This special issue will deal with various current state-of-the-art as well as novel approaches for the management of osteonecrosis. There are original research and review articles about this disease in the hip and knee ranging from cell-based therapies bone grafting osteotomies to the use of pharmacologic agents such as bisphosphonates and iloprost and various prosthetic devices. In addition better ways to learn about this disease and monitor outcome measurements will be reviewed. More difficult to recognize and treat diseases such as subchondral hip insufficiency fractures bone marrow edema syndrome and spontaneous osteonecrosis are also featured.