Osteonecrosis: Causes, Symptoms and Treatment

What is Osteonecrosis?

Osteonecrosis (also known as avascular necrosis or aseptic necrosis) is a condition in which bone tissue dies due to a disrupted or severely reduced blood supply. Without sufficient blood flow, bone cells are deprived of oxygen and nutrients and begin to die. Over time, the affected bone may lose its structural integrity and collapse, leading to significant pain and loss of joint function. The femoral head (the ball of the hip joint) is most commonly affected, although the knee, shoulder, wrist, and other bones can also be involved.

Causes

Osteonecrosis can be triggered by a variety of factors that impair blood supply to the bone:

• Trauma and injury: Fractures or dislocations can damage or sever the blood vessels supplying the bone.
• Long-term corticosteroid therapy: Prolonged use of corticosteroid medications (such as prednisone) is one of the most common non-traumatic causes.
• Alcohol abuse: Chronic excessive alcohol consumption can disrupt fat metabolism and damage blood vessels within the bone.
• Blood disorders: Conditions such as sickle cell disease or clotting disorders can block blood flow to the bone.
• Systemic diseases: Conditions including systemic lupus erythematosus, pancreatitis, and Gaucher disease increase the risk.
• Decompression sickness: Rapid ascent from deep water diving can cause gas bubbles to form in blood vessels, interrupting blood supply to the bone.
• Radiation therapy: Cancer radiation treatment can damage surrounding tissue and blood vessels.
• Idiopathic causes: In some cases, no identifiable cause can be found.

Symptoms

Symptoms of osteonecrosis often develop gradually. Common signs include:

• Pain: Initially triggered by weight-bearing or movement, later occurring at rest or during the night. The pain is typically deep and aching in the affected joint.
• Reduced range of motion: The affected joint progressively loses flexibility and mobility.
• Limping or altered gait: Especially when the hip joint is affected.
• Joint swelling: May occur in more advanced stages.
• Joint collapse: In the end stage, the bone may collapse, destroying the joint and causing severe disability.

In the early stages, individuals may be completely symptom-free, which is why the condition is often diagnosed late.

Diagnosis

Osteonecrosis is diagnosed through a combination of clinical assessment and imaging studies:

• Medical history and physical examination: The physician asks about symptoms, risk factors, and medical history.
• X-ray: Often normal in early stages; advanced disease may show characteristic changes such as bone density irregularities or collapse.
• Magnetic Resonance Imaging (MRI): The most sensitive method, capable of detecting early changes in bone marrow before structural damage becomes visible.
• Computed Tomography (CT): Provides detailed images of bone structure to assess the extent of necrosis.
• Bone scintigraphy: A nuclear medicine technique that detects metabolic changes within the bone.

Treatment

Treatment depends on the stage of the disease, the affected bone, and the individual circumstances of the patient:

Conservative Treatment

• Reduced weight-bearing: Using crutches or other assistive devices to offload the affected joint.
• Pain management: Non-steroidal anti-inflammatory drugs (NSAIDs) and other analgesics to relieve discomfort.
• Physical therapy: Maintaining joint mobility and strengthening surrounding muscles.
• Medication: Bisphosphonates or other agents may be used in certain cases to slow bone loss.

Surgical Treatment

• Core decompression: Drilling channels into the necrotic area to relieve pressure and stimulate blood vessel growth. Typically used in early stages.
• Bone grafting (osteotomy/bone transfer): Healthy bone tissue is transplanted into the affected area to restore structural support.
• Joint replacement (endoprosthesis): In advanced cases with severe joint damage, a total joint replacement (such as a hip prosthesis) may be necessary.

Additional Therapies

• Hyperbaric oxygen therapy: Breathing pure oxygen under elevated pressure may promote circulation and bone healing.
• Extracorporeal shock wave therapy: Can be used in early stages to stimulate bone regeneration.

Prognosis

The prognosis for osteonecrosis depends heavily on the stage at which it is diagnosed. In early stages, stabilization or even healing of the affected bone may be achievable. In advanced stages, surgical intervention is often required to preserve joint function. Early diagnosis and prompt treatment are critical to achieving the best possible outcome.

References

1. Mont MA, Hungerford DS. Non-traumatic avascular necrosis of the femoral head. Journal of Bone and Joint Surgery, 1995;77(3):459-474. PubMed.
2. Assouline-Dayan Y, Chang C, Greenspan A, Shoenfeld Y, Gershwin ME. Pathogenesis and natural history of osteonecrosis. Seminars in Arthritis and Rheumatism, 2002;32(2):94-124. PubMed.
3. Malizos KN, Karantanas AH, Varitimidis SE, Dailiana ZH, Bargiotas K, Maris T. Osteonecrosis of the femoral head: etiology, imaging and treatment. European Journal of Radiology, 2007;63(1):16-28. PubMed.