A stress fracture is a bony injury that is not caused by a single traumatic event (like a fall), but rather by repetitive loading (like running). An analogy can be made with that of a paper clip. If one straightens a paper clip and then bends it back to its original position, the clip remains apparently undamaged. However, if one repeats this dozens of times, the paper clip will break. Unlike a paper clip, our bones are living tissue and have the capacity for repair. However, this repair process takes time. If we overstress a bone and do not allow enough time for repair before we stress it again, there can be some damage to the bone. If this practice is continued, the damage can increase to the point where the bone can develop a crack. If one persists in activities even further, the bone can even break completely in two. Both the crack and complete break are considered fractures.
As you may expect, we typically see these injuries in individuals that do a lot of long distance walking and/or running, especially if they are not used to it. For example, military recruits are often forced to do a lot of marching in boot camp. As a result, they often develop what is called a “march fracture.” This is basically a stress fracture of one of the bones in the foot.
There are many different types of stress fractures. Fortunately, most of them can be treated simply by decreasing one’s activity to the point where it does not hurt. This allows the bone to repair itself. However, there are some stress fractures which should be treated more aggressively in order to achieve healing. Sometimes, this can mean being immobilized in a cast and/or being placed on crutches. Other times, this means surgical intervention.