Hip Avascular Necrosis (Osteonecrosis)

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Dr Kau Chung Yuan (许医生)


MRCS (Ireland)

MMed (Ortho)

FRCSEd (Ortho)


What is Hip Avascular Necrosis (Osteonecrosis)?

Hip Avascular Necrosis (AVN), also known as osteonecrosis, is a medical condition characterised by the death of bone tissue due to a lack of blood supply. This condition primarily affects the hip joint, though it can occur in other joints as well. In the hip, the lack of blood flow can lead to the destruction of the femoral head, the upper part of the femur (thigh bone) that fits into the hip socket.

The process leading to avascular necrosis is typically gradual. Initially, as the blood supply to the bone diminishes, the bone tissue begins to die and lose its structural integrity. Over time, this can lead to the collapse of the bone structure, causing significant pain and loss of joint function.

Causes of Hip Avascular Necrosis

Several factors contribute to the development of Hip AVN, each leading to reduced blood flow to the femoral head:

  • Trauma
    Injuries such as hip dislocations or fractures can disrupt the blood supply to the femoral head, leading to AVN.
  • Steroid Use
    Long-term or high-dose use of corticosteroids is a significant risk factor, as these medications can interfere with blood flow to the bone.
  • Alcoholism
    Excessive alcohol consumption over a prolonged period can cause fatty deposits in blood vessels, impeding blood flow and contributing to AVN.
  • Medical Conditions
    Certain conditions, like sickle cell anaemia and Gaucher’s disease, can lead to impaired blood flow to the hip bone.
  • Blood Clotting and Blood Flow Issues
    Conditions that affect blood clotting or blood flow, such as deep vein thrombosis (DVT) and vasculitis, increase the risk of AVN.


The symptoms of Hip AVN can vary depending on the stage of the condition, but generally include the following:

  • Pain
    Initially, individuals may experience pain when putting pressure on the affected hip. As the condition progresses, the pain might become constant, even when resting.
  • Joint Stiffness
    Stiffness in the hip joint, especially in the mornings or after periods of inactivity, is a common symptom.
  • Limited Range of Motion
    As AVN progresses, the range of motion in the hip joint can become restricted, making it difficult to perform activities such as walking or climbing stairs.
  • Limping
    Due to pain and stiffness, individuals may develop a limp to avoid putting weight on the affected hip.
  • Radiating Pain
    In advanced stages, pain might radiate from the hip to the groin, buttock, or knee area.

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Diagnosing Hip AVN involves a combination of clinical evaluation and imaging studies. Key steps in the diagnostic process include:

Medical History and Physical Examination

A thorough medical history is taken, including questions about any risk factors such as steroid use, alcohol consumption, or previous hip injuries. A physical examination focuses on the hip’s range of motion, pain points, and any signs of limping.

Imaging Tests

  • X-rays: Initial imaging often starts with X-rays, which can show changes in the bone structure of the hip.
  • Magnetic Resonance Imaging (MRI): MRI is more sensitive than X-rays and can detect AVN in its earlier stages before the bone structure changes become apparent.
  • Computed Tomography (CT) Scan: Sometimes used to determine the extent of bone damage.

Bone Scan

In some cases, a bone scan may be conducted to assess the health of the bones.


Rarely, a biopsy of the bone might be performed to confirm the diagnosis.

Non-Surgical Treatment Options

Non-surgical treatments for Hip AVN aim to manage symptoms and slow the progression of the disease. These options are often considered in the early stages of AVN or for patients for whom surgery is not an option:

Pain Relievers

Over-the-counter pain medications, such as ibuprofen or naproxen, can help alleviate pain.


These medications, typically used to strengthen bone, may help slow the progression of AVN.

Limiting Weight-Bearing Activities

Reducing activities that put stress on the hip can alleviate pain and slow the progression of the condition.

Physical Therapy

Exercises and therapies to improve range of motion and strengthen the muscles around the hip joint.

Surgical Treatment Options

In cases where non-surgical treatments are ineffective or the disease has progressed, surgical intervention may be necessary for Hip AVN. The choice of surgery depends on the stage of the disease, the age and activity level of the patient, and the amount of bone affected. Common surgical options include:

  • Core Decompression: This procedure involves drilling into the affected bone to relieve pressure and create channels for new blood vessels to nourish the affected areas.
  • Bone Grafts: Transplanting bone from another part of the body or a donor can help support the hip joint.
  • Osteotomy: This procedure repositions the bone to redistribute weight away from the damaged bone and joint surfaces.
  • Total Hip Replacement (Arthroplasty): In advanced cases, replacing the affected parts of the hip with artificial components may be the best option to restore function and relieve pain.
  • Hip Resurfacing: A less invasive alternative to total hip replacement that involves capping the femoral head with a smooth metal covering.

Dr. Kau Chung Yuan

MBBS (S’pore)

MRCS (Ireland)

MMed (Ortho)

FRCSEd (Ortho)

Dr Kau (许医生) is a Fellowship trained Orthopaedic Surgeon with a subspecialty interest in Hip and Knee surgery and has been in practice for more than 15 years.

He is experienced in trauma and fracture management, sports injuries, and joint replacement surgery.

  • Fellow of the Royal College of Surgeons Edinburgh, Orthopaedics (FRCS, Edin) 2014
  • Master of Medicine (Orthopaedics), Singapore (MMed) 2013
  • Member of the Royal College of Surgeons Ireland (MRCS, Ire) 2009
  • Bachelor of Medicine and Surgery (MBBS, Singapore) 2004

Prevention Measures

Preventing Hip AVN primarily involves addressing the risk factors that can lead to the condition. Some key prevention strategies include:

  • Moderating Alcohol Intake
    Limiting alcohol consumption can reduce the risk of developing AVN.
  • Managing Steroid Use
    If steroid medications are necessary, using the lowest effective dose for the shortest possible time can help minimise the risk.
  • Monitoring and Treating Underlying Conditions
    Conditions such as sickle cell anaemia, Gaucher’s disease, and those that affect blood clotting should be carefully managed.
  • Regular Physical Activity
    Engaging in regular exercise can improve joint health and overall bone strength.
  • Avoiding Hip Trauma
    Taking precautions to prevent injuries to the hip, such as using protective gear during high-impact sports or activities.
  • Healthy Lifestyle Choices
    Maintaining a healthy weight, not smoking, and following a balanced diet can contribute to overall bone health and reduce the risk of AVN.

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Patient Feedback

Ethan Chan
Dr. Kau is an exemplary doctor who is experienced in his field and is very patient with his patients. He walked me through the details of my knee condition and addressed all my concerns. Thanks to Dr. Kau, I had a better understanding of my ACL and MCL injury and the various treatment options available. His advice and treatment have been very valuable to me.
Ming Lee Chua
Dr Kau was very careful and explained clearly the surgery procedures. After surgery, the care while I was in hospital was closely monitored and he even came during weekends! The hip so far has recovered and healed. His ‘predictions’ of when what can happen are so accurate. Trust him.
Teo Pek Suan Diana
I had a very successful total hip replacement done by Dr Kau 4 years ago. 4 months after the operation I was back walking, cycling and swimming. The beautiful job gave me much confidence Dr Kau is most professional and has such great doctor patient communication.

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    Frequently Asked Questions (FAQs)

    Can Hip Avascular Necrosis heal on its own?

    AVN is a progressive condition that typically does not heal on its own. It is characterised by the death of bone tissue due to a lack of blood supply, which, if left untreated, can lead to joint collapse and severe arthritis. Without proper treatment, AVN can lead to permanent joint damage and disability.

    Is exercise beneficial for someone with Hip AVN?

    Exercise can be beneficial for individuals with Hip AVN, especially during the early stages of the condition. Gentle, low-impact exercises, such as swimming or cycling, can help maintain joint mobility and muscle strength without exerting excessive pressure on the hip. Consult with your orthopaedic surgeon before starting any exercise regime.

    Can AVN affect other joints?

    While AVN most commonly affects the hip, it is not exclusive to this joint and can occur in other joints of the body. The shoulder, knee, and ankle are other commonly affected areas. Similar to the hip, AVN in these joints results from a reduced blood supply to the bone, leading to bone tissue death and potentially causing joint pain and impaired function.

    How long does it take to recover from AVN surgery?

    The recovery time following surgery for Hip AVN varies greatly depending on the type of surgery performed and the individual’s overall health and age. For less invasive procedures like core decompression, recovery may take a few weeks to a couple of months. More extensive surgeries such as total hip replacement may require several months of rehabilitation.

    How can I reduce my risk of developing Hip AVN?

    To lower the risk of Hip AVN, it is advised to moderate alcohol intake, use steroids judiciously, manage underlying health conditions affecting blood flow, and maintain a healthy lifestyle. These measures can contribute significantly to bone health and reduce AVN risk.