Stages of Avascular Necrosis

Avascular Necrosis (AVN) is a condition where the blood supply to a bone is reduced, leading to bone damage and possible joint collapse over time.

It most commonly affects the hip joint, which makes understanding the stages of AVN hip and proper AVN grading essential for early diagnosis and treatment.

Stages of AVN

AVN condition is broadly classified into four stages, progressing from reduced blood supply to complete joint collapse and arthritis.

MRI is essential for early detection of AVN because the initial stages may not be visible on X-rays.

Stage 0–1 (Early Stage)

Key Features:

• Reduced blood supply to the bone
• Bone structure remains intact.
• Detected only by MRI
  

Symptoms:

• Mild or no pain
• Discomfort during activity

Stage 2 (Pre-Collapse Stage)

Key Features:

• Bone damage visible on X-ray
• No collapse of bone
  

Symptoms:

• Pain during walking or activity
• Relief with rest

Stage 3A (Early Collapse Stage)

Key Features:

• Fracture develops below the joint surface
• Femoral head depression is 2 mm or less

Symptoms:

• Persistent hip pain
• Limping and stiffness

Stage 3B (Significant Bone Collapse)

Key Features:

• Fracture is present below the joint surface
• Femoral head depression is more than 2 mm

Symptoms:

• Persistent hip pain
• Difficulty walking and stiffness

Stage 4 (Advanced Collapsed Stage)

Key Features:

• Complete bone collapse
• Joint damage and arthritis
  

Symptoms:

• Severe constant pain
• Restricted movement

How Is AVN Graded?

Doctors use imaging tests such as X-rays, MRI scans, and CT scans to determine the stage of AVN. These tests help identify bone damage and check whether the femoral head has started to collapse.

Two commonly used systems classify AVN:

• Ficat-Arlet Classification: A traditional system that divides AVN into progressive stages.
• 2019 Revised ARCO Classification: An updated and more detailed framework for classifying AVN. It identifies early bone changes, fracture development, and the extent of femoral head collapse.

For a consistent explanation of AVN progression, this article follows the 2019 revised ARCO classification.

Symptoms vs Stages of AVN

Understanding symptom progression helps in early diagnosis of AVN stages.

AVN Stage	Pain Level	When Pain Occurs	Mobility Impact	Other Symptoms
Stage 0–1	Mild or none	During activity or absent	No limitation	Often unnoticed
Stage 2	Mild to moderate	During walking	Slight restriction	Early stiffness
Stage 3A	Moderate	During walking or weight-bearing	Difficulty walking	Limping, stiffness
Stage 3B	Moderate to severe	During activity and sometimes at rest	Greater difficulty walking	Arthritis, joint damage
Stage 4	Severe	Constant	Major restriction	Arthritis, joint damage

Symptoms may vary from person to person and do not always match the AVN stage. The stage is determined primarily through imaging findings.

Stage-wise Treatment of AVN

Treatment depends directly on AVN grading and stage of disease.

Early Stages (Stage 1 and 2):

• Regenerative therapies may be considered.
• Hip-preserving treatments.
• Monitoring and activity modification.

Stage 3A (Early Collapse):

• Regenerative approaches may be considered depending on bone damage.
• Hip-preserving procedures may help preserve the natural hip joint.
• Hip replacement may be considered depending on joint condition.

Advanced Stages (Stage 3B and 4):

• Pain management and mobility support.
• Hip replacement may be considered for significant bone collapse and joint damage.

Final Takeaway

AVN is a progressive condition, but early detection can make a significant difference. Understanding the stages of AVN, along with proper AVN grading, helps in choosing the right treatment at the right time.

Early-stage AVN offers the best chance to preserve the joint, while advanced stages may require surgical solutions. Recognizing symptoms early and seeking timely medical advice can help prevent long-term complications.

---

Frequently Asked Questions (FAQs):