Osteonecrosis of the femoral head: pathophysiology and current concepts of treatment

Osteonecrosis of the femoral head is a disabling pathology affecting a young population (average age at treatment, 33 to 38 years) and is the most important cause of total hip arthroplasty in this population. It reflects the endpoint of various disease processes that result in a decrease of the femoral head blood flow. The physiopathology reflects an alteration of the vascularization of the fine blood vessels irrigating the anterior and superior part of the femoral head. This zone of necrosis is the source of the loss of joint congruence that leads to premature wear of the hip. Several different types of medication have been developed to reverse the process of ischemia and/or restore the vascularization of the femoral head. There is no consensus yet on a particular treatment. The surgical treatments aim to preserve the joint as far as the diagnosis could be made before the appearance of a zone of necrosis and the loss of joint congruence. They consist of bone marrow decompressions, osteotomies around the hip, vascular or non-vascular grafts. Future therapies include the use of biologically active molecules as well as implants impregnated with biologically active tissue.