Femoroacetabular Impingement: Etiology and Surgical Concept

Osteoarthritis of the hip is one of the major causes of pain and disability in the developed world. Resulting therapeutic interventions and socioeconomic expenditures pose a considerable burden on health and social services. Based on experimental and clinical studies, including in situ inspection in consecutive adolescents and young adults undergoing surgical dislocations of the hip, we propose femoroacetabular impingement to cause early osteoarthritis in the nondysplastic hip; morphologic deviations of the acetabulum (regional or global overcoverage) and/or proximal femur with a decreased anterior head-neck offset may lead to repetitive trauma of the peripheral articular cartilage during flexion and internal rotation, particularly in individuals taking regular exercises. Frequently, this becomes symptomatic in the second and third decade of life in patients with an increased sportive activity. Based on predominance of the acetabular or femoral pathology, 2 different types of FAI, the pincer and the cam, are differentiated. Apart from these morphological alterations, a supraphysiological mobility and overuse can contribute to the FAI. The impingement concept has led to a new type of mainly intracapsular hip surgery aimed at improving clearance of the hip to avoid pathological contact.