Stress fracture
Also called: hairline fracture, march fracture
What it means
A stress fracture is a small crack in a bone caused by repeated stress over time, rather than a single hard blow.
Knowing how stress fractures form helps you balance enough activity to keep bones strong without overloading them before they're ready.
A stress fracture is a tiny crack in a bone that develops gradually from repeated force, rather than from one sudden injury. It's often called a hairline fracture, and when it happens in the foot or lower leg from repetitive impact, like marching or running, it's sometimes called a march fracture. Common spots include the tibia, fibula, and bones of the foot.
These fractures happen when bone is loaded repeatedly, faster than it can repair itself. Bone constantly remodels in response to the forces placed on it, and a healthy amount of load actually helps maintain strength. But when loading is excessive, too frequent, or ramped up too quickly without enough recovery, microscopic damage builds up faster than the bone can patch it, eventually leading to a visible crack.
Stress fractures are more likely when bone is already weakened, such as with osteoporosis or osteopenia, or when someone suddenly increases activity without easing into it. Symptoms usually include localized pain that worsens with activity and improves with rest. Diagnosis and treatment decisions, including imaging, activity changes, and healing time, should always be guided by your doctor.
Stress fractures form from repeated loading, so bones need enough activity without being overloaded too soon.
Where this leads
WordStress fractures show what happens when bone is pushed past what it's ready for. Curious how bones generally adapt to the loads you give them?
Where the Academy teaches it
This page is the short version. The lessons teach it in full, with the context around it and a quiz to lock it in.
Related words
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The mechanostat is Frost's theory that bone acts like a thermostat, removing, maintaining, or building bone…
Microstrain (µε) is a tiny measure of how much bone bends under force — one millionth of its original length.
An insufficiency fracture is a break that happens in bone already weakened by low bone density, caused by normal…
Bone remodeling is the lifelong cycle where cells called osteoclasts remove old bone and osteoblasts build new bone…
Weight-bearing exercise is any activity, like walking or dancing, where your body supports its own weight against…
Education only, not medical advice. Decisions about tests, medications and treatment belong with your own doctor. OsteoStrong does not diagnose, treat or cure any disease.
