Cam-type Femoroacetabular Impingement (FAI)

Initially raised by Marius Nygaard Smith-Petersen in 1936, the modern definition of Femoro-acetabular impingement (FAI) was then implemented by the team of Reinhold Ganz in Bern in the 1990s. There are two types of deformities that can lead to FAI: a cam femoral-sided lesion or a pincer acetabular-sided lesion. The cam lesion is an asphericity at the head–neck junction putting the hip at risk of symptomatic impingement at the chondrolabral junction. Groin pain is present in deep flexion and internal rotation. On physical exam, pain is reproduced with Flexion-Adduction-Internal rotation test (FADIR). On imaging, the cam lesion is better assessed by the alpha angle on the Dunn radiograph. However, a 3D-CT is essential to better understand the anatomy/extent of the lesion and program the surgical resection. If conservative management does not provide an improvement of symptoms, surgical correction is done with a femoral osteochondroplasty with adapted treatment of the chondrolabral damage with a combination of debridement and labral restabilization. Surgery can be performed by open or arthroscopic approaches. The natural history of symptomatic cam FAI is one of the progressive osteoarthritises. Surgery not only predictably relieves pain but also delays the onset of severe osteoarthritis, with a relatively low complication rate.