is actually an MRI grading system(see video below) and there are studies that give us some idea of how long each grade will take to return to sport. Yet, sadly, I rarely see any mention of classification in patients notes and again often there is an arbitrary 6-weeks return visit to see about getting out of a boot. 

An Example of Two Approaches

I just had a patient who was a competitive runner who developed some shin pain. I saw him and felt the main issue was tendon pain, but that there was a risk of stress reaction. He went for an MRI and it was read by two healthcare providers (radiologist and orthopedist) as “concerning for tibial stress reaction” and “tibial stress fracture in diaphysis”. He wasn’t in pain with walking, only with running, but was provided with a boot and told to wear it for six weeks. Instead of it helping, he was actually in more pain in the boot which led to him questioning the recommendation to the point that he decided to disregard the doctors recommendation and continue PT. Review of his MRIs by me and in consultation with the initial radiologist showed the stress fracture to be a low-risk posteromedial tibial fracture that had features suggestive of grade II-III; This and the fact he was painfree with normal walking highlighted the lack of sense in using a walking boot! He went on to be back running competitively by the time the six weeks in the boot would have come to an end.

To be fair to the different doctors who are charting, MRIs do not tell the whole picture so we have to take the physical examination and the risk factors (e.g. age, sex, gender) for stress fractures into account. We also have to realize that MRIs have false negatives as well as false positives, and that we know that painfree runners have MRIs which show inflammatory changes in the bone (43% of 21 asymptomatic runners had MRI findings consistent with tibial stress reaction!⁴). With this it should be noted that only a subset of suspected stress fractures should have MRI and getting one too soon may cloud the picture. The chart below² shows when MRI should be considered.

(Click to Expand)

Exercise for healthy bones

So, the picture is not necessarily straightforward and given the amount of people prescribed boots you would think it was! Mostly, a low-risk fracture should be treated with activity modification and if pain persists, immobilization can be considered but should be reassessed regularly (i.e. weekly). If pain is well controlled and they do not need a boot, we want to progress onto weightbearing exercise that stimulates bone.

Weightbearing exercise is needed for bone growth – this is not something new, as we all know it is promoted for those with osteoperosis. But, there is weightbearing exercise and there is weightbearing exercise! PT and running researcher Dr Rich Wiley of University of Montana put out a great series of posts about the best exercises and parameters for bone formation (Give him a follow!)

 

View this post on Instagram

 

A post shared by Rich Willy, PT, PhD & Team (@montanarunninglab) on Aug 6, 2019 at 1:51pm PDT

Which Exercises?

Slide 2 from Instagram post by Rich Willy

As you will see from slide two in his post, the exercises people often do when using a boot, such as swimming or cycling, do absolutely nothing to promote bone formation. Even getting back to road running only provides small benefit to bone formation. Instead, we should be considering weightlifting and jumping exercises. Jumping exercises should be taken to the level of a weighted vest or backpack, and zigzag hopping. Zigzag hopping is optimal as not only is there compressive loading going down through the bone, but also there are lateral and medial forces stimulating as well. Someone who is recovering from a stress fracture is not going to start jumping exercises immediately, but as soon as they can tolerate the motion and some repetitions they should be started.

How Many Times?

Slide 4 from Rich Willy’s Instagram Post

This brings us on to another important aspect which is the dosage of the jumps.  We have touched on dosage of exercise in several other blog posts with regards to soft tissue (muscles, tendons), but there is some difference with bone. As Rich points out in his 4th instagram slide, bone adapts to the first 20 repetitions and by 40 repetitions it no longer adapts.

How Often?

Slide 5 from Rich Willy’s Instagram Post

In slide 5, he points out that the bone is not particularly adaptive for another 4 hours. So, short cycles of 20-40 jumps every 4+ hours would be a good dosage as long as they are comfortable. Using these exercises and dosages would in part help someone to better recover from a stress fracture and reduce the chance of reinjury. We do however, have to make some changes to this depending on the contribution to pain from the soft tissues (tendon, muscle, nerve, etc.)

What about Running?

As we have seen, running is not great for building bone and it is important to do other exercise first. However, at some point you are going to be painfree walking for 30-minutes and it will make sense to restart. You may have been doing other aerobic exercise such as biking and swimming and it will feel like you can run an easy 2 or 3 miles, but that would be a big jump after a period of restriction. Instead you could use a couch to 5k as an option for returning, this is a very gradual option. Or you could use the program below that was suggested in a recent research⁵ paper and would get you back to running over a three-week period. While following it you would want to keep any memorable stress fracture pain low to none.

Conclusion

I could probably write several blogs on this and trying to find a balance between being very basic and far too complex is challenging! Most of my patients want to understand what has gone on with their problem and it seems to help them stick to the plan. If you have been in a vicious cycle trying to recover from a stress fracture using a boot, let me know and let’s talk about what other options you might have.

References:

1. Bennell KL, Malcolm SA, Thomas SA, et al. Risk factors for stress fractures in track and field athletes. A twelve-month prospective study. Am J Sports Med. 1996;24(6):810-8.
2. Mandell JC, Khurana B, Smith SE. Stress fractures of the foot and ankle, part 1: biomechanics of bone and principles of imaging and treatment. Skeletal Radiol. 2017;46(8):1021-1029.
3. Mallee WH, Weel H, Van dijk CN, Van tulder MW, Kerkhoffs GM, Lin CW. Surgical versus conservative treatment for high-risk stress fractures of the lower leg (anterior tibial cortex, navicular and fifth metatarsal base): a systematic review. Br J Sports Med. 2015;49(6):370-6.
4. Bergman AG, Fredericson M, Ho C, Matheson GO. Asymptomatic tibial stress reactions: MRI detection and clinical follow-up in distance runners. AJR Am J Roentgenol. 2004;183(3):635-8.
5. Warden SJ, Davis IS, Fredericson M. Management and prevention of bone stress injuries in long-distance runners. J Orthop Sports Phys Ther. 2014;44(10):749-65.