Femoro-acetabular impingement. Classification, diagnosis and treatment.

Abstract

Introduction: The femoro-acetabular impingement (FAI) is the result of a number of congenital or acquired pathologies of the hip and it has as main pathogenetic element an abnormal contact between the two joint components (acetabulum and proximal femoral epiphysis). Mainly male young adults, often athletes, are affected because of the repetition of gestures responsible for the conflict in these subjects. Classification: FAI has specific clinical and radiological characteristics and it can be classified into three types: 1. CAM type (femoral). 2. PINCER type (acetabular). 3. CAM-PINCER mixed-type. Diagnosis: It is based on medical hystory (young and active patients, diseases or previous hip surgery), on physical examination (reduced hip flexion and internal rotation) and on two classical tests: - provocative test for anterior impingement: flexion and internal rotation of the hip with the patient supine. - provocative test for posterior impingement: hip extension and external rotation with the patient prone. The instrumental confirmation of the diagnosis relies on: - Radiography (antero-posterior hip view, 45° axial view of the hip, “false profile” Lequesne view) - Computed Tomography: useful for assessing the centering of the femoral head in respect to the acetabulum and eventual bone promincences, but does not show fibro-cartilagineous alterations. - Magnetic Resonance Imaging an Arthro-MRI: more useful, compared to CT, for evaluating the intra-articular space, labral and cartilagineous lesions, and the presence of subchondral cysts. Treatment: If the conflict has already produced an overt arthritic degeneration, the only justified treatment is prosthetic replacement. If the disease is identified early it is possible indeed a conservative surgical treatment of articular heads in order to eliminate the causes of conflict and to re-delineate the anatomy of the joint. In particular, the aim of this surgery is: 1. to recreate a proper off-set head of the femur neck with removal of bone formation in the neck. 2. to eliminate neck retroversion. 3. to repair any associated injuries of the acetabular labrum and to treat, where possible, other joint injuries. Conclusions: FAI is a condition to suspect, recognize and diagnose in all its aspects at an early stage yet, as if it is addressed in time, it can be treated surgically with conservative techniques, but if the joint degeneration advances becoming excessive, a conservative surgical treatment becomes useless.