Stress fractures are microscopic injuries to bone that cause pain, difficulty walking, and can potentially become true fractures. Unlike true fractures, stress fractures are not usually the result of a twisting injury, crushing injury, or impact injury. These injuries cause an immediate break in the bone material. Stress fractures cause bone damage in a different way. A stress fracture is typically the result of chronic stress to the bone, hence the name. This stress can come from repetitive activity at work or home, such as platform hopping, pedal use, or simply running on hard surfaces like asphalt. Over time, the material within the bone core will become bruised and begin to microscopically crack. This cracking can slowly worsen as the stress continues over weeks and months. Eventually, enough damage will occur that the bone begins to weaken at the point of stress and microscopic fracture. In the foot, this leads to pain, slight warmth, and possibly swelling. As the damage worsens, the outer shell of the bone can eventually crack along with the core, leading to a true fracture.
Stress fractures can be difficult to see on x-rays, at least initially. Eventually, the area with the stress fracture will appear thickened and more dense, as new protective bone if formed to strengthen the stress site. Most of the time, a diagnosis is made based on symptoms rather than the x-ray. An MRI or CT scan can also show stress fractures, and can do so even when the x-ray appears normal. If there is doubt about the diagnosis, one of these two methods may be used.
Treatment of stress fractures involves rest and immobilization of the bone, much like the way a true fracture is treated. This is usually accomplished with a protective walking boot, although some difficult-to-heal stress fractures may need to be immobilized in a cast. Unlike true fractures, a stress fracture can take much longer to heal. It is not uncommon for a stress fracture of the foot to take two to three months before healing is completed. Some stress fractures may even need electronic bone stimulators or surgery if they cannot heal appropriately. The underlying activity that caused the stress fracture also needs to be changed, and precautions need to be employed to keep the condition from re-developing (such as sturdier work shoes or a change in running surface).