Avascular Necrosis of the Hip: What to Look Out For

Hip pain can be caused by a wide range of conditions, from simple muscle strains to serious joint disorders. One lesser-known but potentially debilitating cause is avascular necrosis (AVN) of the hip. This condition can silently damage the hip joint over time, leading to arthritis and loss of mobility if not diagnosed and treated early.

Understanding what avascular necrosis is, its risk factors, and its warning signs can help you protect your hip health and seek timely care.

What Is Avascular Necrosis (AVN)?

Avascular necrosis, also called osteonecrosis, occurs when blood flow to a bone is disrupted. Without adequate blood supply, bone tissue begins to die, weakening the bone structure and increasing the risk of collapse.

In the hip, AVN most commonly affects the femoral head—the rounded top part of the thigh bone that fits into the hip socket. As the bone weakens and breaks down, the smooth joint surface may become irregular, eventually leading to osteoarthritis if untreated.

Causes and Risk Factors

Avascular necrosis develops when blood flow to the hip bone is interrupted. Several factors can contribute to this process:

1. Trauma or Injury
   A hip fracture or dislocation can damage nearby blood vessels, reducing blood supply to the femoral head.

2. Long-Term Corticosteroid Use
   Extended use of steroids, often prescribed for autoimmune or inflammatory conditions, can interfere with the body’s ability to deliver blood to bone tissue.

3. Excessive Alcohol Consumption
   Heavy drinking can affect fat metabolism and blood flow, increasing the risk of AVN.

4. Medical Conditions
   Diseases such as sickle cell anemia, lupus, or certain clotting disorders can compromise blood circulation to the bones.

5. Other Risk Factors
   Smoking, high cholesterol, and prior radiation therapy can also raise the risk of AVN.

Early Signs and Symptoms

Avascular necrosis of the hip can progress silently in its early stages. As the disease advances, symptoms typically develop gradually. Watch out for:

• Dull ache or throbbing pain in the groin, thigh, or buttock
• Pain that worsens with walking, climbing stairs, or weight-bearing activities
• Stiffness and reduced range of motion in the hip
• A limp or difficulty standing for long periods

In advanced cases, the pain may persist even at rest or during the night, indicating that the bone has weakened significantly.

How Avascular Necrosis Is Diagnosed

If you experience persistent hip pain or risk factors for AVN, an orthopaedic specialist will evaluate your symptoms through:

• Physical Examination to check for pain, stiffness, and limited movement
• X-rays to identify bone changes, although early AVN may not be visible
• MRI scans to detect AVN in its earliest stages and assess bone health
• CT scans in complex cases to evaluate the extent of joint damage

An early and accurate diagnosis increases the chances of preserving the hip joint.

Treatment Options

The treatment for avascular necrosis depends on how advanced the condition is at the time of diagnosis.

Non-Surgical Treatments

AVN in its early stages may respond to conservative care aimed at slowing disease progression:

• Activity modification to reduce stress on the hip
• Anti-inflammatory medications for pain relief
• Physiotherapy to maintain strength and mobility
• Use of crutches or canes to limit weight-bearing
• Medications to improve bone density or blood flow in select cases

Surgical Treatments

If the disease is advanced or non-surgical methods fail, surgery may be necessary. Common procedures include:

• Core decompression – Removing part of the inner bone to relieve pressure and improve blood flow
• Bone grafting – Transplanting healthy bone tissue to support the femoral head
• Osteotomy – Realigning the bone to shift weight away from the damaged area
• Total hip replacement – Replacing the damaged joint with an artificial implant, typically reserved for severe cases or advanced arthritis

Recovery and Rehabilitation

Recovery from AVN depends on the stage of the disease and the chosen treatment. Non-surgical approaches may take several months of careful activity management, while surgical recovery can last three to six months or more.

Rehabilitation focuses on:

• Regaining hip strength and flexibility
• Learning safe movement patterns to reduce joint stress
• Gradual return to daily activities or sports under medical supervision

Preventing Avascular Necrosis

Not all cases of AVN are preventable, but certain lifestyle and health choices can reduce your risk:

• Limit alcohol consumption and avoid smoking
• Monitor and manage underlying health conditions like high cholesterol or clotting disorders
• Use corticosteroids only as prescribed and for the shortest duration necessary
• Maintain a healthy weight to reduce hip joint stress
• Seek early evaluation for any persistent hip pain after injury

When to See an Orthopaedic Specialist

Hip pain that persists for more than a few weeks, especially if you have risk factors for AVN, should not be ignored. Early evaluation by an orthopaedic specialist will allow for interventions that can preserve your hip joint and delay or prevent the need for joint replacement.