Ans. is 'd' i.e., None of the above o Osteonecrosis is a pathologic process that has been associated with trauma, with numerous atraumatic conditions, and with therapeutic interventions, most commonly corticosteroid use and excessive alcohol intake. o Compromise of the bone vasculature, leading to the death of bone and marrow cells (bone marrow infarction), and ultimate mechanical failure appears to be the common etiologies shared by the varied proposed causes. o The mean age at diagnosis is less than 40 years. Etiologicfaetqrs associated with osteonecrosis Traumatic o Femoral neck fracture o Dislocation or fracture-dislocation o Minor trauma Nontraumatic o Corticosteroid administration, rarely hypersecretion of cortisol o Alcohol use o Sickle cell hemoglobinopathies o Caisson (dysbarism) disease o Systemic lupus erythematosus o Gaucher's disease o Chronic renal failure or hemodialysis o Pancreatitis o Pregnancy o Hyperlipidemia o Radiation o Organ transplantation o Disseminated o Intravascular coagulation o Thrombophlebitis o Cigarette smoking o Hyperuricemia/gout o Human immunodeficiency virus infection o Idiopathic Clinical features o Early diagnosis of osteonecrosis may provide the opportunity to prevent collapse and the need for joint replacement. o However, most patients present late in the course of the disease, and a high index of suspicion is necessary for those with risk factors, particularly high-dose corticosteroid use. o The most common presenting symptom of osteonecrosis is pain, although a small proportion of patients are asymptomatic. Radiological features on X-ray o Changes in bone density (earliest feature) o Cysts and sclerosis o Crescent sign (Subchondral radiolucency) due to subchondral collapse o The subsequent loss of sphericity or collapse of the femur. o Magnetic resonance imaging (MRI) is far more sensitive than plain radiographs or radionuclide bone scanning and is preferred for diagnostic use in patients with nondiagnostic plain radiography. o A clinical diagnosis is appropriately made in an asymptomatic patient when imaging findings are compatible with this disease and when other causes of pain and bony abnormalities either are unlikely or have been excluded.