Avascular Necrosis (AVN) of the Hip – Causes, Symptoms, Diagnosis & Treatment

Avascular Necrosis (AVN) of the hip — also called osteonecrosis — is a condition where the blood supply to the head of the femur (ball of the hip joint) gradually reduces. Without enough blood flow, the bone becomes weak, starts to collapse, and the smooth joint surface gets damaged.

If not treated early, AVN can lead to early arthritis, severe pain and difficulty walking.

Why Does AVN Occur?

AVN develops when the blood flow to the hip bone is interrupted. Common causes include:

1. Long-term steroid use

One of the most common reasons.

2. Alcohol consumption

Heavy alcohol intake weakens bone cells and blood vessels.

3. Trauma

A hip fracture or dislocation can directly damage the blood supply.

4. Medical conditions

Sickle cell disease
Autoimmune disorders
Kidney disease
Pancreatitis

5. Unknown reasons (Idiopathic)

Many young and healthy individuals develop AVN without any identifiable cause.

AVN is most commonly seen in people between 20–50 years of age.

Symptoms of AVN of the Hip

Early AVN may not cause noticeable symptoms. As the disease progresses, patients may experience:

Groin pain, sometimes felt in the thigh or buttock
Pain that increases with walking or weight-bearing
Difficulty sitting cross-legged or squatting
Stiffness in the hip
Limping
Pain at night in advanced stages

If the bone collapses, the pain becomes more constant and severe.

Diagnosis

Diagnosis usually includes:

Clinical Examination

Evaluation of pain location, movement restriction and walking pattern.

X-ray

Shows changes in bone shape and joint surface, especially in later stages.

MRI

The most sensitive test. It detects AVN very early, even before changes appear on X-ray.

Early diagnosis is important to preserve the hip joint and delay or avoid joint replacement.

Stages of AVN

AVN is classified into stages:

Early stage – Blood supply reduced, but bone shape is maintained
Collapse stage – Bone begins to cave in
Advanced stage – Joint surface damaged; secondary arthritis develops

Treatment decisions depend heavily on the stage at diagnosis.

Treatment Options

1. Non-Surgical Management (Early Stages)

These methods aim to slow the disease but cannot reverse AVN:

Medication for pain
Reduced weight-bearing
Physiotherapy for hip mobility
Bisphosphonates in select cases
PRP or stem-cell–based injections (evidence still evolving)

Non-surgical options are most effective before bone collapse.

2. Core Decompression (Early to Mid Stages)

A minimally invasive surgery where a channel is created inside the femoral head to:

Reduce pressure
Improve blood flow
Relieve pain
Slow progression of AVN

Sometimes bone grafts or biologic materials (stem cells/PRP) are added to improve healing.

This procedure is ideal when the femoral head is still intact.

3. Femoral Head–Preserving Procedures

For selected patients:

Bone grafting
Osteotomy (realigning the bone)

These procedures aim to save the natural hip joint and delay arthritis.

4. Total Hip Replacement (Advanced AVN)

When the femoral head collapses or arthritis has developed, hip replacement becomes the best option.
The damaged ball and socket are replaced with artificial components, giving:

Excellent pain relief
Smooth hip movement
Ability to walk and perform daily activities comfortably

Modern techniques such as the Direct Anterior Approach allow faster recovery with minimal muscle damage.

Self-Care & Lifestyle Guidance

For patients diagnosed with AVN:

Avoid high-impact activities
Reduce or stop alcohol
Avoid long-term steroid use unless medically necessary
Maintain a healthy weight
Do physiotherapy regularly to keep the hip mobile

Early lifestyle adjustments can significantly slow disease progression.

Key Takeaway

Avascular Necrosis of the hip is a progressive condition, but early diagnosis and timely treatment can preserve the hip joint and delay the need for replacement.
Advanced AVN responds very well to hip replacement surgery, offering long-term pain relief and excellent function.