Bone Stress Injury Basics
Stress fracture, stress reaction, mild to moderate periosteal edema, severe marrow edema… Ever heard these terms and been confused? All these things would fall under the category of bone stress injuries or BSI’s. What is a bone stress injury? It is when a bone cannot keep up with the stresses being placed on it, and it starts to accumulate damage. Bone is always changing and remodeling based on the stresses placed on it. When a runner runs or works out, they stress their bones. That can certainly be a good thing to maintain or improve bone health, but if the runner doesn’t have enough recovery time, fuel available, or has risk factors for low bone health, the bone can’t keep up. When the bone can’t keep up but is still stressed it begins to accumulate microdamage and moves to the right on the continuum below.
So from this, you could appreciate this injury doesn’t happen overnight. It’s not like falling and breaking a bone in one moment. There are going to be some warning signs and clues along the way. Also, appreciate that a BSI can mimic other running-related injuries early on which is why imaging is so helpful (last section). Here are some things that raise my antennae 👽 for a bone stress injury:
Symptoms:
Pain that does not “warm-up” after 10-15 minutes of running
A diffuse ache that becomes increasingly painful with continued activity.
Early stages: symptoms occur during running but are gone once running ceases
Intermediate stages: symptoms come on earlier in a run and linger after a run
Advanced stages: running is too painful, pain is present with low-level activities like walking, pain at night
Swelling, redness, bruising, or tenderness around the area (if it is a bone close to the surface)
Doesn’t fit a pattern for a tendon related injury or other common running-related injuries
Risk Factors
Previous history of bone stress injury, especially at the same site
Recently reduced caloric intake while still training at a high level
No ball sports while growing up
Females: 1st menstrual cycle occurred later than 15 years old
Females: disrupted menstrual cycle
A recent large spike in volume or intensity
A big change in footwear, for example, maximalist shoe to zero-drop minimal cushion shoe
A recent change in footstrike pattern
Are all bone stress injuries the same? They are not. Different areas of bone have more or less blood flow which can affect healing and recovery. Also depending on where the injury is within the bone, it can be at a compressive side or tension side of the bone. If the area of bone is under compressive load it is getting squished together versus elongating. This is a more stable situation. So a bone that has a lot of blood flow and is under compressive load is a low-risk site. That bone is in a better place to heal with conservative measures, and recovery times are generally shorter. On the flip side of the coin if a bone has less blood flow and is under tensile load (elongating) it is considered high risk. Healing times are longer and there is potential for surgery if appropriate actions are not taken. Here is a graphic naming the different risk categories and corresponding areas of bones.
The main point of these first two graphics is, if you’re dealing with a potential bone stress injury it’s important to find out where it is on the continuum, and what part of what bone is injured. Knowing that is critical in determining the next steps and optimizing recovery. MRI is the gold standard for diagnosing these injuries in coordination with an orthopedic clinical examination. X-ray or radiographs are not going to be accurate in diagnosing these injuries in the early stages. A negative x-ray could lead someone into a false sense of security and miss the critical window to intervene.
*For certain BSI’s (tarsal navicular, longitudinal tibia, and pars interarticularis) a CT scan can better define the injury.
I hope this helps to give you some basic information about these injuries. If you have other questions please feel free to reach out.
-Steve White, PT, DPT, OCS, CSCS