Femoroacetabular Impingement (FAI) Syndrome : the medical imaging perspective

Abstract

Introduction: Sports persons, physicians, orthopods and radiologists have become increasingly aware of the extra stress that is imposed on the hip joints with excessive activity particularly when superadded weight bearing and asymmetrical variations from the normal hip joint anatomy are present leading to Femoroacetabular Impingement. Subject: Presentation of the abnormalities within the ball and socket areas of the hip joint and the resultant types of impingements, the predominant cam, the predominant pincer or mixed types femoroacetabular impingement (FAI) are discussed and illustrated. The different kind of sportspersons that are prone to FAI and the risk factors involved are discussed. Method: The main methods of investigation: The radiological techniques and radiological signs of the disease entity utilizing plain radiography and computerised transverse scanning techniques are elaborated and graphically depicted. Within the ball part of the hip joint, measurements for femoral head asphericity, that is, the Alpha (?) angle and the offset distance between the femoral head and neck are presented. With regard to pincer type FAI affecting the socket part of the hip joint, the acetabular version angle and the depth (or shallowness) of the acetabulum with their methods of quantification are discussed. Conclusion: Femoroacetabular Impingement is a syndrome which is currently more appreciated within the sports medicine field and various approaches to assessment have been devised regarding how to diagnose and quantify congenital anomalies and developmental abnormalities within both the ball and the socket regions of the hip joint.