This book, Osteonecrosis, deals with bone diseases. Aseptic necrosis occurs when there is loss of blood supply to bone causing bone death. This disease attacks people in their late 30s and 40s, i.e. young adults; and if left untreated, results in total joint destruction with joint replacement remaining the only treatment option. It is an extremely debilitating condition though not life-threatening. The incidence of osteonecrosis is increasing globally mostly due to the use of high dose of steroids for certain medical conditions and increasing alcohol abuse. Sickle cell disease remains a common cause of osteonecrosis. The book is a comprehensive guide on the subject of osteonecrosis encompassing the entire spectrum from etiopathology to various surgical treatments. The importance of early diagnosis and timely intervention is aptly stressed upon in order to ensure a pain free and active life of young adults who are the victims commonly of this debilitating disease. The book covers the etiopathology of the disease including the research studies done on the different conditions associated with osteonecrosis. It will discuss in detail the various diagnostic tools including X-rays, CT scan, MRI and bone scan. Classification and staging are described at length with reference to importance in planning the treatment and correlation to prognosis.