Stress fractures of the foot and ankle, part 2: site-specific etiology, imaging, and treatment, and differential diagnosis.

Stress fractures of the foot and ankle are a commonly encountered problem among athletes and individuals participating in a wide range of activities. This illustrated review, the second of two parts, discusses site-specific etiological factors, imaging appearances, treatment options, and differential considerations of stress fractures of the foot and ankle. The imaging and clinical management of stress fractures of the foot and ankle are highly dependent on the specific location of the fracture, mechanical forces acting upon the injured site, vascular supply of the injured bone, and the proportion of trabecular to cortical bone at the site of injury. The most common stress fractures of the foot and ankle are low risk and include the posteromedial tibia, the calcaneus, and the second and third metatarsals. The distal fibula is a less common location, and stress fractures of the cuboid and cuneiforms are very rare, but are also considered low risk. In contrast, high-risk stress fractures are more prone to delayed union or nonunion and include the anterior tibial cortex, medial malleolus, navicular, base of the second metatarsal, proximal fifth metatarsal, hallux sesamoids, and the talus. Of these high-risk types, stress fractures of the anterior tibial cortex, the navicular, and the proximal tibial cortex may be predisposed to poor healing because of the watershed blood supply in these locations. The radiographic differential diagnosis of stress fracture includes osteoid osteoma, malignancy, and chronic osteomyelitis.