Bone stress injuries suck.
Quite often they happen when we are feeling like everything is just beginning to come together. For many, this will be when our training and activity levels have reached the stage when our fitness and routine benefits have started to kick in and we are excitedly looking forward to what the next period has in store.
If you participate in a repetitive, weight-bearing sport. There is no doubt that you, or someone you know of, has suffered from a bony stress injury.
This is because of all sports related injuries encountered, boney stress injuries are reported to account for 10- 20%! With this increasing to as high as 30% in runners.
So let’s explore what they are, why we get them and how to treat and prevent them.
What is a bone stress injury?
Bones, just like any other structure within the body, have a certain capacity or threshold of work in which they can tolerate.
When we undertake activity, bones experience small and gradual breakdowns. These breakdowns in turn stimulate adaptation and during rest create remodelling, rebuilding and ultimately stronger structures.
This is great, as it enables them to be more resilient to future activity as well as help to reduce the risk of unwanted conditions such as osteoporosis.
Bone stress injuries are the progression of this breakdown, in which the structure and integrity of the bone reaches a stage of failure and disrepair where it no longer has the ability to handle the repetitive loads placed upon it and this is where the issue begins.
Simply, the bone can’t handle the consistent, repetitive work it’s had to do.
Generally, Bone stress injuries can be classified into three progressive stages.
Bone strain/stress response
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There is breakdown of bone on imaging but no pain or symptoms
Stress reaction
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There is breakdown of bone on imaging in combination with localised pain on palpation and high to moderate level activity
Stress Fracture
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There is a definitive break through the bone and pain is evident during low level weight-bearing
A delay in diagnosis of a bone stress injury can result in more significant injury and progressing further down the continuum. Therefore requiring a longer treatment period and more time away from doing what you love.
Why do they happen?
As touched on above, bony stress injury happens as a result of the bone failing under the repetitive, submaximal forces that are placed on it.
Think of these loads a little bit like the straw that broke the camel's back. The bone can handle the pressure put on it for a short period of time, however after consecutive, recurring incidents it breaks down!
Major factors in the presentation of a bony stress injury revolve around factors which intrinsically decrease the bone’s integrity or extrinsic factors which have exposed it to more work.
These include:
Intrinsic factors
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Low Bone Mineral Density
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Low Vitamin D & Calcium Levels
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Reduced Muscular Strength
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Biomechanical loading patterns
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Energy stores and availability
Extrinsic Factors
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Training Errors
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Training Surface
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Shoe Type
Who’s more at risk?
Females
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This is mainly due to the presence of the female athlete triad, which because of the female reproductive system’s interrelationship with energy availability and bone mineral density they are more susceptible to bony breakdown.
Runners
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Due to the repetitive, consistent, highly loading demands that running has on the lower limb
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50% of track and field athletes have reported a history of at least 1 boney stress injury
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With the risk of occurrence increasing specifically for those who run greater than 32km per week
What are the most common sites for bone stress fractures and reactions?
Below are the most common areas for bony stress injuries to occur:
Metatarsals
Inside & front of the tibia
Shaft & Neck of the Femur
Medial Malleolus
Calcaneus
From these they can then be graded into areas of greater risk for complication and severity.
Low
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2nd, 3rd & 4th Metatarsals
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Inside of Tibia
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Fibula
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Lateral Malleolus
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Calcaneus
Moderate
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Cuboid
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Cuneiform
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Shaft of femur
High
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Navicular
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Sesamoids
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Lateral aspect of Talus
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Medial Malleolus
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Neck of Femur
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Bottom of Tibia
How fix a stress fracture:
Short Term
Deload the bone
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This can take a couple of forms and is dictated by severity and location.
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Beginning with simple tweaks to training schedules by the removal of specific, highly loaded repetitive sessions or activities and ranging to full non-weight-bearing in a moon boot, wheelchair or crutches.
Addressing intrinsic factors
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Such as BMD, Vitamin D and Calcium levels
Longer Term
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Gradual re-integration and expose of structure to loading
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Strengthening of surrounding musculature
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Planning longer term training increases in combination with monitoring of site
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Addressing biomechanical factors contributing to localised load.
How do you prevent stress fractures?
The good news is that a lot of the longer term strategies above are fantastic for helping to prevent them.
Additionally to this are:
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Incorporating diversity in activity
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Ensuring consistent bone health
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Getting strong in surrounding soft tissue musculature.