Avascular necrosis of the femoral head (AVN) or osteonecrosis of the hip occurs when, for any reason, the blood supply of the proximal epiphysis of the femur (the femoral head) is no longer effective, leading to a state of insufficient blood supply, leading to a process of hypoxia and death (necrosis) of the bone tissue, which may evolve to the collapse of the head. As a result, the cartilage that covers the femoral head also collapses, and may lead to hip arthrosis.
Avascular Necrosis of the Femoral Head (AVN)
AVN or Osteonecrosis of the Hip
Although the effective cause of the lack of blood supply to the head of the femur is often not identified, there are various risk factors that have been identified and which may lead to the appearance of NAV. Traumas (such as hip dislocations, femur fractures, violent indirect trauma, among others), excessive alcoholic habits, prolonged corticosteroid therapy, blood diseases (sickle cell anaemia), rheumatological diseases, infections (HIV), radiotherapy treatments (adjuvant for tumour pathology), medical diseases (pancreatitis, hypercholesterolemia, diabetes mellitus, among others) are those frequently implicated.
NAV develops in stages. The cardinal symptom and the first to appear is hip pain in the groin or deep gluteal region. As the disease develops, it becomes more and more difficult for the person to stand up and load the affected limb. Mobilization of the hip in this phase usually triggers pain. Progression of the disease may take months to years. In the early stages, hip mobility may be relatively normal, but with disease progression, collapse of the femoral head surface and progression to hip arthrosis, joint mobility is decreased. The tests required for diagnosis are simple x-rays of the hip and pelvis and magnetic resonance imaging of the hip.
Treatment can be medical or surgical.
Within the former, drugs such as anti-inflammatories, analgesics and peripheral vasodilators are used, in addition to the recommendation of discharge with crutches and change in daily activity. These measures can help control pain and slow the progression of the disease.
Within the second group, there are conservative surgical alternatives (with preservation of the native hip) when the disease is diagnosed in its earliest stages and before there is collapse of the femoral head, and arthroplastic alternatives (with hip replacement). Some conservative techniques may be indicated, such as core decompression, osteochondral grafts or vascularised peroneum grafts. Joint replacement with total hip prosthesis is the most effective treatment when there is collapse of the femoral head.
