Avascular Necrosis: Treating Hip Damage with Minimally Invasive Hip Replacement

Dr Suresh Nathan, an orthopaedic surgeon at Mount Elizabeth Hospital, describes what avascular necrosis of the hip is, what causes it and how to treat it.

AVN is a condition that results from the death of bone tissue due to a loss of blood supply to the bone. If left untreated, the affected bone may collapse and cause serious pain. While AVN often affects the hips, it can also occur in the knees, shoulders, hands or feet.

What causes avascular necrosis?

There are several causes of AVN, but one to take note of is steroid use. As Dr Suresh explains, "In Singapore and across Asia, traditional steroid treatments are much more common than they are in the West, which in turn makes the condition occur more frequently in the Asian community." 

Doctors believe steroids impact the body's ability to break down fatty substances, which then narrows the blood vessels and restricts the blood supply to the bone.

Other possible causes of AVN include high alcohol intake, trauma, regular deep sea diving and, more rarely, high cholesterol. 

What symptoms can I look out for?

In the early stages, AVN may cause no symptoms at all, which makes it tricky to recognise. However, as the condition progresses, you may experience:

• Pain when you put weight or pressure on the affected bone
• Constant or serious pain in the affected bone

If these symptoms occur, it is important to seek medical treatment as soon as possible to delay or prevent serious damage to the bone. 

What are the treatment options for AVN?

If AVN is caught early, medications may help to relieve some of the pain. Your doctor may also recommend you use a crutch to take the weight off your damaged joint. 

A 'core decompression' (drilling surgery) can release some of the pressure, reactivate blood flow in the affected area and help to stop the collapse of the bone.

However, if the condition continues to progress, joint replacement surgery may be required.

What is joint replacement surgery?

The first joint replacement surgery was performed in Singapore in 1973. While the techniques have changed dramatically since this time, the goals remain to:

• Relieve the pain
• Restore mobility
• Stop the progression of bone damage
• Restore the body image

In joint replacement surgery, the damaged joint is replaced with a synthetic joint. The aim is for patients to be able to walk independently and without pain.

What happens if AVN occurs in both hips?

When AVN is diagnosed in one hip, the other hip is considered 'at risk'. If AVN eventually develops in both hips, a double hip replacement may be required. 

This is a trickier undertaking, as Dr Suresh explains, "I have done several double hip replacements in the past. The procedure is not to be taken lightly because by moving the hip, the other hip can be dislocated." 

"In such cases, it is better to use minimally invasive techniques, and it is important that the patient is up and about as soon as possible afterwards. I have been doing these surgeries for more than 10 years, and patients tend to bounce back very quickly. Often, they are walking within 2 days."

In traditional open surgery, your doctor needs to make a large cut to access the affected area, whereas with minimally invasive surgery, your surgeon will only need to make a small cut to insert the replacement joint.

This is particularly beneficial for patients who need to be on their feet quicker, or for those with a high-risk cardiac condition such as heart disease or anticoagulation.

Dr Suresh says, "Minimally invasive techniques go between muscle and not through them, so patients do not bleed as much as in conventional hip replacements."

If you experience AVN symptoms or are concerned you are at risk, consult your doctor.