Understanding Avascular Necrosis (AVN)

Overview

AVN, also known as osteonecrosis, is a critical medical condition where a part of the bone tissue starts dying due to insufficient blood supply. Avascular Necrosis of the femoral head is when the rounded end of the thigh bone (femur) does not get any blood flow. Eventually it leads to the death and decay of the bone cells, causing the bone to collapse, and the patient ends up with either arthritis and chronic pain. Although avascular necrosis is commonly associated with the hip joint, it can affect other joints as well, including the knee, shoulder, ankle, and wrist
The root causes can be linked to several factors, such as trauma on impact, prolonged use of corticosteroids, heavy alcohol consumption, radiation therapy, and specific medical conditions like sickle cell anaemia and systemic lupus erythematosus. This will surface in the form of pain, specifically in the hip, groin, or thigh regions, limited range of motion, and in severe cases, collapse of the femoral head.
In this blog post, we’ll discuss avascular necrosis of joints, including its causes, symptoms, diagnosis, and treatment options.

Causes of Avascular Necrosis

The primary cause is the disruption of blood supply to the bone tissue. This can further be traced back to

• Impact trauma on the hip bone or joint.
• Prolonged dependency on corticosteroid based treatments.
• Poor lifestyle choices, especially alcohol abuse.
• Other medical conditions like sickle cell disease and lupus.

In some cases, avascular necrosis cannot be explained. These AVNs occur for no apparent reason, which is why they are referred to as idiopathic avascular necrosis. While the exact cause is unknown, it might be due to a combination of genetic and environmental factors.

Symptoms of Avascular Necrosis

The symptoms of avascular necrosis vary depending upon the location of pain and severity of the condition. In the majority of reported cases, avascular necrosis is found where there is pain in the affected joint. This tends to worsen when the joint is overused or bears weight. Other symptoms may include stiffness, limited range of motion, and joint instability.
In some cases, the condition can further deteriorate to the point where the affected bone may collapse causing a sudden onset of severe pain and disability. Hence it is vividly clear that AVN needs prompt medical attention and a quick as well as safe diagnosis.

Diagnosis of Avascular Necrosis

The diagnosis of avascular necrosis requires a certain level of urgency since this is primarily triggered by a compromised circulation of blood. Initially it starts with a physical exam and assessment of prior medical history. Further your doctor may also prescribe more investigation in the form of imaging tests, such as an X-ray, MRI, or CT scan, to help confirm the diagnosis and determine the extent of the damage.
In some cases, your doctor may also recommend a full body bone scan, which involves injecting a small amount of radioactive material into the body bloodstream, which will flow through the body and help identify areas of bone that are low on blood supply in the imaging report.
Impaired circulation will lead to a smaller window for treatment, hence prompt action is essential. Based on the stage of necrosis here are the various diagnostics performed:

• AVN Stage 1: Normal x-rays can’t detect it, but MRI reveals the actual dead bone.
• AVN Stage 2: Visible on regular x-ray but the femoral ball does not collapse.
• AVN Stage 3: A crescent sign on x-ray shows signs of collapse.
• AVN Stage 4: Complete collapse & cartilage damage visible on x-ray (osteoarthritis).

Treatment of Avascular Necrosis

The treatment of avascular necrosis also depends on the location and severity of the condition. But it differs based on the underlying cause. The ultimate goal of an AVN treatment, surgical or non-surgical are:

• relieve pain
• improve joint function, and
• prevent further damage to the affected bone.

1. Medications: Over-the-counter pain relievers, as prescribed by the orthopaedic may help relieve pain and reduce inflammation.
2. Physical Therapy: A physiotherapist can design an exercise program to help improve the range of motion of the joint and strengthen the muscles surrounding it.
3. Assistive Devices: Using support like crutches or brace can help take pressure off the affected joint and help in walking.
4. Surgical Treatments: If avascular necrosis is detected at an advanced stage, surgery may be necessary. Surgical treatments for avascular necrosis include:
   • Core Decompression: A small section of bone near the affected area is removed to relieve pressure and improve blood flow to the tissue.
   • Bone Grafting: Bone tissue is transplanted from another part of the body or from a donor to replace damaged bone tissue.
   • Joint Replacement: If a significant damage has been detected at the joint, joint replacement surgery may be necessary to restore functionality.

There are no guaranteed ways to prevent avascular necrosis, however, you can reduce your risk, by avoiding excessive alcohol consumption, and managing other medical conditions.

Conclusion:

A person suffering from AVN will not be able to detect the problem easily. Circulation impairment is always a fatal condition which needs timely medical intervention. If and when you notice recurring excruciating pain in the joint areas, it is always recommended to speak to an expert. In this case the specialists would be an orthopaedic surgeon, since most AVN conditions quickly escalate towards surgery.

At the CK Birla Hospital, we ensure patients get holistic medical support which includes treatment in a compassionate environment. This patient-centric approach not only helps patients heal better but also ensures they are aware of the preventive measures as well. In case you need to consult an orthopaedic surgeon, do reach out to our award winning Department of Orthopaedics or book a direct appointment with Dr Debashish Chanda at the CK Birla Hospital. (Booking Link)

FAQs:

Who should I consult for AVN?

This is an orthopaedic ailment that can be treated by an experienced orthopaedic surgeon. This is a fatal condition and needs prompt attention, diagnosis and treatment to prevent death due to blocked blood circulation in the body.

Is AVN curable?

A cure for avascular necrosis does not exist. However, treatment can sometimes slow down the progress, but there is still no confirmed cure. Most people diagnosed with avascular necrosis eventually end up having surgery, which often includes joint replacement. However, in some cases, people with avascular necrosis can also develop a high risk of severe osteoarthritis.

What are the 4 stages of avascular necrosis?

Stage 1: Diagnosis from normal radiographs
Stage 2: Cystic changes and sclerosis visible on imaging
Stage 3: Subchondral collapse or femoral head flattening
Stage 4: Joint space narrowing