Does altered biomechanics cause marrow edema?

PURPOSE

To determine if altered weight bearing causes the appearance of marrow edema on magnetic resonance (MR) images.

MATERIALS AND METHODS

Twelve volunteers underwent MR imaging with a short inversion time inversion-recovery (STIR) sequence at 1.5 T. The hips, knees, ankles, and feet were evaluated before and 2 weeks after altered weight bearing achieved with overpronation of one foot. Three volunteers underwent imaging a third time, 2 weeks after overpronation was stopped. Two observers assessed the images for evidence of marrow edema.

RESULTS

Changes were seen on images in 11 volunteers; the overpronated side only was affected in 10. Most changes occurred in the foot followed by the tibia and the femur. Most changes were a diffuse increase in marrow edema. In two volunteers, the changes resembled those of stress fractures.

CONCLUSION

Altered weight bearing should be added to the list of causes of increased medullary signal intensity (ie, marrow edema) on MR images.