A bone stress reaction is the medical name for a (usually) painful bone irritation.
They’re most commonly see in the legs and feet because of the way that they happen.
Bone stress reactions can occur due to either impact loading (repetitive hard impacts) or connective tissue traction (repetitive strong muscle forces on the bone).
These forces cause the bone to break down, which is a normal and healthy response to bone loading.
The problem is in the recovery!
The bone doesn’t fully repair before its next round of loading, causing a downward spiral of incomplete repair and further breakdown.
Eventually the bone reacts, causing a “bone bruise” on images.
The bone stress reaction causes a dull, usually prolonged, ache around the injury site after loading.
Bone reactions caused by impact loading can progress to bone stress fractures with ongoing overload, so it’s important you get an early and accurate diagnosis.
Diagnosis can be tricky due to the non-descript nature of the pain and how it lingers after exercise.
As a general rule of thumb, if you have pain lasting 24 hours after exercise, you should suspect bone stress reaction or bone stress fracture as possibilities.
Clinical secrets of bone stress reaction diagnosis
Why are bone stress reactions hard to diagnose?
A bone stress reaction is more likely after a period of significantly increased loading (such as return to running after a prolonged absence) or with abnormal loading.
It’s this second point that makes it tricky to diagnose – bone stress reactions often occur with other injuries!
You might be limping due to a sore toe, which is correctly diagnose as a painful bunion.
But after only a few weeks of limping, you’ve developed a bone stress reaction in the heel on the same side as your bunion.
The pain is vague so the focus remains on the bunion pain until, BAM, one day the heel pain becomes excruciating and you’ve cracked the bone.
That might sound a little dramatic (and it kinda is…) but that’s how bone bruising can often go unnoticed until it’s too late.
It’s one of the big reasons why bone stress reactions can be difficult to diagnose in their early stages.
“It’s OK, anti-inflammatories take the pain away”
The other factors that can make it difficult to diagnose is that symptoms from bone stress reactions are significantly relieved by anti-inflammatories.
That might sound like a good thing, however use of these medications can worsen the condition rapidly.
Not only do they mask the pain but they can prevent to bone from effectively recovering and healing due to their effect on bone cell creation.
We often hear people remark that “it can’t be too bad because one Nurofen/Advil/Voltaren and the pain goes away”, but that’s actually a big concern and sign of trouble.
I once treated a very athletic lady who had been running up to 50km/30 miles per run for 12 months on a pelvis with a significant stress fracture – she only realised how significant it was when she ran out of meds mid-run and couldn’t walk back!!!
So clinical secret #2 is that if anti-inflammatory meds completely relieve the pain, it’s a bad sign for bone stress reactions or stress fractures.
How do you grade your bone stress reaction?
Third tip is that the duration of soreness after activity can be an effective gauge of the severity of the reaction.
Bone stress is graded on a four-point scale.
Grade 1 is mild bone stress reaction, often seen after a big day of activity, and recovers fairly quickly with some rest (although too much rest is a very bad thing – read about that here).
Grade 2 is a moderate reaction without any crack appearing…yet.
Grade 3 is a severe bone reaction with lingering pain and a distinct bone bruise seen on MRI. Still no crack though.
Grade 4 is a bone stress fracture. Lots of pain, aches for days and the bone has now broken down to the point that a crack is visible on scans.
If your pain lingers for less than 24 hours, it’s probably in the lower grades of bone stress.
If you pain after running lasts 1-2 days, you’re probably in the higher grades of bone stress reaction and teetering on the brink of a bone stress fracture.
If your pain lingers for 3 days after a run, you’ve probably got yourself a grade 4 bone stress fracture.
Common misconceptions about bone stress reactions
Does a bone reaction mean that I’m going to get a stress fracture?
Not all bone stress reactions are at risk of progressing to stress fracture.
Reactions caused by the pulling force from tendons or other connective tissues cannot progress to stress fractures.
An example of this kind of stress reaction is a reaction in the fibula, the thin bone that runs parallel to your tibia (or shin bone).
The reaction is caused by powerful toe muscles pulling on the bone, so it can become painful but almost never cracks the bone.
Can I reduce the pain?
Treatments that ease the symptoms, such as medication or ice packs, do not directly assist the recovery of the injury.
Essentially feeling better does not equate to getting better.
In the case of using anti-inflammatories to feel better, it usually makes it feel better/pain-free but actually makes the condition a whole lot worse!
As a general guide, if doing an activity hurts, you shouldn’t be doing the activity.
Don’t try to hide the pain – it’s your best guide of what you should or shouldn’t be doing.
Figure out a way of avoiding or modifying the activity so the pain reduces – it’ll usually mean that the bone is able to recover faster as well.
Complete rest is the enemy
Rest alone won’t resolve a bone stress reaction.
It will ease the symptoms within a few days but the bone healing is much slower to respond and usually flares up soon after the return to loading.
Spend your recovery time maintaining your strength and fitness.
You’ll also need to gradually increase the loading on the bone – as a living tissue, it responds to loading.
Too much loading and you breakdown the bone healing.
But too little loading and the bone regrows weak and not ready for athletic stuff.
To read more on why complete rest is a very bad idea, have a read of this post.