Bone can strengthen over time in response to loading, the same way that, conversely, astronauts lose bone mass when the stress of gravity and walking is removed. Stress fractures occur when a cycle of repetitive forces, none on their own sufficient to cause injury, is applied such that these forces exceed the bone’s ability to adapt and cumulatively damage the bone. In cases where the bone is entirely healthy, and the cause is simply too many cycles of load, the injury is denoted as a fatigue or stress fracture. Separately, fractures can also occur in bone that is not healthy, such as in the setting of osteoporosis, and does not stand up to even few cycles of repetitive forces. These are called insufficiency fractures. Repetitive activities such as walking, running and jumping can subject the bones of the foot to large forces that potentially lead to stress fractures, especially if these activities are started abruptly and without a ramp up period that allows the bone to effectively adapt. These injuries are commonly seen in the 2nd or 3rd metatarsal neck region, the base of 5th metatarsal (Jones Fracture), the sesamoid bones of the great toe, the navicular bone, or the calcaneus tuberosity.
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