Knee and shoulder fractures: association of fracture detection and marrow edema on MR images with mechanism of injury.

PURPOSE: To assess the value of magnetic resonance (MR) imaging for enabling the classification of fracture mechanisms and to compare marrow edema caused by compressive forces with that caused by tensile forces. MATERIALS AND METHODS: In 62 knees or shoulders, 78 fractures were identified prospectively on MR images or plain radiographs; compressive or tensile forces were determined retrospectively to have caused impaction or distraction...