Imaging of femoroacetabular impingement: pictorial review.

Femoroacetabular impingement (FAI) is a cause of progressive osteoarthritis of the hip in younger patients. Three types of FAI have been described: a cam-type, a pincer-type and a mixed type. Early recognition of the morphologic hip features of each type of impingement is important, because arthroscopic treatment is still successful in the initial stage to prevent or delay further hip degeneration. This article reviews the imaging features of the different types of FAI. Magnetic resonance arthrography (MRA) is the preferred modality to detect, localise and characterise the type of FAI and the resulting injuries of the acetabular hyaline cartilage and fibrocartilaginous labrum.