Stress fractures, sometimes called hairline fractures, often occur in the feet, because of the weight-bearing responsibility of these bones. Stress fractures are small, microscopic cracks in bone that occur when the bone is unable to handle the load, or weight, placed on it.
Foot stress fractures are often caused by overuse or repetitive activities. Because of this, stress fractures are commonly seen in athletes, such as runners, soccer players, or dancers, but they can also be seen in normal people who have changed their daily activities.
Foot stress fractures also occur more frequently in people with health problems that affect bones such as osteoporosis, or people with abnormal gait or other problems, such as bunions or tendonitis.
Mechanism of Injury: Foot Stress Fractures
Bones are living tissues that are constantly adapting to loads by rebuilding and repairing. This process is called remodeling and is the reason that bones can heal after injury. This process also helps bones become stronger when loaded appropriately, and the reason bones become weaker if they are not exposed to sufficient loads.1
Stress fractures occur when the loading on the bone is greater than the bone’s ability to adapt to stress. Before the bone fractures, there can be pain in the area due to swelling and abnormal remodeling. This is termed a stress reaction, and can be seen on specialized imaging.
Foot Anatomy: Where Stress Fractures Occur
Stress fractures can occur in any bone of the foot, however, certain bones are affected more often than others.
- The metatarsal bones, which connect the toes to the midfoot. The second and third metatarsal, which connect the second and third toe, are most commonly injured, and represent 17-35% of all stress fractures of the foot and ankle.2 Metatarsal fractures are common in dancers and runners.3
- The calcaneus bone, also called the heel bone, forms the foundation of the back of the foot. The calcaneus bone represents approximately 21-28% of stress fractures of the foot and ankle.1,2
- The navicular bone, which sits near the top of the foot.
In children, stress fractures in the foot can occur in areas of bone growth. Common locations for foot stress fractures in children include the calcaneus, cuboid, talus, and navicular bone.4
The anatomical location of the stress fracture determines how it heals. Stress fractures in areas of tensile forces or areas with poor blood flow do not heal as well as stress fracture in areas with compressive forces and good blood flow.1