Osteonecrosis or avascular necrosis (AVN) of the hip is a progressive disease mainly affecting adults in their third, fourth or fifth decade of life. Studies into the natural history of the disease suggest that femoral head collapse occurs within 2-3 yrs with associated degenerative changes and at that stage arthroplasty is the most reliable treatment option. Therefore prevention of femoral head collapse is highly desirable in this young patient group. In early stage disease, before femoral head collapse (Ficat and Arlet stage 1-3) core decompression of the femoral head is currently the most widely used procedure to try to relieve intraosseous pressure in the femoral head and restore blood supply.Greater understanding of the pathogenesis of osteonecrosis has led to research into non-surgical management of early stages of the disease, including pharmacological and biophysical treatments.There may be a reduction in symptoms and evidence of prevention of disease progression following some non-surgical treatments. Further studies are needed, including trials comparing medical management with surgical intervention.