The Hip: Femoro-Acetabular Impingement

Femoro-acetabular impingement (FAI) is a common hip disease, recently recognized more and more frequently due to the wider circulation of its knowledge among orthopedists and radiologists. Very active children and adolescents are prone to develop hip pain if the femoral head–neck junction is dysmorphic and/or the acetabular coverage is augmented, either focally or globally. The former case is named cam-FAI, since the cervical deformity acts as a cam within the socket; the latter is named pincer-FAI, since the overhanging acetabular wall crushes the labrum against the femoral neck just like a pincer. Most FAIs become symptomatic after the second decade of life. When it occurs earlier, usually the deformity is quite severe and is secondary to slipped capital femoral epiphysis or to Perthes disease. Sometimes mild deformities show themselves early due to extremely intensive sports training, involving deep, and repetitive flexion of the hip. Conservative management is recommended till physeal closure, and then selected patients will benefit from corrective surgery.