Avascular Necrosis (Osteonecrosis)

Bones are living tissue, constantly maintained by a steady flow of blood that delivers oxygen and essential nutrients to keep them strong and healthy. When that blood supply is cut off, even briefly, the consequences can be devastating. Avascular necrosis, also called osteonecrosis, is precisely this kind of crisis: a condition in which bone tissue begins to die due to insufficient blood flow, silently weakening the affected bone from within. It can strike any joint in the body, progress with little warning, and if left unaddressed, permanently destroy the joint's structure and function.

Yet despite its severity, avascular necrosis remains widely underrecognized, often going undiagnosed until significant damage has already occurred. Knowing what to look for, understanding who is at risk, and acting early can make all the difference. This guide covers everything you need to know about avascular necrosis from its earliest symptoms and underlying causes to diagnosis, treatment options, and long-term management, so that you or your loved ones can recognize the warning signs and seek timely care.

What is Avascular Necrosis (Osteonecrosis)?

Avascular necrosis is the death of bone tissue caused by a loss of blood supply. The term is straightforward: "avascular" means without blood vessels, and "necrosis" means tissue death. When bone cells are cut off from the oxygen and nutrients that blood delivers, they begin to deteriorate and eventually die — a process also referred to as bone infarction.

The condition can affect any bone in the body, but it most commonly develops in the hip, knee, shoulder, hand, and foot. The hip is by far the most frequently affected joint, with avascular necrosis of the femoral head accounting for the majority of clinical cases worldwide. Left untreated, the affected bone can collapse entirely, leading to debilitating arthritis and permanent loss of joint function.

Avascular Necrosis Symptoms

Avascular necrosis symptoms can be deceptively subtle in the early stages — many people experience no discomfort at all until the bone actually begins to collapse, which is why it is sometimes described as a "silent" disease. As the condition progresses, the following symptoms typically emerge:

• Pain: The most common first sign, usually presenting as a dull ache or throbbing in the affected joint. It tends to worsen with weight-bearing activity and ease with rest, but in later stages it can become persistent and severe even without movement.
• Limited range of motion: Increasing stiffness and reduced mobility as bone and cartilage continue to deteriorate.
• Limping or altered gait: Particularly noticeable in cases affecting the hip or knee, where pain and instability affect normal movement.
• Joint tenderness: Sensitivity around the affected area, even without direct pressure or movement.

The progression from early-stage disease to bone collapse can span several months to over a year, making timely recognition of avascular necrosis symptoms essential.

Causes of Avascular Necrosis

Avascular necrosis causes fall into two broad categories: traumatic and non-traumatic.

Traumatic causes involve direct physical injury to the bone or its surrounding blood vessels. A fracture or dislocation can sever or compress the vessels supplying the bone, cutting off blood flow and triggering tissue death. This is especially common following hip dislocations or femoral neck fractures.

Non-traumatic causes include:

• Corticosteroid use: Long-term or high-dose corticosteroid medications — such as prednisone — are among the most common non-traumatic avascular necrosis causes. They interfere with fat metabolism, leading to fatty deposits that obstruct the small blood vessels within bone tissue.
• Alcohol abuse: Heavy alcohol consumption produces similar fatty changes in the bloodstream, impairing blood flow to the bone and contributing to bone infarction.
• Underlying medical conditions: Sickle cell disease, systemic lupus erythematosus, HIV, Gaucher disease, and Crohn's disease can all disrupt normal blood circulation or increase the risk of clotting.
• Radiation therapy: High-dose radiation used in oncology treatment can damage blood vessels and weaken bone over time.
• Decompression sickness: Known as "the bends," this condition causes nitrogen gas bubbles to form in the bloodstream — most commonly in divers — blocking the vessels that supply bone tissue.

In some cases, no underlying cause can be identified, and the condition is classified as idiopathic avascular necrosis.

Risk Factors for Avascular Necrosis

While the condition can develop in anyone, certain avascular necrosis risk factors significantly raise the likelihood of it occurring. Recognising these early is key to prevention and timely intervention:

• Long-term or high-dose corticosteroid therapy
• Chronic or heavy alcohol consumption
• Previous joint trauma, including fractures and dislocations
• Blood disorders such as sickle cell disease or clotting conditions
• Autoimmune diseases, particularly systemic lupus erythematosus
• Organ transplantation, which typically requires ongoing immunosuppressive medication
• Cancer treatment involving chemotherapy or radiation therapy
• HIV/AIDS and related treatments
• Exposure to high-pressure environments, as experienced by deep-sea divers or caisson workers

Men between the ages of 30 and 60 are statistically most affected, though the condition can occur in people of any age or gender.

Diagnosing Avascular Necrosis

Early and accurate diagnosis is critical to preventing irreversible joint damage. Because symptoms are often minimal in the early stages, physicians typically rely on imaging rather than physical examination alone. Commonly used diagnostic tools include:

• X-rays: Often appear normal in early-stage disease but can reveal bone collapse and joint damage as AVN advances.
• MRI (Magnetic Resonance Imaging): The gold standard for diagnosing avascular necrosis, capable of detecting changes in bone and blood supply well before they appear on X-ray.
• CT scans: Provide detailed cross-sectional images useful for assessing the full extent of bone damage.
• Bone scans: Radionuclide scintigraphy can identify areas of abnormal bone metabolism, though with less specificity than MRI.
• Blood tests: Help identify underlying conditions — such as clotting disorders or autoimmune disease — that may be contributing to the condition.

Physicians use established staging systems such as the ARCO or Ficat classification to determine how far the disease has progressed and to guide treatment planning accordingly.

Avascular Necrosis Treatment Options

Avascular necrosis treatment is guided by the stage of the disease, the joints involved, and the patient's overall health. The primary goals are to relieve pain, stop further bone deterioration, and preserve joint function for as long as possible.

Non-surgical treatment options are most effective in early-stage disease and include:

• Medications: NSAIDs for pain relief, bisphosphonates to slow bone loss, and anticoagulants when clotting disorders are a contributing factor.
• Activity modification and physical therapy: Reducing load on the affected joint through restricted weight-bearing and guided exercise helps protect the bone and maintain mobility.
• Electrical stimulation: Emerging evidence suggests it may promote new bone growth in the early stages of AVN.

Surgical treatment options become necessary as the disease advances:

• Core decompression: Drilling into the bone to relieve internal pressure, improve blood flow, and stimulate the development of new blood vessels — commonly used for early-stage avascular necrosis of the hip.
• Bone grafting: Transplanting healthy bone to replace necrotic tissue and restore structural integrity to the affected joint.
• Osteotomy: Reshaping the bone to shift weight away from the damaged area, particularly relevant for the hip and knee.
• Total joint replacement: The preferred solution in advanced cases where the bone has collapsed — most commonly in the hip and knee — restoring function and relieving chronic pain.

Your orthopedic specialist will assess your individual case and recommend the most appropriate treatment path.

Potential Complications of Untreated AVN

Without timely intervention, avascular necrosis can lead to severe and permanent consequences. The most significant complications include:

• Bone collapse: Progressive weakening of the affected bone leads to the eventual collapse of the joint surface, causing acute and debilitating pain.
• Secondary osteoarthritis: Joint surface irregularities following collapse trigger the onset of arthritis, resulting in chronic pain and deteriorating function.
• Permanent disability: Advanced joint destruction — particularly affecting the hip, knee, or shoulder — can severely restrict mobility and independence.
• Spread to additional joints: The condition may affect multiple sites simultaneously, particularly when the root cause — such as corticosteroid use or sickle cell disease — remains unmanaged.

Early diagnosis and treatment are the most effective ways to prevent these complications and preserve long-term joint health.

Prevention Strategies for Avascular Necrosis

While AVN arising from trauma or unavoidable medical treatment cannot always be prevented, the following avascular necrosis prevention measures can meaningfully reduce your overall risk:

• Moderate alcohol consumption to protect the blood vessels supplying your bones.
• Use corticosteroids at the lowest effective dose and for the shortest possible duration, always under medical supervision.
• Keep cholesterol levels in check through diet, exercise, and medication where appropriate, as elevated lipids can obstruct bone blood vessels.
• Wear protective equipment during sports and physical activities to minimise the risk of joint trauma.
• Actively manage chronic conditions such as lupus, sickle cell disease, and diabetes to reduce the risk of bone infarction.
• Quit smoking, as tobacco use impairs circulation and restricts blood flow to bone tissue.
• Attend regular medical check-ups, especially if you have known risk factors, to enable early detection.

Living with Avascular Necrosis

A diagnosis of avascular necrosis is significant, but with appropriate management many people go on to live full, active lives. Effective long-term care typically involves:

• Ongoing physical therapy to preserve joint mobility, strengthen surrounding muscles, and develop movement habits that reduce pain.
• Assistive devices — such as canes or custom orthotics — to offload stress from affected joints, particularly in cases involving the foot, knee, or hip.
• Weight management to minimise mechanical stress on weight-bearing joints.
• Mental health support through counselling or peer support groups, recognising that the psychological impact of chronic pain and reduced mobility is just as important to address as the physical.

If you are considering treatment abroad, Turkey has become one of the leading destinations for orthopedic care, combining internationally accredited hospitals, experienced specialists, and accessible treatment costs. At Medical Park, our specialists in Orthopedics and Traumatology departments are equipped with the latest diagnostic technology and a full range of treatment options to guide you from early diagnosis through to recovery and long-term care.