Imaging findings of femoroacetabular impingement syndrome: focusing on mixed-type impingement

The aim of our study was to analyze the imaging findings of femoroacetabular impingement (FAI) Eight consecutive patients [age range, 19-46 years (mean, 28 6 years), M/F ratio=7 1] who underwent operation for FAI were analyzed We analyzed bump, acetabular retroversion and protrusion, and osteoarthritis in the radiographs In MR arthrography, we analyzed alpha-angle, anterolateral labral tear, cartilage abnormality, herniation pit, paralabral cyst, subchondral cyst, and marrow edema We correlated the imaging findings with operative findings. In the radiographs, all eight patients showed bump and osteoarthritis (Kellgren Lawrence score II-IV), and live (62 5%) patients showed acetabular retroversion In MR arthrography, anterolateral labral tear and mild cartilage abnormality (Outerbridge grade I and II) were seen in all eight patients, increased alpha-angle was seen in six cases (75%) Anterolateral labral tear, bump, and mild cartilage abnormality were seen in all eight patients during operation According to the above findings, we divided the patients into three earn-type and five mixed-type FAI In the five mixed-type FAI, both bump and acetabular retroversion were seen The mixed-type FAI is the most prevalent type in our study The main imaging findings of mixed-type FAI were acetabular retroversion, bump, and early osteoarthritis in radiographs, and anterolateral labral tear, cartilage abnormality, and increased a-angle in MR arthrography (C) 2010 Elsevier Inc. All rights reserved