[Femoroacetabular impingement. Clinical and radiological diagnostics].

A systematic approach to the examination of the hip region is mandatory to identify patients with femoroacetabular impingement. The patients' age, history, and physical examination may lead to the correct diagnosis. Plain radiographs are the imaging modality of first choice. In addition to obvious findings, more subtle changes such as loss of offset at the head-neck transition or acetabular retroversion have to be assessed. For correct analysis, a high quality of the images must be ensured. Therefore, knowledge of the technique used to take the pictures seems essential. With three-dimensional reconstructed computed tomography, asphericities of the head-neck junction or retroversion of the acetabulum may be visualized. In addition to the accurate demonstration of the head-neck junction, magnetic resonance imaging is particularly suitable to reveal pathological conditions of soft tissues such as articular cartilage or labral lesions.