While they can occur anywhere when muscles, tendons and bones are overworked, stress fractures are more common in the foot than in the ankle. The most susceptible bones are the metatarsal bones that connect the toes to the foot, and the calcaneus bone, which is the heel. These hairline fractures occur because of fatigue in the bone due to overuse. The patient will usually notice some swelling or bruising, and possibly some soreness at the sight of the stress fracture.
Runners are frequently victims of stress fractures, but any athlete can experience them, especially if training is excessive or equipment is subpar. Keeping bones strong with vitamins and calcium can be helpful, but careful training, good technique and properly fitted shoes are the best ways to avoid a stress fracture.