ABSTRACT
This chapter discusses nontraumatic Femoral head osteonecrosis (FHON). Different reasons have been suggested for the basic cause of the necrosis. Obviously patients who have an increased coagulation status can be potential candidates for avascular necrosis. Besides, alcohol and corticosteroids can activate immune mechanisms that can be related to inflammatory factors such as interleukin-1, interleukin-10, tumour necrosis factor-alpha and transforming growth factor-beta. Despite all extended studies the exact mechanism and the common justifying reason of osteonecrosis of the femoral head are still unclear. An anteroposterior view of the pelvis and lateral hip radiographs are the main steps for the primary diagnosis. Magnetic resonance imaging (MRI) is the gold standard and the method of choice in the diagnosis of FHON in the precollapse stages of the femoral head. A computed tomography scan is the most sensitive test for the diagnosis of a small subchondral fracture that cannot be very clear in radiography or MRI.
