Longitudinal stress fracture: patterns of edema and the importance of the nutrient foramen.

Abstract

We reviewed the MR appearances of six cases of longitudinal stress fracture of the lower extremity. One fracture was in the femur and five were in the tibia. Four of the tibial fractures showed edema starting in the mid-tibia at the level of the nutrient foramen with the fracture on the anteromedial cortex. The other tibial fracture started at the nutrient foramen. Three fractures (two tibial and the femur fracture) showed eccentric marrow edema; all fractures showed either eccentric periosteal reaction or soft tissue edema. Primary diagnosis of longitudinal stress fracture is made by finding a vertical cleft on one or more axial images. Secondary signs of position of the nutrient foramen and patterns of edema may be useful.