Book excerpt: Osteonecrosis is a disease caused by reduced blood flow to bones in the joints, including the hip, knee, shoulder, and ankle. The disease, which is usually progressive and leads to joint failure, occurs in young adults aged from their twenties to their fifties. The pathogenesis of osteonecrosis is still unclear, and treatment remains controversial. This textbook provides up-to-date and comprehensive information on the pathophysiology, etiology, diagnosis, classification, and treatment of osteonecrosis. The role of various imaging modalities is considered, and both non-surgical and surgical treatment approaches are clearly explained. The contributions, all from experts in the field, are based on presentations at leading international meetings during the past 10 years and on peer-reviewed papers. The book will be of interest not only to clinical practitioners but also to those engaged in basic research.