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

Suk Joo Hong, Won Yong Shon, Chang Yoon Lee, Jae Sung Myung, Chang Ho Kang, Baek Hyun Kim

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    14 Citations (Scopus)


    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 α-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 five (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 α-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 cam-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 α-angle in MR arthrography.

    Original languageEnglish
    Pages (from-to)116-120
    Number of pages5
    JournalClinical Imaging
    Issue number2
    Publication statusPublished - 2010 Mar


    • Acetabulum
    • Hip joint
    • Joint diseases
    • Magnetic resonance imaging

    ASJC Scopus subject areas

    • Radiology Nuclear Medicine and imaging


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