Diagnosis and management of femoroacetabular impingement

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Femoroacetabular impingement (FAI) is a pathological hip condition characterised by abnormal contact between the acetabulum and femoral head–neck junction.1 This can occur within the normal physiological range of motion as a result of osseous abnormalities described as either cam or pincer deformities. Cam deformities describe an abnormal anterosuperior femoral head–neck junction, whereas pincer deformities describe abnormalities in the shape or orientation of the acetabulum (Figure 1). Some patients have both deformities, designated mixed pathology.2 Impingement can also occur in a morphologically normal hip as a result of extreme range of motion activities, such as in ballet dancers or gymnasts. Figure 1 Illustrative lateral view of a hip showing a) cam deformity with additional bone at the anterior femoral headneck junction (shown in red) b) normal hip c) pincer deformity with additional bone at the anterior acetabular rim (shown in red). The deformities in a) and c) cause the femoral neck to impact against the labrum and acetabular rim on flexion and internal rotation. Repeated abutment of the femoral neck against the acetabular rim can result in injury to the labrum and adjacent cartilage.3 Over time these focal lesions may progress to more extensive degenerative disease. There is increasing evidence implicating FAI in the development of osteoarthritis (OA).1,4 In a large population study, cam …