MR Imaging Findings of Fatigue Fractures of Lower Extremity in Young Soldiers

ABSTRACT

PURPOSE: To evaluate the MR imaging findings of fatigue fractures of the lower extremity in young soldiers. MATERIALS AND METHODS: In 22 cases of fatigue fractures of the lower extremity in young soldiers proven byclinical findings and radiological follow up, the MRI findings were retrospectively evalvated. All patients weremale and aged between 19 and 21 years. As seen on MRI, the bone marrow edema, intramedullary low signal intensityband, cortical fracture line, periosteal reaction, surrounding soft tissue edema, and enhancement pattern wereanalyzed and the site of involvement was determined in the axial plane. RESULTS: The locations of fatiguefractures of the lower extremity were the tibia (n=12), fibula (n=8), femur (n=1) and second metatarsus (n=1). Alloccurred in diaphyses the junction of the proximal and middle (n=10), middle (n=9), proximal (n=2), and distalshaft (n=1). The sites of involvement were the posteromedial (n=6) and medial side (n=6) of the tibia, and theentire portion of the fibula(n=5) in the axial plane. MRI findings were bone marrow edema in 20 cases,intramedullary low signal intensity band in 14 (which were continuous with the cortex or cortical fracture line),cortical fracture line in 13, and periosteal reaction and surrounding soft tissue edema in all. Ongadolinium-enhanced images, enhancement was seen in the bone marrow in 19 cases, in the subperiosteal region in18, and in the surrounding soft tissue in 22. CONCLUSION: In fatigue fractures of the lower extremity in youngsoldiers, the main locations were the tibia and fibula, and characteristic MR imaging findings were intramedullarylow signal intensity bands, which were continuous with the cortex or cortical fracture line and often accompaniedby bone marrow edema, periosteal reaction, and surrounding soft tissue edema.